Publikationen

Fraunhofer-Institut für Graphische Datenverarbeitung IGD

Kaklanis, Nick; Tzovaras, Dimitrios; Biswas, Pradipta; Langdon, Pat; Mohamad, Yehya; Gonzalez, Mari Feli; Peissner, Matthias; Jung, Christoph
Towards Standardisation of User Models for Simulation and Adaptation Purposes
Kaklanis, Nick; Tzovaras, Dimitrios; Biswas, Pradipta; Langdon, Pat; Mohamad, Yehya; Gonzalez, Mari Feli; Peissner, Matthias; Jung, Christoph
Towards Standardisation of User Models for Simulation and Adaptation Purposes
Universal Access in the Information Society, Vol.15 (2016), 1, Article 15, pp. 21-48. Published online: 10 August 2014
ISSN: 1615-5297
ISSN: 1615-5289
The use of user models can be very valuable when trying to develop accessible and ergonomic products and services taking into account users' specific needs and preferences. Simulation of user-product interaction using user models may reveal accessibility issues at the early stages of design and development, and this results to a significant reduction in costs and development time. Moreover, user models can be used in adaptive interfaces enabling the personalised customisation of user interfaces that enhances the accessibility and usability of products and services. This paper presents the efforts of the Virtual User Modelling and Simulation Standardisation 'VUMS' cluster of projects towards the development of an interoperable user model, able to describe both able-bodied and people with various kinds of disabilities. The VUMS cluster is consisted by the VERITAS, MyUI, GUIDE, and VICON FP7 European projects, all involved in user modelling from different perspectives. The main goal of the VUMS cluster was the development of a unified user model that could be used by all the participant projects and that could be the basis of a new user model standard. Currently, within the VUMS cluster, a common user model has been defined and converters that enable the transformation from each project's specific user model to the VUMS user model and vice versa have been developed enabling, thus, the exchange of user models between the projects.
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Noll, Matthias; Nadolny, Anne; Wesarg, Stefan
Automated Kidney Detection for 3D Ultrasound Using Scan Line Searching
Noll, Matthias; Nadolny, Anne; Wesarg, Stefan
Automated Kidney Detection for 3D Ultrasound Using Scan Line Searching
The International Society for Optical Engineering (SPIE): Proceedings of SPIE, Article 9790-46, 6 p.
SPIE Medical Imaging Symposium <2016, San Diego, CA, USA>
Ultrasound (U/S) is a fast and non-expensive imaging modality that is used for the examination of various anatomical structures, e.g. the kidneys. One important task for automatic organ tracking or computer-aided diagnosis is the identification of the organ region. During this process the exact information about the transducer location and orientation is usually unavailable. This renders the implementation of such automatic methods exceedingly challenging. In this work we like to introduce a new automatic method for the detection of the kidney in 3D U/S images. This novel technique analyses the U/S image data along virtual scan lines. Here, characteristic texture changes when entering and leaving the symmetric tissue regions of the renal cortex are searched for. A subsequent feature accumulation along a second scan direction produces a 2D heat map of renal cortex candidates, from which the kidney location is extracted in two steps. First, the strongest candidate as well as its counterpart are extracted by heat map intensity ranking and renal cortex size analysis. This process exploits the heat map gap caused by the renal pelvis region. Substituting the renal pelvis detection with this combined cortex tissue feature increases the detection robustness. In contrast to model based methods that generate characteristic pattern matches, our method is simpler and therefore faster. An evaluation performed on 61 3D U/S data sets showed, that in 55 cases showing none or minor shadowing the kidney location could be correctly identified.
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Oyarzun Laura, Cristina; Oelmann, Simon; Drechsler, Klaus; Wesarg, Stefan
Reducing Over- and Undersegmentations of the Liver in Computed Tomographies Using Anatomical Knowledge
Oyarzun Laura, Cristina; Oelmann, Simon; Drechsler, Klaus; Wesarg, Stefan
Reducing Over- and Undersegmentations of the Liver in Computed Tomographies Using Anatomical Knowledge
Efthyvoulos, Kyriacou (Ed.) et al.: XIV Mediterranean Conference on Medical and Biological Engineering and Computing : MEDICON 2016. Berlin, Heidelberg, New York: Springer, 2016. (IFMBE Proceedings 57), pp. 382-387
Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON) <14, 2016, Paphos, Cyprus>
In the last decades several liver segmentation methods have been proposed. The proposed methods go from region growing to the more complex statistical shape models. Despite the robustness of those algorithms, liver segmentation is still a challenging task especially in areas in which its neighboring organs have similar intensities, e.g., heart and ribcage. In addition to this, pathological organs that contain tumors near their surface present additional difficulties. This paper presents a solution to increase the accuracy of those algorithms in the aforementioned areas. The effect of the improvement using the generated heart and ribcage walls (7% and 1% respectively) is evaluated on 9 clinical computer tomographies (CT). The improvement (12 %) when tumors are near the surface, on the contrary, is tested on 7 clinical CT images.
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Prinold, Joe A. I.; Mazzà, Claudia; Di Marco, Roberto; Hannah, Iain; Malattia, Clara; Magni-Manzoni, Silvia; Petrarca, Maurizio; Ronchetti, Anna B.; Tanturri De Horatio, Laura; van Dijkhuizen, Pieter E.H.; Wesarg, Stefan; Viceconti, Marco
A Patient-Specific Foot Model for the Estimate of Ankle Joint Forces in Patients with Juvenile Idiopathic Arthritis
Prinold, Joe A. I.; Mazzà, Claudia; Di Marco, Roberto; Hannah, Iain; Malattia, Clara; Magni-Manzoni, Silvia; Petrarca, Maurizio; Ronchetti, Anna B.; Tanturri De Horatio, Laura; van Dijkhuizen, Pieter E.H.; Wesarg, Stefan; Viceconti, Marco
A Patient-Specific Foot Model for the Estimate of Ankle Joint Forces in Patients with Juvenile Idiopathic Arthritis
Annals of Biomedical Engineering, Vol.44 (2016), 1, pp. 247-257. First online: 15 September 2015
Juvenile idiopathic arthritis (JIA) is the leading cause of childhood disability from a musculoskeletal disorder. It generally affects large joints such as the knee and the ankle, often causing structural damage. Different factors contribute to the damage onset, including altered joint loading and other mechanical factors, associated with pain and inflammation. The prediction of patients' joint loading can hence be a valuable tool in understanding the disease mechanisms involved in structural damage progression. A number of lower-limb musculoskeletal models have been proposed to analyse the hip and knee joints, but juvenile models of the foot are still lacking. This paper presents a modelling pipeline that allows the creation of juvenile patient-specific models starting from lower limb kinematics and foot and ankle MRI data. This pipeline has been applied to data from three children with JIA and the importance of patient-specific parameters and modelling assumptions has been tested in a sensitivity analysis focused on the variation of the joint reaction forces. This analysis highlighted the criticality of patient-specific definition of the ankle joint axes and location of the Achilles tendon insertions. Patient-specific detection of the Tibialis Anterior, Tibialis Posterior, and Peroneus Longus origins and insertions were also shown to be important.
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Appelhans,Lukas; Sakas, Georgios (Betreuer); Jung, Florian (Betreuer)
Adaptive Voxel-based Classifier for Semi-automatic Segmentation of Tumors in the Head and Neck Area Based on T2-Weighted MRI Image Data
Appelhans,Lukas; Sakas, Georgios (Betreuer); Jung, Florian (Betreuer)
Adaptive Voxel-based Classifier for Semi-automatic Segmentation of Tumors in the Head and Neck Area Based on T2-Weighted MRI Image Data
Darmstadt, TU, Bachelor Thesis, 2015
Measuring the size and location of a tumor is a major part of cancer staging and thus also crucial to plan treatment and predict the success chances of the same. Both properties can be extracted from a segmentation. We present a new method for semi-automatic segmentation of tumors in the head and neck area using MR images. The new method incorporates known segmentations that were manually created by medical doctors. Other than that the only user interaction needed is setting a seed point. After the seed point and an input image are entered, the algorithm starts by searching for a similar one in the database. The underlying assumption is that the intensities of a tumor in two comparable images also have comparable values. Using histograms for both the database image as well as the manual segmentation of it, the intensities that are likely to be featured in the tumor are calculated. After creating a basic segmentation, the actual tumor is extracted using opening, closing and a connected threshold filter. The algorithm was developed using five datasets of T2-weighted MR images with a leave-one-out cross validation technique. When comparing the generated tumor segmentations with the manual ones, they had a DSC in the range of 0.41 and 0.77, with an average of 0.60. Furthermore the new method was also tested on lymph nodes. Further suggestions for improvements are given.
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Fuchs, Roland; Oyarzun Laura, Cristina (Betreuer)
Automatisierte Segmentierung von Strukturen im Bereich der Nasennebenhöhlen auf Basis von CT-Daten
Fuchs, Roland; Oyarzun Laura, Cristina (Betreuer)
Automatisierte Segmentierung von Strukturen im Bereich der Nasennebenhöhlen auf Basis von CT-Daten
Darmstadt, Hochschule, Bachelor Thesis, 2015
Die vorliegende Arbeit setzt sich mit dem Problem der automatisierten Segmentierung von Strukturen im Bereich der Nasennebenhöhlen auf Basis von computertomographischen Bilddaten auseinander. Diese medizinischen Bilddaten enthalten anatomische Informationen, deren Extraktion, gerade im dreidimensionalen, nur aufwändig durchführbar ist. Da die bisherigen Methoden zur Segmentierung im Nasen/-nebenhöhlenbereich entweder viel Zeit in Anspruch nehmen oder einen Mangel an Genauigkeit aufweisen, wird in dieser Arbeit versucht, über das Konzept des artikulierten Atlas ein Verfahren zu entwickeln, das in der Lage ist, die zeitaufwendige manuelle Segmentierung größtenteils zu ersetzen. Dafür wird ein Modell des Zielbereichs erstellt und dieses zur darauffolgenden Struktursegmentierung in einem Zieldatensatz angepasst. Die Hindernisse, die sich durch die markanten Unterschiede der Datensätze in Form und Größe stellen, konnten durch eine dynamische Adaption mit zielgerichteter Initialisierung überwunden werden. Insgesamt lässt sich die vorgestellte Methode als ein Fortschritt hinsichtlich der Segmentierung im Nasen/-nebenhöhlenbereich betrachten, da für den Zielbereich mit geringem Zeitaufwand der Methode und zusätzlicher Nachbereitung eine zufriedenstellende Struktursegmentierung erstellt werden kann, und somit das Ziel der Arbeit erreicht wurde. Zusätzlich ist das neue Verfahren generisch und kann mit geringen Adaptionen auch für Fragestellungen jenseits des Nasennebenhöhlenbereichs eingesetzt werden.
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Jung, Florian; Hilpert, Julia; Wesarg, Stefan
Segmentierung von zervikalen Lymphknoten in T1-gewichteten MRT-Aufnahmen
Jung, Florian; Hilpert, Julia; Wesarg, Stefan
Segmentierung von zervikalen Lymphknoten in T1-gewichteten MRT-Aufnahmen
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2015 : Algorithmen - Systeme - Anwendungen. Proceedings des Workshops. Berlin; Heidelberg; New York: Springer, 2015. (Informatik aktuell), pp. 353-358
Workshop Bildverarbeitung für die Medizin (BVM) <18, 2015, Lübeck, Germany>
Die Untersuchung von Größe und Aussehen eines Lymphknotens kann ein entscheidender Indikator für die Existenz eines Tumors sein und ist außerdem ein probates Mittel, um Verlaufsanalysen bei einem Patienten durchzuführen, welche wiederum maßgeblichen Einfluss auf die Behandlung haben können. Um die Größe und andere Parameter des Lymphknotens bestimmen zu können, ist zuerst eine Segmentierung vonnöten. Wir präsentieren ein neues Verfahren für die halbautomatische Segmentierung von Lymphknoten auf MR-Datensätzen. Unser Ansatz verwendet eine Wasserscheidentransformation als Grundlage und kombiniert diese mit einem Radialstrahlbasierten Verfahren, um eine möglichst akkurate Segmentierung des Lymphknotens zu erhalten. Für die Evaluation wurden 95 Lymphknoten-Segmentierungen aus 17 verschiedenen, kontrastverstärkten T1-gewichteten Patientendatensätzen verwendet. Das durchschnittliche Dice Ähnlichkeitsmaß lag bei 0.69}0.15 und die mittlere Oberflächendistanz bei 0.65}0.54mm.
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Kalali Emghani, Amir; Sakas, Georgios (Betreuer); Jung, Florian (Betreuer)
Vertebrae Detection in Head and Neck MRI Images Using a Particle Filter Method Based on Image Features.
Kalali Emghani, Amir; Sakas, Georgios (Betreuer); Jung, Florian (Betreuer)
Vertebrae Detection in Head and Neck MRI Images Using a Particle Filter Method Based on Image Features.
Darmstadt, TU, Master Thesis, 2015
Detection of the human spine in MRI scans is a frequently used task in medical image analysis for the diagnosis of spinal conditions and diseases. MRI scans provide important information about relevant soft tissue. However, manual detection of vertebrae is an elaborate and error-prone process. This work aims at the development and evaluation of a semi-automatic method for vertebrae detection in head and neck MRI images. The goal is to correctly position an available articulated atlas that consists of statistical shape models of bones. The presented approach is based on a probabilistic graphical model for modeling the structure of the vertebral column. A particle filter is used to define the position of vertebral bodies in relation to previously detected vertebral bodies. Two models are used to model the geometric constraints of the position, the size and the orientation of the vertebral bodies on the one hand and to describe the vertebral body appearance with extracted image features on the other hand. The advantage of this approach is the probabilistic analysis of potential vertebral bodies: It does neither depend on exact prior knowledge about the anatomical structure of the vertebral column nor any training data to learn the image features is needed. The presented approach is tested and the vertebrae detection results are evaluated on 22 MRI scans. The MRI scans are T1-weighted sagittal 2D slices. Subsequently the method is used to initially position the articulated atlas in the MRI images for further processing. Visual inspections show a noticeable improvement of the initial position of the atlas compared to the approach used so far.
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Nadolny, Anne; Noll, Matthias (Betreuer)
Strahlenbasierte Segmentierung der Niere in 3D Ultraschall Daten
Nadolny, Anne; Noll, Matthias (Betreuer)
Strahlenbasierte Segmentierung der Niere in 3D Ultraschall Daten
Brandenburg/Havel, FH, Master Thesis, 2015
Im Verlauf dieser Arbeit wird ein Verfahren zur vollautomatischen Segmentierung der Niere in 3D Ultraschalldaten entwickelt und die Ergebnisse präsentiert. Dafür wird zu Beginn Hintergrundwissen zusammengetragen und der Stand der Technik ermittelt. Anschließend erfolgt eine umfangreiche Vorverarbeitung der Daten, welche die Grundlage für die Detektion und Segmentierung der Niere bildet. Für diese wird auf strahlenbasierte Verfahren zurückgegriffen. Derartige Verfahren wurden bereits auf CT und MRT Daten erfolgreich für Segmentierungen verwendet und sollen nun auf ihre Übertragung auf Ultraschalldaten geprüft werden. Abschließend erfolgt eine Evaluation der Ergebnisse sowie eine Problemdefinition. Zudem werden mögliche Weiterentwicklungen vorgestellt.
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Oelmann, Simon; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Active Contour based Segmentation of Resected Livers in CT Images
Oelmann, Simon; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Active Contour based Segmentation of Resected Livers in CT Images
Ourselin, Sébastien (Ed.) et al.: Medical Imaging 2015: Image Processing. Bellingham: SPIE Press, 2015. (Proceedings of SPIE 9413), pp. 941316-1 - 941316-6
SPIE Medical Imaging Symposium <2015, Orlando, FL, USA>
The majority of state of the art segmentation algorithms are able to give proper results in healthy organs but not in pathological ones. However, many clinical applications require an accurate segmentation of pathological organs. The determination of the target boundaries for radiotherapy or liver volumetry calculations are examples of this. Volumetry measurements are of special interest after tumor resection for follow up of liver regrow. The segmentation of resected livers presents additional challenges that were not addressed by state of the art algorithms. This paper presents a snakes based algorithm specially developed for the segmentation of resected livers. The algorithm is enhanced with a novel dynamic smoothing technique that allows the active contour to propagate with different speeds depending on the intensities visible in its neighborhood. The algorithm is evaluated in 6 clinical CT images as well as 18 artificial datasets generated from additional clinical CT images.
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Oyarzun Laura, Cristina; Fellner, Dieter W.; Sakas, Georgios; Bale, Reto
Graph-matching and FEM-based Registration of Computed Tomographies for Outcome Validation of Liver Interventions
Oyarzun Laura, Cristina; Fellner, Dieter W.; Sakas, Georgios; Bale, Reto
Graph-matching and FEM-based Registration of Computed Tomographies for Outcome Validation of Liver Interventions
Liver cancer is one of the leading causes of death worldwide. One of the reasons for that is the high tumor recurrence rate. The only way to reduce the recurrence rate is to ensure that all carcinogenic cells are destroyed after intervention. Unfortunately, the information available to assess the outcome of an intervention is limited. In the clinical routine, a pair of pre- and post-operatively gathered computed tomographies (CT) of the abdomen are typically compared to decide whether the patient needs further treatment. However, the post-operative liver will be deformed due to breathing and intervention which will complicate the comparison task by simple inspection of both images. The results presented in this thesis will support the physician during the outcome validation process after minimally invasive interventions and open liver surgeries. Therefore, the physician is provided with qualitative measures and visualizations that support him in the decision making task. The basis of a reliable outcome validation is an accurate non-rigid registration method. This thesis proposes to combine internal correspondences at vessel ramifications and landmarks at the surface of the organ to increase the accuracy of the registration results. The internal correspondences are the result of a novel efficient and fully automatic graph matching method. Landmarks at the surface of the liver are given by a method that detects the organs that are adjacent to it at each surface point. Both types of landmarks are incorporated in a FEM-based registration. The registration method has been tested in 25 pairs of pre- and post-operative clinical CT images achieving an average accuracy of 1.22 mm and a positive predictive value of 0.95. In consequence of the accuracy obtained with the proposed methods the physician is able to determine with certainty if the outcome of the intervention was satisfactory. Hence, he can without delay decide to re-treat the patient if needed to remove the remnant tumor. This fast response could at the end reduce the tumor recurrence rate.
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Wang, Anqi; Noll, Matthias; Wesarg, Stefan
Tumorsegmentierung in CD3/CD8-gefärbten Histopathologien
Wang, Anqi; Noll, Matthias; Wesarg, Stefan
Tumorsegmentierung in CD3/CD8-gefärbten Histopathologien
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2015 : Algorithmen - Systeme - Anwendungen. Proceedings des Workshops. Berlin; Heidelberg; New York: Springer, 2015. (Informatik aktuell), pp. 347-352
Workshop Bildverarbeitung für die Medizin (BVM) <18, 2015, Lübeck, Germany>
Segmentierung von bestimmten Gewebetypen in Histopathologien ist eine oft untersuchte Fragestellung. Üblicherweise werden dafür Gewebeproben mit Hämatoxylin-Eosin(HE)-Färbung verwendet. CD3/CD8-F¨arbungen hingegen sind nötig zur Sichtbarmachung von Immunzellen, differenzieren aber nur wenig zwischen unterschiedlichen Gewebearten. Vorteilhaft wäre es, wenn aus nur einem Gewebeschnitt mit einer bestimmten Färbung beide Informationen extrahiert werden könnten. In dieser Arbeit stellen wir ein Segmentierungsverfahren auf CD3/CD8-gef¨arbten Gewebeproben vor, das effizient zu berechnende und gleichzeitig aussagekräftige Features als Eingabe für einen Clustering- Algorithmus verwendet. In der Evaluation wird ein durchschnittlicher Accuracy-Wert von 94,44% erzielt. Dieser Wert ist vergleichbar mit den Ergebnissen verwandter State of the Art Methoden, die HE-gefärbte Proben einsetzen.
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Wichmann, Julian L.; Booz, Christian; Wesarg, Stefan; Bauer, Ralf W.; Kerl, J. Matthias; Fischer, Sebastian; Lehnert, Thomas; Vogl, Thomas J.; Khan, M. Fawad; Kafchitsas, Konstantinos
Quantitative Dual-energy CT for Phantomless Evaluation of Cancellous Bone Mineral Density of the Vertebral Pedicle: Correlation with Pedicle Screw Pull-out Strength
Wichmann, Julian L.; Booz, Christian; Wesarg, Stefan; Bauer, Ralf W.; Kerl, J. Matthias; Fischer, Sebastian; Lehnert, Thomas; Vogl, Thomas J.; Khan, M. Fawad; Kafchitsas, Konstantinos
Quantitative Dual-energy CT for Phantomless Evaluation of Cancellous Bone Mineral Density of the Vertebral Pedicle: Correlation with Pedicle Screw Pull-out Strength
European Radiology, Vol.25 (2015), 6, pp. 1714-1720. Published online 07. December 2014
Objectives: To evaluate quantitative dual-energy computed tomography (DECT) for phantomless analysis of cancellous bone mineral density (BMD) of vertebral pedicles and to assess the correlation with pedicle screw pull-out strength. Methods: Twenty-nine thoracic and lumbar vertebrae from cadaver specimens were examined with DECT. Using dedicated post-processing software, a pedicle screw vector was mapped (R1, intrapedicular segment of the pedicle vector; R2, intermediate segment; R3, intracorporal segment; global, all segments) and BMD was calculated. To invasively evaluate pedicle stability, pedicle screws were drilled through both pedicles and left pedicle screw pull-out strength was measured. Resulting values were correlated using the paired t test and Pearson's linear correlation. Results: Average pedicle screw vector BMD (R1, 0.232 g/cm3; R2, 0.166 g/cm3; R3, 0.173 g/cm3; global, 0.236 g/cm3) showed significant differences between R1-R2 (P<0.002) and R1-R3 (P<0.034) segments while comparison of R2-R3 did not reach significance (P>0.668). Average screw pull-out strength (639.2 N) showed a far stronger correlation with R1 (r=0.80; P<0.0001) than global BMD (r=0.42; P=0.025), R2 (r=0.37; P=0.048) and R3 (r=0.33; P=0.078) segments. Conclusions: Quantitative DECT allows for phantomless BMD assessment of the vertebral pedicle. BMD of the intrapedicular segment shows a significantly stronger correlation with pedicle screw pull-out strength than other segments.
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Becker, Meike; Hansen, Stefan; Wesarg, Stefan; Sakas, Georgios
Path Planning for Multi-port Lateral Skull Base Surgery Based on First Clinical Experiences
Becker, Meike; Hansen, Stefan; Wesarg, Stefan; Sakas, Georgios
Path Planning for Multi-port Lateral Skull Base Surgery Based on First Clinical Experiences
Erdt, Marius (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8361), pp. 23-30
International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>
Our research project investigates a multi-port minimally-traumatic approach for lateral skull base surgery, where the surgical target shall be reached through up to three drill canals. For this purpose, an accurate path planning is crucial. In the present work, we propose a semiautomatic path planning approach for multi-port minimally-traumatic lateral skull base surgery. The best path combinations are automatically determined by optimizing the angles and distance buffers of the drill canals. We compare the automatically computed path combinations for 20 data sets to those selected manually by two different clinicians. The experiments prove that we can adequately reproduce the clinicians' choice.
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Drechsler, Klaus; Knaub, Anton; Oyarzun Laura, Cristina; Wesarg, Stefan
Liver Segmentation in Contrast Enhanced MR Datasets Using a Probabilistic Active Shape and Appearance Model
Drechsler, Klaus; Knaub, Anton; Oyarzun Laura, Cristina; Wesarg, Stefan
Liver Segmentation in Contrast Enhanced MR Datasets Using a Probabilistic Active Shape and Appearance Model
IEEE Computer Society: IEEE 27th International Symposium on Computer-Based Medical Systems : CBMS 2014. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2014, pp. 523-524
IEEE Symposium on Computer-Based Medical Systems (CBMS) <27, 2014, New York, NY, USA>
The current standard for diagnosing liver tumors is contrast-enhanced multiphase computed tomography. On this basis, several software tools have been developed by different research groups worldwide to support physicians for example in measuring remnant liver volume, analyzing tumors, and planning resections. Several algorithms have been developed to perform these tasks. Most of the time, the segmentation of the liver is at the beginning of the processing chain. Therefore, a vast amount of CT-based liver segmentation algorithms have been developed. However, clinics slowly move from CT as the current gold standard for diagnosing liver diseases towards magnetic resonance imaging. In this work, we utilize a Probabilistic Active Shape Model with an MR specific preprocessing and appearance model to segment the liver in contrast enhanced MR images. Evaluation is based on 8 clinical datasets.
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Erdt, Marius; Linguraru, Marius George; Oyarzun Laura, Cristina; Shekhar, Raj; Wesarg, Stefan; González Ballester, Miguel Angel; Drechsler, Klaus
Clinical Image-Based Procedures. Translational Research in Medical Imaging: Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013
Erdt, Marius; Linguraru, Marius George; Oyarzun Laura, Cristina; Shekhar, Raj; Wesarg, Stefan; González Ballester, Miguel Angel; Drechsler, Klaus
Clinical Image-Based Procedures. Translational Research in Medical Imaging: Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013
International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>
Lecture Notes in Computer Science (LNCS) 8361
ISSN: 0302-9743
ISBN: 9783319056654
This book constitutes revised selected papers from the International Workshop on Clinical Image-Based Procedures, CLIP 2013, held in conjunction with MICCAI 2012 in Nagoya, Japan, in September 2013. The 19 papers presented in this volume were carefully reviewed and selected from 26 submissions. The workshop was a productive and exciting forum for the discussion and dissemination of clinically tested, state-of-the-art methods for image-based planning, monitoring and evaluation of medical procedures.
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Gollmer, Sebastian T.; Kirschner, Matthias; Buzug, Thorsten M.; Wesarg, Stefan
Using Image Segmentation for Evaluating 3D Statistical Shape Models Built With Groupwise Correspondence Optimization
Gollmer, Sebastian T.; Kirschner, Matthias; Buzug, Thorsten M.; Wesarg, Stefan
Using Image Segmentation for Evaluating 3D Statistical Shape Models Built With Groupwise Correspondence Optimization
Computer Vision and Image Understanding, Vol.125 (2014), pp. 283-303
Statistical shape models (SSMs) are a well-established tool in medical image analysis. The most challenging part of SSM construction, which cannot be solved trivially in 3D, is the establishment of corresponding points, so-called landmarks. A popular approach for solving the correspondence problem is to minimize a groupwise objective function using the optimization by re-parameterization approach. To this end, several objective functions, optimization strategies and re-parameterization functions have been proposed. While previous evaluation studies focused mainly on the objective function, we provide a detailed evaluation of different correspondence methods, objective functions, re-parameterization, and optimization strategies. Moreover and contrary to previous works, we use distance measures that compare landmark shape vectors to the original input shapes, thus adequately accounting for correspondences which undersample certain regions of the input shapes. Additionally, we segment binary expert segmentations to benchmark SSMs constructed from different correspondences. This new evaluation technique overcomes limitations of the correspondence based evaluation and allows for directly quantifying the influence of the correspondence on the expected segmentation accuracy. From our evaluation results we identify pitfalls of the current approach and derive practical recommendations for implementing a groupwise optimization pipeline.
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Hammon, Matthias; Cavallaro, Alexander; Erdt, Marius; Dankerl, Peter; Kirschner, Matthias; Drechsler, Klaus; Wesarg, Stefan; Uder, Michael; Janka, Rolf
Model-Based Pancreas Segmentation in Portal Venous Phase Contrast-Enhanced CT Images
Hammon, Matthias; Cavallaro, Alexander; Erdt, Marius; Dankerl, Peter; Kirschner, Matthias; Drechsler, Klaus; Wesarg, Stefan; Uder, Michael; Janka, Rolf
Model-Based Pancreas Segmentation in Portal Venous Phase Contrast-Enhanced CT Images
Journal of Digital Imaging, Vol.26 (2014), 6, pp. 1082-1090. First published online 08 March 2013
This study aims to automatically detect and segment the pancreas in portal venous phase contrast-enhanced computed tomography (CT) images. The institutional review board of the University of Erlangen-Nuremberg approved this study and waived the need for informed consent. Discriminative learning is used to build a pancreas tissue classifier incorporating spatial relationships between the pancreas and surrounding organs and vessels. Furthermore, discrete cosine and wavelet transforms are used to build texture features to describe local tissue appearance. Classification is used to guide a constrained statistical shape model to fit the data. The algorithm to detect and segment the pancreas was evaluated on 40 consecutive CT data that were acquired in the portal venous contrast agent phase. Manual segmentation of the pancreas was carried out by experienced radiologists and served as reference standard. Threefold cross validation was performed. The algorithm-based detection and segmentation yielded an average surface distance of 1.7 mm and an average overlap of 61.2 % compared with the reference standard. The overall runtime of the system was 20.4 min. The presented novel approach enables automatic pancreas segmentation in portal venous phase contrast-enhanced CT images which are included in almost every clinical routine abdominal CT examination. Reliable pancreatic segmentation is crucial for computer-aided detection systems and an organ-specific decision support.
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Hilpert, Julia; Jung, Florian (Betreuer)
Halbautomatische Segmentierung von Lymphknoten aus Magnetresonanztomographiedaten des Kopf- und Halsbereichs
Hilpert, Julia; Jung, Florian (Betreuer)
Halbautomatische Segmentierung von Lymphknoten aus Magnetresonanztomographiedaten des Kopf- und Halsbereichs
Mannheim, Hochschule, Bachelor Thesis, 2014
Die Größe und das Aussehen von Lymphknoten kann bei Krebspatienten Aufschluss über die Streuung eines Tumors geben. Deshalb ist ihre Vermessung bei der Behandlung sowie Nachsorge von großer Bedeutung. Der erste Schritt ist hierbei die Segmentierung der Lymphknoten. Bisher sind jedoch nur wenige Ansätze zur automatisierten Segmentierung von Lymphknoten auf MRT-Daten bekannt. In dieser Arbeit wird deshalb ein Verfahren vorgestellt, welches Lymphknoten aus MRT-Daten des Kopf- und Halsbereichs segmentiert. Diese Segmentierung findet mit minimaler Nutzerinteraktion, nur durch Setzen eines Punktes innerhalb des Lymphknotengewebes, statt. Die Hauptkomponente der gewählten Methode zur Segmentierung ist eine Wasserscheidentransformation, die das Bild über seine Gradienten in verschiedene Segmente einteilt. Mittels eines Radialstrahlverfahrens wird zusätzlich die Oberfläche des Lymphknotens angenähert. Diese Oberfläche dient nach weiteren, untergeordneten Verarbeitungsschritten dazu, aus der Menge der Bildsegmente jene auszuwählen, die den Lymphknoten repräsentieren. Evaluiert wurde das entwickelte Verfahren an 95 Lymphknoten aus 17 verschiedenen, T1- gewichteten MRT-Datensätzen. Es ergab sich ein durchschnittlicher Dice Similarity Coefficient von 0,69±0,15. Auf dem Weg zu einer vollautomatischen Segmentierung von Lymphknoten stellt das entwickelte Verfahren somit einen vielversprechenden ersten Schritt dar.
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Hoßbach, Martin; Sakas, Georgios; Fellner, Dieter W.
Integrierte miniaturisierte Kameras zur Instrument- und Zielfindung in medizinischen Anwendungen
Hoßbach, Martin; Sakas, Georgios; Fellner, Dieter W.
Integrierte miniaturisierte Kameras zur Instrument- und Zielfindung in medizinischen Anwendungen
Im Bereich der Mikroelektronik hat in den vergangenen Jahrzehnten eine rasante technische und technologische Entwicklung stattgefunden, die neben den offensichtlichen Auswirkungen auf das tägliche Leben auch die Werkzeuge der Ärzte beeinflusst hat. Ein Beispiel dafür sind Trackingverfahren, die vielfältig und erfolgreich in der Medizin Anwendung finden und eine Reihe von neuen Behandlungstechniken ermöglicht haben. In medizinischen Anwendungen kommen verschiedenste Trackingsysteme zum Einsatz. Häufig sind es magnetische und optische Trackingsysteme. Beide haben im OP-Umfeld Nachteile: magnetische Trackingsysteme reagieren empfindlich auf Metalle, die im OP häufig vorkommen; optische Trackingsysteme sind wegen der Line-of-Sight-Problematik im OP umständlich zu benutzen. Allgemein sind diese Systeme häufig teuer in der Anschaffung und rechtfertigen bisweilen, verglichen mit den Kosten des jeweiligen Eingriffs, ihren Einsatz nicht. Demgegenüber steht der aktuelle Trend der Miniaturisierung. Kameras werden derzeit immer kleiner und preiswerter. Es wird daher die These aufgestellt, dass die Nachteile von bisherigen Trackingsystemen in bestimmten medizinischen Anwendungen durch die Verwendung miniaturisierter Kameras ausgeglichen werden können, weil diese deutlich dichter am Ort des Geschehens positioniert werden können. Dadurch fällt auch eine unter Umständen schlechtere Bildqualität (im Vergleich zu präzisen Trackingkameras) nicht ins Gewicht. Diese These wird exemplarisch an zwei Anwendungen untersucht. Es wird ein MRT-kompatibles optisches Kopftrackingsystem entwickelt, das die Kopfbewegung eines Patienten mit Hilfe von runden, planaren, einfarbigen Markern auf der Stirn des Patienten verfolgt. Dafür werden Kameras verwendet, die im Innern des Tomografen mit einer Halterung an der Kopfspule befestigt werden. Algorithmen, die in Infrarot-Trackingsystemen Verwendung finden, mussten wegen der Bildqualität der Kameras, den klinischen Anforderungen (Belästigung des Patienten und Belastung des Personals) und den Gegebenheiten im MR-Tomograf teilweise angepasst werden. Für dieses Trackingsystem wurde ein Kreuzkalibrierverfahren entwickelt, das aus wassergefüllten Kugeln ein virtuelles Kalibrierphantom bildet. Es unterscheidet sich damit von bekannten Verfahren, bei denen bei der Kreuzkalibrierung die verwendeten Strukturen, die im MRT-Bild sichtbar sind, und die Strukturen, die im Kamerabild sichtbar sind, unterschiedlich sind. Entsprechende Kalibrierphantome müssen also aufwändig hergestellt oder präzise vermessen werden. Das Trackingsystem wurde theoretisch, praktisch im Labor und klinisch im Probandenversuch evaluiert. Im Rahmen eines klinischen Projektes, bei dem über einen sehr langen Zeitraum wiederholt MRTAufnahmen mit niedriger Auflösung gemacht wurden, konnte mit dem Trackingsystem eine virtuelle Immobilisation erreicht werden. Weiterhin wurde ein Navigationssystem für die ultraschallgesteuerte Punktion entwickelt. Der Arzt wird dabei durch die Visualisierung des Verlaufs der Nadel im Ultraschallbild bei der Punktion unterstützt. Dafür wurde ein Nadeltrackingsystem entwickelt, das aus zwei preiswerten Kameras besteht, die am Schallkopf befestigt sind. Aus den Bildern der Kameras wird kantenbasiert die Nadel extrahiert, ihr Verlauf relativ zum Ultraschallkopf ermittelt, und Verlauf und Schnittpunkt der Nadel mit dem Ultraschallbild dargestellt. Das Navigationssystem wurde sowohl theoretisch als auch praktisch im Labor am Phantom evaluiert. Daran waren Ärzte beteiligt, die entsprechende Eingriffe in ihrem Arbeitsalltag durchführen. Es konnte gezeigt werden, dass die Genauigkeit gegenüber dem Stand der Technik verbessert werden konnte.
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Jung, Florian; Steger, Sebastian; Knapp, Oliver; Noll, Matthias; Wesarg, Stefan
COSMO - Coupled Shape Model for Radiation Therapy Planning of Head and Neck Cancer
Jung, Florian; Steger, Sebastian; Knapp, Oliver; Noll, Matthias; Wesarg, Stefan
COSMO - Coupled Shape Model for Radiation Therapy Planning of Head and Neck Cancer
Linguraru, Marius George (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Third International Workshop, CLIP 2014. Held in Conjunction with MICCAI 2014. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8680), pp. 25-32
International Workshop on Clinical Image-based Procedures (CLIP) <3, 2014, Boston, MA, USA>
Radiation therapy plays a major role in head and neck cancer treatment. Segmentation of organs at risk prior to the radiation therapy helps to prevent the radiation beam from damaging healthy tissue, whereas a concentrated ray can target the cancerous regions. Unfortunately, the manual annotation of all relevant structures in the head and neck area is very time-consuming and existing atlas-based solutions don't provide sufficient segmentation accuracy. Therefore, we propose a coupled shape model (CoSMo) for the segmentation of key structures within the head and neck area. The model's adaptation to a test image is done with respect to the appearance of its items and the trained articulation space. 40 data sets labeled by clinicians containing 22 structures were used to build the CoSMo. Even on very challenging data sets with unnatural postures, which occur far more often than expected, the model adaptation algorithm succeeds. A first evaluation showed an average directed Hausdorff distance of 13.22mm and an average DICE overlap of 0.62. Furthermore, we review some of the challenges we encountered during the course of building our model from image data, taken from actual radiation therapy planing cases.
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Knaub, Anton; Drechsler, Klaus (Betreuer)
Entwicklung eines Appearance Models zur modellbasierten Lebersegmentierung in MRT-Daten
Knaub, Anton; Drechsler, Klaus (Betreuer)
Entwicklung eines Appearance Models zur modellbasierten Lebersegmentierung in MRT-Daten
Darmstadt, Hochschule, Bachelor Thesis, 2014
Der Standard der Diagnostizierung von Lebertumoren in der Radiologie ist bis heute die Computertomographie (CT). Auf Basis dieser Daten wurden zahlreiche Segmentierungsverfahren entwickelt und erfolgreich für die automatisierte Diagnose und Planung von Interventionen eingesetzt. Die Gefahr bei CT besteht darin, dass der Patient einer erhöhten Strahlungsdosis ausgesetzt wird. Dies ist einer der Gründe, weswegen die Magnetresonanztomographie (MRT) verstärkt von Radiologen zur Diagnose eingesetzt wird. Es gibt viele Ansätze zur Segmentierung von Organen wie der Leber. Besonders gute Ergebnisse wurden mit modellbasierten Ansätzen für die automatische Segmentierung der Leber in CT-Daten entwickelt. Auf den Wunsch der Radiologen soll auch eine Lebersegmentierung auf MRT-Daten ermöglicht werden. Aus diesem Grund wird in dieser Arbeit ein bestehendes modellbasierendes Verfahren, das Probabilistic Active Shape Model von Matthias Kirschner, aufgegriffen und um ein Appearance Model für MRT-Daten erweitert und somit eine Lebersegmentierung auf MRT-Daten ermöglicht. Dazu wird eine geeignete Vorverarbeitungspipeline für MRT-Lebern gewählt. Des Weiteren werden verschiedene Trainingsmethoden des Appearance Models untersucht und die geeignetste selektiert und evaluiert. Die Ergebnisse der Evaluation der Segmentierung auf acht kontrastinjizierten Lebern liefern einen durchschnittlichen Volumenüberlappungsfehler von 13,37 % bei einer durchschnittlichen Oberflächendistanz von 2,39 mm.
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Liang, Rong-Hao; Chan, Liwei; Tseng, Hung-Yu; Kuo, Han-Chih; Huang, Da-Yuan; Yang, De-Nian; Chen, Bing-Yu; Große-Puppendahl, Tobias; Beck, Sebastian; Wilbers, Daniel; Kuijper, Arjan; Heo, Heejeong; Park, Hyungkun; Kim, Seungki; Chung, Jeeyong; Lee, Geehyuk; Lee, Woohun; Unander-Scharin, Carl; Unander-Scharin, Aasa; Höök, Kristina; Elblaus, Ludvig
Demo Hour
Liang, Rong-Hao; Chan, Liwei; Tseng, Hung-Yu; Kuo, Han-Chih; Huang, Da-Yuan; Yang, De-Nian; Chen, Bing-Yu; Große-Puppendahl, Tobias; Beck, Sebastian; Wilbers, Daniel; Kuijper, Arjan; Heo, Heejeong; Park, Hyungkun; Kim, Seungki; Chung, Jeeyong; Lee, Geehyuk; Lee, Woohun; Unander-Scharin, Carl; Unander-Scharin, Aasa; Höök, Kristina; Elblaus, Ludvig
Demo Hour
Interactions, Vol.21 (2014), 5, pp.6-9
Conference on Human Factors in Computing Systems (CHI) <32, 2014, Toronto,Canada>
Interactivity is a unique forum of the ACM CHI Conference that showcases hands-on demonstrations, novel interactive technologies, and artistic installations. At CHI 2014, we aimed to create a "one of a CHInd" Interactivity experience with more than 60 interactive exhibits to highlight the diverse group of computer scientists, sociologists, designers, psychologists, artists, and many more that make up the CHI community.
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Linguraru, Marius George; Oyarzun Laura, Cristina; Shekhar, Raj; Wesarg, Stefan; González Ballester, Miguel Angel; Drechsler, Klaus; Sato, Yoshinobu; Erdt, Marius
Clinical Image-Based Procedures. Translational Research in Medical Imaging: Third International Workshop, CLIP 2014. Held in Conjunction with MICCAI 2014
Linguraru, Marius George; Oyarzun Laura, Cristina; Shekhar, Raj; Wesarg, Stefan; González Ballester, Miguel Angel; Drechsler, Klaus; Sato, Yoshinobu; Erdt, Marius
Clinical Image-Based Procedures. Translational Research in Medical Imaging: Third International Workshop, CLIP 2014. Held in Conjunction with MICCAI 2014
International Workshop on Clinical Image-based Procedures (CLIP) <3, 2014, Boston, MA, USA>
Lecture Notes in Computer Science (LNCS) 8680
ISSN: 0302-9743
ISBN: 9783319139081
CLIP 2014 provided a successful forum for the dissemination of emerging image-based clinical techniques. Specific topics included pre-interventional image segmentation and classification (to support diagnosis and clinical decision making), interventional and surgical planning and analysis of dynamic images, and evaluation, visualization and correction techniques for image-based procedures. Clinical applications covered the skull and the brain, cardiac defects, blood vessels, abdominal organs, and cancer in adults and children. The presentations and discussions around the meeting emphasized current challenges and emerging techniques in image-based procedures, strategies for clinical translation of image-based techniques, the role of computational anatomy and image analysis for surgical planning and interventions, and the contribution of medical image analysis to open and minimally invasive surgery.
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Martinelli, Elena; Poli, Tito; Exarchos, Konstantinos; Steger, Sebastian
Multilevel and Multiscale Modeling Approach for VPH-Based Prediction of Oral Cancer Reoccurrences. Results of the FP7 NeoMark Project
Martinelli, Elena; Poli, Tito; Exarchos, Konstantinos; Steger, Sebastian
Multilevel and Multiscale Modeling Approach for VPH-Based Prediction of Oral Cancer Reoccurrences. Results of the FP7 NeoMark Project
IEEE Engineering in Medicine and Biology Society (EMBS): 2014 IEEE-EMBS International Conference on Biomedical and Health Informatics (BHI) : BHI 2014, pp. 781-784
International Conference on Biomedical and Health Informatics (BHI) <2, 2014, Valencia, Spain>
In this work we present the approach adopted to stratify patients at high vs. low risk for reoccurrence of Oral Squamous Cell Carcinoma (OSCC) and to model the disease progression after remission. For this purpose we developed a multiscale and multilevel model, which integrates thousands of heterogeneous data including genomics, collected by means of innovative technologies such as Point-of-Care (PoC) Real Time PCR and lab-on-chip and advanced image fusion techniques. The realized predictive model produced a bio-signature of high-risk patients and identified a set of biomarkers from tumor tissues and blood cells, indicative of potential disease reoccurrence. The NeoMark predictive model was trained and initially validated in a multicentre pilot study (three European clinical centers involved in Italy and in Spain) on a cohort of 86 patients affected by OSCC with a minimum follow up of 12 months. We discuss how the disease bio-profile identified by NeoMark was considered extremely useful by the clinicians to evaluate the risk of disease reoccurrence of a patient at the time of diagnosis and to provide a "tailored therapy" to each case.
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Noll, Matthias; Li, Xin; Wesarg, Stefan
Automated Kidney Detection and Segmentation in 3D Ultrasound
Noll, Matthias; Li, Xin; Wesarg, Stefan
Automated Kidney Detection and Segmentation in 3D Ultrasound
Erdt, Marius (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8361), pp. 83-90
International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>
Ultrasound provides the physical capabilities for a fast and save disease diagnosis in various medical scenarios including renal exams and patient trauma assessment. However, the experience of the ultrasound operator is the key element in performing ultrasound diagnosis. Thus, we like to introduce our automatic kidney detection and segmentation algorithm for 3D ultrasound. The approach utilizes basic kidney shape information to detect the kidney position. Following, the Level Set algorithm is applied to segment the detection result. In combination this method may help physicians and inexperienced trainees to achieve kidney detection and segmentation for diagnostic purposes.
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Noll, Matthias; Puhl, Julian; Wesarg, Stefan
Enhanced Shadow Detection for 3D Ultrasound
Noll, Matthias; Puhl, Julian; Wesarg, Stefan
Enhanced Shadow Detection for 3D Ultrasound
Deserno, Thomas Martin (Ed.) et al.: Bildverarbeitung für die Medizin 2014 : Algorithmen, Systeme, Anwendungen. Proceedings des Workshops. Berlin, Heidelberg, New York: Springer, 2014. (Informatik aktuell), pp. 234-239
Workshop Bildverarbeitung für die Medizin (BVM) <17, 2014, Aachen, Germany>
Ultrasound imaging offers a fast, convenient and save instrument to conduct patient examinations for various medical scenarios. However, depending on the target region, occluding bone segments and other materials cause large and undesirable shadowing artifacts. Thus, the experience of the ultrasound operator is crucial for obtaining an ultrasound without artifacts for patient diagnosis. Even more so, when applying automated image processing algorithms. We therefore like to introduce our automatic 3D ultrasound shadow detection method that employs scan line energy and local image entropy information. Applying the method can help to prevent low quality image acquisitions with large shadowing artifacts by indicating shadow occurrences.
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Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Two-Step FEM-Based Liver-CT Registration: Improving Internal and External Accuracy
Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Two-Step FEM-Based Liver-CT Registration: Improving Internal and External Accuracy
Ourselin, Sébastien (Ed.) et al.: Medical Imaging 2014: Image Processing : Progress in Biomedical Optics and Imaging Vol. 15 No. 35. Bellingham: SPIE Press, 2014. (Proceedings of SPIE 9034), 7 p.
SPIE Medical Imaging Symposium <2014, San Diego, CA, USA>
To know the exact location of the internal structures of the organs, especially the vasculature, is of great importance for the clinicians. This information allows them to know which structures/vessels will be affected by certain therapy and therefore to better treat the patients. However the use of internal structures for registration is often disregarded especially in physical based registration methods. In this paper we propose an algorithm that uses finite element methods to carry out a registration of liver volumes that will not only have accuracy in the boundaries of the organ but also in the interior. Therefore a graph matching algorithm is used to find correspondences between the vessel trees of the two livers to be registered. In addition to this an adaptive volumetric mesh is generated that contains nodes in the locations in which correspondences were found. The displacements derived from those correspondences are the input for the initial deformation of the model. The first deformation brings the internal structures to their final deformed positions and the surfaces close to it. Finally, thin plate splines are used to refine the solution at the boundaries of the organ achieving an improvement in the accuracy of 71%. The algorithm has been evaluated in CT clinical images of the abdomen.
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Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Anatomical Discovery: Finding Organs in the Neighborhood of the Liver
Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Anatomical Discovery: Finding Organs in the Neighborhood of the Liver
Romero, Laura M. Roa (Ed.): XIII Mediterranean Conference on Medical and Biological Engineering and Computing : MEDICON 2013. Berlin, Heidelberg, New York: Springer, 2014. (IFMBE Proceedings 41), pp. 348-351
The Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON) <13, 2013, Seville, Spain>
Image segmentation and registration algorithms are fundamental to assist medical doctors for better treatment of the patients. To this end accuracy in the results given by those algorithms is crucial. The surroundings of the organ to be segmented or registered can provide additional information that at the end improves the result. In this paper a novel algorithm to detect the organs that surround the liver is introduced. Even though our work is focused on the liver, the algorithm could be extended to other parts of the body. The algorithm has been tested in 24 clinical CT datasets. In addition to this, an example application is introduced for which the detection is a useful tool.
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Stamatakos, Georgios; Dionysiou, Dimitra; Lunzer, Aran; Belleman, Robert; Kolokotroni, Eleni; Georgiadi, Eleni; Erdt, Marius; Pukacki, Juliusz; Rueping, Stefan; Giatili, Stavroula; d`Onofrio, Alberto; Sfakianakis, Stelios; Marias, Kostas; Desmedt, Christine; Tsiknakis, Manolis; Graf, Norbert
The Technologically Integrated Oncosimulator: Combining Multiscale Cancer Modeling with Information Technology in the In Silico Oncology Context
Stamatakos, Georgios; Dionysiou, Dimitra; Lunzer, Aran; Belleman, Robert; Kolokotroni, Eleni; Georgiadi, Eleni; Erdt, Marius; Pukacki, Juliusz; Rueping, Stefan; Giatili, Stavroula; d`Onofrio, Alberto; Sfakianakis, Stelios; Marias, Kostas; Desmedt, Christine; Tsiknakis, Manolis; Graf, Norbert
The Technologically Integrated Oncosimulator: Combining Multiscale Cancer Modeling with Information Technology in the In Silico Oncology Context
IEEE Journal of Biomedical and Health Informatics, Vol.18 (2014), 3, pp. 840-854. Published online: 29 December 2013
This paper outlines the major components and function of the Technologically Integrated Oncosimulator developed primarily within the ACGT (Advancing Clinico Genomic Trials on Cancer) project. The Oncosimulator is defined as an information technology system simulating in vivo tumor response to therapeutic modalities within the clinical trial context. Chemotherapy in the neoadjuvant setting, according to two real clinical trials concerning nephroblastoma and breast cancer, has been considered. The spatiotemporal simulation module embedded in the Oncosimulator is based on the multiscale, predominantly top-down, discrete entity - discrete event cancer simulation technique developed by the In Silico Oncology Group, National Technical University of Athens. The technology modules include multiscale data handling, image processing, invocation of code execution via a spreadsheet-inspired environment portal, execution of the code on the grid and visualization of the predictions. A refining scenario for the eventual coupling of the Oncosimulator with immunological models is also presented. Parameter values have been adapted to multiscale clinical trial data in a consistent way, thus supporting the predictive potential of the Oncosimulator. Indicative results demonstrating various aspects of the clinical adaptation and validation process are presented. Completion of these processes is expected to pave the way for the clinical translation of the system.
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Steger, Sebastian; El Hakimi, Wissam; Wesarg, Stefan
Tracking von Instrumenten auf fluoroskopischen Aufnahmen für die navigierte Bronchoskopie
Steger, Sebastian; El Hakimi, Wissam; Wesarg, Stefan
Tracking von Instrumenten auf fluoroskopischen Aufnahmen für die navigierte Bronchoskopie
Deserno, Thomas Martin (Ed.) et al.: Bildverarbeitung für die Medizin 2014 : Algorithmen, Systeme, Anwendungen. Proceedings des Workshops. Berlin, Heidelberg, New York: Springer, 2014. (Informatik aktuell), pp. 228-233
Workshop Bildverarbeitung für die Medizin (BVM) <17, 2014, Aachen, Germany>
Intraoperative C-Bogen-Fluoroskopie dient bei der bronchoskopischen Biopsie zur Lokalisation des Bronchoskops und der Biospiezange innerhalb des Patiententhorax. Bei bekannter C-Bogen Pose ist es möglich, aus der 2D-Position der Instrumentenspitze auf der Fluoroskopie deren 3D-Position innerhalb des Bronchialbaums zu berechnen. Während die Pose mit Hilfe einer Markerplatte auf dem Patiententisch bestimmt werden kann, fehlt bisher eine automatische Verfolgung der Instrumentenspitze auf der kontinuierlichen Fluoroskopie. In dieser Arbeit wird eine solche Tracking-Methode vorgestellt und evaluiert. Erste Experimente an einem Bronchialbaum-Phantom lieferten sehr robuste und präzise Ergebnisse und auch die Echtzeitfähigkeit konnte gezeigt werden.
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Steger, Sebastian; Jung, Florian; Wesarg, Stefan
Personalized Articulated Atlas with a Dynamic Adaptation Strategy for Bone Segmentation in CT- or CT/MR Head & Neck Images
Steger, Sebastian; Jung, Florian; Wesarg, Stefan
Personalized Articulated Atlas with a Dynamic Adaptation Strategy for Bone Segmentation in CT- or CT/MR Head & Neck Images
Ourselin, Sébastien (Ed.) et al.: Medical Imaging 2014: Image Processing : Progress in Biomedical Optics and Imaging Vol. 15 No. 35. Bellingham: SPIE Press, 2014. (Proceedings of SPIE 9034), 6 p.
SPIE Medical Imaging Symposium <2014, San Diego, CA, USA>
This paper presents a novel segmentation method for the joint segmentation of individual bones in CT- or CT/MR- head & neck images. It is based on an articulated atlas for CT images that learned the shape and appearance of the individual bones along with the articulation between them from annotated training instances. First, a novel dynamic adaptation strategy for the atlas is presented in order to increase the rate of successful adaptations. Then, if a corresponding CT image is available the atlas can be enriched with personalized information about shape, appearance and size of the individual bones from that image. Using mutual information, this personalized atlas is adapted to an MR image in order to propagate segmentations. For evaluation, a head & neck bone atlas created from 15 manually annotated training images was adapted to 58 clinically acquired head & neck CT datasets. Visual inspection showed that the automatic dynamic adaptation strategy was successful for all bones in 86% of the cases. This is a 22% improvement compared to the traditional gradient descent based approach. In leave-one-out cross validation manner the average surface distance of the correctly adapted items was found to be 0.68 mm. In 20 cases corresponding CT/MR image pairs were available and the atlas could be personalized and adapted to the MR image. This was successful in 19 cases.
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Steger, Teena; Drechsler, Klaus; Wesarg, Stefan
Image-Based Bronchoscopy Navigation System Based on CT and C-arm Fluoroscopy
Steger, Teena; Drechsler, Klaus; Wesarg, Stefan
Image-Based Bronchoscopy Navigation System Based on CT and C-arm Fluoroscopy
Erdt, Marius (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8361), pp. 15-22
International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>
Lung cancer diagnosis requires biopsy of airway tissue, which is mostly done by bronchoscopy. Although preoperative CT is available, intraoperatively only 2D information provided by the bronchoscopic camera and fluoroscopy is used. But, guidance of the bronchoscope to the target site would highly benefit from knowing the exact 3D position of the instrument inside the airways. In this paper, we present a system for preoperative planning and intraoperative navigation during bronchoscopy. The preoperative components are automatic bronchial tree segmentation and skeletonization, semi-automatic tumor segmentation and a virtual fly-through simulation for planning purposes. During the intervention, we apply C-arm pose estimation using a marker plate on the patient table to align preoperative CT and intraoperative fluoroscopy. Thus, we can calculate the current 3D position of the bronchoscope inside the bronchial tree. Evaluation of the system components on patient CT and phantom fluoroscopy images showed promising results with high accuracy and robustness.
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Steger, Teena; Fellner, Dieter W.; Sakas, Georgios; Wagner, Manfred
Bronchoskopische Navigation mittels Pose Estimation des C-Bogens aus musterkodierten Fluoroskopie-Aufnahmen
Steger, Teena; Fellner, Dieter W.; Sakas, Georgios; Wagner, Manfred
Bronchoskopische Navigation mittels Pose Estimation des C-Bogens aus musterkodierten Fluoroskopie-Aufnahmen
Die Bronchoskopie ist die wichtigste und sicherste Untersuchungsmethode bei Verdacht auf Lungenkrebs. Sie dient sowohl der visuellen Inspektion der Atemwege als auch der Gewebeentnahme an verdächtigen Läsionen. Erst aufgrund der so gewonnenen Probe kann entschieden werden, ob es sich um bösartiges Gewebe handelt. Damit die Biopsie an der korrekten Stelle durchgeführt wird, ist es besonders wichtig, dass die bronchoskopischen Operationsinstrumente präzise innerhalb des Bronchialbaums geführt werden können. Dabei behilft sich der Arzt zum einen mit der Kamera an der Bronchoskopspitze und zum anderen mit der intraoperativen C-Bogen-Durchleuchtung. Leider liefert keine dieser Visualisierungstechniken eine 3D-Sicht des Bronchialbaums oder die aktuelle 3D-Position des Instruments. Genau diese Hilfestellung leisten bronchoskopische Navigationssysteme und tragen somit erheblich zur Genauigkeit der Instrumentenführung und Beschleunigung des Eingriffs bei. Bronchoskopische Navigationssysteme verwenden meist EM-Sensoren, um die aktuelle Position des Instruments innerhalb der Bronchien zu verfolgen. Solche Systeme müssen nicht nur kostspielig und aufwändig installiert, sondern die jeweiligen getrackten Instrumente auch nach jedem Gebrauch teuer ersetzt werden. Um dieses Problem zu umgehen, wird auch an Systemen entwickelt, die lediglich die Bronchoskopvideobilder zur 2D/3D-Registrierung verwenden. Damit kann die Navigation aber nur so lange angeboten werden, wie die Bronchoskopspitze in die Bronchien vorgeschoben werden kann. Im Normalfall wird aber gerade in den nicht erreichbaren peripheren Verästelungen eine Navigationsstütze benötigt. Deshalb wird in dieser Arbeit ein Verfahren vorgestellt, welches unabhängig von der Bronchoskopreichweite anwendbar ist und ausschließlich auf die bereits vorhandene Ausstattung im OP-Saal zurückgreift. Somit wird eine höhere klinische Einsetzbarkeit und Akzeptanz erwartet. Die neuartige Grundidee ist hierbei, dass bei bekannter Aufnahmeposition des C-Bogens ein virtueller Strahl von C-Bogen-Röntgenquelle durch das Patienten-CT zur Instrumentenspitzenposition auf dem Durchleuchtungsbild generiert werden kann. Dieser 3D-Strahl schneidet dann den Bronchialbaum im CT genau an der Stelle, wo sich das Instrument aktuell befindet. Die große Herausforderung ist nun die C-Bogen Pose während der Aufnahme zu bestimmen. Dafür wurde von mir eine innovative Markerplatte entwickelt, die auf dem Patiententisch befestigt wird. Bei jeder Aufnahme wird ein Teil der radioopaken Marker auf der Durchleuchtung abgebildet. Um nun eine C-Bogen Pose Estimation durchzuführen, müssen die abgebildeten 2D-Marker eindeutig ihren korrespondierenden 3D-Markern auf der Platte zugeordnet werden. Deshalb habe ich bei der Anordnung der Marker erstmals die projektive Invariante Doppelverhältnis eingesetzt. Dies ermöglicht, dass die Marker auch nach Projektion verlässlich identifiziert und zugeordnet werden. Die entworfene Markerplatte wurde zahlreichen Experimenten unterzogen, darunter auch Phantom- und Tierkadavertests. Dabei wurden sehr gute quantitative Ergebnisse für die C-Bogen Pose Estimation bezüglich Erfolgsraten und Genauigkeiten gemessen. In dieser Arbeit stellt weitere wichtige Komponenten eines Bronchoskopie-Navigationssystems vor: Bronchialbaumsegmentierung und -skeletonisierung, Tumorsegmentierung, 2D-Instrumentenverfolgung, Patient-zu-Tisch-Registrierung, Pfadberechnung und 3D-Visualisierung. Dabei wurden vorhandene Lösungen aus der Literatur aufgegriffen bzw. erweitert aber auch neue Methoden entwickelt. Alle diese Komponenten wurden sowohl einzeln und als auch im Zusammenspiel miteinander untersucht. Bei Tests mit einem Bronchialbaumphantom erzielte sehr gute qualitative Ergebnisse..
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Steger, Teena; Wesarg, Stefan
Quantitative Analysis of Marker Segmentation for C-Arm Pose Based Navigation
Steger, Teena; Wesarg, Stefan
Quantitative Analysis of Marker Segmentation for C-Arm Pose Based Navigation
Romero, Laura M. Roa (Ed.): XIII Mediterranean Conference on Medical and Biological Engineering and Computing : MEDICON 2013. Berlin, Heidelberg, New York: Springer, 2014. (IFMBE Proceedings 41), pp. 487-490
The Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON) <13, 2013, Seville, Spain>
Intraoperative C-arm fluoroscopy is used for better instrument guidance during bronchoscopy. Unfortunately, C-arm images do not provide depth information. But, offering 3D instrument localization would enable faster and more accurate guidance of the bronchoscope. Using the C-arm pose, this can be achieved by combining intraoperative fluoroscopy with a preoperative CT. Thus, the 3D position of the bronchoscope tip inside the bronchial tree can be located and visualized. We developed a marker plate for C-arm pose estimation, which is placed on the patient table. The markers are made of steel and appear in two different shapes: spheres and sticks. Detecting the markers is essential for the C-arm pose estimation method. In this work, we present and evaluate two detection methods for detecting the projected markers on the fluoroscopy images. Tests on cadaver images showed very good results regarding robustness and precision: For circles and lines, 80% and 85%, respectively, of all visible markers were detected, whereas only 1% and 3%, respectively, of all detected markers were missegmented.
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Wang, Anqi; Sakas, Georgios (Betreuer); Noll, Matthias (Betreuer)
Detektion von Tumorgewebe und invasiver Tumorgrenze in CD3/CD8 gefärbten Gewebeschnitten (Histopathologien)
Wang, Anqi; Sakas, Georgios (Betreuer); Noll, Matthias (Betreuer)
Detektion von Tumorgewebe und invasiver Tumorgrenze in CD3/CD8 gefärbten Gewebeschnitten (Histopathologien)
Darmstadt, TU, Master Thesis, 2014
Konventionelle Krankheitsprognose bei Krebserkrankungen basiert auf Größe des Tumors, Auftrittsort von Krebszellen und Vorliegen von Metastasen. Diese Anzeichen lassen jedoch keine Aussage über den postoperativen Krankheitsverlauf zu. Erste Studien haben ergeben, dass in solchen Fällen die Betrachtung der Immunantwort des Körpers eine zuverlässigere Vorhersage treffen kann. Die Immunantwort drückt sich in Art und Auftrittshäufigkeit von Immunzellen (sogenannte T-Zellen) in und um den Tumor aus. Zur Validierung dieser These wird in der vorliegenden Arbeit ein Verfahren entwickelt, das automatisch auf CD3/CD8-gefärbten histopathologischen Aufnahmen den Tumor und die invasive Tumorgrenze segmentiert. In Kombination mit einer anderen Arbeit, die ein Verfahren zur Zellenzählung implementiert, sollen große Datenmengen von Patienten evaluiert werden, deren Krankheitsverlauf bekannt ist. Die größte Herausforderung dieser Arbeit besteht im verwendeten Material. Üblicherweise wird Gewebe auf HE-gefärbten Aufnahmen segmentiert. CD3/CD8 sind hingegen Färbungen, welche T-Zellen klar erkennbar darstellen, aber unterschiedliche Gewebearten nur wenig differenzieren. Eine zusätzliche Schwierigkeit ist die Entwicklung des Verfahrens bei einer kleinen Menge an verfügbaren Trainings- und Testdaten. Aus der Aufgabenstellung ergeben sich für das Verfahren die Anforderungen Geschwindigkeit (Evaluation großer Datenmengen) und Genauigkeit der Segmentierung. Die Geschwindigkeitsanforderung wird erfüllt, indem effizient zu berechnende und gleichzeitig aussagekräftige Features als Eingabe für ein Clustering-Algorithmus verwendet werden. Die Verarbeitung einer Aufnahme dauert durchschnittlich 5 Minuten. Gemessen an dem Zeitaufwand eines Pathologen für die gleiche Aufgabe ist dies eine große Zeitersparnis. Die Evaluation ergab einen durchschnittlichen Accuracy-Wert von 0,94. Dieser Wert ist vergleichbar mit den Ergebnissen verwandter State of the Art Methoden, welche auf HE-gefärbten Aufnahmen arbeiten.
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Wesarg, Stefan; Jung, Florian; Steger, Sebastian
Abbildung anatomischen Wissens: Ein Kopf-/Hals-Atlas multipler gekoppelter Strukturen
Wesarg, Stefan; Jung, Florian; Steger, Sebastian
Abbildung anatomischen Wissens: Ein Kopf-/Hals-Atlas multipler gekoppelter Strukturen
Endoskopie heute, Vol.27 (2014), 3, pp. 141-145
Medizinische Bilddaten enthalten anatomische Informationen. Die Extraktion derselben durch manuelles Markieren ist unter Berücksichtigung der Datenmenge vor allem bei radiologischen 3D-Bilddaten nicht mehr vernünftig durchführbar. Hier helfen computerbasierte, automatische Verfahren. Nicht alle anatomischen Regionen heben sich durch deutliche Kontrastunterschiede von der Umgebung ab. Dennoch sind Radiologen in der Lage, auch solche Bereiche in den Bilddaten zuzuordnen. Für automatisch ablaufende Algorithmen besteht dabei die Herausforderung, das anatomische Wissen eines klinischen Experten in einer für den Computer verständlichen Form zu repräsentieren. Für den Kopf-/Hals-Bereich haben wir ein solches Modell entwickelt, das anatomische Strukturen enthält, die miteinander gekoppelt sind. Das Modell repräsentiert diese hinsichtlich ihrer Form und Größe als auch ihrer relativen Lage zueinander. Dabei wird zwischen aktiven und passiven Strukturen unterschieden. Erstere repräsentieren deutlich von der Umgebung abgrenzbare Bildbereiche, letztere Regionen, die nur aufgrund ihrer relativen Lage zu anderen Organen identifizierbar sind. Der neue Modellierungsansatz ist dabei einerseits flexibler als klassische atlasbasierte Segmentierungsverfahren. Andererseits sind das neue Verfahren und das dafür entwickelte Framework generisch und können mit geringen Adaptionen auch für Fragestellungen jenseits des Kopf-/Hals-Bereichs eingesetzt werden.
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Wesarg, Stefan; Wichmann, Julian L.; Booz, Christian; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
First Clinical Experience with BMD Assessment in Vertebrae Using Dual-Energy CT
Wesarg, Stefan; Wichmann, Julian L.; Booz, Christian; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
First Clinical Experience with BMD Assessment in Vertebrae Using Dual-Energy CT
Erdt, Marius (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8361), pp. 151-159
International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>
Dual-energy CT (DECT) can be performed with state-of-the- art dual-source CT (DSCT) scanners and allows for assessing bone mineral density (BMD). In this work, we present first clinical experience with in vivo BMD assessment of vertebrae based on DECT data which has been acquired with a state-of-the-art DSCT scanner in the clinical routine. In contrast to previous work where we did in vitro tests of our method, we apply it her for the first time to in vivo data and prove the feasibility of our technique in a clinical setting. For 25 patients, DXA as well as DECT data have been acquired and BMD of vertebrae was assessed. Advantages of DECT are its 3D capabilities allowing to compute the spatial BMD distribution and to focus the examination on the trabecular bone. Correlations between both imaging techniques regarding the averaged BMD values per vertebra are only moderate.
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Wichmann, Julian L.; Booz, Christian; Wesarg, Stefan; Kafchitsas, Konstantinos; Bauer, Ralf W.; Kerl, J. Matthias; Lehnert, Thomas; Vogl, Thomas J.; Khan, M. Fawad
Dual-Energy CT-based Phantomless in Vivo Three-dimensional Bone Mineral Density Assessment of the Lumbar Spine
Wichmann, Julian L.; Booz, Christian; Wesarg, Stefan; Kafchitsas, Konstantinos; Bauer, Ralf W.; Kerl, J. Matthias; Lehnert, Thomas; Vogl, Thomas J.; Khan, M. Fawad
Dual-Energy CT-based Phantomless in Vivo Three-dimensional Bone Mineral Density Assessment of the Lumbar Spine
Radiology, Vol.271 (2014), 3, pp. 778-784
Purpose: To evaluate the feasibility of phantomless in vivo dual-energy computed tomography (CT)-based three-dimensional (3D) bone mineral density (BMD) assessment in comparison with dual x-ray absorptiometry (DXA). Materials and Methods: This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Data from clinically indicated dual-energy CT and DXA examinations within 2 months, comprising the lumbar spine of 40 patients, were included. By using automated dedicated postprocessing dual-energy CT software, the trabecular bone of lumbar vertebrae L1-L4 were analyzed and segmented. A mixed-effects model was used to assess the correlations between BMD values derived from dual-energy CT and DXA. Results: One hundred sixty lumbar vertebrae were analyzed in 40 patients (mean age, 57.1 years; range, 24-85 years), 21 male (mean age, 54.3 years; range, 24-85 years) and 19 female (mean age, 58.5 years; range, 31-80 years). Mean BMD of L1-L4 determined with DXA was 0.995 g/ cm², and 18 patients (45%) showed an osteoporotic BMD (T score less than 22.5) of at least two vertebrae. Mean dual-energy CT-based BMD of L1-L4 was 0.254 g/cm³. Bland-Altman analysis with mixed effects demonstrated a lack of correlation between dual-energy CT-based and DXA-based BMD values, with a mean difference of 0.7441 and 95% limits of agreement of 0.7441 +/- 0.4080. Conclusion: Dedicated postprocessing of dual-energy CT data allows for phantomless in vivo BMD assessment of the trabecular bone of lumbar vertebrae and enables freely rotatable color-coded 3D visualization of intravertebral BMD distribution.
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Wichmann, Julian L.; Majenka, Pavel; Beeres, Martin; Kromen, Wolfgang; Schulz, Boris; Wesarg, Stefan; Bauer, Ralf W.; Kerl, J. Matthias; Gruber-Rouh, Tatjana; Hammerstingl, Renate; Vogl, Thomas J.; Lehnert, Thomas
Single-portal-phase Low-tube-voltage Dual-energy CT for Short-term Follow-up of Acute Pancreatitis: Evaluation of CT Severity Index, Interobserver Agreement and Radiation Dose
Wichmann, Julian L.; Majenka, Pavel; Beeres, Martin; Kromen, Wolfgang; Schulz, Boris; Wesarg, Stefan; Bauer, Ralf W.; Kerl, J. Matthias; Gruber-Rouh, Tatjana; Hammerstingl, Renate; Vogl, Thomas J.; Lehnert, Thomas
Single-portal-phase Low-tube-voltage Dual-energy CT for Short-term Follow-up of Acute Pancreatitis: Evaluation of CT Severity Index, Interobserver Agreement and Radiation Dose
European Radiology, Vol.24 (2014), 11, pp. 2927-2935
Objectives: To intra-individually compare single-portal-phase low-tube-voltage (100-kVp) computed tomography (CT) with 120-kVp images for short-term follow-up assessment of CT severity index (CTSI) of acute pancreatitis, interobserver agreement and radiation dose. Methods: We retrospectively analysed 66 patients with acute pancreatitis who underwent initial dual-contrast-phase CT (unenhanced, arterial, portal phase) at admission and short-term (mean interval 11.4 days) follow-up dual-contrast-phase dual-energy CT. The 100-kVp and linearly blended images representing 120-kVp acquisition follow-up CT images were independently evaluated by three radiologists using a modified CTSI assessing pancreatic inflammation, necrosis and extrapancreatic complications. Scores were compared with paired t test and interobserver agreement was evaluated using intraclass correlation coefficients (ICC). Results: Mean CTSI scores on unenhanced, portal- and dual-contrast-phase images were 4.9, 6.1 and 6.2 (120 kVp) and 5.0, 6.0 and 6.1 (100 kVp), respectively. Contrast-enhanced series showed a higher CTSI compared to unenhanced images (P<0.05) but no significant differences between single- and dual-contrast-phase series (P>0.7). CTSI scores were comparable for 100-kVp and 120-kVp images (P>0.05). Interobserver agreement was substantial for all evaluated series and subcategories (ICC 0.67-0.93). DLP of single-portal-phase 100-kVp images was reduced by 41 % compared to 120-kVp images (363.8 versus 615.9 mGy cm). Conclusions: Low-tube-voltage single-phase 100-kVp CT provides sufficient information for follow-up evaluation of acute pancreatitis and significantly reduces radiation exposure.
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Zillner, Sonja; Seifert, Sascha; Erdt, Marius; Daumke, Philipp; Kramer, Martin
Semantic Processing of Medical Data
Zillner, Sonja; Seifert, Sascha; Erdt, Marius; Daumke, Philipp; Kramer, Martin
Semantic Processing of Medical Data
Wahlster, Wolfgang (Ed.) et al.: Towards the Internet of Services: The THESEUS Research Program. Berlin, Heidelberg, New York: Springer, 2014. (Cognitive Technologies), pp. 343-356
Medical images increase in quality and quantity: More and more detailed image content can be represented on the pixel level, and increasing amounts of medical images are produced in the context of clinical diagnosis. Technological solutions are needed to enhance existing clinical IT solutions helping clinicians to access and use medical images optimally. Within MEDICO, we developed methods and tools (a) to parse and describe the content of medical images, (b) to extract and annotate the related information from radiology reports, and (c) to provide and manage medical ontologies as a common language for labeling and integrating the various information entities.
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Becker, Meike; Gutbell, Ralf; Stenin, Igor; Wesarg, Stefan
Towards Automatic Path Planning for Multi-port Minimally-Traumatic Lateral Skull Base Surgery
Becker, Meike; Gutbell, Ralf; Stenin, Igor; Wesarg, Stefan
Towards Automatic Path Planning for Multi-port Minimally-Traumatic Lateral Skull Base Surgery
Drechsler, Klaus (Ed.) et al.: Clinical Image-Based Procedures. From Planning to Intervention : International Workshop, CLIP 2012. Held in Conjunction with MICCAI 2012. Berlin, Heidelberg, New York: Springer, 2013. (Lecture Notes in Computer Science (LNCS) 7761), pp. 59-66
International Workshop on Clinical Image-based Procedures (CLIP) <1, 2012, Nice, France>
We investigate a multi-port minimally-traumatic approach for lateral skull base surgery. Our long-term goal is to automatically determine the best combination of three paths from the skull surface to the surgical target. Since this multi-port approach is not yet in clinical use, it is difficult to define what the best combination of paths is. Therefore, we present a planning tool which allows to manually selecting a combination of three paths. A clinician used this planning tool to select the best combination of three paths for three target structures in computed tomography data sets of 20 patients. From this choice we derived initial constraints for an automatic planning of the best combination of paths.
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Biswas, Pradipta; Duarte, Carlos; Langdon, Patrick; Almeida, Luis; Jung, Christoph
A Multimodal End-2-End Approach to Accessible Computing
Biswas, Pradipta; Duarte, Carlos; Langdon, Patrick; Almeida, Luis; Jung, Christoph
A Multimodal End-2-End Approach to Accessible Computing
Human-Computer Interaction Series
ISSN: 1571-5035
ISBN: 9781447150817
Modern research in intelligent interactive systems can offer valuable assistance to elderly and disabled population by helping them to engage more fully with the world. However, many users find it difficult to use existing interaction devices either for physical or aging-related impairments, though researches on intelligent voice recognition, adaptable pointing, browsing and navigation, affect and gesture recognition can hugely benefit them.
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Biswas, Pradipta; Kaklanis, Nick; Mohamad, Yehya; Peissner, Matthias; Jung, Christoph
An Interoperable and Inclusive User Modeling Concept for Simulation and Adaptation
Biswas, Pradipta; Kaklanis, Nick; Mohamad, Yehya; Peissner, Matthias; Jung, Christoph
An Interoperable and Inclusive User Modeling Concept for Simulation and Adaptation
Biswas, Pradipta (Ed.) et al.: A Multimodal End-2-End Approach to Accessible Computing. London, Heidelberg, New York, Dordrecht: Springer, 2013. (Human-Computer Interaction Series), pp. 195-236
User models can be considered as explicit representations of the properties of an individual user including user's needs, preferences as well as physical, cognitive and behavioral characteristics. Due to the wide range of applications, it is often difficult to have a common format or even definition of user models. The lack of a common definition also makes different user models - even if developed for the same purpose-incompatible to each other. It does not only reduce the portability of user models but also restricts new models to leverage benefit from earlier research on similar field. This chapter presents a brief literature survey on user models and concept of an interoperable user model that takes a more inclusive approach than previous research. It is an initiative of the EU VUMS cluster of projects which aims to simulate user interaction and adapt interfaces across a wide variety of digital and non-digital platforms for both able bodied and disabled users.We have already been successful to define an application and platform-independent user model exchange format and the importing of any user profile across all projects.
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Biswas, Pradipta; Langdon, Pat; Duarte, Carlos; Coelho, Jose; Guerreiro, Tiago; Jung, Christoph
An Accessible, Adaptive and Multimodal Digital TV Framework and Corresponding Development Tool
Biswas, Pradipta; Langdon, Pat; Duarte, Carlos; Coelho, Jose; Guerreiro, Tiago; Jung, Christoph
An Accessible, Adaptive and Multimodal Digital TV Framework and Corresponding Development Tool
Science and Information Organization (SAI): Proceedings of 2013 Science and Information Conference : SAI 2013, pp. 28-37
Science and Information Conference (SAI) <2013, London, UK>
This paper presents a tool and a framework to develop accessible and adaptable digital TV interfaces for disabled and elderly users. The development methodology involves disabled and elderly users early in the design process and optimizes interfaces using a simulation system. The simulator complements existing user centred design processes and helps designers to understand, visualize and measure effect of impairments on interaction. The adaptive framework supports a wide variety of applications through its easy-to-use APIs. The system is validated through a series of user trials confirming its usefulness for users with different range of abilities.
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Drechsler, Klaus; Erdt, Marius; Linguraru, Marius George; Oyarzun Laura, Cristina; Sharma, Karun; Shekhar, Raj; Wesarg, Stefan
Clinical Image-Based Procedures. From Planning to Intervention: International Workshop, CLIP 2012. Held in Conjunction with MICCAI 2012
Drechsler, Klaus; Erdt, Marius; Linguraru, Marius George; Oyarzun Laura, Cristina; Sharma, Karun; Shekhar, Raj; Wesarg, Stefan
Clinical Image-Based Procedures. From Planning to Intervention: International Workshop, CLIP 2012. Held in Conjunction with MICCAI 2012
International Workshop on Clinical Image-based Procedures (CLIP) <1, 2012, Nice, France>
Lecture Notes in Computer Science (LNCS) 7761
ISSN: 0302-9743
ISBN: 9783642380785
CLIP 2012 provided a successful forum for the dissemination of emerging image-based clinical techniques. Specific topics included pre-interventional image segmentation and classification (to support diagnosis and clinical decision making), interventional and surgical planning and analysis of dynamic images, and evaluation, visualization and correction techniques for image-based procedures. Clinical applications covered the skull and the brain, cardiac defects, blood vessels, abdominal organs, and cancer in adults and children. The presentations and discussions around the meeting emphasized current challenges and emerging techniques in image-based procedures, strategies for clinical translation of image-based techniques, the role of computational anatomy and image analysis for surgical planning and interventions, and the contribution of medical image analysis to open and minimally invasive surgery.
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Drechsler, Klaus; Meixner, Steven; Oyarzun Laura, Cristina; Wesarg, Stefan
A Framework for Validation of Vessel Segmentation Algorithms
Drechsler, Klaus; Meixner, Steven; Oyarzun Laura, Cristina; Wesarg, Stefan
A Framework for Validation of Vessel Segmentation Algorithms
Rodrigues, Pedro Pereira (Ed.) et al.: Proceedings of CBMS 2013 : The 26th IEEE International Symposium on Computer-Based Medical Systems. New York: IEEE, Inc., 2013, pp. 518-519
IEEE Symposium on Computer-Based Medical Systems (CBMS) <26, 2013, Porto, Portugal>
Validation methods used in literature to evaluate vessel segmentation algorithms suffer to a great extent from objectiveness, reliability and reproducibility. This is because almost each group has its own way to evaluate an algorithms. In this paper, an extendable standardized evaluation framework for quantitative validation of vessel segmentation algorithms is presented. As ground-truth, it uses a physical vascular model to simulate the growth of vessels within organ masks extracted from clinical CT datasets. A set of image- and graph- based evaluation metrics are calculated to analyze various aspects of the algorithms under study. Using the proposed framework helps to meet the aforementioned quality criteria.
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Drechsler, Klaus; Oyarzun Laura, Cristina; Wesarg, Stefan
Hepatic Vein Segmentation Using Wavefront Propagation and Multiscale Vessel Enhancement
Drechsler, Klaus; Oyarzun Laura, Cristina; Wesarg, Stefan
Hepatic Vein Segmentation Using Wavefront Propagation and Multiscale Vessel Enhancement
Ourselin, Sebastien (Ed.) et al.: Medical Imaging 2013: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 36. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8669), pp. 86691A-1 - 86691A-7
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Modern volumetric imaging techniques such as CT or MRI, aid in the understanding of a patient's anatomy and pathologies. Depending on the medical use case, various anatomical structures are of interest. Blood vessels play an important role in several applications, e.g. surgical planning. Manual delineation of blood vessels in volumetric images is error prone and time consuming. Automated vessel segmentation is a challenging problem due to acquisition-dependent problems such as noise, contrast, spatial resolution, and artifacts. In this paper, a vessel segmentation method is presented that combines a wavefront propagation technique with Hessian-based vessel enhancement. The latter has proven its usefulness as a preprocessing step to detect tubular structures before the actual segmentation is carried out. The former allows for an ordered growing process, which enables topological analysis. The contribution of this work is as follows. 1. A new vessel enhancement filter for tubular structures based on the Laplacian is proposed, 2. a wavefront propagation technique is proposed that prevents leaks by imposing a threshold on the maximum number of voxels that the propagating front must contain, and 3. a volumetric hole filling method is proposed to fill holes, bays, and tunnels which are caused at locations where the tubular structure assumption is violated. The proposed method reduces approximately 50% of the necessary eigenvalue calculations for vessel enhancement and prevents leaks starting at small spots, which usually occur using standard region growing. Qualitative and quantitative evaluation based on several metrics (statistical measures, dice and symmetric average surface distance) is presented.
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Dörr, Vincent; Hoßbach, Martin (Betreuer); Tausch, Reimar (Betreuer)
Zahnsegmentierung auf Intraoralaufnahmen zur Plaque-Quantifizierung
Dörr, Vincent; Hoßbach, Martin (Betreuer); Tausch, Reimar (Betreuer)
Zahnsegmentierung auf Intraoralaufnahmen zur Plaque-Quantifizierung
Darmstadt, Hochschule, Bachelor Thesis, 2013
In dieser Arbeit geht es um die Segmentierung von einzelnen Zähnen und der anschließenden Analyse des Plaque-Befalls. Zur deutlicheren Visualisierung von Plaque können verschiedene Indikatoren mit jeweils unterschiedlichen Farbstoffen eingesetzt werden. Die am weitest verbreiteten Farbstoffe werden vorgestellt. Nach der Generierung, der Zahnaufnahmen mit einer Intraoralkamera unter Verwendung emes Plaque-Indikators, werden zwei mögliche Verfahren zur Segmentierung auf ihre Einsatzmöglichkeiten in diesem Anwendungsfall untersucht. Die Segmentierung wurde ebenfalls auf ein bestehendes Verfahren zur Plaque-Quantifizierung mit einem fluoreszierenden Farbstoff erfolgreich angewendet. Weitestgehend separat wurde eine Klassifizierung durch einen Klassifikator zur Einteilung festgelegter Bereiche getestet. Der Klassifikator, repräsentiert durch eine Support Vector Machine, wurde zur Unterscheidung zwischen Zahn und Plaque auf ultravioletten Aufnahmen eingesetzt. Auf den Aufnahmen wurde zuvor mittels einer Maske ein Bereich, in dem nur die Zähne mit der Plaque sichtbar sind, bestimmt. Mit einer 10-fachen Kreuzvalidierung konnte eine Genauigkeit von 90% bei der Klassifizierung erzielt werden. Dies ist eine Verbesserung gegenüber den derzeit bestehenden Verfahren.
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El Hakimi, Wissam; Wesarg, Stefan
Accurate Super-Resolution Reconstruction for CT and MR Images
El Hakimi, Wissam; Wesarg, Stefan
Accurate Super-Resolution Reconstruction for CT and MR Images
Rodrigues, Pedro Pereira (Ed.) et al.: Proceedings of CBMS 2013 : The 26th IEEE International Symposium on Computer-Based Medical Systems. New York: IEEE, Inc., 2013, pp. 445-448
IEEE Symposium on Computer-Based Medical Systems (CBMS) <26, 2013, Porto, Portugal>
The resolution and accuracy of medical images play an important role for early medical diagnosis, since a wrong resolution may increase the risk of making a poor decision. In practice, magnetic resonance and computed tomography images often suffer from anisotropic resolution, so that the image quality is high only within the slices. In this paper we propose a further development of a previously presented super-resolution approach, to reconstruct isotropic high resolution images from only two orthogonal low resolution data sets. Thereby, voxel uncertainties, which arise during image acquisition and preprocessing, are considered. Furthermore, an adapted inpainting method is introduced to ensure a better initial estimation of missing data. Reconstruction quality is also improved, by combining regional and local information. Experiments on synthetic and clinical data sets reveal significant improvement of image quality and accuracy, yielding better results when compared with conventional reconstruction approaches.
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Erdt, Marius; Knapp, Oliver; Drechsler, Klaus; Wesarg, Stefan
Region Detection in Medical Images Using HOG Classifiers and a Body Landmark Network
Erdt, Marius; Knapp, Oliver; Drechsler, Klaus; Wesarg, Stefan
Region Detection in Medical Images Using HOG Classifiers and a Body Landmark Network
Novak, Carol L. (Ed.) et al.: Medical Imaging 2013: Computer-Aided Diagnosis. Part One. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8670), pp. 867004-1 - 867004-7
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Automatic detection of anatomical structures and regions in 3D medical images is important for several computer aided diagnosis tasks. In this work, a new method for simultaneous detection of multiple anatomical areas is proposed. The method consists of two steps: first, single rectangular region candidates are detected independently using 3D variants of Histograms of Oriented Gradients (HOG) features. These features are robust against small changes between regions in rotation and scale which typically occur between different individuals. In a second step, the positions of the detected candidates are refined by incorporating a body landmark network that exploits anatomical relations between different structures. The landmark network consists of a principle component based statistical modeling of the relative positions between the detected regions in training images. The method has been evaluated on thoracic/abdominal CT images of the portal venous phase. In 216 CT images, eight different structures have been trained. Results show an increase in performance using the combination of HOGs and the landmark network in comparison to using independent classifiers without anatomical relations.
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Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Head Motion Compensation for Arterial Spin Labeling Using Optical Motion Tracking
Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Head Motion Compensation for Arterial Spin Labeling Using Optical Motion Tracking
Drechsler, Klaus (Ed.) et al.: Clinical Image-Based Procedures. From Planning to Intervention : International Workshop, CLIP 2012. Held in Conjunction with MICCAI 2012. Berlin, Heidelberg, New York: Springer, 2013. (Lecture Notes in Computer Science (LNCS) 7761), pp. 1-8
International Workshop on Clinical Image-based Procedures (CLIP) <1, 2012, Nice, France>
Monitoring of Brain perfusion using Arterial Spin Labeling (ASL) during thrombolysis is an example of an MR procedure that will take over one hour. During this time, patient head motion is inevitable. Among the solutions to this problem is motion tracking, which is used to provide the patient's head motion to the MRI scanner to compensate for this motion. We present an approach for head motion tracking which is designed to fit into clinical workflow: Blue paper dots are attached to the patient's forehead and tracked using a stereo camera setup which is mounted to the MRI head coil and easily removed and replaced. The core algorithms are explained and evaluated. Results from clinical experiments conclude the evaluation.
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Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Design and Analysis of a Calibration-method for Stereo-optical Motion Tracking in MRI using a Virtual Calibration Phantom
Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Design and Analysis of a Calibration-method for Stereo-optical Motion Tracking in MRI using a Virtual Calibration Phantom
Nishikawa, Robert M. (Ed.) et al.: Medical Imaging 2013: Physics of Medical Imaging. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 35. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8668), pp. 86682E-1 - 86682E-7
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Motion tracking for head motion compensation in MRI has been a research topic for several years. However, literature is not giving much attention to the calibration of such setups. We present a method to calibrate the coordinate systems of a stereo-optical camera setup mounted to the MRI head coil. Though using a simple setup and visible instead of infrared light for tracking, it is possible to achieve a sub-millimeter tracking precision. Blue water-filled spheres are positioned throughout the whole MRI imaging volume and detected in images of the tracking cameras as well as MRI scans. In order to register the coordinate systems of both camera system and MRI scanner, a heuristic-enhanced brute-force approach is used to match detected spheres in the different images. Then, a rigid transformation is calculated and applied to the cameras' external parameters to align the coordinate systems. The precision of our setup was evaluated using leave-one-out cross validation both for the camera calibration and the scanner coordinate system registration. We found that the cameras' locations and orientations are correct within 0:03mm and 0:03°, using a number of 45 spheres. Evaluation of the MRI coordinate system registration showed an average reprojection error of 1:1 mm. Influence of a feature point jitter of 0:5 px is 0:03mm for a point close to the cameras and 0:3mm for a point close to the back of the patient's head. Tracked poses are correct within 0:17mm and 0:001°.
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Hoßbach, Martin; Noll, Matthias; Wesarg, Stefan
Simplified Stereo-Optical Ultrasound Plane Calibration
Hoßbach, Martin; Noll, Matthias; Wesarg, Stefan
Simplified Stereo-Optical Ultrasound Plane Calibration
Bosch, Johan G. (Ed.) et al.: Medical Imaging 2013: Ultrasonic Imaging, Tomography, and Therapy : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 42. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8675), pp. 86750X-1 - 86750X-7
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Image guided therapy is a natural concept and commonly used in medicine. In anesthesia, a common task is the injection of an anesthetic close to a nerve under freehand ultrasound guidance. Several guidance systems exist using electromagnetic tracking of the ultrasound probe as well as the needle, providing the physician with a precise projection of the needle into the ultrasound image. This, however, requires additional expensive devices. We suggest using optical tracking with miniature cameras attached to a 2D ultrasound probe to achieve a higher acceptance among physicians. The purpose of this paper is to present an intuitive method to calibrate freehand ultrasound needle guidance systems employing a rigid stereo camera system. State of the art methods are based on a complex series of error prone coordinate system transformations which makes them susceptible to error accumulation. By reducing the amount of calibration steps to a single calibration procedure we provide a calibration method that is equivalent, yet not prone to error accumulation. It requires a linear calibration object and is validated on three datasets utilizing different calibration objects: a 6mm metal bar and a 1:25mm biopsy needle were used for experiments. Compared to existing calibration methods for freehand ultrasound needle guidance systems, we are able to achieve higher accuracy results while additionally reducing the overall calibration complexity.
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Jung, Florian; Kirschner, Matthias; Wesarg, Stefan
A Generic Approach to Organ Detection Using 3D Haar-Like Features
Jung, Florian; Kirschner, Matthias; Wesarg, Stefan
A Generic Approach to Organ Detection Using 3D Haar-Like Features
Meinzer, Hans-Peter (Ed.) et al.: Bildverarbeitung für die Medizin 2013 : Algorithmen, Systeme, Anwendungen. Proceedings des Workshops. Berlin; Heidelberg; New York: Springer, 2013. (Informatik aktuell), pp. 320-325
Workshop Bildverarbeitung für die Medizin (BVM) <16, 2013, Heidelberg, Germany>
Automatic segmentation of medical images requires accurate detection of the desired organ as a first step. In contrast to application specific approaches, learning-based object detection algorithms are easily adaptable to new applications. We present a learning-based object detection approach based on the Viola-Jones algorithm. We propose several extensions to the original approach, including a new 3D feature type and a multi-organ detection scheme. The algorithm is used to detect six different organs in CT scans as well as the prostate in MRI data. Our evaluation shows that the algorithm provides fast and reliable detection results in all cases.
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Keil, Matthias; Kaisler, Alexander; Oyarzun Laura, Cristina; Wesarg, Stefan
Refinement and Expansion of Matched Vessel Graphs for Intraoperative Deformable Registration of Hepatic CT and Ultrasound
Keil, Matthias; Kaisler, Alexander; Oyarzun Laura, Cristina; Wesarg, Stefan
Refinement and Expansion of Matched Vessel Graphs for Intraoperative Deformable Registration of Hepatic CT and Ultrasound
Holmes III, David R. (Ed.) et al.: Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 38. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8671), pp. 867107-1 - 867107-10
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Multimodal registration of intraoperative ultrasound and preoperative contrast enhanced computed tomography (CT) imaging is the basis for image guided percutaneous hepatic interventions. Currently, the surgeon manually performs a rigid registration using vessel structures and other anatomical landmarks for visual guidance. We have previously presented our approach for an automation of this intraoperative registration step based on the definition of bijective correspondences between the vessel structures using an automatic graph matching.¹ This paper describes our method for refinement and expansion of the matched vessel graphs, resulting in a high number of bijective correspondences. Based on these landmarks, we could extend our method to a fully deformable registration. Our system was applied successfully on CT and ultrasound data of nine patients, which are studied in this paper. The number of corresponding vessel points could be raised from a mean of 9.6 points after the graph matching to 70.2 points using the presented refinement method. This allows for the computation of a smooth deformation field. Furthermore, we can show that our deformation calculation raises the registration accuracy for 3 of the 4 chosen target vessels in pre-/postoperative CT with a mean accuracy improvement of 44%.
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Keil, Matthias; Sakas, Georgios; Fellner, Dieter W.; Mönch, Christian
Ultraschallbasierte Navigation für die minimalinvasive onkologische Nieren- und Leberchirurgie
Keil, Matthias; Sakas, Georgios; Fellner, Dieter W.; Mönch, Christian
Ultraschallbasierte Navigation für die minimalinvasive onkologische Nieren- und Leberchirurgie
In der minimalinvasiven onkologischen Nieren- und Leberchirurgie mit vielen Vorteilen für den Patienten wird der Chirurg häufig mit Orientierungsproblemen konfrontiert. Hauptursachen hierfür sind die indirekte Sicht auf die Patientenanatomie, das eingeschränkte Blickfeld und die intraoperative Deformation der Organe. Abhilfe können Navigationssysteme schaffen, welche häufig auf intraoperativem Ultraschall basieren. Durch die Echtzeit-Bildgebung kann die Deformation des Organs bestimmt werden. Da viele Tumore im Schallbild nicht sichtbar sind, wird eine robuste automatische und deformierbare Registrierung mit dem präoperativen CT benötigt. Ferner ist eine permanente Visualisierung auch während der Manipulation am Organ notwendig. Für die Niere wurde die Eignung von Ultraschall-Elastographieaufnahmen für die bildbasierte Registrierung unter Verwendung der Mutual Information evaluiert. Aufgrund schlechter Bildqualität und geringer Ausdehnung der Bilddaten hatte dies jedoch nur mäßigen Erfolg. Die Verzweigungspunkte der Blutgefäße in der Leber werden als natürliche Landmarken für die Registrierung genutzt. Dafür wurden Gefäßsegmentierungsalgorithmen für die beiden häufigsten Arten der Ultraschallbildgebung B-Mode und Power Doppler entwickelt. Die vorgeschlagene Kombination beider Modalitäten steigerte die Menge an Gefäßverzweigungen im Mittel um 35 %. Für die rigide Registrierung der Gefäße aus dem Ultraschall und CT werden mithilfe eines bestehenden Graph Matching Verfahrens [OLD11b] im Mittel 9 bijektive Punktkorrespondenzen definiert. Die mittlere Registrierungsgenauigkeit liegt bei 3,45 mm. Die Menge an Punktkorrespondenzen ist für eine deformierbare Registrierung nicht ausreichend. Das entwickelte Verfahren zur Landmarkenverfeinerung fügt zwischen gematchten Punkte weitere Landmarken entlang der Gefäßmittellinien ein und sucht nach weiteren korrespondierenden Gefäßsegmenten wodurch die Zahl der Punktkorrespondenzen im Mittel auf 70 gesteigert wird. Dies erlaubt die Bestimmung der Organdeformation anhand des unterschiedlichen Gefäßverlaufes. Anhand dieser Punktkorrespondenzen kann mithilfe der Thin-Plate-Splines ein Deformationsfeld für das gesamte Organ berechnet werden. Auf diese Weise wird die Genauigkeit der Registrierung im Mittel um 44 % gesteigert. Die wichtigste Voraussetzung für das Gelingen der deformierbaren Registrierung ist eine möglichst umfassende Segmentierung der Gefäße aus dem Ultraschall. Im Rahmen der Arbeit wurde erstmals der Begriff der Regmentation auf die Segmentierung von Gefäßen und die gefäßbasierte Registrierung ausgeweitet. Durch diese Kombination beider Verfahren wurde die extrahierte Gefäßlänge im Mittel um 32 % gesteigert, woraus ein Anstieg der Anzahl korrespondierender Landmarken auf 98 resultiert. Hierdurch lässt sich die Deformation des Organs und somit auch die Lageveränderung des Tumors genauer und mit höherer Sicherheit bestimmen. Mit dem Wissen über die Lage des Tumors im Organ und durch Verwendung eines Markierungsdrahtes kann die Lageveränderung des Tumors während der chirurgischen Manipulation mit einem elektromagnetischen Trackingsystem überwacht werden. Durch dieses Tumortracking wird eine permanente Visualisierung mittels Video Overlay im laparoskopischen Videobild möglich. Die wichtigsten Beiträge dieser Arbeit zur gefäßbasierten Registrierung sind die Gefäßsegmentierung aus Ultraschallbilddaten, die Landmarkenverfeinerung zur Gewinnung einer hohen Anzahl bijektiver Punktkorrespondenzen und die Einführung der Regmentation zur Verbesserung der Gefäßsegmentierung und der deformierbaren Registrierung. Das Tumortracking für die Navigation ermöglicht die permanente Visualisierung des Tumors während des gesamten Eingriffes.
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Keyhani, Mohammad Hossein; El Hakimi, Wissam; Wesarg, Stefan
Anisotropy Correction of Medical Image Data Employing Patch Similarity
Keyhani, Mohammad Hossein; El Hakimi, Wissam; Wesarg, Stefan
Anisotropy Correction of Medical Image Data Employing Patch Similarity
Rodrigues, Pedro Pereira (Ed.) et al.: Proceedings of CBMS 2013 : The 26th IEEE International Symposium on Computer-Based Medical Systems. New York: IEEE, Inc., 2013, pp. 385-388
IEEE Symposium on Computer-Based Medical Systems (CBMS) <26, 2013, Porto, Portugal>
CT or MR image data is typically anisotropic. But, it is desirable to base image processing as well as diagnosis on isotropic image data. In this work, we propose a novel method for correcting anisotropy of 3D image data sets by employing the recurrence of small 2D patches across different scales. We base our method on previous work dealing with super-resolution of single natural 2D images, show the applicability of that approach also to medical images, and extend it to a 3D solution for anisotropy correction. Our results show that the image quality can be significantly improved. For clinical CT and MRI data, we present feedback from the clinical end user.
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Landesberger, Tatiana von; Andrienko, Gennady; Andrienko, Natalia; Bremm, Sebastian; Kirschner, Matthias; Wesarg, Stefan; Kuijper, Arjan
Opening Up the "Black Box" of Medical Image Segmentation with Statistical Shape Models
Landesberger, Tatiana von; Andrienko, Gennady; Andrienko, Natalia; Bremm, Sebastian; Kirschner, Matthias; Wesarg, Stefan; Kuijper, Arjan
Opening Up the "Black Box" of Medical Image Segmentation with Statistical Shape Models
The Visual Computer, Vol.29 (2013), 9, pp. 893-905
The importance of medical image segmentation increases in fields like treatment planning or computer aided diagnosis. For high quality automatic segmentations, algorithms based on statistical shape models (SSMs) are often used. They segment the image in an iterative way. However, segmentation experts and other users can only asses the final segmentation results, as the segmentation is performed in a "black box manner". Users cannot get deeper knowledge on how the (possibly bad) output was produced. Moreover, they do not see whether the final output is the result of a stabilized process. We present a novel Visual Analytics method, which offers this desired deeper insight into the image segmentation. Our approach combines interactive visualization and automatic data analysis. It allows the expert to assess the quality development (convergence) of the model both on global (full organ) and local (organ areas, landmarks) level. Thereby, local patterns in time and space, e.g., non-converging parts of the organ during the segmentation, can be identified. The localization and specifications of such problems helps the experts creating segmentation algorithms to identify algorithm drawbacks and thus it may point out possible ways how to improve the algorithms systematically. We apply our approach on real-world data showing its usefulness for the analysis of the segmentation process with statistical shape models.
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Landesberger, Tatiana von; Bremm, Sebastian; Kirschner, Matthias; Wesarg, Stefan; Kuijper, Arjan
Visual Analytics for Model-based Medical Image Segmentation: Opportunities and Challenges
Landesberger, Tatiana von; Bremm, Sebastian; Kirschner, Matthias; Wesarg, Stefan; Kuijper, Arjan
Visual Analytics for Model-based Medical Image Segmentation: Opportunities and Challenges
Expert Systems with Applications, Vol.40 (2013), 12, pp. 4934-4943
Segmentation of medical images is a prerequisite in clinical practice. Many segmentation algorithms use statistical shape models. Due to the lack of tools providing prior information on the data, standard models are frequently used. However, they do not necessarily describe the data in an optimal way. Model-based segmentation can be supported by Visual Analytics tools, which give the user a deeper insight into the correspondence between data and model result. Combining both approaches, better models for segmentation of organs in medical images are created. In this work, we identify the main tasks and problems in model-based image segmentation. As a proof of concept, we show that already small visual-interactive extensions can be very beneficial. Based on these results, we present research challenges for Visual Analytics in this area.
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Oyarzun Laura, Cristina; Plaza, Pablo Bueno; Drechsler, Klaus; Wesarg, Stefan
Skeleton Based Refinement of Multi-Material Volumetric Meshes
Oyarzun Laura, Cristina; Plaza, Pablo Bueno; Drechsler, Klaus; Wesarg, Stefan
Skeleton Based Refinement of Multi-Material Volumetric Meshes
Ourselin, Sebastien (Ed.) et al.: Medical Imaging 2013: Image Processing. Part Two : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 36. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8669), pp. 866936-1 - 866936-6
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
Accurate multi-material mesh generation is necessary for many applications, e.g. image-guided surgery, in which precision is important. For this application, it is necessary to enhance conventional algorithms with physiological information that adds accuracy to the results. There are several approaches working on the generation of such meshes. However, state of the art approaches show inaccuracies in the areas in which thin structures are, e.g. liver vasculature. These algorithms are not able to detect the vessels in areas in which they are narrow and they assign their elements to wrong materials, e.g., parenchyma. We propose to extend two state of the art algorithms, namely that by Boltcheva et al. and that by Pons et al. and enhance them making use of the skeleton of these structures to solve this problem. By analyzing the mesh generated by the aforementioned algorithms one can find several intersections between the mesh belonging to the vessels and the skeleton, showing that some elements must be mismatched. We evaluate the proposed algorithm in 23 clinical datasets of the liver, in which we previously segmented parenchyma and vessels. For quantitative evaluation, the meshes generated with and without skeleton information are compared. The improvements are shown by means of intersection number, volume and length differences of the vasculature mesh using the different methods. The results show an improvement of 65% for the number of intersections, 4% for the volume and 22% for the length.
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Steger, Sebastian; Bozoglu, Y. Nazli; Kuijper, Arjan; Wesarg, Stefan
Application of Radial Ray Based Segmentation to Cervical Lymph Nodes in CT Images
Steger, Sebastian; Bozoglu, Y. Nazli; Kuijper, Arjan; Wesarg, Stefan
Application of Radial Ray Based Segmentation to Cervical Lymph Nodes in CT Images
IEEE Transactions on Medical Imagaing, Vol.32 (2013), 5, pp. 888-900
The 3D-segmentation of lymph nodes in CT images is required for staging and disease progression monitoring. Major challenges are shape and size variance, as well as low contrast, image noise, and pathologies. In this paper, radial ray based segmentation is applied to lymph nodes: From a seed point, rays are cast into all directions and an optimization technique determines a radius for each ray based on image appearance and shape knowledge. Lymph node specific appearance cost functions are introduced and their optimal parameters are determined. For the first time, the resulting segmentation accuracy of different appearance cost functions and optimization strategies are compared. Further contributions are extensions to reduce the dependency on the seed point, to support a larger variety of shapes, and to enable interaction. The best results are obtained using graph-cut on a combination of the direction weighted image gradient and accumulated intensities outside a predefined intensity range. Evaluation on 100 lymph nodes shows that with an average symmetric surface distance of 0.41 mm the segmentation accuracy is close to manual segmentation and outperforms existing radial ray and model based methods. The method's inter-observer-variability of 5.9% for volume assessment is lower than the 15.9% obtained using manual segmentation.
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Steger, Sebastian; Fellner, Dieter W.; Sakas, Georgios
Registrierung und Segmentierung von Lymphknoten aus multimodalen Zeitreihen im Kopf-Hals-Bereich
Steger, Sebastian; Fellner, Dieter W.; Sakas, Georgios
Registrierung und Segmentierung von Lymphknoten aus multimodalen Zeitreihen im Kopf-Hals-Bereich
Der verlässlichste unabhängige prognostische Faktor für den Krankheitsverlauf von Patienten mit Kopf-Hals-Karzinom ist das Vorhandensein von Lymphknotenmetastasen. Eine computergestützte Untersuchung und zeitliche Verfolgung von Lymphknoten in mehreren Bildmodalitäten durch ein multimodales, multitemporales Modell bietet viele Vorteile, insbesondere in Bezug auf Reproduzierbarkeit. Grundvoraussetzung dafür ist jedoch eine robuste automatische Registrierung und Segmentierung von Lymphknoten aus multimodalen Zeitreihen. Da existierende Verfahren den Anforderungen nicht genügen, werden dazu in dieser Arbeit neuartige Methoden entwickelt und evaluiert. Zur Lymphknotensegmentierung aus CT-Datensätzen wird ein Radialstrahl-basiertes 3D-Verfahren umfangreich behandelt. Ausgehend von einem Saatpunkt werden Strahlen radial in alle möglichen Richtungen gleichverteilt geschickt und ein Optimierungsverfahren bestimmt für jeden Strahl unter Einbeziehung von Bildinformation und lokalem Formwissen den bestmöglichen Radius und somit eine Segmentierung. Erstmalig findet ein Vergleich unterschiedlicher bildbasierter Kostenfunktionen statt und die Parameter werden durch ein datengetriebenes Verfahren bestimmt. Mit einer durchschnittlichen Oberflächendistanz von nur 0.46 mm ist die Segmentierungsgenauigkeit im Bereich der manuellen Expertensegmentierung und deutlich besser als existierende semi-automatische Verfahren. Die Inter-Observer-Variabilität zur Volumenbestimmung ist um den Faktor 3 geringer als bei manueller Volumenbestimmung. Neben Lymphknoten eignet sich das Verfahren auch zur Segmentierung anderer rundlicher Strukturen, wie z.B. Tumore, und bietet auch für einige Organe, wie z.B. die Prostata, eine Alternative zur modellbasierten Segmentierung. Die Registrierung einzelner Lymphknoten erfordert die automatische deformierbare Registrierung des gesamten Kopf-Hals-Bereichs. Dazu wird in dieser Arbeit die erste vollautomatische generalisierbare multi-rigide Methode vorgestellt. Sie basiert auf einem neuartigen artikulierten Atlas, welcher neben Wissen über Form und Aussehen einzelner Knochen auch deren relative Lagen (Artikulation) aus Trainingsdaten lernt. Dieser wird zunächst zur gleichzeitigen Segmentierung der Knochen aus dem CT-Datensatz verwendet. Ausgehend davon wird er durch personalisiertes Wissen angereichert und an die andere Bildmodalität oder Zeitserienaufnahme unter Berücksichtigung des gelernten Artikulationsraums angepasst. Die daraus berechneten rigiden Transformationen werden in einem zweistufigen Prozess in das umliegende Weichteilgewebe propagiert und ein dichtes Deformationsfeld entsteht. Abschließend wird die Registrierungsgenauigkeit innerhalb der Lymphknoten durch ein lokal rigides Registrierungsverfahren verbessert. Die Vorteile der multi-rigiden Registrierung liegen in dem großen Konvergenzbereich und der geringen Anfälligkeit für Bildartefakte aufgrund der einzigartigen globalen Regularisierung. Innerhalb von Lymphknotenzentren wird eine Registrierungsgenauigkeit von durchschnittlich 5.05 mm erreicht. Gegenüber der B-Spline Registrierung ergibt sich eine Verbesserung um 37% und eine subjektiv deutlich besser empfundene Qualität der erzeugten deformierten Bilder. Die wichtigsten Beiträge dieser Arbeit sind zur Segmentierung von Lymphknoten eine neue Kostenfunktion, ein umfangreicher Vergleich verschiedener Kostenfunktionen und eine datengetriebene Parameterwahl. Die Hauptbeiträge zur Bildregistrierung sind das Lernen der relativen Elementlagen, ein adaptives Anpassungsverfahren und die Personalisierung des artikulierten Atlas.
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Steger, Teena; Hoßbach, Martin; Wesarg, Stefan
Marker Detection Evaluation by Phantom and Cadaver Experiments for C-arm Pose Estimation Pattern
Steger, Teena; Hoßbach, Martin; Wesarg, Stefan
Marker Detection Evaluation by Phantom and Cadaver Experiments for C-arm Pose Estimation Pattern
Holmes III, David R. (Ed.) et al.: Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 14, No. 38. Bellingham: SPIE Press, 2013. (Proceedings of SPIE 8671), pp. 86711V-1 - 86711V-9
SPIE Medical Imaging Symposium <2013, Lake Buena Vista, FL, USA>
C-arm fluoroscopy is used for guidance during several clinical exams, e.g. in bronchoscopy to locate the bronchoscope inside the airways. Unfortunately, these images provide only 2D information. However, if the C-arm pose is known, it can be used to overlay the intrainterventional fluoroscopy images with 3D visualizations of airways, acquired from preinterventional CT images. Thus, the physician's view is enhanced and localization of the instrument at the correct position inside the bronchial tree is facilitated. We present a novel method for C-arm pose estimation introducing a marker-based pattern, which is placed on the patient table. The steel markers form a pattern, allowing to deduce the C-arm pose by use of the projective invariant cross-ratio. Simulations show that the C-arm pose estimation is reliable and accurate for translations inside an imaging area of 30 cm x 50 cm and rotations up to 30°. Mean error values are 0.33 mm in 3D space and 0.48 px in the 2D imaging plane. First tests on C-arm images resulted in similarly compelling accuracy values and high reliability in an imaging area of 30 cm x 42.5 cm. Even in the presence of interfering structures, tested both with anatomy phantoms and a turkey cadaver, high success rates over 90% and fully satisfying execution times below 4 sec for 1024 px × 1024 px images could be achieved.
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Steger, Teena; Steger, Sebastian; Wesarg, Stefan
Marker Removal for C-Arm Pose Estimation Based Bronchoscope Navigation Using Image Inpainting
Steger, Teena; Steger, Sebastian; Wesarg, Stefan
Marker Removal for C-Arm Pose Estimation Based Bronchoscope Navigation Using Image Inpainting
Österreichische Gesellschaft für Biomedizinische Technik (ÖGBMT): Proceedings BMT (Biomedizinische Technik) 2013 - Dreiländertagung der Deutschen, Schweizerischen und Österreichischen Gesellschaft für Biomedizinische Technik : Biomedizinische Technik - Biomedical Engineering, Vol. 58 (2013) Heft SI-1. Berlin: de Gruyter, 2013, pp. 637-638
Dreiländertagung der Deutschen, Schweizerischen und Österreichischen Gesellschaft für Biomedizinische Technik (BMT) <2013, Graz, Austria>
Using marker-based C-arm pose estimation during bronchoscopy in combination with a preoperative CT segmentation of the bronchial tree, the 3D spatial position of the bronchoscope tip inside the airways can be deter-mined. Naturally, the markers used for pose estimation appear on the fluoroscopy images, which can be disturbing for the physician`s view. To address this issue, we deploy inpainting to remove the reprojected markers from the fluoroscopy. The method was applied to phantom and cadaver images acquired from almost 50 different C-arm poses in total. Pose estimation was successful in 97, 5% of the test cases. Employing our inpainting method to these cases resulted in thorough removal of all markers in the fluoroscopy thereby ostensibly preserving anatomy structures.
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Steger, Teena; Wesarg, Stefan
Virtual and Augmented 3D Bronchoscopy Navigation Based on C-arm Fluoroscopy
Steger, Teena; Wesarg, Stefan
Virtual and Augmented 3D Bronchoscopy Navigation Based on C-arm Fluoroscopy
Paul, Lothar (Ed.) et al.: 3D-NordOst 2013 : 16. Anwendungsbezogener Workshop zur Erfassung, Modellierung, Verarbeitung und Auswertung von 3D-Daten. Berlin: GFaI, 2013, pp. 65-74
Anwendungsbezogener Workshop zur Erfassung, Modellierung, Verarbeitung und Auswertung von 3D-Daten (3D-NordOst) <16, 2013, Berlin, Germany>
Instrument guidance during bronchoscopy is a very intricate task, which demands profound anatomical knowledge and good orientation skills from the physician. Apart from bronchoscopic video, intraoperative C-arm images of the instruments inside the airways are the only auxiliary means available. By tracing the 2D position of the instrument on the fluoroscopy back to its 3D position inside the bronchial tree, an effective navigation support is provided. Given the intraoperative C-arm pose, a preoperative segmentation of the airways and automatic tracking of the 2D position of the instrument on the fluoroscopy, this 3D position of the bronchoscopic instruments can be followed during the whole intervention without manual user interaction. In this paper, we present a bronchoscopy navigation system for virtual preoperative planning and augmented intraoperative guidance. The whole system was successfully tested by inserting a bronchoscope into a bronchial tree model under continuous fluoroscopy. During the procedure, the current 3D position of the bronchoscope's tip could be tracked and visualized inside the bronchial tree segmentation.
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Weiler, Marcel; Sakas, Georgios (Betreuer); Keil, Matthias (Betreuer)
Enhanced Vessel Segmentation in Ultrasound by Registration with CT
Weiler, Marcel; Sakas, Georgios (Betreuer); Keil, Matthias (Betreuer)
Enhanced Vessel Segmentation in Ultrasound by Registration with CT
Darmstadt, TU, Bachelor Thesis, 2013
In navigated liver surgery the surgeon depends on the combination of pre-operative CT scans, which are already acquired and used during the planning phase, and intra-operative ultrasound (U/S) scans, which reflect the current situation, especially the deformation the liver undergoes due to a different positioning of the patient. However, the high amount of noise and the low contrast in ultrasound scans makes the segmentation of the liver vascularity in ultrasound scans difficult. CT scans on the other hand offer a much better image quality and thereby a clear segmentations. Because of this, the two scans are often registered against each other to offer a basis of comparison for the surgeon. I take this approach even one step further and propose a segmentation technique that uses the information from the CT scan directly to improve the ultrasound segmentation. The new segmentation now serves two purposes: For one, the surgeon is supplied with additional information about the current situation of the liver and its deformation. The second purpose is that the newly found vessels offer an additional set of natural landmarks, which can be used in further registration steps.
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Wilbers, Daniel; Roth, Stefan (Betreuer); Jung, Christoph (Betreuer)
Robust Real-Time Gesture Recognition Based on Hidden Conditional Random Fields
Wilbers, Daniel; Roth, Stefan (Betreuer); Jung, Christoph (Betreuer)
Robust Real-Time Gesture Recognition Based on Hidden Conditional Random Fields
Darmstadt, TU, Bachelor Thesis, 2013
Using innovative input methods, such as speech commands and hand gestures, is of growing interest for controlling consumer devices. The currently available systems mostly provide a remote control as the main-way for controlling the device. In recent research the focus more often switches to providing a multi-modal system, meaning that can be controlled with various input methods. One contribution to such a system is the in this thesis examined aspect of using gestures as an input method Therefore, the aim is to investigate and develop a gesture recognition system, which is able to spot and classify a limited set of gesture within a continuous data stream. Due to that this thesis covers the two necessary aspects of a continuous gesture recognition system. To address the problem of spotting, which is detecting the start and end of a gesture, the use of a special activation posture is proposed, while the class of the gesture type is computed by a gesture classification module. For this, instead of using the well-known generative graphical model Hidden Markov Model (HMM), the gesture recognition module is based on the recently introduced discriminative graphical model Hidden Conditional Random Fields (HCRF), which in contrast to the HMM lacks the necessary independence of observations and hence performs generally better in human gesture recognition. The features used by the HCRF classification scheme are extracted from 3D skeleton joint data provided by the Microsoft Kinect SDK. This skeleton data only contains the upper body joints, which results from the typically seated position of the user and is in contrast to recently proposed gesture recognition modules. In addition two different gesture sets are explored and discussed. The evaluation shows that the proposed gesture spotting method achieved 91.38% accuracy, whereas the gesture classification with hidden conditional random fields best performed with up 98.33% accuracy.
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Bozoglu, Y. Nazli; Sakas, Georgios (Betreuer); Steger, Sebastian (Betreuer)
Evaluierung von Algorithmen zur Segmentierung von Lymphknoten in CT Datensätzen
Bozoglu, Y. Nazli; Sakas, Georgios (Betreuer); Steger, Sebastian (Betreuer)
Evaluierung von Algorithmen zur Segmentierung von Lymphknoten in CT Datensätzen
Hannover, Leibniz-Univ., Master Thesis, 2012
Die Untersuchung der Größe und Form von Lymphknoten spielt in der Diagnostik und Verlaufskontrolle von Krebspatienten eine wichtige Rolle. Für diese Untersuchung müssen die Lymphknoten in Computertomographie (CT) Datensätzen segmentiert werden. Die manuelle Segmentierung ist zeitaufwändig und fehleranfällig. Für eine präzise Segmentierung von Lymphknoten sind automatische Segmentierungsverfahren erwünscht. In der Literatur werden einige vielversprechende Segmentierungsalgorithmen beschrieben. Alle diese Algorithmen haben ihre Vor- und Nachteile. Eine Gegenüberstellung der Algorithmen wird vermisst. In dieser Arbeit werden vier neue automatische Segmentierungsalgorithmen entwickelt. Die Parameter der Verfahren werden optimiert. Anhand Goldstandards von Experten werden im Anschluss diese vier Methoden und Regionen-, modell- und strahlenbasierte Segmentierungsalgorithmen aus der Literatur in Bezug auf die Genauigkeit, Laufzeit und Robustheit evaluiert und gegenübergestellt. Für die Evaluierung steht ein CT-Datensatz zur Verfügung, für den manuelle Segmentierungen von Experten vorliegen. Der Datensatz besteht aus 49 Lymphknoten der Kopf- und Halsregion von Patienten mit Mundhöhlenkarzinomen. Bei der Gegenüberstellung der Algorithmen wurde festgestellt, dass der strahlenbasierte Ansatz, bei dem die Segmentierung unter Berücksichtigung lokaler Gradienteneigenschaften und Intensitätseigenschaften von Lymphknoten mit anschließender globaler Optimierung erfolgt, am besten für die Segmentierung von Lymphknoten geeignet ist. Die Laufzeit der Segmentierung ist mit 8 Sekunden pro Lymphknoten 3-5 fache der anderen Segmentierungsverfahren. Die Segmentierung ist aber sehr präzise. Der durchschnittliche DSC beträgt 0.80. Bei der Initialisierung mit unterschiedlichen Saatpunkten ist die Methode sehr robust. Bei der Segmentierung von vergrößerten Lymphknoten beträgt der durchschnittliche DSC 0.86, bei der Segmentierung von nekrotischen Lymphknoten 0.81. Anhand von automatischen Segmentierungsalgorithmen können Lymphknoten erfolgreich segmentiert werden. Die Ergebnisse der Segmentierung können z.B. für die dreidimensionale Visualisierung, Verlaufskontrolle von Krebspatienten oder Operationsplanung weiterverarbeitet werden.
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Drechsler, Klaus; Erdt, Marius; Oyarzun Laura, Cristina; Wesarg, Stefan
Multiphase Risk Assessment of Atypical Liver Resections
Drechsler, Klaus; Erdt, Marius; Oyarzun Laura, Cristina; Wesarg, Stefan
Multiphase Risk Assessment of Atypical Liver Resections
Soda, Paolo (Ed.) et al.: 25th IEEE Symposium on Computer-Based Medical Systems and HealthGrid Conference : The 25th IEEE International Symposium on Computer-Based Medical Systems. New York: IEEE, Inc., 2012, 4 p.
IEEE Symposium on Computer-Based Medical Systems (CBMS) <25, 2012, Rome, Italy>
In this work, we present a system based on open-source toolkits that can utilize multiple phases of a liver CT dataset to plan a surgery before the patient enters the operation room. The contributions are an optimized deformable registration of arterial and venous phases of the liver and a methodology to assess surgical risk utilizing both phases. It is shown by the example of two clinical cases, how our system enables the fusion of complementary information into a 3D representation of the patient anatomy. Processing times of single processing steps on a modern machine are quite low, which allows for an integration into clinical routine.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Simulation of Portal Vein Clamping and the Impact of Safety Margins for Liver Resection Planning
Drechsler, Klaus; Oyarzun Laura, Cristina
Simulation of Portal Vein Clamping and the Impact of Safety Margins for Liver Resection Planning
Yoshida, Hiroyuki (Ed.) et al.: Abdominal Imaging: Computational and Clinical Applications : Third International Workshop Held in Conjunction with MICCAI 2011. Berlin, Heidelberg, New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7029), pp. 149-156
International Workshop on Computational and Clinical Applications in Abdominal Imaging <3, 2011, Toronto, Canada>
In this work, we present a planning tool for liver interventions. It allows for a simulation of the color change on the liver surface after clamping the portal vein at a user defined position. The result is a patient-specific approximation of the (sub-) segmental borders on the liver surface. Furthermore, the impact of different safety margins around a tumor can be simulated to assess the risk of a resection. In addition, it provides delinated portal- and hepatic vein, which can be overlapped to the 2D CT slices, and 3D visualization of the results.
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Drechsler, Klaus; Oyarzun Laura, Cristina; Wesarg, Stefan
Interventional Planning of Liver Resections: An Overview
Drechsler, Klaus; Oyarzun Laura, Cristina; Wesarg, Stefan
Interventional Planning of Liver Resections: An Overview
IEEE Engineering in Medicine and Biology Society (EMBS): 34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Proceedings : EMBC 2012. Stoughton: Printing House, 2012, pp. 3744-3747
Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) <34, 2012, San Diego, CA, USA>
Liver cancer is the third most common type of cancer. Among available treatment options, a surgical resection offers the best prognosis for long-term survival. It is important that such a surgical procedure is carefully prepared. Modern computer technology offers convenient ways to simulate different resection scenarios and help to determine the best treatment for a given case. This paper provides a non-exhaustive overview of existing computer-based systems for interventional planning of liver resections. They are reviewed according to their medical use case, e.g. if they support typical or atypical resections.
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Drechsler, Klaus; Sakas, Georgios; Fellner, Dieter W.; Mönch, Christian
Extraction of Hepatic Veins in Contrast Enhanced CT with Application to Interventional Planning
Drechsler, Klaus; Sakas, Georgios; Fellner, Dieter W.; Mönch, Christian
Extraction of Hepatic Veins in Contrast Enhanced CT with Application to Interventional Planning
The Liver performs several important tasks that are essential for survival. However, liver cancer, the third most common type of cancer, affects these functions significantly. Different treatment options are available, but a surgical resection, if possible, offers the best prognosis for the patient. Thus, the decision, whether a surgical resection is feasible, is important and must be taken with care in a pre-interventional planning stage. Modern volumetric imaging techniques such as CT or magnetic resonance imaging (MRI) are utilized to decide which treatment is best for the patient and to plan the intervention. However, the amount of anatomical details visible in the acquired volumes is steadily increasing. This comes along with an increasing amount of data per patient. Manual examination is time consuming and prone to errors. As a matter of fact, several software systems were proposed to support the surgeon during the planning phase. The extraction of blood vessels plays an important role in these applications. The segmentation of vessels is a challenging problem that has to deal with acquisition-dependent problems such as noise, contrast, spatial resolution, and artifacts. Furthermore, blood vessel specific characteristics like high variability of size and curvature result in additional difficulties for segmentation algorithms. The liver, in particular, exhibits another challenge to vessel segmentation algorithms. Its supply and drain vessel systems are densely distributed within the liver, and because of partial volume effects and motion artifacts, they seem to be connected at some points. The focus of the present thesis is the robust extraction of hepatic veins in multiphase CT volumes. Therefore, an image processing pipeline is presented that covers vessel enhancement, vessel segmentation, graph creation and tree reconstruction. The pipeline was used to develop an application for interventional planning. It allows for the simulation of intraoperative hepatic vein clamping for (sub-)segment oriented liver resections and the execution of risk analysis to judge surgical risk during an atypical resection. Furthermore, results of the present thesis were also successfully used in an application for intraoperative navigation to extract liver vessels in 3D ultrasound data and matching of anatomical vessel trees and graphs of the liver for registration of 3D volumes.
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El Hakimi, Wissam; Wesarg, Stefan
Confidence Map Based Super-resolution Reconstruction
El Hakimi, Wissam; Wesarg, Stefan
Confidence Map Based Super-resolution Reconstruction
Haynor, David R. (Ed.) et al.: Medical Imaging 2012: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 13, No. 30. Bellingham: SPIE Press, 2012. (Proceedings of SPIE 8314), pp. 831440-1 - 831440-10
SPIE Medical Imaging Symposium <2012, San Diego, CA, USA>
Magnetic Resonance Imaging and Computed Tomography usually provide highly anisotropic image data, so that the resolution in the slice-selection direction is poorer than in the in-plane directions. An isotropic high-resolution image can be reconstructed from two orthogonal scans of the same object. While combining the different data sets, all input data are usually equally weighted, without considering the fidelity level of each input information. In this paper we introduce a novel super-resolution method, which considers the fidelity level of each input data by introducing an adaptive confidence map. Experimental results on simulated and real data sets have shown the improved accuracy of reconstructed images, whose resolution approximate the original in-plane resolution in all directions. The quality of the reconstructed high resolution image was improved for noiseless input data sets, and even in the presence of different noise types with a low peak signal to noise ratio.
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Erdt, Marius; Oyarzun Laura, Cristina; Drechsler, Klaus; De Beni, Stefano; Solbiati, Luigi
Improving Diagnosis and Intervention: A Complete Approach for Registration of Liver CT Data
Erdt, Marius; Oyarzun Laura, Cristina; Drechsler, Klaus; De Beni, Stefano; Solbiati, Luigi
Improving Diagnosis and Intervention: A Complete Approach for Registration of Liver CT Data
Yoshida, Hiroyuki (Ed.) et al.: Abdominal Imaging: Computational and Clinical Applications : Third International Workshop Held in Conjunction with MICCAI 2011. Berlin, Heidelberg, New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7029), pp. 108-115
International Workshop on Computational and Clinical Applications in Abdominal Imaging <3, 2011, Toronto, Canada>
Registration of liver CT scans from different points in time or different phases of contrast agent saturation is a highly demanded tool for computer aided diagnosis, operation planning and intervention. This work presents a complete registration workflow to precisely overlap scans from 4 different application scenarios including registration of pretreatment and post-treatment data as well as registration of multi-phase CT. Various state of the art techniques in shape modeling and matching, visualization as well as augmented interaction are applied to cover all of the described scenarios in a clinically usable system. Our system has been in use for clinical evaluation under real life conditions and has been tested on more than 30 patients.
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Erdt, Marius; Sakas, Georgios; Fellner, Dieter W.; Vogl, Thomas J.
Non-Uniform Deformable Volumetric Objects for Medical Organ Segmentation and Registration
Erdt, Marius; Sakas, Georgios; Fellner, Dieter W.; Vogl, Thomas J.
Non-Uniform Deformable Volumetric Objects for Medical Organ Segmentation and Registration
In medical imaging, large amounts of data are created during each patient examination, especially using 3-dimensional image acquisition techniques such as Computed Tomography. This data becomes more and more difficult to handle by humans without the aid of automated or semi-automated image processing means and analysis. Particularly, the manual segmentation of target structures in 3D image data is one of the most time consuming tasks for the physician in the context of using computerized medical applications. In addition, 3D image data increases the difficulty of mentally comparing two different images of the same structure. Robust automated organ segmentation and registration methods are therefore needed in order to fully utilize the potentials of modern medical imaging. This thesis addresses the described issues by introducing a new model based method for automated segmentation and registration of organs in 3D Computed Tomography images. In order to be able to robustly segment organs in low contrast images, a volumetric model based approach is proposed that incorporates texture information from the model's interior during adaptation. It is generalizable and extendable such that it can be combined with statistical shape modeling methods and standard boundary detection approaches. In order to increase the robustness of the segmentation in cases where the shape of the target organ significantly deviates from the model, local elasticity constraints are proposed. They limit the flexibility of the model in areas where shape deviation is unlikely. This allows for a better segmentation of untrained shapes and improves the segmentation of organs with complex shape variation like the liver. The model based methods are evaluated on the liver in the portal venous and arterial contrast phase, the bladder, the pancreas, and the kidneys. An average surface distance error between 0.5 mm and 2.0 mm is obtained for the tested structures which is in most cases close to the interobserver variability between different humans segmenting the same structure. In the case of the pancreas, for the first time, an automatic segmentation from single phase contrast enhanced CT becomes feasible. In the context of organ registration, the developed methods are applied to deformable registration of multi-phase contrast enhanced liver CT data. The method is integrated into a clinical demonstrator and is currently in use for testing in two clinics. The presented method for automatic deformable multi-phase registration has been quantitatively and qualitatively evaluated in the clinic. In nearly all tested cases, the registration quality is sufficient for clinical needs. The result of this thesis is a new approach for automatic organ segmentation and registration that can be applied to various clinical problems. In many cases, it can be used to significantly reduce or even remove the amount of manual contour drawing. In the context of registration, the approach can be used to improve clinical diagnosis by overlaying different images of the same anatomical structure with higher quality than existing methods. The combination of proposed segmentation and registration therefore saves valuable clinician time in dealing with today's 3D medical imaging data.
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Erdt, Marius; Steger, Sebastian; Sakas, Georgios
Regmentation: A New View of Image Segmentation and Registration
Erdt, Marius; Steger, Sebastian; Sakas, Georgios
Regmentation: A New View of Image Segmentation and Registration
JROI-Journal of Radiation Oncology Informatics, Vol.4 (2012), 1, pp. 1-23
Image segmentation and registration have been the two major areas of research in the medical imaging community for decades and still are. In the context of radiation oncology, segmentation and registration methods are widely used for target structure definition such as prostate or head and neck lymph node areas. In the past two years, 45% of all articles published in the most important medical imaging journals and conferences have presented either segmentation or registration methods. In the literature, both categories are treated rather separately even though they have much in common. Registration techniques are used to solve segmentation tasks (e.g. atlas based methods) and vice versa (e.g. segmentation of structures used in a landmark based registration). This article reviews the literature on image segmentation methods by introducing a novel taxonomy based on the amount of shape knowledge being incorporated in the segmentation process. Based on that, we argue that all global shape prior segmentation methods are identical to image registration methods and that such methods thus cannot be characterized as either image segmentation or registration methods. Therefore we propose a new class of methods that are able solve both segmentation and registration tasks. We call it regmentation. Quantified on a survey of the current state of the art medical imaging literature, it turns out that 25% of the methods are pure registration methods, 46% are pure segmentation methods and 29% are regmentation methods. The new view on image segmentation and registration provides a consistent taxonomy in this context and emphasizes the importance of regmentation in current medical image processing research and radiation oncology image-guided applications.
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Erdt, Marius; Steger, Sebastian; Wesarg, Stefan
Deformable Registration of MR Images using a Hierarchical Patch Based Approach With a Normalized Metric Quality Measure
Erdt, Marius; Steger, Sebastian; Wesarg, Stefan
Deformable Registration of MR Images using a Hierarchical Patch Based Approach With a Normalized Metric Quality Measure
IEEE Engineering in Medicine and Biology Society (EMBS): 2012 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2012. New York: IEEE Press, 2012, pp. 1347-1350
IEEE International Symposium on Biomedical Imaging (ISBI) <9, 2012, Barcelona, Spain>
Magnitude Diffusion Weighted Magnetic Resonance Imaging (DW-MRI) is used to detect lesions in abdominal organs such as the liver. For diagnosis and interventional planning, DW-MRI needs to be registered with Magnetic Resonance (MRI) images in order to provide an anatomical context. DWMRI usually generates images that contain large regions with only little image information. This makes it difficult to elastically register those images to images from other imaging modalities. In this work, we apply a deformable registration approach in order to register magnitude DW-MRI data with MRI images. A normalized quality measure is used to sort out local deformations in low image signal areas that cause non-plausible local deformations. An evaluation on 5 patients shows promising results.
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Gregori, Johannes; Hoßbach, Martin; Kern, R.; Günther, Matthias
Real Time Correction of Extended Segmented Arterial Spin Labeling Protocols using Stereoscopic Optical Head Motion Tracking
Gregori, Johannes; Hoßbach, Martin; Kern, R.; Günther, Matthias
Real Time Correction of Extended Segmented Arterial Spin Labeling Protocols using Stereoscopic Optical Head Motion Tracking
Magnetic Resonance Materials in Physics, Biology and Medicine, Vol.25 (2012), 1 Supplement, p. 227
The Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB) <29, 2012, Lisbon, Portugal>
Head motion results in severe image artifacts especially in Arterial Spin Labeling (ASL), which relies on identical positioning of label and control images. This issue is amplified when using segmented readout - which cannot be corrected in post processing - and running extended clinical protocols. A real-time head motion tracking system is evaluated using MR-compatible cameras attached to the head coil, tracking blue dot markers on the forehead. Two ASL protocols were evaluated based on the protocols of a current clinical acute stroke treatment study, where monitoring during thrombolysis is done using repeated ASL perfusion imaging over a period of one hour.
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Gutbell, Ralf; Becker, Meike; Wesarg, Stefan
Ein Prototyp zur Planung von Bohrpfaden für die minimal-invasive Chirurgie an der Otobasis
Gutbell, Ralf; Becker, Meike; Wesarg, Stefan
Ein Prototyp zur Planung von Bohrpfaden für die minimal-invasive Chirurgie an der Otobasis
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2012 : Algorithmen, Systeme, Anwendungen. Berlin; Heidelberg; New York: Springer, 2012. (Informatik aktuell), pp. 171-176
Workshop Bildverarbeitung für die Medizin (BVM) <15, 2012, Berlin, Germany>
Bei Operationen an der Otobasis ist es wichtig, umliegende Risikostrukturen wie Gesichtsnerv oder Blutgefäße nicht zu verletzen. Bisher legt der Arzt dazu alle Strukturen frei. Unser Forschungsprojekt untersucht nun einen minimal-invasiven Multi-Port-Ansatz. Im Rahmen dieses Projektes haben wir basierend auf SOFA einen Prototypen zur Planung von Bohrpfaden an der Otobasis entwickelt. Damit kann der Arzt sowohl einen Bohrkanal genauer analysieren als auch sich die Menge aller zulässigen Pfade anzeigen lassen, aus der er schließlich die besten Bohrpfade für die Operation auswählt. Dies ist ein erster Schritt, den Arzt bei der Planung von mehreren Bohrkanälen zu unterstützen.
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Herb, Daniel; Tausch, Reimar (Betreuer); Amend, Bernd (Betreuer)
GPU basierte Berechnung von Disparitätskarten zum Zusammensetzen von übergangslosen 360° Panoramen in Echtzeit
Herb, Daniel; Tausch, Reimar (Betreuer); Amend, Bernd (Betreuer)
GPU basierte Berechnung von Disparitätskarten zum Zusammensetzen von übergangslosen 360° Panoramen in Echtzeit
Darmstadt, Hochschule, Bachelor Thesis, 2012
In dieser Arbeit wird ein System zum übergangslosen Zusammenfügen von Videos implementiert. Die zugrunde liegende Hardware besteht aus acht fest miteinander verbundenen Kameras, die so ausgerichtet sind, dass das Gesamtsystem einen Bereich von 360° abdeckt. Die Objektive der Kameras sind dabei so gewählt, dass zwischen den Einzelbildern Überlappungsbereiche entstehen, in denen der gleiche Teil der Szene erfasst wird. Da das optische Zentrum der Kameras nicht im selben Punkt liegt, kommt es zwischen den Bildern zu Parallaxenfehlern, wodurch ein direktes Zusammenfügen nicht möglich ist. In dieser Arbeit werden zur korrekten Behandlung der Überlappungsbereiche Stereokorrespondenzverfahren verwendet, um sogenannte Stitchmaps zu berechnen, welche Informationen darüber beinhalten, welche Bildpunkte aus beiden Bildern dieselben Weltkoordinaten darstellen und somit kombiniert werden sollen. Da die Auswahl des Stereokorrespondenzverfahrens starke Auswirkungen auf das resultierende Panorama hat, gleichzeitig aber eine große Auswahl an unterschiedlichen Verfahren existiert, wurde eine visuelle, qualitative Evaluation zwischen zwei ausgewählten Verfahren durchgeführt. Dabei handelt es sich um das Constant-Space-Belief-Propagation und das Semi- Global-Matching-Verfahren. Hierbei wurde festgestellt, dass sich die Verfahren bei geeigneter Parametrisierung nur unmerklich unterscheiden. Da ein echtzeitfähiges Gesamtsystem angestrebt wurde, fand eine GPU-Implementierung mit OpenCL statt. Hierfür wurde auf Basis der durch die qualitative Evaluation gewonnenen Erkenntnisse und aufgrund der besseren Parametrisierbarkeit das Belief-Propagation-Verfahren ausgewählt. Für diese Implementierung fand eine zeitliche Evaluation gegenüber einer vergleichbaren, existierenden Implementierung aus der OpenCV Bibliothek statt. Hierbei konnte für die meisten Parameterkonfigurationen ein Beschleunigungsfaktor von etwa zwei erreicht werden.
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Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Clinical Workflow Optimized Calibration-Method for Stereo-Optical Tracking in MRI
Hoßbach, Martin; Gregori, Johannes; Wesarg, Stefan; Günther, Matthias
Clinical Workflow Optimized Calibration-Method for Stereo-Optical Tracking in MRI
Magnetic Resonance Materials in Physics, Biology and Medicine, Vol.25 (2012), 1 Supplement, p. 580
The Annual Scientific Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB) <29, 2012, Lisbon, Portugal>
Though motion tracking for head motion compensation in MRI has been a research topic for some time [1-4], literature is not giving much attention to the calibration of such systems. We present a method to calibrate the coordinate systems of a stereo-optical camera setup mounted to the MRI head coil and show that, though using a simple setup and visible light [1], it is possible to achieve a sub-millimeter tracking precision.
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Keil, Matthias; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Combining B-Mode and Color Flow Vessel Segmentation for Registration of Hepatic CT and Ultrasound Volumes
Keil, Matthias; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan
Combining B-Mode and Color Flow Vessel Segmentation for Registration of Hepatic CT and Ultrasound Volumes
Ropinski, Timo (Ed.) et al.: Eurographics Workshop on Visual Computing for Biology and Medicine : EG VCBM 2012. Goslar: Eurographics Association, 2012, pp. 57-64
Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM) <3, 2012, Norrköping, Sweden>
Multimodal registration of intraoperative ultrasound and preoperative computed tomography imaging is the basis for percutaneous hepatic interventions. Currently, a rigid registration is performed manually by the surgeon using vessel structures and other anatomical landmarks for visual guidance. In this work our approach for intraoperative vessel segmentation from two ultrasound imaging modes, namely B-Mode and color flow mode, is presented. This segmentation is an important step for automation of the intraoperative registration which relies on vessel structures visible in contrast enhanced CT and ultrasound volumes. This paper describes the problems that arise when using B-mode ultrasound for segmentation of vessels and how they can be solved by introducing additional vessel information from color flow imaging. On a total number of 21 patients, our system was applied successfully in 15 cases. For nine randomly chosen patients studied in this paper, our system achieves a 3.45 mm accuracy at points used for registration and 5.01 mm for other landmarks which were not used for the registration process.
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Kirschner, Matthias; Jung, Florian; Wesarg, Stefan
Automatic Prostate Segmentation in MR Images with a Probabilistic Active Shape Model
Kirschner, Matthias; Jung, Florian; Wesarg, Stefan
Automatic Prostate Segmentation in MR Images with a Probabilistic Active Shape Model
Barratt, Dean (Workshop Organizer) et al.: PROMISE12. Proceedings : MICCAI 2012 Grand Challenge on Prostate MR Image Segmentation, pp. 28-35
Prostate MR Image Segmentation Challenge (PROMISE12) <2012, Nice, France>
Segmentation of the prostate gland in Magnetic Resonance (MR) images is an important task for image-guided prostate cancer therapy. The low contrast of the prostate to surrounding tissue in MR images makes automatic segmentation very challenging. In this paper, we propose an automatic approach for robust and accurate prostate segmentation in T2-weighted MR scans. We first employ a boosted prostate detector to locate the prostate in the images, and then use a Probabilistic Active Shape Model for the delineation of its contour. Our approach has been quantitatively evaluated on 50 MR images, on which we achieve a median dice coefficient of 0.85 (IQR: 0.09).
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Kirschner, Matthias; Wesarg, Stefan
Regularisierung lokaler Deformation im probabilistischen Active Shape Model
Kirschner, Matthias; Wesarg, Stefan
Regularisierung lokaler Deformation im probabilistischen Active Shape Model
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2012 : Algorithmen, Systeme, Anwendungen. Berlin; Heidelberg; New York: Springer, 2012. (Informatik aktuell), pp. 328-333
Workshop Bildverarbeitung für die Medizin (BVM) <15, 2012, Berlin, Germany>
Zur robusten und präzisen Segmentierung von Organen in medizinischen Bilddaten werden oft Varianten des Active Shape Models (ASM) verwendet, die über eine Energieminimierung einen Kompromiss zwischen Bildinformation und Vorwissen über die zu erwartende Organform bestimmen. Im probabilistischen ASM (PASM) wird die Plausibilität einer Form mit Hilfe einer Wahrscheinlichkeitsverteilung bewertet. Da diese lediglich globale, nicht aber lokale Formvariation ausreichend modelliert, kann der PASM ungleichmäßige und damit unplausible Segmentierungskonturen erzeugen. In dieser Arbeit wird der PASM um ein lokales Deformationsmodell erweitert, welches zu glatten Segmentierungskonturen führt. Das lokale Deformationsmodell wird an einem linearen PASM zur Lebersegmentierung und einem nichtlinearen PASM zur Wirbelsegmentierung evaluiert. Die Ergebnisse zeigen, dass die Erweiterung quantitativ wie qualitativ bessere Segmentierungen liefert.
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Meixner, Steven; Drechsler, Klaus (Betreuer)
Konzeption und Realisierung einer Testumgebung zum standardisierten Evaluieren von Gefäßsegmentierungs-Algorithmen
Meixner, Steven; Drechsler, Klaus (Betreuer)
Konzeption und Realisierung einer Testumgebung zum standardisierten Evaluieren von Gefäßsegmentierungs-Algorithmen
Darmstadt, Hochschule, Bachelor Thesis, 2012
Computersimulationen zur Unterstützung von Ärzten bei der Diagnose und Therapie (z.B. zur Navigation bei chirurgischen Eingriffen) sind im Vormarsch. Solche medizinischen Softwareapplikationen bieten ein hohes Maß an Präzision und unterstützen den Chirurgen bei der Operation. Bei der operativen Entfernung eines Tumors aus der Leber beispielsweise werden auch Teile der Leber mit entfernt. Diese operative Entfernung von Gewebe aus einem Organ wird auch als Resektion bezeichnet. Eine computergestützte Planung von Resektionsstellen in der präoperativen Phase ermöglicht eine exakte Bestimmung der Gefäße, welche den Tumor versorgen und welche Gefäße zur weiteren Durchblutung anderer Segmente der Leber benötigt werden. Diese Möglichkeit der Operationsplanung führt zu einer Minimierung von Komplikationen während der Operation und somit nicht zuletzt zu einer höheren Heilungsquote und schnelleren Genesung des Patienten. Hierzu werden in der präoperativen Phase die Gefäße aus einem durch Computertomographie (CT) gewonnenen Volumenbild der Leber segmentiert. Der verwendete Segmentierungsalgorithmus muss dabei trotz unterschiedlich starkem Kontrast und Rauschen der CT-Bilddaten möglichst präzise Ergebnisse erzielen. Es ist daher immens wichtig, bei der Erstellung einer solchen medizinischen Applikation ein geeignetes Segmentierungsverfahren zu wählen oder aber auch selbst zu entwickeln. Die Ergebnisse, die dieser Segmentierungsalgorithmus liefert, sollten frühzeitig evaluiert werden. Zwar wird in zahlreichen Publikationen für neu entwickelte Segmentierungsalgorithmen mit guten Evaluationsergebnissen geworben, jedoch wurden diese getrennt voneinander und mit unterschiedlicher Herangehensweise in der Implementierung und Wahl der Metriken evaluiert. Ein quantitativer Vergleich zwischen diesen Segmentierungsalgorithmen ist deshalb nicht möglich. Diese Arbeit zeigt nun den Weg von der Konzipierung bis hin zur Umsetzung einer Testumgebung, die eine standardisierte und somit objektive und zuverlässige Evaluierung von Segmentierungsalgorithmen ermöglicht. Diese Algorithmen werden dabei mit Hilfe derselben Evaluationsmetriken untersucht und die Ergebnisse in einen quantitativen Vergleich gesetzt. Als "Ground-Truth-Segmentierung" dienen Gefäßbäume, die auf Basis biologischer Wachstumsprozesse simuliert werden. Demonstriert wird die Funktionalität der Testumgebung in Form einer beispielhaften Evaluierung von zwei Segmentierungsalgorithmen.
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Oyarzun Laura, Cristina; Drechsler, Klaus; Erdt, Marius; Keil, Matthias; Noll, Matthias; De Beni, Stefano; Sakas, Georgios; Solbiati, Luigi
Intraoperative Registration for Liver Tumor Ablation
Oyarzun Laura, Cristina; Drechsler, Klaus; Erdt, Marius; Keil, Matthias; Noll, Matthias; De Beni, Stefano; Sakas, Georgios; Solbiati, Luigi
Intraoperative Registration for Liver Tumor Ablation
Yoshida, Hiroyuki (Ed.) et al.: Abdominal Imaging: Computational and Clinical Applications : Third International Workshop Held in Conjunction with MICCAI 2011. Berlin, Heidelberg, New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7029), pp. 133-140
International Workshop on Computational and Clinical Applications in Abdominal Imaging <3, 2011, Toronto, Canada>
Computer aided navigation augments intraoperatively gathered U/S with planning information that the doctor carries out before the intervention on a CT volume. A crucial step for the navigation is the registration between CT and U/S. Our approach consists on a landmark based registration. The correspondences between both modalities are found automatically using a graph to graph matching algorithm. Therefore, liver and vessels are previously segmented. The whole process has being tested on 15 pairs of real clinical data. The results are promising.
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Rahman, Sami ur; Thöne, Clara; Wesarg, Stefan; Völker, Wolfram
Simulation Based Patient-specific Optimal Catheter Selection for Right Coronary Angiography
Rahman, Sami ur; Thöne, Clara; Wesarg, Stefan; Völker, Wolfram
Simulation Based Patient-specific Optimal Catheter Selection for Right Coronary Angiography
Holmes III, David R. (Ed.) et al.: Medical Imaging 2012: Image-Guided Procedures, Robotic Interventions, and Modeling : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 13, No. 32. Bellingham: SPIE Press, 2012. (Proceedings of SPIE 8316), pp. 83162S-1 - 83162S-8
SPIE Medical Imaging Symposium <2012, San Diego, CA, USA>
Selecting the best catheter prior to coronary angiography significantly reduces the exposure time to radiation as well as the risk of artery punctures and internal bleeding. In this paper we describe a simulation based technique for selecting an optimal catheter for right coronary angiography using the Simulation Open Framework Architecture (SOFA). We simulate different catheters in a patient-specific arteries model, obtain final placement of different catheters and suggest an optimally placed catheter. The patient-specific arteries model is computed from the patient image data acquired prior to the intervention and the catheters are modeled using Finite Element Method (FEM).
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Rahman, Sami ur; Vateva, Tsvetoslava; Wesarg, Stefan
Enhancing Super-resolution Reconstructed Image Quality in 3D MR Images Using Simulated Annealing
Rahman, Sami ur; Vateva, Tsvetoslava; Wesarg, Stefan
Enhancing Super-resolution Reconstructed Image Quality in 3D MR Images Using Simulated Annealing
Haynor, David R. (Ed.) et al.: Medical Imaging 2012: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 13, No. 30. Bellingham: SPIE Press, 2012. (Proceedings of SPIE 8314), pp. 831441-1 - 831441-9
SPIE Medical Imaging Symposium <2012, San Diego, CA, USA>
Super-resolution reconstruction (SRR) algorithms are used for getting high-resolution (HR) data from low-resolution observations. In Maximum a posteriori (MAP) based SRR the observation model is employed for estimating a HR image that best reproduces the two low-resolution input data sets. The parameters of the prior play a significant role in the MAP based SRR. This work concentrates on the investigation of the influence of one such parameter, called temperature, on the reconstructed 3D MR images. The existing approaches on SRR in 3D MR images use a constant value for this parameter. We use a cooling schedule similar to simulated annealing for computing the value of the temperature parameter at each iteration of the SRR. We have used 3D MR cardiac data sets in our experiments and have shown that the iterative computation of the temperature which resembles simulated annealing delivers better results.
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Salvi, Dario; Picone, Marco; Arredondo, María Teresa; Cabrera-Umpierrez, Maria Fernanda; Esteban, Angel; Steger, Sebastian; Poli, Tito
Merging Person-Specific Bio-Markers for Predicting Oral Cancer Recurrence through an Ontology
Salvi, Dario; Picone, Marco; Arredondo, María Teresa; Cabrera-Umpierrez, Maria Fernanda; Esteban, Angel; Steger, Sebastian; Poli, Tito
Merging Person-Specific Bio-Markers for Predicting Oral Cancer Recurrence through an Ontology
IEEE Transactions on Biomedical Engineering, (2012), Early Access Articles. 31 August 2012, 5 p.
One of the major problems related to cancer treatment is its recurrence. Without knowing in advance how likely the cancer will relapse, clinical practice usually recommends adjuvant treatments that have strong side-effects. A way to optimize treatments is to predict the recurrence probability by analysing a set of bio-markers. The NeoMark European project has identified a set of preliminary bio-markers for the case of oral cancer by collecting a large series of data from genomic, imaging and clinical evidences. This heterogeneous set of data needs a proper representation in order to be stored, computed and communicated efficiently. Ontologies are often considered the proper mean to integrate biomedical data, for their high level of formality and for the need of interoperable, universally accepted, models. This paper presents the NeoMark system and how an ontology has been designed to integrate all its heterogeneous data. The system has been validated in a pilot which data will populate the ontology and will be made public for further research.
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Steger, Sebastian; Kirschner, Matthias; Wesarg, Stefan
Articulated Atlas for Segmentation of the Skeleton from Head & Neck CT Datasets
Steger, Sebastian; Kirschner, Matthias; Wesarg, Stefan
Articulated Atlas for Segmentation of the Skeleton from Head & Neck CT Datasets
IEEE Engineering in Medicine and Biology Society (EMBS): 2012 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2012. New York: IEEE Press, 2012, pp. 1256-1259
IEEE International Symposium on Biomedical Imaging (ISBI) <9, 2012, Barcelona, Spain>
In this paper a novel articulated atlas for the fully automated segmentation of the skeleton from head & neck CT datasets is presented. An individual atlas describing the shape and appearance is created for each individual bone. Principal Component Analysis is used to learn spatial relations between those atlases resulting in a unified articulated atlas. Transformations are parameterized using the matrix exponential to enable linear combinations required for learning. The adaptation to test images considers appearance, distance to bone structures and the trained articulation space. For evaluation, an atlas created from 10 manually labeled training images has been applied to 46 clinically acquired head & neck CT datasets. Visual inspection showed that in 74% of the cases, the adaptation process was successful. In a second experiment leave-one-out validation was used to quantify the segmentation accuracy. The successfully adapted cases resulted in an average volume overlap error of 30.67 and an average symmetric surface distance of 0.76 mm.
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Steger, Sebastian; Sakas, Georgios
Image Gradient Based Shape Prior for the Segmentation of not that Spherical Structures
Steger, Sebastian; Sakas, Georgios
Image Gradient Based Shape Prior for the Segmentation of not that Spherical Structures
IEEE Engineering in Medicine and Biology Society (EMBS): 2012 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2012. New York: IEEE Press, 2012, pp. 1252-1255
IEEE International Symposium on Biomedical Imaging (ISBI) <9, 2012, Barcelona, Spain>
A popular method for the segmentation of somewhat spherical structures (e.g. certain types of tumors, lymph nodes, lung nodules) from 3D medical images is sending out radial rays from a central point and determining the most likely radius for each ray, resulting in a closed surface. Besides satisfying some image based criteria, a regularization term or shape prior typically ensures a smooth contour by preferring similar radii of neighboring rays. In this paper we show that the structures it is often applied to, are in fact not that spherical. We propose an alternate shape prior depending on the gradient direction, preferring smooth structures that are not necessarily spherical. We quantitatively evaluate the proposed shape prior with the traditionally used shape prior on a set of 49 lymph nodes from clinical images. A dice similarity coefficient improvement of 4% has been observed (0.80 vs. 0.77), yielding in segmentation accuracy close to manual segmentation (DSC of 0.83).
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Steger, Sebastian; Sakas, Georgios
FIST: Fast Interactive Segmentation of Tumors
Steger, Sebastian; Sakas, Georgios
FIST: Fast Interactive Segmentation of Tumors
Yoshida, Hiroyuki (Ed.) et al.: Abdominal Imaging: Computational and Clinical Applications : Third International Workshop Held in Conjunction with MICCAI 2011. Berlin, Heidelberg, New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7029), pp. 125-132
International Workshop on Computational and Clinical Applications in Abdominal Imaging <3, 2011, Toronto, Canada>
Automatic segmentation methods for tumors are typically only suitable for a specific type of tumor in a specific imaging modality and sometimes lack in accuracy whereas manual tumor segmentation achieves the desired results but is very time consuming. Interactive segmentation however speeds up the process while still being able to maintain the accuracy of manual segmentation. This paper presents a novel method for fast interactive segmentation of tumors (called FIST) from medical images, which is suitable for all somewhat spherical tumors in any 3d medical imaging modality. The user clicks in the center of the tumor and a belief propagation based iterative adaption process is initiated, thereby considering image gradients as well as local smoothness priors of the surface. During that process, instant visual feedback is given, enabling to intervene in the adaption process by sketching parts of the contour in any cross section. The approach has successfully been applied to the segmentation of liver tumors in CT datasets. Satisfactory results could be achieved in 15.21 seconds on the average. Further trials on oropharynx tumors, liver tumors and the prostate from MR images as well as lymph nodes and the bladder from CT volumes demonstrate the generality of the presented approach.
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Steger, Sebastian; Wesarg, Stefan
Automated Skeleton Based Multi-modal Deformable Registration of Head&Neck Datasets
Steger, Sebastian; Wesarg, Stefan
Automated Skeleton Based Multi-modal Deformable Registration of Head&Neck Datasets
Ayache, Nicholas (Ed.) et al.: Medical Image Computing and Computer-Assisted Intervention - MICCAI 2012: Part II : 15th International Conference. Berlin; Heidelberg; New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7511), pp. 66-73
International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI) <15, 2012, Nice, France>
This paper presents a novel skeleton based method for the registration of head&neck datasets. Unlike existing approaches it is fully automated, spatial relation of the bones is considered during their registration and only one of the images must be a CT scan. An articulated atlas is used to jointly obtain a segmentation of the skull, the mandible and the vertebrae C1-Th2 from the CT image. These bones are then successively rigidly registered with the moving image, beginning at the skull, resulting in a rigid transformation for each of the bones. Linear combinations of those transformations describe the deformation in the soft tissue. The weights for the transformations are given by the solution of the Laplace equation. Optionally, the skin surface can be incorporated. The approach is evaluated on 20 CT/MRI pairs of head&neck datasets acquired in clinical routine. Visual inspection shows that the segmentation of the bones was successful in all cases and their successive alignment was successful in 19 cases. Based on manual segmentations of lymph nodes in both modalities, the registration accuracy in the soft tissue was assessed. The mean target registration error of the lymph node centroids was 5.33 ± 2.44 mm when the registration was solely based on the deformation of the skeleton and 5.00 ± 2.38 mm when the skin surface was additionally considered. The method's capture range is sufficient to cope with strongly deformed images and it can be modified to support other parts of the body. The overall registration process typically takes less than 2 minutes.
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Steger, Teena; Hoßbach, Martin
Navigated Bronchoscopy Using Intraoperative Fluoroscopy and Preoperative CT
Steger, Teena; Hoßbach, Martin
Navigated Bronchoscopy Using Intraoperative Fluoroscopy and Preoperative CT
IEEE Engineering in Medicine and Biology Society (EMBS): 2012 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2012. New York: IEEE Press, 2012, pp. 1220-1223
IEEE International Symposium on Biomedical Imaging (ISBI) <9, 2012, Barcelona, Spain>
Bronchoscopic biopsies for diagnosis of lung cancer are usually done with the help of intraoperative fluoroscopy. But fluoroscopy images lack 3D information and do not provide a clear view of the bronchi or lesions. Our goal is to enhance the physician's view by overlaying the intraoperative fluoroscopy images with both 2D and 3D airway visualizations from preoperatively taken CT scans. The presented system provides automatic airway segmentation and skeletonization as well as automatic 2D/3D alignment of fluoroscopy to CT. The results are used for correctly overlaying the airways and visualizing bronchoscopic paths. The only additional equipment needed is a specifically designed pattern of steel spheres and sticks on acrylic glass, which is fixed on the patient table. It is used for estimating the C-arm pose during image acquisition and allows 2D/3D image alignment in clinically feasible time (<6 s) and accuracy (mTRE<0.33mm on simulated data). No interference with the physician's standard bronchoscopy procedure is introduced and no additional radiation exposure is required. On the contrary, by improving the physician's view and orientation inside the bronchial tree, a faster and more target-oriented guidance to the site of interest is possible.
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Wesarg, Stefan; Kirschner, Matthias; Becker, Meike; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Dual-energy CT-based Assessment of the Trabecular Bone in Vertebrae
Wesarg, Stefan; Kirschner, Matthias; Becker, Meike; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Dual-energy CT-based Assessment of the Trabecular Bone in Vertebrae
Methods of Information in Medicine, Vol.51 (2012), 5, pp. 398-405
Background: Osteoporosis can cause severe fractures of bone structures. One important indicator for pathology is a lowered bone mineral density (BMD) - conventionally assessed by dual-energy X-ray absorptiometry (DXA). Dual-energy CT (DECT) - being an alternative that is increasingly used in the clinics - allows the computation of the spatial BMD distribution. Objectives: Using DECT, the trabecular bone of vertebrae is examined. Several analysis methods for revealing the bone density distribution as well as appropriate visualization methods for detecting regions of lowered BMD are needed for computer-assisted diagnosis (CAD) of osteoporosis. The hypothesis that DECT is better suited than DXA for the computation of local BMD is investigated. Methods: Building on a model of the interaction of X-rays with bone tissue, novel methods for assessing the spatial structure of the trabecular bone are presented. CAD of DECT image data is facilitated by segmenting the regions of interest interactively and with an Active Shape Model, respectively. The barycentric space of fractional volumes is introduced as a novel means for analyzing bone constitution. For 29 cadaver specimens, DECT as well as DXA has been examined. BMD values derived from both modalities are compared to local force measurements. In addition, clinical data from two patients who underwent DECT scanning for a different reason is analyzed retrospectively. Results: A novel automated delineation method for vertebrae has been successfully applied to DECT data sets. It is shown that localized BMD measurements based on DECT show a stronger linear correlation (R² = 0.8242, linear regression) to local force measurements than density values derived from DXA (R² = 0.4815). Conclusions: DECT based BMD assessment is a method to extend the usage of increasingly acquired DECT image data. The developed DECT based analysis methods in conjunction with the visualization provide more detailed information for both, the radiologist and the orthopedist, compared to standard DXA based analysis.
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Yoshida, Hiroyuki; Sakas, Georgios; Linguraru, Marius George
Abdominal Imaging: Computational and Clinical Applications: Third International Workshop Held in Conjunction with MICCAI 2011
Yoshida, Hiroyuki; Sakas, Georgios; Linguraru, Marius George
Abdominal Imaging: Computational and Clinical Applications: Third International Workshop Held in Conjunction with MICCAI 2011
International Workshop on Computational and Clinical Applications in Abdominal Imaging <3, 2011, Toronto, Canada>
Lecture Notes in Computer Science (LNCS) 7029
ISSN: 0302-9743
ISBN: 9783642285561
The third international workshop focused on three areas in computational abdominal imaging: virtual colonoscopy and computer-aided diagnosis, abdominal intervention, and computational abdominal anatomy. The workshop aimed to bring together leading researchers and clinicians active in these fields around the world to discuss emerging techniques and clinical challenges in computational and clinical applications in abdominal imaging.
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Billings, Seth; Kapoor, Ankur; Wood, Bradford J.; Keil, Matthias; Boctor, Emad
A Hybrid Surface/Image-Based Approach to Facilitate Ultrasound/CT Registration
Billings, Seth; Kapoor, Ankur; Wood, Bradford J.; Keil, Matthias; Boctor, Emad
A Hybrid Surface/Image-Based Approach to Facilitate Ultrasound/CT Registration
D'hooge, Jan (Ed.) et al.: Medical Imaging 2011: Ultrasonic Imaging, Tomography, and Therapy : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 12, No. 37. Bellingham: SPIE Press, 2011. (Proceedings of SPIE 7968), pp. 79680V-1 - 79680V-12
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
Registration of intra-operative ultrasound with preoperative CT is highly desirable as a navigational aid for surgeons and interventional radiologists. Image-based solutions generally achieve poor results due to substantially different image appearance of ultrasound and CT. A method is presented that uses surface information and tracked ultrasound to improve registration results. Tracked ultrasound is combined with surface and image-based registration techniques to register ultrasound to CT. Surface data is acquired using an optically tracked range sensor, for example time-of-flight camera. Range data is registered to CT using robust point-set registration; this registration provides an approximate transformation from tracker to CT coordinates. The ultrasound probe is also optically tracked. The probe position and surface-based registration provide a first estimate for the position of the ultrasound image in CT coordinates. This estimate is subsequently refined by a final image-based registration stage. Initial tests using Coherent Point Drift algorithm for registering surface data to CT show favorable results. Tests using both simulated and real time-of-flight range data have good convergence over a wide initial translation and rotation misalignment domain. Preliminary testing using time-of-flight surface data suggests that surface to CT registration may be useful as an initial guess enabling later more precise (but less robust) image based methods for registering ultrasound images to CT. We believe this method will enable image-based algorithms to robustly converge to an optimal registration solution.
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Brauer, Achim; Erdt, Marius (Betreuer)
Automatische lernbasierte Landmarkendetektion in medizinischen Bilddaten
Brauer, Achim; Erdt, Marius (Betreuer)
Automatische lernbasierte Landmarkendetektion in medizinischen Bilddaten
Darmstadt, Hochschule, Master Thesis, 2011
Computertomographische (CT) Ganzkörper-Bilddaten werden im medizinischen Umfeld üblicherweise zur Diagnose von Erkrankungen im Inneren des menschlichen Körpers verwendet, wie zum Beispiel der Diagnose von Krebs. Die automatische Detektion von räumlich markanten Strukturen - sogenannten Landmarken - in CT-Bilddaten stellt die Basis für Segmentierungsverfahren dar, mit deren Hilfe die Lage und Ausdehnung von Organen, wie zum Beispiel der Leber und der Nieren, ermittelt werden kann. Die Landmarkendetektion unterstützt die Analyse und fördert das Verständnis des Bildinhaltes medizinischer Bilddaten. Im Folgenden wird ein Konzept zur automatischen lernbasierten Detekion von dreidimensionalen Landmarken in Ganzkörper-CT-Bilddaten unter Verwendung des maschinellen Lernverfahrens AdaBoost und zweier neuwertiger generischer Bildmerkmale, dem sogenannten 3D-HOG- und 3D-HOGI-Bildmerkmal [Three-dimensional Histogram of Oriented Gradients (and Intensities)], vorgestellt. Es wurden Landmarken-Klassifikatoren für jeweils beide Nieren und die Leber erstellt, mit deren Hilfe die Lage und grobe räumliche Ausdehung der Organe innerhalb eines CT-Datensatzes bestimmt werden können, ohne auf organspezifisches Wissen zurückgreifen zu müssen. Durch Evaluation der Klassifikatoren anhand von 25 Ganz- und Teilkörper-CT-Datensätzen konnte gezeigt werden, dass die Klassifikatoren eine sehr robuste und präzise Detektion der jeweiligen Organe ermöglichen.
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Chen, Yufei; Drechsler, Klaus; Oyarzun Laura, Cristina; Zhao, Weidong; Liu, Yanli
A Graph Description and Analysis Framework of Liver Vascular System
Chen, Yufei; Drechsler, Klaus; Oyarzun Laura, Cristina; Zhao, Weidong; Liu, Yanli
A Graph Description and Analysis Framework of Liver Vascular System
Journal of Computational Information Systems, Vol.7 (2011), 6, pp. 1998-2005
Accurate description and analysis of liver vascular system is critical in diagnosis and treatment of liver diseases. Even though there are plenty of researches put their efforts on the acquisition of optimal visual information in liver vascular system, quite a few studies focus on the quantitatively geometrical and structural analysis on them. In this paper, we proposed a graph description and analysis framework for liver vascular structure representation. First of all, the vessels were enhanced through Hessian eigenvalue calculation in order to be conveniently segmented from the liver image. Secondly, a three dimensional thinning based skeletonization method was applied on the vessel image to obtain the topological structure of the liver vessels. The skeleton result was then represented as a graph, followed by the geometrical attributes computation. Finally, the graph was efficiently pruned to form a directed acyclic vascular tree without redundant and irrelevant branches based on a flow conservation approach. The experiments on liver CT datasets show that the proposed framework can effectively obtain the liver vascular structure and its quantitative description.
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Chen, Yufei; Drechsler, Klaus; Zhao, Weidong; Oyarzun Laura, Cristina
Liver Vessel Tree Generation Based on Skeletonization and Graph Representation
Chen, Yufei; Drechsler, Klaus; Zhao, Weidong; Oyarzun Laura, Cristina
Liver Vessel Tree Generation Based on Skeletonization and Graph Representation
The 5th International Conference on Bioinformatics and Biomedical Engineering : iCBBE 2011. New York: The Institute of Electrical and Electronics Engineers (IEEE), 2011, 4 p.
International Conference on Bioinformatics and Biomedical Engineering (iCBBE) <5, 2011, Wuhan, China>
Liver vessel tree generation is of importance for liver disease diagnosis and surgery plan. In this paper, we propose a method for generation of the liver vessel tree based on skeletonization and graph representation. First of all, basic methodology in the proposed method is introduced. Secondly, the 3D-thinning skeletonization algorithm together with the graph-based technique are employed on the liver vasculature to form an undirected cyclic graph. Thirdly, a new flow conservation based approach is applied to efficiently prune the graph into a directed acyclic tree. Experiments on a variety of liver CT datasets show the effectiveness and efficiency of the proposed method.
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Chen, Yufei; Drechsler, Klaus; Zhao, Weidong; Oyarzun Laura, Cristina
A Thinning-based Liver Vessel Skeletonization Method
Chen, Yufei; Drechsler, Klaus; Zhao, Weidong; Oyarzun Laura, Cristina
A Thinning-based Liver Vessel Skeletonization Method
IEEE Communications Society: 2011 International Conference on Internet Computing and Information Services : ICICIS 2011. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2011, pp. 152-155
International Conference on Internet Computing and Information Services (ICICIS) <2011, Hong Kong, China)
In the clinical practice of diagnosis and treatment of liver disease, how to effectively represent and analyze the vascular structure has been a widely studied topic for a long time. In this paper, we propose a method for the three-dimensional skeletal graph generation of liver vessels using 3D thinning algorithm and graph theory. First of all, the principal methods for skeletonization are introduced, followed by their comparative analysis. Secondly, the 3D thinning-based skeletonization method together with a filling hole pre-processing on liver vessel image is employed to form the liver skeleton. A graph-based technique is then employed on the skeleton image to efficiently form the liver vascular graph. The thinning-based liver vessel skeletonization method was evaluated on liver vessel images with other two kinds of skeletonization approaches to show its effectiveness and efficiency.
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Diamantopoulos, Stefanos; Milickovic, Natasa; Butt, Saeed; Katsilieri, Zaira; Kefala, Vasiliki; Zogal, Pawel; Sakas, Georgios; Baltas, Dimos
Effect of Using Different U/S Probe Standoff Materials in Image Geometry for Interventional Procedures: The Example of Prostate
Diamantopoulos, Stefanos; Milickovic, Natasa; Butt, Saeed; Katsilieri, Zaira; Kefala, Vasiliki; Zogal, Pawel; Sakas, Georgios; Baltas, Dimos
Effect of Using Different U/S Probe Standoff Materials in Image Geometry for Interventional Procedures: The Example of Prostate
Journal of Contemporary Brachytherapy, Vol.3 (2011), 4, pp. 209-219
Purpose: This study investigates the distortion of geometry of catheters and anatomy in acquired U/S images, caused by utilizing various stand-off materials for covering a transrectal bi-planar ultrasound probe in HDR and LDR prostate brachytherapy, biopsy and other interventional procedures. Furthermore, an evaluation of currently established waterbath based quality assurance (QA) procedures is presented. Material and methods: Image acquisitions of an ultrasound QA setup were carried out at 5 MHz and 7 MHz. The U/S probe was covered by EA 4015 Silicone Standoff kit, or UA0059 Endocavity balloon filled either with water or one of the following: 40 ml of Endosgel®, Instillagel®, Ultraschall gel or Space OARTM gel. The differences between images were recorded. Consequently, the dosimetric impact of the observed image distortion was investigated, using a tissue equivalent ultrasound prostate phantom - Model number 053 (CIRS Inc., Norfolk, VA, USA). Results: By using the EA 4015 Silicone Standoff kit in normal water with sound speed of 1525 m/s, a 3 mm needle shift was observed. The expansion of objects appeared in radial direction. The shift deforms also the PTV (prostate in our case) and other organs at risk (OARs) in the same way leading to overestimation of volume and underestimation of the dose. On the other hand, Instillagel® and Space OARTM "shrinks" objects in an ultrasound image for 0.65 mm and 0.40 mm, respectively. Conclusions: The use of EA 4015 Silicone Standoff kit for image acquisition, leads to erroneous contouring of PTV and OARs and reconstruction and placement of catheters, which results to incorrect dose calculation during prostate brachytherapy. Moreover, the reliability of QA procedures lies mostly in the right temperature of the water used for accurate simulation of real conditions of transrectal ultrasound imaging.
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Drechsler, Klaus; Oelmann, Simon; Oyarzun Laura, Cristina
Separation of Interconnected Hepatic Veins
Drechsler, Klaus; Oelmann, Simon; Oyarzun Laura, Cristina
Separation of Interconnected Hepatic Veins
Olive, Mark (Ed.) et al.: Twenty-Fourth IEEE Symposium on Computer-Based Medical Systems and HealthGrid Conference : CBMS 2011 + HG 2011. Los Alamitos, Calif.: IEEE Computer Society, 2011, 6 p.
IEEE Symposium on Computer-Based Medical Systems (CBMS) <24, 2011, Bristol, UK>
The proper separation of hepatic veins is crucial for discriminative visualization during surgical planning and intraoperative navigation, automated analysis and liver segment approximation. However, due to several reasons liver and portal vein may be connected at some points and may contain loops. In this work, we propose a novel graphbased method to separate interconnected hepatic veins. Furthermore, we show how to transfer the graph-based separation results back to the imaging data to improve the initial segmentation and discriminate portal and liver vein. In addition, we propose a majority voting operation to correct some segmentation imperfections. Promising qualitative and quantitative evaluation results are presented.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Closing the Gap: From Planning to Intervention in Cardiology
Drechsler, Klaus; Oyarzun Laura, Cristina
Closing the Gap: From Planning to Intervention in Cardiology
Richard, Paul (Ed.) et al.: Computer Vision, Imaging and Computer Graphics : Theory and Applications. Berlin, Heidelberg, New York: Springer, 2011. (Communications in Computer and Information Science 229), pp. 187-200
International Joint Conference on Computer Vision and Computer Graphics Theory and Applications (VISIGRAPP) <5, 2010, Angers, France>
It is likely that in the near future the diagnostic of coronary arteries will be done using non-invasive computed tomography angiography and that only the intervention, if necessary, will be carried out using invasive techniques. Preinterventional gathered CTA data can be used to carry out an automated quantitative analysis of the arteries, which can provide complementary information during a cardiac catheterization when only coronary angiograms are available. We propose an anatomical landmark-based rigid 3D/2D registration algorithm which enables the fusion of both modalities. It has to solve for six transformation parameters (three rotation and three translation parameters). An exhaustive search in a six dimensional search space is usually computationally very expensive and algorithms using optimization strategies can get lost in local minima. We propose a method based on centroids to reduce search space from six to four dimensions and use information stored in modern C-Arm devices to further reduce the search space. With our method registration errors of < 2 mm are feasible. Execution times of < 1 sec. can be reached on a QuadCore CPU.
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Drechsler, Klaus; Strosche, Michael; Oyarzun Laura, Cristina
Automatic ROI Identification for Fast Liver Tumor Segmentation Using Graph-Cuts
Drechsler, Klaus; Strosche, Michael; Oyarzun Laura, Cristina
Automatic ROI Identification for Fast Liver Tumor Segmentation Using Graph-Cuts
Dawant, Benoit M. (Ed.) et al.: Medical Imaging 2011: Image Processing. Part Two : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 12, No. 31. Bellingham: SPIE Press, 2011. (Proceedings of SPIE 7962), pp. 79622S-1 - 79622S-7
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
The key challenge in tumor segmentation is to determine their exact location and volume. Difficulties arise because of low intensity boundaries, varying shapes and sizes. Furthermore, tumors can be located everywhere in the liver. Interactive segmentation methods seem to be the most appropriate in terms of reliability and robustness. In this work, we use a graph-cut based method to interactively segment tumors. However, complexity of the underlying graphs is enormous for clinical 3D datasets. We propose a method to identify automatically a region of interest using a coarse resolution image, which is then used to construct a reduced graph for final segmentation in the original image in full resolution. We compared our results to ground truth segmentations done by experts. Our results suggest that accuracy is comparable to other approaches. The average overlap was 80%, the average surface distance 0.73 mm and the average maximum surface distance 5.31 mm.
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Duarte, Carlos; Langdon, Pat; Jung, Christoph; Coelho, Jose; Biswas, Pradipta; Hamisu, Pascal
GUIDE: Creating Accessible TV Applications
Duarte, Carlos; Langdon, Pat; Jung, Christoph; Coelho, Jose; Biswas, Pradipta; Hamisu, Pascal
GUIDE: Creating Accessible TV Applications
Gelderblom, Gert Jan (Ed.) et al.: Everyday Technology for Independence and Care : AAATE 2011. Amsterdam; Berlin: IOS Press, 2011. (Assistive Technology Research Series 29), pp. 905-912
European Conference for the Advancement of Assistive Technology (AAATE) <11, 2011, Maastricht, Netherlands>
Objective. In this paper we describe a novel adaptive accessibility framework for Hybrid TV platforms and the user-centred approach that is being used in its design. It integrates various types of user interface (UI) technologies, supports multimodal interaction, performs adaptation to individual needs and limitations of elderly users, and uses virtual user simulation for efficient UI testing in the design process. Main content. Digital TV has gained importance as an interactive and personalized media terminal, now combining traditional broadcast content with internet and legacy web services. However, the elderly face problems when using these services. The availability of accessible user interfaces and supporting software is very limited. For developers, user-centred design and provision of accessible user interfaces is expensive and time-consuming. In order to support developers we propose a solution comprising of (1) an adaptive software framework and (2) a set of tools to support development, including a simulation tool. The software framework can be integrated in existing applications and provides an API for developers to automatically perform adaptation of user interface input and output data. The simulation tool is able to render simulated perception of elderly users for the developers. Results. The approach presented relies on user modeling identifying the most relevant impairment configurations among users in comprehensive trials. Using the simulation tool, developers can iteratively make modifications in order to optimize their application's UI. Simulation considers models for perception, cognition and motor functions. The resulting design is then executed in a framework where first time users are characterized by a procedure which measures their individual abilities. A user model instance is then the foundation of a multi-modal adaptation module performing input fusion and output fission for various combinations of user interface technologies considering the user impairments and high level events describing the interaction context. As a result, the system selects proper combinations and configurations of available input and output modalities. Conclusion. For elderly users, accessible ICT can make much more of a difference in living quality, by enabling and simplifying participation and inclusion in their surrounding communities. By supporting TV application developers through a design time simulation tool, and a run time adaptive framework, we lay the basis to drastically improve overall accessibility of these applications.
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Eckeren, Katharina van; Tausch, Reimar (Betreuer)
Evaluierung von verschiedenen Verfahren zur automatischen Bestimmung der Kopforientierung von Personen
Eckeren, Katharina van; Tausch, Reimar (Betreuer)
Evaluierung von verschiedenen Verfahren zur automatischen Bestimmung der Kopforientierung von Personen
Darmstadt, Hochschule, Bachelor Thesis, 2011
In dieser Arbeit wird ein klassifikator-basierter Ansatz vorgestellt und evaluiert. Er ermöglicht es, mit den Daten einer monokularen Kamera die Kopfpose von Personen, die als Indikator der Blickrichtung und Aufmerksamkeit verwendet werden kann, diskret zu bestimmen. Der Raum aller Kopfposen, der aus den Kopfbewegungen von links nach rechts (Zeilen) und von oben nach unten (Spalten) besteht, wird mittels eines Rasters diskret in Klassen unterteilt. Der verwendete Klassifikator ist eine lineare Support Vector Machine. Als Deskriptoren werden verkleinerte Vorschaubilder in Farbe, Graustufen und Gradienten, sowie die Histogram of oriented gradients (HOG) evaluiert. Sie wurden für jede Klasseneinteilung getestet und ihre Ergebnisse ausgewertet. Es wurden drei verschiedene Poseneinteilungen vorgenommen: Fünf (1 x 5), neun (3 x 3) und 15 (3 x 5)Klassen. Im ersten Durchlauf wurde der Klassifikator für fünf (1 x 5) mögliche Kopfposen getestet. Anschließend wurde die Anzahl der möglichen Kopfposen auf neun (3 x 3) erhöht. Und zuletzt wurde eine Kopfposenanzahl von 15 (3 x 5) Posen getestet. Zur Evaluierung wurde die Pointing '04 Bilderdatenbank verwendet, wobei in einem Vorbereitungsschritt basierend auf Template Matching der relevante Kopfbereich aus den Bildern extrahiert wurde. Mit Hilfe der Evaluierung wird gezeigt werden, dass der HOG-Deskriptor mit Abstand die besten Ergebnisse erzielt, um erfolgreich die Kopfpose einer Person zu bestimmen. Bei einer Einteilung in f unf Kopfposen wurde die beste Klassifizierungsrate von 80,6% durch den HOG-Deskriptor erreicht. Wie zu erwarten, sinkt die Klassfikationsgenauigkeit bei steigender Kopfposenanzahl ab. Mit einer erhöhten Anzahl an Kopfposen erbrachte der HOG-Deskriptor, bei neun Klassen mit einer Genauigkeit von 72,7% und bei 15 Klassen mit einer Genauigkeit von 66,0%, das beste Resultat.
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Erdt, Marius; Kirschner, Matthias; Drechsler, Klaus; Wesarg, Stefan; Hammon, Matthias; Cavallaro, Alexander
Automatic Pancreas Segmentation in Contrast Enhanced CT Data Using Learned Spatial Anatomy and Texture Descriptors
Erdt, Marius; Kirschner, Matthias; Drechsler, Klaus; Wesarg, Stefan; Hammon, Matthias; Cavallaro, Alexander
Automatic Pancreas Segmentation in Contrast Enhanced CT Data Using Learned Spatial Anatomy and Texture Descriptors
IEEE Engineering in Medicine and Biology Society (EMBS): 2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2011. New York: IEEE Press, 2011, pp. 2076-2082
IEEE International Symposium on Biomedical Imaging (ISBI) <8, 2011, Chicago, IL, USA>
Pancreas segmentation in 3-D computed tomography (CT) data is of high clinical relevance, but extremely difficult since the pancreas is often not visibly distinguishable from the small bowel. So far no automated approach using only single phase contrast enhancement exist. In this work, a novel fully automated algorithm to extract the pancreas from such CT images is proposed. Discriminative learning is used to build a pancreas tissue classifier that incorporates spatial relationships between the pancreas and surrounding organs and vessels. Furthermore, discrete cosine and wavelet transforms are used to build computationally inexpensive but meaningful texture features in order to describe local tissue appearance. Classification is then used to guide a constrained statistical shape model to fit the data. Cross-validation on 40 CT datasets yielded an average surface distance of 1.7 mm compared to ground truth which shows that automatic pancreas segmentation from single phase contrast enhanced CT is feasible. The method even outperforms automatic solutions using multiple-phase CT both in accuracy and computation time.
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Erdt, Marius; Sakas, Georgios; Hammon, Matthias; De Beni, Stefano; Solbiati, Luigi; Cavallaro, Alexander
Automatic Shape Based Deformable Registration of Multiphase Contrast Enhanced Liver CT Volumes
Erdt, Marius; Sakas, Georgios; Hammon, Matthias; De Beni, Stefano; Solbiati, Luigi; Cavallaro, Alexander
Automatic Shape Based Deformable Registration of Multiphase Contrast Enhanced Liver CT Volumes
Haynor, David R. (Ed.) et al.: Medical Imaging 2011: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 13, No. 30. Bellingham: SPIE Press, 2012. (Proceedings of SPIE 8314), pp. 796212-1 - 796212-6
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
The detection and assessment of many hepatic diseases is based on examination of multiphase liver CT volumes. Since phases contain complementary information, registration enables the radiologist to fuse the needed information for diagnosis or operation planning. This work presents a novel multi-stage approach for automatic registration of the liver in contrast enhanced CT volumes. Unlike other methods, our approach is based on automatic pre-segmentation of the liver in the different phases. Using the resulting shape information the volumes are coarsely registered using a landmark-based registration. Subsequently, deformations caused by the patient's breathing are compensated by an elastic Demons algorithm with a boundary distance based speed function. This allows for a high accuracy natural deformation without having to rely on error-prone extraction and matching of the liver's internal structure in complementary phases. Furthermore, since shape information is given, surrounding structures can be omitted which significantly speeds up registration. We evaluated our method using 22 CT volumes from 11 patients. The matching quality of outer shape and internal structures was validated by radiology experts. The high quality results of our approach suggest its applicability in clinical practice.
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Friedl, Sven; Drechsler, Klaus; Oyarzun Laura, Cristina; Kuleschow, Andreas; Kondruweit, Markus; Wittenberg, Thomas
A Holistic Approach Using Multimodal Image-Data for the Support of Cardiac Surgery Interventions
Friedl, Sven; Drechsler, Klaus; Oyarzun Laura, Cristina; Kuleschow, Andreas; Kondruweit, Markus; Wittenberg, Thomas
A Holistic Approach Using Multimodal Image-Data for the Support of Cardiac Surgery Interventions
Lemke, Heinz U. (Ed.) et al.: CARS 2011. Computer Assisted Radiology and Surgery : Proceedings of the 25st International Congress and Exhibition : International Journal of Computer Assisted Radiology and Surgery, Vol. 6 (2011), Supplement 1. Berlin, Heidelberg, New York: Springer, 2011, pp. S235-S238
Computer Assisted Radiology and Surgery (CARS) <25, 2011, Berlin, Germany>
This work addresses the exploitation of multi-modal images in the planning phase and transfer of the acquired planning data to intra-operative procedures in cardiac surgery interventions. Specifically, within this work, for intervention planning the registration of coronary angiography images with CCT data (3D/2D registration), and the transfer from the acquired images and planning data to the intra-operative use and availability during the intervention by the registration of angiography data with live optical video (or endoscopy) at the operation site (2D/2D+T registration is) are focused on.
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Haberstich, Tobias; Oyarzun Laura, Cristina (Betreuer)
Rigide Registrierung durch automatische Erkennung stark verformter Bereiche der Leber
Haberstich, Tobias; Oyarzun Laura, Cristina (Betreuer)
Rigide Registrierung durch automatische Erkennung stark verformter Bereiche der Leber
Darmstadt, TU, Bachelor Thesis, 2011
Deformationen von weichem Gewebe während einer Operation sind ein Problem für eine intraoperative Unterstützung durch Rechner. Eine andauernde Veränderung der Form eines Organs erschwert es, eine gute Registrierung zwischen intra- und präoperativen Daten zu finden. Diese Thesis befasst sich mit der Realisierung einer rigiden Registrierung zur Kompensation von Deformation bei verwendeten Leberdaten. Dies wird durch eine Kombination einiger vorgeschlagener Methoden mit einem eigenen Ansatz erreicht, der die Krümmung der Oberfläche mit einbezieht.
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Hadaschik, Boris A.; Kuru, Timur H.; Tulea, Corina; Rieker, Philip; Popeneciu, Ionel V.; Simpfendörfer, Tobias; Huber, Johannes; Zogal, Pawel; Teber, Dogu; Pahernik, Sascha; Roethke, Matthias; Zamecnik, Patrik; Roth, Wilfried; Sakas, Georgios; Schlemmer, Heinz-Peter; Hohenfellner, Markus
A Novel Stereotactic Prostate Biopsy System Integrating Pre-Interventional Magnetic Resonance Imaging and Live Ultrasound Fusion
Hadaschik, Boris A.; Kuru, Timur H.; Tulea, Corina; Rieker, Philip; Popeneciu, Ionel V.; Simpfendörfer, Tobias; Huber, Johannes; Zogal, Pawel; Teber, Dogu; Pahernik, Sascha; Roethke, Matthias; Zamecnik, Patrik; Roth, Wilfried; Sakas, Georgios; Schlemmer, Heinz-Peter; Hohenfellner, Markus
A Novel Stereotactic Prostate Biopsy System Integrating Pre-Interventional Magnetic Resonance Imaging and Live Ultrasound Fusion
The Journal of Urology, Vol.186 (2011), 6, pp. 2214-2220
Purpose: We developed an effective way to precisely diagnose prostate cancer using a novel prostate biopsy system that integrates pre-interventional magnetic resonance imaging with peri-interventional ultrasound for perineal navigated prostate biopsy. Materials and Methods: A total of 106 men with findings suspicious for prostate cancer (median age 66 years, prostate specific antigen 8.0 ng/ml and prostate volume 47 ml) underwent multiparametric 3 Tesla magnetic resonance imaging. Suspicious lesions were marked and data were transferred to the novel biopsy system. Using a custom-made biplane transrectal ultrasound probe mounted on a stepper we gathered 3-dimensional ultrasound data and fused them with magnetic resonance imaging data. As a result, suspicious magnetic resonance imaging lesions were superimposed over the transrectal ultrasound data. Three-dimensional biopsy planning was done, including systematic biopsies. Perineal biopsies were taken under live ultrasound guidance and the precise site of each biopsy was documented in 3 dimensions. We evaluated feasibility, safety and cancer detection. Results: Prostate cancer was detected in 63 of 106 patients (59.4%). Magnetic resonance imaging findings correlated positively with histopathology in 71 of 103 patients (68.9%). In magnetic resonance imaging lesions marked as highly suspicious, the detection rate was 95.8% (23 of 24 cases). Lesion targeted cores had a significantly higher positivity rate than nontargeted cores. The procedural targeting error of the first 2,461 biopsy cores was 1.7 mm. regarding adverse effects, 2 patients' experienced urinary retention and 1 had a perineal hematoma. Urinary tract infections did not develop. Conclusions: Perineal stereotactic prostate biopsies guided by the combination of magnetic resonance imaging and ultrasound enable effective examination of suspicious magnetic resonance imaging lesions. Each biopsy core taken is documented accurately for its location in 3 dimensions, enabling magnetic resonance imaging validation and tailored treatment planning. The morbidity of the procedure was minimal.
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Hamisu, Pascal; Heinrich, Gregor; Jung, Christoph; Hahn, Volker; Duarte, Carlos; Langdon, Pat; Biswas, Pradipta
Accessible UI Design and Multimodal Interaction through Hybrid TV Platforms: Towards a Virtual-User Centered Design Framework
Hamisu, Pascal; Heinrich, Gregor; Jung, Christoph; Hahn, Volker; Duarte, Carlos; Langdon, Pat; Biswas, Pradipta
Accessible UI Design and Multimodal Interaction through Hybrid TV Platforms: Towards a Virtual-User Centered Design Framework
Stephanidis, Constantine (Ed.): Universal Access in Human-Computer Interaction: Part II : Users Diversity. Berlin, Heidelberg, New York: Springer, 2011. (Lecture Notes in Computer Science (LNCS) 6766), pp. 32-41
International Conference on Universal Access in Human-Computer Interaction (UAHCI) <6, 2011, Orlando, FL, USA>
We report on work towards an architecture that incorporates accessible design methods, guidelines and support tools for building and testing adaptive and accessible user interfaces (UI) for users with mild impairments. We especially address interaction constraints for elderly people, both during application design time and at run time, targeting on hybrid TV platforms. The functional principle of our architecture is twofold: At runtime, it lets users interact with hybrid TV applications through an ensemble of accessible UIs that cover different input and output modalities and are jointly adapted via user profiles and real-time feedback. At design time, it allows developers to re-use UIs and representative user personas in simulating the effect of the UI modalities on different impairments.
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Jung, Christoph; Tausch, Reimar; Thekkeveettil , Jens; Oundouh, Tarik; Han, Bin; Schmidt, Roman Gabriel; Wilbers, Daniel; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Chameleo-AD: Real-time Targeted Interactive Advertisement for Digital Signage
Jung, Christoph; Tausch, Reimar; Thekkeveettil , Jens; Oundouh, Tarik; Han, Bin; Schmidt, Roman Gabriel; Wilbers, Daniel; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Chameleo-AD: Real-time Targeted Interactive Advertisement for Digital Signage
International Broadcasting Convention (IBC) <2011, Amsterdam, The Netherlands>
In this paper we present an integrated approach to interactive, real-time targeted multimedia advertisement for digital signage, based on visual audience analysis. Digital Signage and Digital-out-of-Home (DooH) systems nowadays still employ static content scheduling, and only few of them offer basic interaction capabilities, usually based on touch screens. In our approach we use visual sensors attached to a display to measure anonymous properties of the present audience in real-time and to enable touch-less interaction. A combined visual classification scheme analyses facial and full-body image data and integrates results in a long-term observation of individuals. Based on a measured audience profile, considering gender and age, an adaptive media player queries targeted rich media content from a database and presents it to the audience. Content selection is based on an audience state model which considers the spatio-temporal characteristics of the audience (distance, dwell-time) and a content model representing the relations of content and audience. The system automatically offers free-hand gesture interaction to the user, once a certain level of attention is reached. To our knowledge the presented system is the first approach to integrating long-term observation based on facial/full-body visual data, content adaptation and gesture interaction.
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Keil, Matthias; Noll, Matthias
A Real-Time Online Video Overlay Navigation System for Minimally Invasive Laparoscopic Tumor Resection
Keil, Matthias; Noll, Matthias
A Real-Time Online Video Overlay Navigation System for Minimally Invasive Laparoscopic Tumor Resection
Wong, Kenneth H. (Ed.) et al.: Medical Imaging 2011: Visualization, Image-Guided Procedures, and Modeling. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 12, No. 33. Bellingham: SPIE Press, 2011. (Proceedings of SPIE 7964), pp. 796416-1 - 796416-8
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
The purpose of this paper is to present a detailed description of our real-time navigation system for computer assisted surgery. The system was developed with laparoscopic partial nephrectomies as a first application scenario. The main goal of the application is to enable tracking of the tumor position and orientation during a surgery. Our system is based on ultrasound to CT registration and electromagnetic tracking. The basic idea is to process tracking information to generate an augmented reality (AR) visualization of a tumor model in the camera image of a laparoscopic camera. Thereby it enhances the surgeon's view on the current scene and therefore facilitates higher safety during the surgery. So far we have applied our system in vitro during two phantom trials with a surgeon which yielded promising results.
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Nitsch, Robert Stefan; Roth, Stefan (Betreuer); Jung, Christoph (Betreuer)
Online Learning of Appearance for Robust Data Association in Person Tracking
Nitsch, Robert Stefan; Roth, Stefan (Betreuer); Jung, Christoph (Betreuer)
Online Learning of Appearance for Robust Data Association in Person Tracking
Darmstadt, TU, Bachelor Thesis, 2011
Robust tracking of persons in video sequences is an important task in many applications, like for example video surveillance, human-machine-interaction or adaptive public advertisement. Modern tracking schemes usually first apply person detection in subsequent image frames, perform an association of detections to tracked person and then update the state of the individual tracked persons. Therefore, the overall performance of the tracking strongly relies on correct assignments of observations (detections) to tracked persons. In order to improve identification among different images, visual appearance can be used to distinguish individuals. As individuals and their appearance are usually not known in advance, appearance has to be learned online, while the person is being tracked. In this thesis, an approach to online learning of person appearance will be implemented and evaluated. Online learning will be based on Random Forests®, a tree-based classifier that has proven to be suitable for real-time learning. In order to improve identification, several image features will be evaluated (e.g. RGB, HOG), based on published datasets, which are commonly used in the literature. For colour-based features, background-subtraction will be evaluated as a means of avoiding the common problem that backgroundrelated appearance information is often mistaken by the classifier for being related to a person.
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Oelmann, Simon; Drechsler, Klaus (Betreuer)
Konzeption und Realisierung eines Verfahrens zur automatischen Erkennung von fehlerhaften Verbindungsstellen in einer Graphenrepräsentation des Gefäßsystems der Leber
Oelmann, Simon; Drechsler, Klaus (Betreuer)
Konzeption und Realisierung eines Verfahrens zur automatischen Erkennung von fehlerhaften Verbindungsstellen in einer Graphenrepräsentation des Gefäßsystems der Leber
Darmstadt, TU, Bachelor Thesis, 2011
Bei der Planung von Leberoperationen ist es hilfreich, den Verlauf der Portal- sowie der Lebervene zu kennen, um bestimmte Lebersegmente sowie verschiedene Typen von Tumoren identifizieren zu können. Auch wenn die beiden Venen in der Realität vollständig voneinander getrennt sind, kommt es aufgrund der niedrigen optischen Auflösung, mit der CT-Daten gewonnen werden, in den segmentierten Volumendaten der beiden Venen zu Verschmelzungen. Diese Bachelorarbeit beschreibt ein eigenes, neues Verfahren zur Identifizierung dieser Verbindungsstellen innerhalb einer Graphenrepräsention der Portal- und der Lebervene. Nach einer Erläuterung benötigter Grundlagen folgt eine zusammenfassende Beschreibung bereits existierender Trennungsalgorithmen. Auf diesen aufbauend wird die Idee des neuen Verfahrens formuliert, das die Festlegung auf eine Trennungsstelle von dem häufigsten Zusammentreffen derjenigen Kriterien abhängig macht, die für die Trennung an dieser Stelle sprechen. Anschließend wird der neue Trennungsalgorithmus ausführlich beschrieben. Da der Algorithmus die als Wurzeln bezeichneten Eingänge in das Gefäßsystem kennen muss, wird für die Detektion der Wurzeln die Modifizierung eines bestehenden Verfahrens sowie ein weiteres, eigenes Verfahren vorgestellt. Auf Möglichkeiten zur Identifizierung von Zyklen in Graphen sowie zur Suche von wurzelverbindenden Kantenpfaden wird ebenfalls eingegangen, da diese zur Implementierung des Trennungsalgorithmus bekannt sein müssen. Abschließend werden die Ergebnisse vorgestellt, die das Trennungsverfahren bei Testdatensätzen lieferte. Hierbei wurden für 21 Verbindungsstellen 17 Trennungsvorschläge korrekt generiert.
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Oyarzun Laura, Cristina; Drechsler, Klaus
Computer Assisted Matching of Anatomical Vessel Trees
Oyarzun Laura, Cristina; Drechsler, Klaus
Computer Assisted Matching of Anatomical Vessel Trees
Computers & Graphics, Vol.35 (2011), 2, pp. 299-311
Many inexact automatic tree matching algorithms are available. However, they provide matches that are not completely error free. Another option is to use manually matched node-pairs, but this enormously slows down the process. Our contribution to the state of the art is to combine the advantages of both solutions. We enhance the automatic tree matching algorithm designed by Graham et al., so that it is possible to interact with it by previously selecting important matches or by subsequently fixing the provided wrong matches. We apply the tree matching algorithm to the anatomical vasculature of the liver. Furthermore, we developed several visualization features to make manual tree interaction as easy as possible. Both, the interactive and automatic part of the implemented component were evaluated. As a result, the speed of the automatic tree matching algorithm is increased. It takes 7.45 s for trees up to 192 nodes and less than 1 s if three input matches are provided. In addition to this, an in-depth evaluation of the robustness of the algorithm is presented. The results are remarkable. The average of wrong matches varies between 1.17 and 1.4 node-pairs in the worst cases. The rate of correct matches is high. The evaluation of the visualization features for interactive refinement of matches showed that the percentage of wrong matches found is increased from 56.25% to 78.43%. The mean time to find them is decreased from 227 to 122 s.
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Oyarzun Laura, Cristina; Drechsler, Klaus
Graph to Graph Matching: Facing Clinical Challenges
Oyarzun Laura, Cristina; Drechsler, Klaus
Graph to Graph Matching: Facing Clinical Challenges
Olive, Mark (Ed.) et al.: Twenty-Fourth IEEE Symposium on Computer-Based Medical Systems and HealthGrid Conference : CBMS 2011 + HG 2011. Los Alamitos, Calif.: IEEE Computer Society, 2011, 6 p.
IEEE Symposium on Computer-Based Medical Systems (CBMS) <24, 2011, Bristol, UK>
State of the art anatomical tree matching algorithms find correspondences between trees that contain topological differences. However there are still open problems that were not considered until now. For example, when the liver vasculature is segmented, portal and hepatic vein are not separated due to segmentation errors. Because of this reason the resulting structure is not a tree but a graph. On the other hand, inaccuracies in the generation of the graph, as well as artifacts or inhomogeneities in the contrast medium result in graphs containing gaps. In this work, we present a novel graph to graph matching algorithm. It solves the aforementioned problems by taking the whole graph structure into account and does not depend on separated trees. In addition to this it is robust against gaps in the graph. We developed our algorithm so that it does not depend on the root of the graph which is often assumed to be known. The algorithm was evaluated on real clinical data of the liver.
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Picone, Marco; Steger, Sebastian; Exarchos, Konstantinos; Fazio, Marco De; Goletsis, Yorgos; Fotiadis, Dimitrios I.; Martinelli, Elena; Ardigo, Diego
Enabling Heterogeneous Data Integration and Biomedical Event Prediction Through ICT: The Test Case of Cancer Reoccurrence
Picone, Marco; Steger, Sebastian; Exarchos, Konstantinos; Fazio, Marco De; Goletsis, Yorgos; Fotiadis, Dimitrios I.; Martinelli, Elena; Ardigo, Diego
Enabling Heterogeneous Data Integration and Biomedical Event Prediction Through ICT: The Test Case of Cancer Reoccurrence
Arabnia, Hamid R. (Ed.) et al.: Software Tools and Algorithms for Biological Systems. Berlin, Heidelberg, New York: Springer, 2011. (Advances in Experimental Medicine and Biology 696), pp. 367-375
Early prediction of cancer reoccurrence constitutes a challenge for oncologists and surgeons. This paper describes one ongoing experience, the EU-Project NeoMark, where scientists from different medical and biology research fields joined efforts with Information Technology experts to identify methods and algorithms able to early predict the reoccurrence risk for one of the most devastating tumors, the Oral cavity Squamous Cell Carcinoma (OSCC). The challenge of NeoMark is to develop algorithms able to identify a "signature" or bio-profile of the disease, by integrating multiscale and multivariate data from medical images, genomic profile from tissue and circulating cells RNA and other medical parameters collected from patients before and after treatment. A limited number of relevant biomarkers will be identified and used in a real-time PCR device, for early detection of disease reoccurrence.
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Pierorazio, Phillip M.; Stolka, Philipp J.; Keil, Matthias; Boctor, Emad; Allaf, Mohamad E.
A 3D Elastrography-guided System for Laparoscopic Partial Nephrectomy
Pierorazio, Phillip M.; Stolka, Philipp J.; Keil, Matthias; Boctor, Emad; Allaf, Mohamad E.
A 3D Elastrography-guided System for Laparoscopic Partial Nephrectomy
Journal of Endourology, Vol.25 (2011), 9, A.36-A.37, Abstract 61
Annual Meeting of the Engineering and Urology Society (EUS) <26, 2011, Washington D.C., USA>
Ultrasound elastography, relying on the elastic properties of tissues, can discriminate and classify lesions in a number of tumor models. In order to improve the safety, applicability and dissemination of LPN and related surgeries, a real-time, image-guided intervention system using 3D elastic imaging (EI) registered to preoperative CT was created.
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Santos, Pedro; Schmedt, Hendrik; Amend, Bernd; Hammer, Philip; Giera, Ronny; Hergenröther, Elke; Stork, André
LIS3D: Low-Cost 6DOF Laser Interaction for Outdoor Mixed Reality
Santos, Pedro; Schmedt, Hendrik; Amend, Bernd; Hammer, Philip; Giera, Ronny; Hergenröther, Elke; Stork, André
LIS3D: Low-Cost 6DOF Laser Interaction for Outdoor Mixed Reality
Shumaker, Randall (Ed.): Virtual and Mixed Reality - New Trends: Part I : International Conference, Virtual and Mixed Reality 2011. Berlin, Heidelberg, New York: Springer, 2011. (Lecture Notes in Computer Science (LNCS) 6773), pp. 270-279
International Conference on Virtual and Mixed Reality (VMR) <4, 2011, Orlando, FL, USA>
This paper introduces a new low-cost, laser-based 6DOF interaction technology for outdoor mixed reality applications. It can be used in a variety of outdoor mixed reality scenarios for making 3D annotations or correctly placing 3D virtual content anywhere in the real world. In addition, it can also be used with virtual back-projection displays for scene navigation purposes. Applications can range from design review in the architecture domain to cultural heritage experiences on location. Previous laser-based interaction techniques only yielded 2D or 3D intersection coordinates of the laser beam with a real world object. The main contribution of our solution is that we are able to reconstruct the full pose of an area targeted by our laser device in relation to the user. In practice, this means that our device can be used to navigate any scene in 6DOF. Moreover, we can place any virtual object or any 3D annotation anywhere in a scene, so it correctly matches the user's perspective.
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Steger, Sebastian
Local Rigid Registration for Multimodal Texture Feature Extraction from Medical Images
Steger, Sebastian
Local Rigid Registration for Multimodal Texture Feature Extraction from Medical Images
Haynor, David R. (Ed.) et al.: Medical Imaging 2011: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 13, No. 30. Bellingham: SPIE Press, 2012. (Proceedings of SPIE 8314), pp. 79621V-1 - 79621V-6
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
The joint extraction of texture features from medical images of different modalities requires an accurate image registration at the target structures. In many cases rigid registration of the entire images does not achieve the desired accuracy whereas deformable registration is too complex and may result in undesired deformations. This paper presents a novel region of interest alignment approach based on local rigid registration enabling image fusion for multimodal texture feature extraction. First rigid registration on the entire images is performed to obtain an initial guess. Then small cubic regions around the target structure are clipped from all images and individually rigidly registered. The approach was applied to extract texture features in clinically acquired CT and MR images from lymph nodes in the oropharynx for an oral cancer reoccurrence prediction framework. Visual inspection showed that in all of the 30 cases at least a subtle misalignment was perceivable for the globally rigidly aligned images. After applying the presented approach the alignment of the target structure significantly improved in 19 cases. In 12 cases no alignment mismatch whatsoever was perceptible without requiring the complexity of deformable registration and without deforming the target structure. Further investigation showed that if the resolutions of the individual modalities differ significantly, partial volume effects occur, diminishing the significance of the multimodal features even for perfectly aligned images.
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Steger, Sebastian; Ebert, Daniel; Erdt, Marius
Lymph Node Segmentation in CT Slices Using Dynamic Programming
Steger, Sebastian; Ebert, Daniel; Erdt, Marius
Lymph Node Segmentation in CT Slices Using Dynamic Programming
IEEE Engineering in Medicine and Biology Society (EMBS): 2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2011. New York: IEEE Press, 2011, pp. 1990-1993
IEEE International Symposium on Biomedical Imaging (ISBI) <8, 2011, Chicago, IL, USA>
An automatically extracted 2d contour of a lymph node in a single CT slice is required for size assessment as well as for the initialization of model based 3d lymph node segmentation algorithms. This paper presents a novel single slice lymph node segmentation approach. It finds a closed path around a seed point thereby minimizing an energy function which depends on gradients, intensities and shape priors. A globally optimal solution is guaranteed to be found using dynamic programming. The approach is evaluated on a set of 49 representative lymph nodes from clinical images for which manual expert segmentation is available. The resulting average dice similarity coefficient of 0.81 is close to manual segmentation (0.89).
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Steger, Sebastian; Franco, Fabio; Sverzellati, Nicola; Chiari, Gianfranco; Colomer, Ramon
3D Assessment of Lymph Nodes vs. RECIST 1.1
Steger, Sebastian; Franco, Fabio; Sverzellati, Nicola; Chiari, Gianfranco; Colomer, Ramon
3D Assessment of Lymph Nodes vs. RECIST 1.1
Academic Radiology, (2011), Article in Press. Corrected Proof 7 January 2011. DOI: 10.1016/j.acra.2010.11.010, 4 p.
Rationale and Objectives: In today's clinical practice, the size of lymph nodes is assessed by measuring the long and the short axis in the axial plane. This study compares this approach with three-dimensional (3D) assessment. Materials and Methods: For a representative set of 49 lymph nodes, the axes in the axial plane have been measured and a 3D model has been created manually. Based on the 3D model, the real axial long and short axis as well as the three 3D axes and the volume have been computed and compared to the measured axial axes. Results: The inter-observer variability is around 10% for all measured lengths and almost 16% for the computed volume. The average relative error of the measured long (short) axial axis is 9.73% (24.57%) to the computed axial axis and 25.05% (19.97%) to the computed 3D axis, respectively. The product of the axial long axis and the square of the axial short axis provide best correlation to the volume. Conclusion: This study confirms Response Evaluation Criteria in Solid Tumors 1.1 that measuring the short axis is more robust than measuring the long axis because of less impact of the node's spatial orientation. Nonetheless it is shown that considering both axes is a better prognostic factor for the volume than measuring the short axis only.
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Uspenskiy, Artem; Sakas, Georgios (Betreuer)
Evaluierung von CT-Rekonstruktionsalgorithmen in OpenCL
Uspenskiy, Artem; Sakas, Georgios (Betreuer)
Evaluierung von CT-Rekonstruktionsalgorithmen in OpenCL
Darmstadt, TU, Master Thesis, 2011
Die vorliegende Arbeit beschäftigt sich mit der Entwicklung, Implementierung und Evaluierung von CT-Rekonstruktionsalgorithmen mittels OpenCL auf verschiedenen Hardwarearchitekturen. Insbesondere befasst sie sich mit der Evaluierung von OpenCL Technologie und Übertragbarkeit damit entwickelten Programmen. Für die Implementierung wurde die Rückprojektion des Feldkamp Algorithmus für Cone-Bean CT-Rekonstruktion gewählt. Im ersten Teil der Arbeit wird Überblick über CT-Rekonstruktionsverfahren, evaluierte Hardwarearchitekturen sowie OpenCL Technologie gegeben. Im zweiten Teil werden Implementierungsstrategien erläutert. Dabei werden eine plattformunabhängige Referenz-Implementierung der Rückprojektion und mehrere für Optimierungsstrategien dargestellt, die zum Teil hardwareabhängig sind. Anschließend wird die entwickelte Software auf NVidia GPU, AMD GPU sowie Intel Multi-Core Prozessoren evaluiert. Anhand der Ergebnisse der Evaluierung wird gezeigt, dass die NVidia GPUs besser als CPUs und AMD GPUs für die Berechnung der Rückprojektion geeignet sind. Außerdem wird gezeigt, dass die Software, die mit OpenCL entwickelt ist, zum Teil hardwareabhängig und nicht übertragbar ist.
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Wesarg, Stefan; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Direct Visualization of Regions with Lowered Bone Mineral Density in Dual-Energy CT Images of Vertebrae
Wesarg, Stefan; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Direct Visualization of Regions with Lowered Bone Mineral Density in Dual-Energy CT Images of Vertebrae
Summers, Ronald M. (Ed.) et al.: Medical Imaging 2011: Computer-Aided Diagnosis. Part Two : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 12, No. 32. Bellingham: SPIE Press, 2011. (Proceedings of SPIE 7963), pp. 79633J-1 - 79633J-10
SPIE Medical Imaging Symposium <2011, Lake Buena Vista, FL, USA>
Dual-energy CT allows for a better material differentiation than conventional CT. For the purpose of osteoporosis diagnosis, a detection of regions with lowered bone mineral density (BMD) is of high clinical interest. Based on an existing biophysical model of the trabecular bone in vertebrae a new method for directly highlighting those low density regions in the image data has been developed. For this, we combine image data acquired at 80 kV and 140 kV with information about the BMD range in different vertebrae and derive a method for computing a color enhanced image which clearly indicates low density regions. An evaluation of our method which compares it with a quantitative method for BMD assessment shows a very good correspondence between both methods. The strength of our method lies in its simplicity and speed.
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Wesarg, Stefan; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Quantifizierung und Visualisierung der Struktur des trabekulären Knochens in Wirbelkörpern
Wesarg, Stefan; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad
Quantifizierung und Visualisierung der Struktur des trabekulären Knochens in Wirbelkörpern
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2011 : Algorithmen, Systeme, Anwendungen. Berlin; Heidelberg; New York: Springer, 2011. (Informatik aktuell), pp. 309-313
Workshop Bildverarbeitung für die Medizin (BVM) <14, 2011, Aachen, Germany>
Dual-Energy CT (DECT) ist seit einigen Jahren im klinischen Einsatz. Wir stellen eine Methode vor, wie mittels DECT die räumliche Verteilung der Knochendichte in Wirbeln bestimmt und für die Diagnose von Osteoporose verwendet werden kann. Des Weiteren beschreiben wir einen neuen Ansatz für die Bestimmung der Zusammensetzung des trabekulären Knochens. Unsere Methoden wurden erfolgreich an DECT-Daten von 29 Wirbeln getestet und bedeuten einen Informationsgewinn für den Bereich der Orthopädie.
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Burisch, Michael; Guerrero Ichaso, David; Kuijper, Arjan
Stripe Propagation for Color Encoded Structured Light
Burisch, Michael; Guerrero Ichaso, David; Kuijper, Arjan
Stripe Propagation for Color Encoded Structured Light
Fifth International Symposium on 3D Data Processing, Visualization and Transmission. Proceedings [online]. [cited 17 January 2011] Available from: http://campwww.informatik.tu-muenchen.de/3DPVT2010/data/media/e-proceeding/index.html 2010, 8 p.
International Symposium on 3D Data Processing, Visualization and Transmission (3DPVT) <5, 2010, Paris, France>
We present a method to improve surface reconstruction using color encoded structured light. A video camera is used to obtain a color encoded pattern projected onto the object using a projector. A multi-stage method is presented to reconstruct the surface from the captured pattern. It consists of i) a robust edge detection step, ii) a color decoding using feedback from previous stripes and iii) a propagation step to detect errors and propagate detected stripes. Using feedback and propagation we can reconstruct areas where regular color detection fails by bridging small gaps which happen due to illumination variations or noise. The reconstruction results are illustrated for human skin.
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Chakravarthy, Ajay; Beales, Richard M.; Jung, Yvonne; Wagner, Sebastian; Jung, Christoph; Yannopoulous, Angelos; Koutsoutos, Stefanos; Schiffmann, Rolf; Hedtke, Rolf; Saenen, Ignace
A Notation Based Approach to Film Pre-vis
Chakravarthy, Ajay; Beales, Richard M.; Jung, Yvonne; Wagner, Sebastian; Jung, Christoph; Yannopoulous, Angelos; Koutsoutos, Stefanos; Schiffmann, Rolf; Hedtke, Rolf; Saenen, Ignace
A Notation Based Approach to Film Pre-vis
IEEE Computer Society: 2010 Conference on Visual Media Production. Proceedings : CVMP 2010. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2010, pp. 58-63
Conference on Visual Media Production (CVMP) <7, 2010, London, UK>
This paper describes ANSWER which is a new approach to the creative process of film production. It is based on a symbolic notation system called Director Notation (DN) through which film directors are free to express their creative intent much like a music composer uses musical notation. The notation populates a semantic model which is machine processable and this input is automatically converted into a lightweight 3D pre-vis. ANSWER is integrated with DFT BONES Dailies, so that in post-production editors can quickly synchronise and compare pre-vised and actual footage. In this paper we will describe the various software tools which have been developed as part of the ANSWER project to achieve this goal.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Hierarchical Decomposition of Vessel Skeletons for Graph Creation and Feature Extraction
Drechsler, Klaus; Oyarzun Laura, Cristina
Hierarchical Decomposition of Vessel Skeletons for Graph Creation and Feature Extraction
Park, Taesung (Ed.) et al.: 2010 IEEE International Conference on Bioinformatics and Biomedicine. Proceedings. New York: The Institute of Electrical and Electronics Engineers (IEEE), 2010, pp. 456-461
IEEE International Conference on Bioinformatics and Biomedicine (BIBM) <4, 2010, Hong Kong, China>
Graphs are useful representations of the liver vasculature. They support tree matching algorithms in landmark based registration algorithms, they are useful to separate connected vessels from two different vessel systems and are the basis of vessel annotation tools. In this paper, we propose a hierarchical decomposition of vessel skeletons into subbranches. This simplifies the process of creating labeled graphs and extracting features. Furthermore, we propose a measure to classify voxels as branch voxels. We applied our method to several datasets with satisfying results and found that the number of sub-branches is normal distributed under rotation.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Dimension Reduction Based on Centroids for Multimodal Anatomical Landmark-Based 3d/2d Registration of Coronary Angiograms
Drechsler, Klaus; Oyarzun Laura, Cristina
Dimension Reduction Based on Centroids for Multimodal Anatomical Landmark-Based 3d/2d Registration of Coronary Angiograms
IMAGAPP 2010, IVAPP 2010. Proceedings. Portugal: INSTICC (Institute for Systems and Technologies of Information, Control and Communication), 2010, pp. 171-178
International Conference on Information Visualization Theory and Applications (IVAPP) <1, 2010, Angers, France>
We present an anatomical landmark-based rigid 3D/2D registration algorithm to register computed tomography angiography (CTA) datasets with coronary angiograms (CA) gathered during a cardiac catheterization. It has to solve for six transformation parameters (three rotation and three translation parameters). An exhaustive search in a six dimensional search space is usually computationally very expensive and algorithms using optimization strategies can get lost in local minima. We propose a method based on centroids to reduce search space from six to four dimensions. Modern C-Arm devices store a lot of information about the acquisition geometry that are used to further reduce the search space. We use this method to develop an efficient smart exhaustive search to solve for the six transformation parameters in a competitive time. With our method registration errors of < 2 mm are feasible. Execution times of < 1 sec. can be reached on a QuadCore CPU.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Comparison of Vesselness Functions for Multiscale Analysis of the Liver Vasculature
Drechsler, Klaus; Oyarzun Laura, Cristina
Comparison of Vesselness Functions for Multiscale Analysis of the Liver Vasculature
University of Ioannina: ITAB 2010 : 10th International Conference on Information Technology and Applications in Biomedicine. New York: IEEE, Inc., 2010, 5 p.
International Conference on Information Technology and Applications in Biomedicine (ITAB) <10, 2010, Corfu, Greece>
The accurate segmentation of liver vessels is an important step for further computer assisted analysis in oncologic planning tools. Multiscale based vessel enhancement methods are very famous and many papers about this topic were published. Vesselness filters proposed by Sato et al., Frangi et al. and Erdt et al. are based on eigenvalue analysis of the Hessian matrix. They were developed using completely different approaches, namely experimental, geometrical and analytical. In this paper, their behavior at junctions and nearby vessels is systematically compared and evaluated for the enhancement of the liver vasculature. We found that the filter function proposed by Frangi et al. has problems at junctions, while the ones developed by Sato et al and Erdt et al. have problems with nearby vessels. The latter are preferred for the task of liver vessel enhancement.
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Drechsler, Klaus; Oyarzun Laura, Cristina
A Novel Multiscale Integration Approach for Vessel Enhancement
Drechsler, Klaus; Oyarzun Laura, Cristina
A Novel Multiscale Integration Approach for Vessel Enhancement
Dillon, Tharam et al.: Twenty-Third IEEE Symposium on Computer-Based Medical Systems : CBMS 2010. Los Alamitos, Calif.: IEEE Computer Society, 2010, pp. 92-97
IEEE Symposium on Computer-Based Medical Systems (CBMS) <23, 2010, Perth, Australia >
A novel multiscale integration method to be used for vessel enhancement, called Weighted Additive Response, is presented. It overcomes limitations of the widely used maximum response approach in terms of separation of nearby vessels and robustness to noise. Furthermore, its usefulness as a preprocessing step for a subsequent segmentation is shown. The practicability of the proposed method is quantitatively and qualitatively evaluated with public available artificial and clinical datasets.
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Drechsler, Klaus; Oyarzun Laura, Cristina; Chen, Yufei; Erdt, Marius
Semi-Automatic Anatomical Tree Matching for Landmark-Based Elastic Registration of Liver Volumes
Drechsler, Klaus; Oyarzun Laura, Cristina; Chen, Yufei; Erdt, Marius
Semi-Automatic Anatomical Tree Matching for Landmark-Based Elastic Registration of Liver Volumes
Journal of Healthcare Engineering, Vol.1 (2010), 1, pp. 101-123
One promising approach to register liver volume acquisitions is based on the branching points of the vessel trees as anatomical landmarks inherently available in the liver. Automated tree matching algorithms were proposed to automatically find pair-wise correspondences between two vessel trees. However, to the best of our knowledge, none of the existing automatic methods are completely error free. After a review of current literature and methodologies on the topic, we propose an efficient interaction method that can be employed to support tree matching algorithms with important pre-selected correspondences or after an automatic matching to manually correct wrongly matched nodes. We used this method in combination with a promising automatic tree matching algorithm also presented in this work. The proposed method was evaluated by 4 participants and a CT dataset that we used to derive multiple artificial datasets.
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Erdt, Marius; Kirschner, Matthias; Wesarg, Stefan
Smart Manual Landmarking of Organs
Erdt, Marius; Kirschner, Matthias; Wesarg, Stefan
Smart Manual Landmarking of Organs
Dawant, Benoit M. (Ed.) et al.: Medical Imaging 2010: Image Processing. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 11, No. 33. Bellingham: SPIE Press, 2010. (Proceedings of SPIE 7623), pp. 76234Y-1 - 76234Y-9
SPIE Medical Imaging Symposium <2010, San Diego, CA, USA>
Statistical shape models play a very important role in most modern medical segmentation frameworks. In this work we propose an extension to an existing approach for statistical shape model generation based on manual mesh deformation. Since the manual acquisition of ground truth segmentation data is a prerequisite for shape model creation, we developed a method that integrates a solution to the landmark correspondence problem in this particular step. This is done by coupling a user guided mesh adaptation for ground truth segmentation with a simultaneous real time optimization of the mesh in order to preserve point correspondences. First, a reference model with evenly distributed points is created that is taken as the basis of manual deformation. Afterwards the user adapts the model to the data set using a 3D Gaussian deformation of varying stiffness. The resulting meshes can be directly used for shape model construction. Furthermore, our approach allows the creation of shape models of arbitrary topology. We evaluate our method on CT data sets of the kidney and 4D MRI time series images of the cardiac left ventricle. A comparison with standard ICP-based and population-based optimization based correspondence algorithms showed better results both in terms of generalization capability and specificity for the model generated by our approach. The proposed method can therefore be used to considerably speed up and ease the process of shape model generation as well as remove potential error sources of landmark and correspondence optimization algorithms needed so far.
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Erdt, Marius; Sakas, Georgios
Computer Aided Segmentation of Kidneys Using Locally Shape Constrained Deformable Models on CT Images
Erdt, Marius; Sakas, Georgios
Computer Aided Segmentation of Kidneys Using Locally Shape Constrained Deformable Models on CT Images
Karssemeijer, Nico (Ed.) et al.: Medical Imaging 2010: Computer-Aided Diagnosis : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 11, No. 34. Bellingham: SPIE Press, 2010. (Proceedings of SPIE 7624), pp. 762419-1 - 762419-7
SPIE Medical Imaging Symposium <2010, San Diego, CA, USA>
This work presents a novel approach for model based segmentation of the kidney in images acquired by Computed Tomography (CT). The developed computer aided segmentation system is expected to support computer aided diagnosis and operation planning. We have developed a deformable model based approach based on local shape constraints that prevents the model from deforming into neighboring structures while allowing the global shape to adapt freely to the data. Those local constraints are derived from the anatomical structure of the kidney and the presence and appearance of neighboring organs. The adaptation process is guided by a rule-based deformation logic in order to improve the robustness of the segmentation in areas of diffuse organ boundaries. Our work flow consists of two steps: 1.) a user guided positioning and 2.) an automatic model adaptation using affine and free form deformation in order to robustly extract the kidney. In cases which show pronounced pathologies, the system also offers real time mesh editing tools for a quick refinement of the segmentation result. Evaluation results based on 30 clinical cases using CT data sets show an average dice correlation coefficient of 93% compared to the ground truth. The results are therefore in most cases comparable to manual delineation. Computation times of the automatic adaptation step are lower than 6 seconds which makes the proposed system suitable for an application in clinical practice.
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Erdt, Marius; Schlegel, Patrice; Wesarg, Stefan
Multi-Layer Deformable Models for Medical Image Segmentation
Erdt, Marius; Schlegel, Patrice; Wesarg, Stefan
Multi-Layer Deformable Models for Medical Image Segmentation
University of Ioannina: 10th International Conference on Information Technology and Applications in Biomedicine. Proceedings CD-ROM : 10th International Conference on Information Technology and Applications in Biomedicine. New York: IEEE, Inc., 2010, 4 p.
International Conference on Information Technology and Applications in Biomedicine (ITAB) <10, 2010, Corfu, Greece>
In this work, a Multi-Layer Deformable Model (MLDM) for medical image segmentation is proposed. In contrast to common deformable model based segmentation approaches our new method incorporates a multi-layer geometric model that allows a sampling of the organ's interior. An adaptation logic processes the additional information gained from interior layers in order to fit the model to the data. The deformation is coupled with a dynamic internal energy function represented by a link-oriented flexibility in order to allow the model to accurately adapt to cavities. Exploiting the additional depth information, our approach detects low contrasted transitions between organs more reliably and recovers better from bad model initialization than existing methods. Our approach has been evaluated using representative CT data sets of the liver as well as CT bladder scans. Evaluation using ground truth data showed that our multi-layer technique yields superior results in contrast to common single surface segmentation. Since the amount of layers is flexible, the most interior regions which only carry little regional information can be excluded from optimization. Together with the linear nature of MLDM optimization our approach outperforms other volumetric segmentation methods in terms of speed.
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Erdt, Marius; Steger, Sebastian; Kirschner, Matthias; Wesarg, Stefan
Fast Automatic Liver Segmentation Combining Learned Shape Priors with Observed Shape Deviation
Erdt, Marius; Steger, Sebastian; Kirschner, Matthias; Wesarg, Stefan
Fast Automatic Liver Segmentation Combining Learned Shape Priors with Observed Shape Deviation
Dillon, Tharam et al.: Twenty-Third IEEE Symposium on Computer-Based Medical Systems : CBMS 2010. Los Alamitos, Calif.: IEEE Computer Society, 2010, pp. 249-254
IEEE Symposium on Computer-Based Medical Systems (CBMS) <23, 2010, Perth, Australia >
We present a novel statistical shape model approach for fully automatic CT liver segmentation. Unlike previous techniques, our method combines learned local shape priors with constraints that are directly derived from the current curvature of the model in order to restrict adaptation to regions where large deformations are expected and observed. Our approach is based on a multi-tiered framework that is more robust against model initialization errors than existing methods, because the model's degrees of freedom are step-wise increased. We evaluated our method on a large data base of 86 CT liver scans from different vendors, protocols, varying resolution and contrast enhancement. For comparison, 50 of the scans were taken from 2 public data bases, one of it being the MICCAI'07 liver segmentation challenge data base. Evaluation shows state of the art results with an average mean surface distance between 1.3 mm and 1.85 mm compared to ground truth depending on the image resolution. With an average segmentation time of 45 seconds our approach outperforms other automatic methods.
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Hahn, Volker; Hamisu, Pascal; Jung, Christoph; Heinrich, Gregor; Duarte, Carlos; Langdon, Pat
Workshop AccessibleTV "Accessible User Interfaces for Future TV Applications"
Hahn, Volker; Hamisu, Pascal; Jung, Christoph; Heinrich, Gregor; Duarte, Carlos; Langdon, Pat
Workshop AccessibleTV "Accessible User Interfaces for Future TV Applications"
Ruyter, Boris de (Ed.) et al.: Ambient Intelligence : AmI 2010. Berlin; Heidelberg; New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6439), pp. 346-348
International Joint Conference on Ambient Intelligence (AmI) <1, 2010, Malaga, Spain>
Approximately half of the elderly people over 55 suffer from some type of typically mild visual, auditory, motor or cognitive impairment. For them interaction, especially with PCs and other complex devices is sometimes challenging, although accessible ICT applications could make much of a difference for their living quality. Basically they have the potential to enable or simplify participation and inclusion in their surrounding private and professional communities. However, the availability of accessible user interfaces being capable to adapt to the specific needs and requirements of users with individual impairments is very limited. Although there are a number of APIs [1, 2, 3, 4] available for various platforms that allow developers to provide accessibility features within their applications, today none of them provides features for the automatic adaptation of multimodal interfaces being capable to automatically fit the individual requirements of users with different kinds of impairments. Moreover, the provision of accessible user interfaces is still expensive and risky for application developers, as they need special experience and effort for user tests. Today many implementations simply neglect the needs of elderly people, thus locking out a large portion of their potential users. The workshop is organized as part of the dissemination activity for the European-funded project GUIDE "Gentle user interfaces for elderly people", which aims to address this situation with a comprehensive approach for the realization of multimodal user interfaces being capable to adapt to the needs of users with different kinds of mild impairments. As application platform, GUIDE will mainly target TVs and Set-Top Boxes, such as the emerging Connected-TV or WebTV platforms, as they have the potential to address the needs of the elderly users with applications such as for home automation, communication or continuing education.
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Hedtke, Rolf; Schiffmann, Rolf; Jung, Yvonne; Jung, Christoph
Automatische 3D-Visualisierung für die Film- und Fernsehproduktion
Hedtke, Rolf; Schiffmann, Rolf; Jung, Yvonne; Jung, Christoph
Automatische 3D-Visualisierung für die Film- und Fernsehproduktion
FKT, Vol.64 (2010), 12, pp. 645-652
Das Europäische Forschungsprojekt "Answer" zeigt einen neuen Weg für die kreative Filmproduktion auf und bietet Werkzeuge für die Optimierung des Arbeitsablaufs von der Vorplanung bis hin zur Nachbearbeitung. Das basiert auf einer symbolischen Beschreibung, der "Director Notation" (DN), die über einen grafischen Editor und eine Ontologie ein semantisches Modell für eine automatische 3D-Animation erzeugt. Damit kann die beschriebene Szene sofort visualisiert und geändert werden. Durch die Integration in ein Film-Nachbearbeitungssystem wird die Animation mit den realen Filmbildern unter Nutzung automatischer inhaltsbasierender Videoanalyseverfahren synchronisiert. Im Beitrag werden das Projekt "Answer" und die Forschungsergebnisse beschrieben.
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Hoßbach, Martin
MR Compatible Optical Motion Tracking: Building an Optical Tracking System for Head Motion Compensation in MRI
Hoßbach, Martin
MR Compatible Optical Motion Tracking: Building an Optical Tracking System for Head Motion Compensation in MRI
Institute for Systems and Technologies of Information, Control and Communication (INSTICC): VISIGRAPP 2010. Proceedings : International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications. INSTICC Press, 2010, pp. 453-456
International Conference on Computer Vision Theory and Applications (VISAPP) <5, 2010, Angers, France>
Magnetic Resonance Imaging (MRI), in spite of its potential in medical diagnosis, has one major drawback: Image acquisition is a slow process, requiring the patient to not move for several minutes. This renders MRI useless in a number of cases. In the case of MR Imaging of the Head, optical motion tracking can be used for motion compensation, thereby greatly improving image quality. In this paper, an MR-compatible approach of tracking the patient's head is presented which does not require his or her cooperation, based on stereo-optical marker tracking. It is adapted to work in the MRI scanner, does not influence the MR image acquisition and is easily integrated into clinical routine.
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Jung, Christoph; Tausch, Reimar; Wojek, Christian
Real-time Full-body Visual Traits Recognition from Image Sequences
Jung, Christoph; Tausch, Reimar; Wojek, Christian
Real-time Full-body Visual Traits Recognition from Image Sequences
Koch, Reinhard (Ed.) et al.: VMV 2010 : Vision, Modeling, and Visualization. Goslar: Eurographics Association, 2010, pp. 57-64
Vision, Modeling, and Visualization Workshop (VMV) <15, 2010, Siegen, Germany>
The automatic recognition of human visual traits from images is a challenging computer vision task. Visual traits describe for example gender and age, or other properties of a person that can be derived from visual appearance. Gathering anonymous knowledge about people from visual cues bears potential for many interesting applications, as for example in the area of human machine interfacing, targeted advertisement or video surveillance. Most related work investigates visual traits recognition from facial features of a person, with good recognition performance. Few systems have recently applied recognition on low resolution full-body images, which shows lower performance than the facial regions but already can deliver classification results even if no face is visible. Obviously full-body classification is more challenging, mainly due to large variations in body pose, clothing and occlusion. In our study we present an approach to human visual traits recognition, based on Histogram of oriented Gradients (HoG), colour features and Support Vector Machines (SVM). In this experimental study we focus on gender classification. Motivated by our application of real-time adaptive advertisement on public situated displays, and unlike previous works, we perform a thorough evaluation on much more comprehensive datasets that include hard cases like side- and back views. The extended annotations used in our evaluation will be published. We further show that a hierarchical classification scheme to disambiguate a person's directional orientation and additional colour features can increase recognition rates. Finally, we demonstrate that temporal integration of per-frame classification scores significantly improves the overall classification performance for tracked individuals and clearly outperforms current state-of-the-art accuracy for single images.
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Jung, Yvonne; Wagner, Sebastian; Jung, Christoph; Behr, Johannes; Fellner, Dieter W.
Storyboarding and Pre-Visualization with X3D
Jung, Yvonne; Wagner, Sebastian; Jung, Christoph; Behr, Johannes; Fellner, Dieter W.
Storyboarding and Pre-Visualization with X3D
ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 73-81
International Conference on 3D Web Technology (WEB3D) <15, 2010, Los Angeles, USA>
This paper presents methods based on the open standard X3D to rapidly describe life-like characters and other scene elements in the context of storyboarding and pre-visualization. Current frameworks that employ virtual agents often rely on non-standardized pipelines and lack functionality to describe lighting, camera staging or character behavior in a descriptive and simple manner. Even though demand for such a system is high, ranging from edutainment to pre-visualization in the movie industry, few such systems exist. Thereto, we present the ANSWER framework, which provides a set of interconnected components that aid a film director in the process of film production from the planning stage to post-production. Rich and intuitive user interfaces are used for scene authoring and the underlying knowledge model is populated using semantic web technologies over which reasoning is applied. This transforms the user input into animated pre-visualizations that enable a director to experience and understand certain film making decisions before production begins. In this context we also propose some extensions to the current X3D standard for describing cinematic contents.
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Keil, Matthias; Noll, Matthias
Extending MITK by a Real-Time Online Video Overlay Navigation System for Minimally Invasive Surgery: Release 2.00
Keil, Matthias; Noll, Matthias
Extending MITK by a Real-Time Online Video Overlay Navigation System for Minimally Invasive Surgery: Release 2.00
MIDAS Journal, (2010), 9 p.
International Workshop on Systems and Architectures for Computer Assisted Interventions (ICCAS) <3, 2010, Beijing, China>
The purpose of this paper is to present our extension of the MITK toolkit by a real-time navigation system for computer assisted surgery. The system was developed with laparoscopic partial nephrectomies as a first application scenario. The main goal of the application is to enable tracking of the tumor position and orientation during surgery. Our system is based on ultrasound to CT registration and electromagnetic tracking. The basic idea is to process tracking information to generate an augmented reality (AR) visualization of a tumor model in the camera image of a laparoscopic camera. Our system will enhance the surgeon's view on the current scene and therefore facilitates higher safety during the surgery. A key intention of the development was to use only open source toolkits such as VTK, MITK and OpenCV in order to implement the desired functionality. So far we have applied our system in vitro in two phantom trials with a surgeon which yielded promising results.
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Noll, Matthias; Keil, Matthias (Betreuer)
Intraoperative Navigation für die minimalinvasive Resektion von Nierentumoren
Noll, Matthias; Keil, Matthias (Betreuer)
Intraoperative Navigation für die minimalinvasive Resektion von Nierentumoren
Darmstadt, TU, Diplomarbeit, 2010
The purpose of this diploma thesis is to present a detailed description of a real-time navigation system for computer assisted surgery. The system that is based on open source technology was developed with laparoscopic partial nephrectomies as a first application scenario. The main goal of the application is to enable tracking of the tumor position and orientation during a surgery. The system is based on ultrasound to CT registration and electromagnetic tracking. The basic idea is to process electromagnetic tracking information to generate an augmented reality (AR) visualization of a tumor model in a laparoscopic camera image. This way the system enhances the surgeon's view on the operating field and therefore facilitates higher safety during the surgery. So far the system was applied in vitro with two phantom trials with the aid of a surgeon which yielded promising results.
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Oyarzun Laura, Cristina; Drechsler, Klaus
Efficient Globally Optimal Matching of Anatomical Trees of the Liver
Oyarzun Laura, Cristina; Drechsler, Klaus
Efficient Globally Optimal Matching of Anatomical Trees of the Liver
Bartz, Dirk (Ed.) et al.: Eurographics Workshop on Visual Computing for Biology and Medicine : EG VCBM 2010. Goslar: Eurographics Association, 2010, pp. 75-82
Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM) 2, 2010, Leipzig, Germany>
Many inexact automatic tree matching algorithms are nowadays available. However, they provide matches that are not completely error free. Another option is to use manually matched node-pairs, but this enormously slows down the process. Our contribution to the state of the art is to combine the advantages of both solutions. We enhance the automatic tree matching algorithm designed by Graham et al., so that it is possible to interact with it by previously selecting important matches or by subsequently fixing the provided wrong matches. Thanks to this enhancement the speed of the algorithm is greatly increased. It takes 7.45 seconds for trees up to 192 nodes and less than 1 second if three input matches are provided. In addition to this an in-depth evaluation of the robustness of the algorithm is presented. The results are remarkable. The average of wrong matches varies between 1.17 and 1.4 node-pairs in the worst cases. The rate of correct matches is high.
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Rizou, Despoina; Sesma, Laura; Salvatore, Luca
Doctors Mobility Covered by Traumastation
Rizou, Despoina; Sesma, Laura; Salvatore, Luca
Doctors Mobility Covered by Traumastation
University of Ioannina: ITAB 2010 : 10th International Conference on Information Technology and Applications in Biomedicine. New York: IEEE, Inc., 2010, 4 p.
International Conference on Information Technology and Applications in Biomedicine (ITAB) <10, 2010, Corfu, Greece>
TraumaStation II / TeleConsult is an active diagnostic, portable 3D ultrasound imaging device for medical professionals, which is able to acquire, process, display and transfer two- and three- dimensional medical images in a telemedical environment. The term "telemedical" here refers to the ability to send and receive image data either offline or in an online mode via a network connection. In the offline mode the user defines a message that may include text and image data and selects the destination. In the online mode two TraumaStation devices / TeleConsult clients are connected and share the same view on the image data enabling the live discussion of a certain case. For data security TraumaStation II / TeleConsult uses validated encryption and authenticity mechanisms. The image display part is capable of loading two and three dimensional DICOM 3 images and volume files. The software provides image display and rendering routines as well as measurement and annotation tools. The device is ready for field deployment in a military context.
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Sakas, Georgios
Data Fusion and Image-Guided Medical Interventions
Sakas, Georgios
Data Fusion and Image-Guided Medical Interventions
Defence Research and Development Canada: Combat Casualty Resuscitation : Diagnosis and Intervention, 1 p.
Combat Casualty Resuscitation Symposium <2010, Toronto, Canada>
With today's diagnostic imaging capabilities, two issues remain to be addressed on the way to standardized image guided procedures: data fusion - merging data of the same patient acquired by one or many imaging modalities at different times; and data-patient registration - with which modality can the intraoperative patient data be gathered.
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Sakas, Georgios; Baltas, Dimos; Zamboglou, Nikos
Simulation and "VirtuaI Patient" in Radiotherapy
Sakas, Georgios; Baltas, Dimos; Zamboglou, Nikos
Simulation and "VirtuaI Patient" in Radiotherapy
it - Information Technology, Vol.52 (2010), 5, pp. 272-279
CT simulators are software systems used in the radiotherapy clinics for simulating the radiation beams of a radiotherapy treatment plan. They use acquired Computed Tomography (CT) data set of the patient, including the external patient's skin landmarks, instead of the physical patient. The implemented high-end visualization techniques allow the users to simulate every function of the treatment machine including the mechanical component movements, radiation beam projection and fluoroscopy. The virtual simulation concept provides the physicians with ergonomic volume definition and anatomy navigation tools.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, Wolfgang-Dieter; Stilla, Uwe
A Radiometry Tolerant Method for Direct 3D/2D Registration of Computed Tomography Data to X-ray Images: Transfer Function Independent Registration
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, Wolfgang-Dieter; Stilla, Uwe
A Radiometry Tolerant Method for Direct 3D/2D Registration of Computed Tomography Data to X-ray Images: Transfer Function Independent Registration
Deserno, Thomas M. (Ed.) et al.: Bildverarbeitung für die Medizin 2010. Proceedings : Algorithmen, Systeme, Anwendungen. Berlin; Heidelberg; New York: Springer, 2010. (Informatik aktuell), pp. 117-121
Workshop Bildverarbeitung für die Medizin (BVM) <13, 2010, Aachen, Germany>
As exact dose delivery is essential for radiological cancer treatment, image-guided radiotherapy (IGRT) methods are used to estimate corrections of the tumor alignment. This is often done through comparison of a Computed Tomography (CT) to the patient alignment visible in digital radiography images (DRs) acquired from within the treatment device. Digitally Reconstructed Radiography Images (DRRs) computed from the CT are then geometrically registered to the DRs. A problem is that radiometric properties of DRs and DRRs can vary profoundly. If a registration algorithm does not use volumetric CT data directly it is unable to regard deviations of the physical image formation to the simulated image formation. We present a novel method allowing direct DR to CT registration. It is designed to be radiometry tolerant by adapting the simulated X-ray transfer function to observed DR intensities. This is done by solving an overdetermined system of equations given by the histograms along rays through the voxel matrix of the CT. Remaining errors serve as measure for the image dissimilarity, thus minimization in 6 degrees of freedom (DOF) gives the transformation between the images. Thereby higher radiometric tolerance can be achieved, as misalignments can be identified even if DR images are acquired with inappropriate radiation parameters.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, Wolfgang-Dieter; Stilla, Uwe
The Effects of Radiometry on the Accuracy of Intensity Based Registration
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, Wolfgang-Dieter; Stilla, Uwe
The Effects of Radiometry on the Accuracy of Intensity Based Registration
Institute of Electrical and Electronics Engineers (IEEE): 20th International Conference on Pattern Recognition. Proceedings : ICPR 2010. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2010, pp. 4528-4531
International Conference on Pattern Recognition (ICPR) <20, 2010, Istanbul, Turkey>
Besides several other factors, radiometric differences between a reference and a floating image greatly influence the achievable accuracy of image registration. In this work we derive the magnitude of registration inaccuracy coming from changes in radiometric properties. This is done for the example of medical X-ray image registration. We therefore estimate the change of image intensity with respect to object shape, X-ray attenuation of the object material and the initial X-ray energy by modelling a simplified image formation process. The change in intensity is then used to determine a closed form estimation of the resulting registration error, independent from a specific registration algorithm. Finally the theoretical calculations are compared to the accuracy of intensity based registration performed on X-ray images with different radiometric properties. Results show that the herewith derived accuracy estimation is well suited to predict the achievable accuracy of a registration for images with radiometric differences.
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Stallkamp, Jan; Drechsler, Klaus; Bergen, Tobias; Kaltenbacher, Dominik; Burisch, Michael; Kage, Andreas; Münzenmayer, Christian; Sakas, Georgios; Werner, Norman; Wechsler, Axel; Winter, Christian; Wittenberg, Thomas
Whole'O'Hand - A Holistic Intervention and Interaction System: A Novel Concept for Closed-Loop Liver Surgery
Stallkamp, Jan; Drechsler, Klaus; Bergen, Tobias; Kaltenbacher, Dominik; Burisch, Michael; Kage, Andreas; Münzenmayer, Christian; Sakas, Georgios; Werner, Norman; Wechsler, Axel; Winter, Christian; Wittenberg, Thomas
Whole'O'Hand - A Holistic Intervention and Interaction System: A Novel Concept for Closed-Loop Liver Surgery
Biomedizinische Technik, Vol.55 (2010), Supplement 1, pp. 27-31 in Section G Computergestützte Chirurgie
Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik im VDE (BMT) <44, 2010, Rostock, Germany>
Minimal-invasive surgery (MIS) and similar technologies are known to reduce the trauma for the patients. Nevertheless, the keyhole incisions also reduce vision, orientation and maneuverability of the surgeon. To compensate these losses, MIS interventions have always been dependent on technical equipment, as e.g. endoscopes. Within the generation of instruments currently available the increasing technological possibilities are barely used. To overcome the named disadvantages, the project Whole'O'Hand supports the surgeon's vision, orientation, and dexterity with a new concept for the integration and fusion of endoscopy, robotics, mechatronics, sensing and measuring devices, computer-assisted diagnosis, navigation, and visual computing.
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Steger, Sebastian; Erdt, Marius
Lymph Node Segmentation in CT Images Using a Size Invariant Mass Spring Model
Steger, Sebastian; Erdt, Marius
Lymph Node Segmentation in CT Images Using a Size Invariant Mass Spring Model
University of Ioannina: ITAB 2010 : 10th International Conference on Information Technology and Applications in Biomedicine. New York: IEEE, Inc., 2010, 4 p.
International Conference on Information Technology and Applications in Biomedicine (ITAB) <10, 2010, Corfu, Greece>
One major challenge in automated segmentation of lymph nodes in CT scans is the high variance in terms of texture, surrounding tissue, shape and also size. Mass Spring Models have been proven to be suitable for this task. However due to their size preserving property, their performance is highly affected by the size of the target structures. This paper addresses this point by introducing a size invariant Mass Spring Model, which relates to relative rest lengths, has balanced torsion forces and an initial model expansion. We evaluated our method on a set of 25 lymph nodes from routinely gathered CT images and compared it to state of the art Mass Spring Models with different initial sizes. The average Dice Similarity Coefficient toward gold standard was 0.72 for our method compared to 0.61 for the best fitted state of the art model. Thus our method can be successfully applied to clinical relevant lymph nodes of different size without prior knowledge about the size of the target structures in contrast to existing methods
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Steger, Sebastian; Keil, Matthias
Automated Initialization and Region of Interest Detection for Successful Head Registration of Truncated CT/MR Head & Neck Images
Steger, Sebastian; Keil, Matthias
Automated Initialization and Region of Interest Detection for Successful Head Registration of Truncated CT/MR Head & Neck Images
University of Ioannina: ITAB 2010 : 10th International Conference on Information Technology and Applications in Biomedicine. New York: IEEE, Inc., 2010, 5 p.
International Conference on Information Technology and Applications in Biomedicine (ITAB) <10, 2010, Corfu, Greece>
Maximization of a voxel based similarity metric like mutual information is the state of the art for the multimodal rigid registration of the head. To achieve satisfactory results the transform needs to be initialized properly and the region of interest (ROI) containing only rigid structures has to be defined in both images. In this paper we present and comprehensively evaluate an automated initialization and ROI detection method that enables the fully automated rigid registration of routinely gathered head CT and MR images. For ROI definition an automated head detection heuristic is presented that is robust against truncation and can be applied to images of different modalities. The registration transform is initialized based on a novel automated landmark detection method. Combined with standard mutual information based registration techniques, this result in a fully automated rigid registration framework for truncated CT/MR head & neck images. We evaluated the landmark detection in 81 routinely gathered truncated MR and CT images of the head & neck. Those images form 57 intra subject CT/MR pairs to which the overall approach was applied and evaluated by visual inspection. We show that the presented approach is robust against truncation and influence of non rigid structures. Not requiring any user interaction at all, it enables new applications in clinical practice.
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Stolka, Philipp J.; Keil, Matthias; Sakas, Georgios; McVeigh, Elliot R.; Allaf, Mohamad E.; Taylor, Russell H.; Boctor, Emad
A 3D-Elastography-Guided System for Laparoscopic Partial Nephrectomies
Stolka, Philipp J.; Keil, Matthias; Sakas, Georgios; McVeigh, Elliot R.; Allaf, Mohamad E.; Taylor, Russell H.; Boctor, Emad
A 3D-Elastography-Guided System for Laparoscopic Partial Nephrectomies
H. Wong, Kenneth (Ed.) et al.: Medical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling. Part One : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 11, No. 35. Bellingham: SPIE Press, 2010. (Proceedings of SPIE 7625), pp. 76251I-1 - 76251I-12
SPIE Medical Imaging Symposium <2010, San Diego, CA, USA>
We present an image-guided intervention system based on tracked 3D elasticity imaging (EI) to provide a novel interventional modality for registration with pre-operative CT. The system can be integrated in both laparoscopic and robotic partial nephrectomies scenarios, where this new use of EI makes exact intra-operative execution of pre-operative planning possible. Quick acquisition and registration of 3D-B-Mode and 3D-EI volume data allows intra-operative registration with CT and thus with pre-defined target and critical regions (e.g. tumors and vasculature). Their real-time location information is then overlaid onto a tracked endoscopic video stream to help the surgeon avoid vessel damage and still completely resect tumors including safety boundaries. The presented system promises to increase the success rate for partial nephrectomies and potentially for a wide range of other laparoscopic and robotic soft tissue interventions. This is enabled by the three components of robust real-time elastography, fast 3D-EI/CT registration, and intra-operative tracking. With high quality, robust strain imaging (through a combination of parallelized 2D-EI, optimal frame pair selection, and optimized palpation motions), kidney tumors that were previously unregistrable or sometimes even considered isoechoic with conventional B-mode ultrasound can now be imaged reliably in interventional settings. Furthermore, this allows the transformation of planning CT data of kidney ROIs to the intra-operative setting with a markerless mutual-information-based registration, using EM sensors for intraoperative motion tracking. Overall, we present a complete procedure and its development, including new phantom models - both ex vivo and synthetic - to validate image-guided technology and training, tracked elasticity imaging, real-time EI frame selection, registration of CT with EI, and finally a real-time, distributed software architecture. Together, the system allows the surgeon to concentrate on intervention completion with less time pressure.
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Strosche, Michael; Drechsler, Klaus (Betreuer)
Interaktive Tumor-Segmentierung in medizinischen Volumendaten
Strosche, Michael; Drechsler, Klaus (Betreuer)
Interaktive Tumor-Segmentierung in medizinischen Volumendaten
Darmstadt, TU, Bachelor Thesis, 2010
In der heutigen Medizin spielt die computergestützte Bildverarbeitung eine sehr große Rolle. Diese ist beispielsweise bei der Operationsplanung zur Resektion von Tumoren oder bei der computergestützten Diagnose sehr hilfreich. Hierbei ist, in Abhängigkeit der Fragestellung, oftmals eine Segmentierung der Bilddaten notwendig. Zur Segmentierung der Bilddaten steht eine Reihe verschiedener Pixel-, Kanten-, Regionen und modellbasierter Verfahren zur Verfügung, welche allerdings oftmals Schwächen in der Qualität des Segmentierungsergebnisses aufweisen, vor allem im Bezug auf Rauschen im Bild, und einen hohen Aufwand für die Vor- und Nachbearbeitung haben. Das Graph-Cut- Segmentierungsverfahren kann diesen Aufwand vermindern, da der Benutzer intuitiv Saatpunkte im Bilddatensatz setzen und das Ergebnis interaktiv beeinflussen kann. Des Weiteren kann es durch die Modifikation der Kostenfunktion auf individuelle Problemstellungen angepasst werden. Aufgrund des hohen Speicherbedarfs des Graph-Cut-Verfahrens wurde im Rahmen dieser Bachelorarbeit ein Verfahren zur Anwendung auf große Datensätze entwickelt, welches durch einen Multi-Resolution-Ansatz in mehreren Schritten die Segmentierung eines Bilddatensatzes zulässt. Für das Graph-Cut-Verfahren wurde des Weiteren eine auf Lebertumore optimierte Kostenfunktion entwickelt. Bei der Evaluation des implementierten Verfahrens hat sich gezeigt, dass der Speicherverbrauch durch die Anwendung eines Multi-Resolution-Ansatzes erheblich reduziert und auch die Laufzeit des Verfahrens hierdurch minimiert werden konnte.
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Tausch, Reimar; Jung, Christoph (Betreuer)
Visual Human Traits Recognition
Tausch, Reimar; Jung, Christoph (Betreuer)
Visual Human Traits Recognition
Darmstadt, TU, Master Thesis, 2010
In this thesis state-of-the-art machine vision and learning technologies are applied to train a computer to perform human-like recognition from experience and classify pedestrians from image and video data with respect to directional orientation, gender, age group, and body physique. In order to perform the classification task, distinctive visual traits are extracted and learned from the full human body. Compared to the many successful studies, which exclusively focus on faces, full body based classification has been rarely addressed before, partly because much harder challenges have to be dealt with, such as the high variety of body postures, clothing styles and irritating background. Nevertheless, if no faces are exposed, it is often the only option. To the best of the author's knowledge, this study is the first to address the problem of gender and age recognition from low resolution full body images of persons in arbitrary upright postures, without being constrained to only frontal views. In the process numerous configurations of image descriptors and classifiers are investigated, with regard to their suitability for visual person profiling. Features include histograms of oriented gradients (HOG) as shape descriptors and local RGB histograms as color descriptors. These image representations are learned and combined by multiple support vector machines (SVM) in a hierarchical classifier structure. Thus, the most discriminating visual traits could be identified and their effect evaluated, whereby the fusion of multiple cues representing shape and color resulted in an improvement of the classification performance. Best and robust results, 86% gender recognition accuracy, were achieved by the additional introduction of temporal integration strategies when classifying tracked people from video. Moreover, the evaluated practical approach is economically motivated and integrated into a software application that serves as prototype of a novel automated audience measurement system for adaptive digital signage, whose major design and use case is demonstrated and discussed. As an additional contribution, the large, manually performed annotations (utilized for the classifier training and testing), which refer to a compilation of online available image and video datasets (most originally designed for people detection and tracking tasks), are planned to be published.
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Vronskyi, Dmytro; Steger, Sebastian (Betreuer)
Rigide Registrierung von 3D anatomischen MRI und 2D biochemischen MRSI Daten
Vronskyi, Dmytro; Steger, Sebastian (Betreuer)
Rigide Registrierung von 3D anatomischen MRI und 2D biochemischen MRSI Daten
Darmstadt, TU, Master Thesis, 2010
Die Magnetresonanzspektroskopie ist eine junge Disziplin, die viele neue Möglichkeiten bei der medizinischen Diagnostik und der Therapie eröffnet. Sie ermöglicht eine nichtinvasive Bestimmung von physiologischen und biochemischen Parametern des Gewebes. Um anhand dieser Parameter aussagekräftige Schlussfolgerungen ziehen zu können, müssen sie mit anatomischen MRT-Informationen kombiniert werden. Dazu ist eine Registrierung von anatomischen und spektroskopischen Daten erforderlich. Allerdings gibt es dafür noch keine standardisierte Methode. Im Rahmen dieser Masterarbeit soll eine auf geometrischen Berechnungen und Transformationen basierende Methode zur automatischen Registrierung von anatomischen und spektroskopischen Datensätzen entwickelt werden. Dabei sollen die spektroskopischen Datensätze in ein geeignetes Bildformat umgewandelt werden. Die entwickelte Methode soll durch eine in vivo Untersuchung ausgewertet werden.
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Wagener, Sebastien; Hoßbach, Martin (Betreuer); Sakas, Georgios (Betreuer); Schultz, Tanja (Betreuer)
Optische Verfolgung von Kopfbewegungen während der Magnetresonanztomographie durch ein modellbasiertes Verfahren
Wagener, Sebastien; Hoßbach, Martin (Betreuer); Sakas, Georgios (Betreuer); Schultz, Tanja (Betreuer)
Optische Verfolgung von Kopfbewegungen während der Magnetresonanztomographie durch ein modellbasiertes Verfahren
Darmstadt, TU, Diplomarbeit, 2010
Bewegt ein Patient während einer Aufnahme des Schädels im Magnetresonanztomographen (MRT) den Kopf, so kann dies zu Artefakten führen. In diesem Fall bietet es sich an, die Magnetfelder automatisch den Bewegungen des Kopfes nachzuführen. Im Rahmen dieser Diplomarbeit wird deshalb ein Verfahren entwickelt, um mit einem Stereokamerasystem die Lage des Schädels markerlos in Echtzeit zu verfolgen. Wegen der geringen Bildqualität und der Positionierung der Kameras scheiden Standardverfahren aus. Deshalb wird ein modellbasiertes Verfahren entwickelt, um das jeweils sichtbare Nasenloch in den Kamerabildern zu tracken. Beide Phasen nutzen aktive Konturen, den Gradient-Vector-Flow und beziehen die Linsenverzerrung analytisch mit ein. In einer ersten Phase wird außerhalb des MRT eine Stereoaufnahme der Nasenlöcher gemacht, welche segmentiert und zu einem 3-D-Modell rekonstruiert wird. Für das Stereomatching wird das Verfahren für die minimale Editierdistanz angepasst und eine randomisierte Variante davon entwickelt. Da sich Fehler in der Segmentierung auf das Matching auswirken, werden beide Schritte durch eine Kopplung über die Epipolargeometrie kombiniert. Wegen dem wesentlichen Einfluss der Kalibrierung wird versucht, die Kameraparameter mit anzupassen. Zudem wird mit einer Planaritätsbedingung versucht, die Schlangen über eine Homographie zu koppeln. Beide Ansätze konvergieren jedoch nicht. In einer zweiten Phase wird zu jedem Zeitpunkt die Lage des 3-D-Modells bestimmt, damit Projektion und Kamerabild übereinstimmen. Ein Ansatz besteht darin, die Werte der sechs Freiheitsgrade so zu bestimmen, dass auf der Projektion des transformierten Modells ein maximaler Gradient auftritt. Der zugehörige Metrikraum erlaubt jedoch nur eine zeitintensive erschöpfende Suche. Ein Iterative-Closest-Point Verfahren aus einer verwandten Arbeit scheitert daran, dass das Modell ungenau ist und eine gute Initialisierung vorausgesetzt wird. Deshalb wird die Lage über eine Minimierung des Hausdorffabstands des projizierten Modells zur Segmentierung bestimmt. Neben einer synthetischen Evaluierung wird das Verfahren experimentell mit einem magnetischen Trackingsystem verglichen. Um beide Messreihen in Übereinstimmung zu bringen, werden Methoden des Hand-Eye-Problems angewendet. Die Standardlösung scheitert aufgrund der Ungenauigkeit der Rotationsangaben. Deshalb wird ein weiterführender iterativer Lösungsansatz, welcher Translation und Rotation gleichzeitig bestimmt und eine statistische Fehlerverteilung zugrunde legt, angepasst. Die erreichte Genauigkeit ist 5; 65mm Standardabweichung für den Translationsanteil und 3,76° für den Rotationsanteil. Ein unbekannter Anteil ist auf den magnetische Tracker und das Evaluierungsverfahren zurückzuführen. Evaluiert man auf gleiche Art den markerbasierten Tracker aus [Hoß10], erhält man zum Vergleich 3,57 mm und 2,46°.
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Wesarg, Stefan; Kafchitsas, Konstantinos; Erdt, Marius; Khan, M. Fawad
CAD of Osteoporosis in Vertebrae Using Dual-energy CT
Wesarg, Stefan; Kafchitsas, Konstantinos; Erdt, Marius; Khan, M. Fawad
CAD of Osteoporosis in Vertebrae Using Dual-energy CT
Dillon, Tharam et al.: Twenty-Third IEEE Symposium on Computer-Based Medical Systems : CBMS 2010. Los Alamitos, Calif.: IEEE Computer Society, 2010, pp. 358-363
IEEE Symposium on Computer-Based Medical Systems (CBMS) <23, 2010, Perth, Australia >
The assessment of bone mineral density (BMD) in vertebrae is critical for the diagnosis of osteoporosis. Recent developments in dual-source CT allow for the simultaneous acquisition of two image data sets with different X-ray tube energies - dual-energy CT (DECT). We present a comprehensive approach for assessing the density of the trabecular bone in vertebrae of the spine based on DECT image data. For this, we apply and combine methods from different areas: the deformation of a template mesh for delineating the structures of interest, a biophysical model of the trabecular bone for the computation of BMD values, and different visualization approaches for the display of the results. In addition, we investigate the correlation between the computed BMD values with concurrently measured pull-out forces for pedicle screws. We show that there is a linear correlation between both measures and thus, DECT provides correct BMD values for the trabecular bone. We conclude that our approach enables the radiologist to diagnose osteoporosis based on DECT image data which has the potential to replace the current gold standard dual-energy X-ray absorptiometry.
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Adam, Michael; Jung, Christoph; Roth, Stefan; Brunnett, Guido
Real-time Stereo-Image Stitching Using GPU-based Belief Propagation
Adam, Michael; Jung, Christoph; Roth, Stefan; Brunnett, Guido
Real-time Stereo-Image Stitching Using GPU-based Belief Propagation
Magnor, Marcus A. (Ed.) et al.: Proceedings of the Vision, Modeling, and Visualization Workshop 2009 : VMV 2009. Magdeburg: Otto-von-Guericke-Universität, 2009, pp. 215-224
Vision, Modeling, and Visualization Workshop (VMV) <14, 2009, Braunschweig, Germany>
Image stitching or mosaicing is a challenging vision problem, especially when considering aspects like high definition content, real-time, and proper compensation of the parallax error of objects at different distances to the camera system. Today many approaches to image stitching exist, most of them deal with medium resolution images, offline processing, or are restricted to objects at similar distance. Our approach is based on calculation of disparities between corresponding points in stereo images by employing standard belief propagation. Instead of computing depth-maps like in previous approaches, we compute stitch-maps modifying cost functions in the underlying Markov random field model, which makes further projection steps dispensable and thereby overall computation more efficient. Our GPU-based implementation is real-time capable, allowing to stitch high definition images at constant frame rates. We show exemplary results from our system to demonstrate the quality of the merged images.
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Akram, Shahid; Drechsler, Klaus (Betreuer); Lacalli, Christina (Betreuer)
Coronary Tree Segmentation Using an Enhanced Corkscrew Algorithm
Akram, Shahid; Drechsler, Klaus (Betreuer); Lacalli, Christina (Betreuer)
Coronary Tree Segmentation Using an Enhanced Corkscrew Algorithm
Darmstadt, TU, Master Thesis, 2009
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Beales, Richard M.; Chakravarthy, Ajay; Hedtke, R.; Huther, W.; Jung, Christoph; Jung, Yvonne; Koutsoutos, S.; Yannopoulos, A.
Automated 3D Pre-Vis for Modern Production
Beales, Richard M.; Chakravarthy, Ajay; Hedtke, R.; Huther, W.; Jung, Christoph; Jung, Yvonne; Koutsoutos, S.; Yannopoulos, A.
Automated 3D Pre-Vis for Modern Production
International Broadcasting Convention (IBC): IBC 2009. Conference Publication : Technical Papers. London, 2009, 8 p.
International Broadcasting Convention (IBC) <2009, Amsterdam, The Netherlands>
Hand-drawn storyboards have served the industry for decades and in recent years artist-created digital pre-vis animations have allowed directors, screenwriters and commissioners to 'see' their film long before the first scene is shot. However the nature of programmemaking is changing. Digital effects, mixed-reality production and now stereoscopic 3D are becoming mainstream. Blurring the distinction between production and post-production, they bring complex planning issues that leave linear pre-vis approaches wanting. This paper describes ANSWER, a new approach to the creative process of film production based on a symbolic notation system akin to a musical score. The notation populates a machine-processable semantic model, or ontology, of the director's creative intent, which in turn is used to automatically create lightweight 3D pre-vis animations. ANSWER is also integrated with DFT BONES Dailies, so that in post-production editors can quickly synchronise and compare pre-vised and actual footage.
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Bobda, Christophe; Cheng, Kevin; Mühlbauer, Felix; Drechsler, Klaus; Schulte, Jan; Murr, Dominik; Tanougast, Camel
Enabling Self-Organization in Embedded Systems with Reconfigurable Hardware
Bobda, Christophe; Cheng, Kevin; Mühlbauer, Felix; Drechsler, Klaus; Schulte, Jan; Murr, Dominik; Tanougast, Camel
Enabling Self-Organization in Embedded Systems with Reconfigurable Hardware
Cumplido, René (Ed.): International Journal of Reconfigurable Computing. New York, USA: Hindawi Publishing Corporation, 2009, 9 p.
We present a methodology based on self-organization to manage resources in networked embedded systems based on reconfigurable hardware. Two points are detailed in this paper, the monitoring system used to analyse the system and the Local Marketplaces Global Symbiosis (LMGS) concept defined for self-organization of dynamically reconfigurable nodes.
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Chen, Yufei; Oyarzun Laura, Cristina; Drechsler, Klaus
Generation of a Graph Representation from Three-Dimensional Skeletons of the Liver Vasculature
Chen, Yufei; Oyarzun Laura, Cristina; Drechsler, Klaus
Generation of a Graph Representation from Three-Dimensional Skeletons of the Liver Vasculature
Shi, Riyi (Ed.) et al.: Proceedings of the 2009 2nd International Conference on Biomedical Engineering and Informatics. New York: IEEE, Inc., 2009, 5 p.
International Conference on Biomedical Engineering and Informatics (BMEI) <2, 2009, Tianjin, China>
Extracting hepatic vasculature from three dimensional imagery is important for diagnosis of liver disease and planning of liver surgery. In this paper we propose a method for generation of 3D skeletal graph of liver vessels using thinning algorithm and graph theory. First of all, basic methodology in the proposed method is introduced. Secondly, the skeletonization method together with a pre-processing method on liver vessel images is employed to form liver skeleton image. Thirdly, a graphbased technique is then employed on the skeleton result to efficiently form the hepatic vessel system. The liver vessel tree generation method was evaluated on liver CT datasets to show its effectiveness and efficiency.
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Cogollos van der Linden, Jacobo Josep; Jung, Christoph (Betreuer)
Scene Classication Using a Hybrid Generative/Discriminative Approach
Cogollos van der Linden, Jacobo Josep; Jung, Christoph (Betreuer)
Scene Classication Using a Hybrid Generative/Discriminative Approach
Darmstadt, TU, Diplomarbeit, 2009
The scene classification area has been growing over the last years, becoming relevant in order to be able to work with the many digital images that are being taken every day around the world. The scope of this thesis is the scene classification task. The purpose of it is, having a group of image categories, to be able to classify new images into one of those categories. The approach done is based on the work of Bosch et al.[7], using the SIFT (Scale Invariant Feature Transform) features extracted from the image applying the k-Means clustering method to have a visual vocabulary and making a quantization over the features resulting on a BoW (Bag of Words). To the BoW a hybrid approach is applied for the classification, using the pLSA(probabilistic Latent Semantic Analysis technique) and the SVM (Support Vector Machine) classification technique. The pLSA is used to decrease the dimensionality of the information that is treated and find relations between it, and the SVM for the posterior classification applying the one-vs-all rule. In this work it is shown that the concatenation of the PHOG (Pyramid of Histograms of Orientation Gradients) descriptor with the BoW leads to a better global performance. Further the inclusion of color information through histograms improved the results. The approach has been applied to different data-sets using several parameter configurations.
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Drechsler, Klaus; Oyarzun Laura, Cristina
Registration of Cardiac CT Data with Coronary Angiograms Using Digitally Reconstructed Radiographs
Drechsler, Klaus; Oyarzun Laura, Cristina
Registration of Cardiac CT Data with Coronary Angiograms Using Digitally Reconstructed Radiographs
Dössel, Olaf (Ed.) et al.: World Congress on Medical Physics and Biomedical Engineering 2009. Proceedings DVD-ROM. Berlin, Heidelberg, New York: Springer, 2009. (IFMBE Proceedings 25), IFMBE 25/IV, pp. 1431-1434
World Congress on Medical Physics and Biomedical Engineering (WC) <11, 2009, Munich, Germany>
A semi-automatic point-based 3D-2D registration approach to register computed tomography (CT) data with coronary angiograms using digitally reconstructed radiographs (DRR) is presented. It allows us to augment the coronary angiograms with pathologies (e.g. calcifications) found in CT data with an automated analysis tool that was previously developed in our department. We also present an efficient method to enable a backprojection from 2D into 3D space and to detect overlapping vessels. First qualitative results are presented.
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Drechsler, Klaus; Oyarzun Laura, Cristina; Sakas, Georgios
Towards Computer Assisted Cardiac Catheterization: How 3D Visualization Supports It
Drechsler, Klaus; Oyarzun Laura, Cristina; Sakas, Georgios
Towards Computer Assisted Cardiac Catheterization: How 3D Visualization Supports It
Institute for Systems and Technologies of Information, Control and Communication (INSTICC): VISIGRAPP 2009. Proceedings : International Joint Conference on Computer Vision and Computer Graphics Theory and Applications [CD-ROM]. INSTICC Press, 2009, IMAGAPP; pp. 159-165
International Conference on Imaging Theory and Applications (IMAGAPP) <1, 2009, Lisboa, Portugal>
Although cardiac catheterization procedures take place under x-ray guidance, the doctor is almost blind. Vessels are almost invisible until he injects a contrast agent and looking only at 2D x-ray images and reconstructing a 3D image in his head makes it error prone and tedious. Only experienced doctors are able to accomplish this procedure with the expected results. This paper describes our preliminary work and work in progress to support doctors during cardiac catheterizations using 3D visualization.
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Drechsler, Klaus; Oyarzun Laura, Cristina; Sakas, Georgios
Towards Improving Cardiac Catheterizations through 3D Visualization Using CT Angiography
Drechsler, Klaus; Oyarzun Laura, Cristina; Sakas, Georgios
Towards Improving Cardiac Catheterizations through 3D Visualization Using CT Angiography
European Heart Journal. Supplements, Vol.11 (2009), Supplement B, p. S59, Abstract 282
International Conference of Non-Invasive Cardiovascular Imaging <9, 2009, Barcelona, Spain>
Our purpose is to assist the catheterization using a preoperatively generated CT angiography to extract the heart, segment the vessels, analyse them and register it intraoperatively with the x-ray angiography to present the "scene" to the doctor in 3D and thus enabling catheterizations also for less experienced doctors.
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Erdt, Marius
Segmentation, Registration, and Fusion of Medical Images
Erdt, Marius
Segmentation, Registration, and Fusion of Medical Images
Stergiopoulos, Stergios (Ed.): Advanced Signal Processing : Theory and Implementation for Sonar, Radar, and Non-Invasive Medical Diagnostic Systems. Boca Raton: Taylor & Francis, CRC Press, 2009. (The Electrical Engineering and Signal Processing Series), pp. 251-275
6.1 Segmentation 252 6.1.1 Intensity-based Segmentation 252 6.1.1.1 Point-based Segmentation 252 6.1.1.2 Edge-based Segmentation 254 6.1.1.3 Region-based Segmentation 256 6.1.2 Model-based Segmentation 258 6.1.3 Atlas-based Segmentation 258 6.2 Registration 259 6.2.1 Choice of Transformation 260 6.2.1.1 Rigid 261 6.2.1.2 Affine 261 6.2.1.3 Projective 262 6.2.1.4 Elastic 263 6.2.2 Finding Correspondences 263 6.2.2.1 Extrinsic Landmarks 264 6.2.2.2 Intrinsic Landmarks 264 6.2.2.3 Segmentations 264 6.2.2.4 Grids and Voxel Properties 265 6.2.3 Computing Transformations 266 6.2.3.1 Known Point to Point Correspondences 266 6.2.3.2 Point Clouds 266 6.2.3.3 Voxel Based Registration 268 6.2.4 Integration 270 6.2.4.1 Rigid Registration 270 6.2.4.2 Elastic Registration 271 6.3 Fusion 271 Acknowledgments 273 References 274
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Erdt, Marius; Kirschner, Matthias; Wesarg, Stefan
Simultaneous Segmentation and Correspondence Establishment for Statistical Shape Models
Erdt, Marius; Kirschner, Matthias; Wesarg, Stefan
Simultaneous Segmentation and Correspondence Establishment for Statistical Shape Models
Magnenat-Thalmann, Nadia (Ed.): Modelling the Physiological Human : 3D Physiological Human Workshop. Proceedings. Berlin, Heidelberg, New York: Springer, 2009. (Lecture Notes in Computer Science (LNCS) 5903), pp. 25-35
3D Physiologigal Human Workshop (3DPH) <2, 2009, Zermatt, Switzerland>
Statistical Shape Models have been proven to be valuable tools for segmenting anatomical structures of arbitrary topology. Being based on the statistical description of representative shapes, an initial segmentation is required - preferably done by an expert. For this purpose, mostly manual segmentation methods followed by a mesh generation step are employed. A prerequisite for generating the training data based on these segmentations is the establishment of correspondences between all training meshes. While existing approaches decouple the expert segmentation from the correspondence establishment step, we propose in this work a segmentation approach that simultaneously establishes the landmark correspondences needed for the subsequent generation of shape models. Our approach uses a reference segmentation given as a regular mesh. After an initial placement of this reference mesh, it is manually deformed in order to best match the boundaries of the considered anatomical structure. This deformation is coupled with a real time optimization that preserves point correspondences and thus ensures that a pair of landmark points in two different data sets represents the same anatomical feature. We applied our new method to different anatomical structures: vertebra of the spinal chord, kidney, and cardiac left ventricle. In order to perform a visual evaluation of the degree of correspondence between different data sets, we have developed well adapted visualization methods. From our tests we conclude that the expected correspondences are established during the manual mesh deformation. Furthermore, our approach considerably speeds up the shape model generation, since there is no need for an independent correspondence establishment step. Finally, it allows the creation of shape models of arbitrary topology and removes potential error sources of landmark and correspondence optimization algorithms needed so far.
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Erdt, Marius; Tulchiner, Roman; Sakas, Georgios
Erweiterung modellbasierter Segmentierung durch lokale Deformationskriterien
Erdt, Marius; Tulchiner, Roman; Sakas, Georgios
Erweiterung modellbasierter Segmentierung durch lokale Deformationskriterien
Meinzer, Hans-Peter (Ed.) et al.: Bildverarbeitung für die Medizin 2009. Proceedings : Algorithmen, Systeme, Anwendungen. Berlin; Heidelberg; New York: Springer, 2009. (Informatik aktuell), pp. 326-330
Workshop Bildverarbeitung für die Medizin (BVM) <12, 2009, Heidelberg, Germany>
Modellbasierte Ansätze sind heutzutage Stand der Technik zur automatischen Organsegmentierung in medizinischen Bilddatensätzen. In dieser Arbeit wird ein Verfahren vorgestellt, welches die modellbasierte Segmentierung durch lokale Deformationskriterien erweitert, um eine bessere lokale Anpassung der Oberflächenmodelle an Bildstrukturen sowohl hoher als auch niedriger Frequenz zu erreichen. Die beschriebene Methode wird anhand von Computer-Tomographie Datensätzen der Niere beschrieben und evaluiert.
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Graf, Norbert; Hoppe, Alexander; Georgiadi, Eleni; Belleman, Robert; Desmedt, Christine; Dionysiou, Dimitra; Erdt, Marius; Jacques, Julien; Kolokotroni, Eleni; Lunzer, Aran; Tsiknakis, Manolis; Stamatakos, Georgios
'In Silico' Oncology for Clinical Decision Making in the Context of Nephroblastoma
Graf, Norbert; Hoppe, Alexander; Georgiadi, Eleni; Belleman, Robert; Desmedt, Christine; Dionysiou, Dimitra; Erdt, Marius; Jacques, Julien; Kolokotroni, Eleni; Lunzer, Aran; Tsiknakis, Manolis; Stamatakos, Georgios
'In Silico' Oncology for Clinical Decision Making in the Context of Nephroblastoma
Klinische Pädiatrie, (2009), 221, pp. 141-149
The present paper outlines the initial version of the ACGT (Advancing Clinico-Genomic Trials) - an Integrated Project, partly funded by the EC (FP6-2005-IST-026996)I-Oncosimulator as an integrated software system simulating in vivo tumour response to therapeutic modalities within the clinical trials environment aiming to support clinical decision making in individual patients. Cancer treatment optimization is the main goal of the system. The document refers to the technology of the system and the clinical requirements and the types of medical data needed for exploitation in the case of nephroblastoma. The outcome of an initial step towards the clinical adaptation and validation of the system is presented and discussed. Use of anonymized real data before and after chemotherapeutic treatment for the case of the SIOP 2001 / GPOH nephroblastoma clinical trial constitutes the basis of the clinical adaptation and validation process. By using real medical data concerning nephroblastoma for a single patient in conjunction with plausible values for the model parameters (based on available literature) a reasonable prediction of the actual tumour volume shrinkage has been made possible. Obviously as more and more sets of medical data are exploited the reliability of the model " tuning" is expected to increase. The successful performance of the initial combined ACGT Oncosimulator platform, although usable up to now only as a test of principle, has been a particularly encouraging step towards the clinical translation of the system, being the first of its kind worldwide.
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Heinrich, Gregor
A Generic Approach to Topic Models
Heinrich, Gregor
A Generic Approach to Topic Models
Buntine, Wray (Ed.) et al.: Machine Learning and Knowledge Discovery in Databases : European Conference, ECML PKDD 2009. Proceedings, Part I. Berlin, Heidelberg, New York: Springer, 2009. (Lecture Notes in Computer Science (LNCS) 5781), pp. 517-532
European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD) <9, 2009, Bled, Slovenia>
This article contributes a generic model of topic models. To define the problem space, general characteristics for this class of models are derived, which give rise to a representation of topic models as "mixture networks", a domainspecific compact alternative to Bayesian networks. Besides illustrating the interconnection of mixtures in topic models, the benefit of this representation is ist straight-forward mapping to inference equations and algorithms, which is shown with the derivation and implementation of a generic Gibbs sampling algorithm.
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Heinrich, Gregor; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Parameter Estimation for Text Analysis
Heinrich, Gregor; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Parameter Estimation for Text Analysis
Presents parameter estimation methods common with discrete probability distributions, which is of particular interest in text modeling. Starting with maximum likelihood, a posteriori and Bayesian estimation, central concepts like conjugate distributions and Bayesian networks are reviewed. As an application, the model of latent Dirichlet allocation (LDA) is explained in detail with a full derivation of an approximate inference algorithm based on Gibbs sampling, including a discussion of Dirichlet hyperparameter estimation. Finally, analysis methods of LDA models are discussed.
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Heinrich, Gregor; Goesele, Michael
Variational Bayes for Generic Topic Models
Heinrich, Gregor; Goesele, Michael
Variational Bayes for Generic Topic Models
Mertsching, Baerbel (Ed.) et al.: KI 2009: Advances in Artificial Intelligence : 32nd Annual German Conference on AI. Berlin; Heidelberg; New York: Springer, 2009. (Lecture Notes in Artificial Intelligence (LNAI) 5803), pp. 161-168
Annual German Conference on Artificial Intelligence (KI) <32, 2009, Paderborn, Germany>
The article contributes a derivation of variational Bayes for a large class of topic models by generalising from the well-known model of latent Dirichlet allocation. For an abstraction of these models as systems of interconnected mixtures, variational update equations are obtained, leading to inference algorithms for models that so far have used Gibbs sampling exclusively.
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Keil, Matthias; Stolka, Philipp J.; Wiebel, Marion; Sakas, Georgios; McVeigh, Elliot R.; Taylor, Russell H.; Boctor, Emad
Ultrasound and CT Registration Quality: Elastography vs. Classical B-Mode
Keil, Matthias; Stolka, Philipp J.; Wiebel, Marion; Sakas, Georgios; McVeigh, Elliot R.; Taylor, Russell H.; Boctor, Emad
Ultrasound and CT Registration Quality: Elastography vs. Classical B-Mode
IEEE Signal Processing Society (SPS): 6th IEEE International Symposium on Biomedical Imaging: From Nano to Macro : ISBI 2009. New York: IEEE Press, 2009, pp. 967-970
IEEE International Symposium on Biomedical Imaging (ISBI) <2009, Boston, MA, USA>
Ultrasound and computed tomography registration is a valuable tool for interventional imaging and navigation, but current methods are limited in reliability or usefulness, requiring large fields of view, large ultrasound penetration depth, distinct image features, or contours of the investigated organs. Computationally cheap, small-field- of-view registration proved elusive so far. We propose the use of interventional ultrasound elastography imaging to perform limited-field-of-view, limited-features registration reliably, examining the image acquisition and registration in the example application of partial nephrectomies. Furthermore, the benefits of elastography vs. conventional B-Mode ultrasound imaging are investigated.
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Khalid, Imran; Rizou, Despina (Betreuer)
Development of an Online Telemedicine Platform Using the Extensible Messaging and Presence Protocol (XMPP) for Real Time Communication
Khalid, Imran; Rizou, Despina (Betreuer)
Development of an Online Telemedicine Platform Using the Extensible Messaging and Presence Protocol (XMPP) for Real Time Communication
Darmstadt, TU, Master Thesis, 2009
This Master thesis is based on the principle of "scanning the data and not the patient". This approach will help in bridging the technology gap, thus allowing doctors and patients to be anywhere in the world. The main idea is to establish a kind of "information equivalence" between the patient and the representation of that patient in digital form, so that there is little to no loss in examining the patient through the data representation, compared with what would be lost during a direct in-person examination. Given that it is faster and cheaper to ship information around than to ship people (patients and doctors), an Integrated Development Enviroment is provided which provides all necessary functionalities for visualization, storage, and exchange of medical images. The presentation of medical information is central and important task in telemedicine application. Based on the data presentation the physicians perform a medical diagnosis and apply a treatment plan, accordingly. To provide medical information this thesis work includes modules for Data visualization, Data Storage, Data Capture and Communication. The data visualization allows visualization of both synchronous (real time) and asynchronous (store and forward) data. Also the communication module not only provides the facility of data exchange between online and offline physicians but also allows them to communicate via instant messaging.
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Kreitz, Christopher; Drechsler, Klaus (Betreuer)
Segmentvisualisierung der Leber für die intraoperative Navigation
Kreitz, Christopher; Drechsler, Klaus (Betreuer)
Segmentvisualisierung der Leber für die intraoperative Navigation
Darmstadt, TU, Diplomarbeit, 2009
Für einige Lebertumore ist die vollständige chirurgische Entfernung die derzeit einzige potentiell heilende Therapie. Die Operabilität ist von diversen Faktoren abhängig: 1. Der Tumor muß mit ausreichend Sicherheitsabstand zum gesunden Gewebe entfernt werden. 2. Das restliche Lebergewebe muß eine ausreichende Funktionsleistung erbringen, welche vom verbleibenden Lebervolumen abhängt. 3. Von der Durchblutung abgetrennte Bereiche müssen erkannt und ebenfalls entfernt werden. Drei Operationsstrategien berücksichtigen diese Faktoren: 1. Hemihepatektomie (komplette Entfernung einer Leberhälfte). 2. Tumororientierte Operation (Keilförmiges Stück der Leber wird entfernt). 3. Segmentorientierte Operation (Eins oder mehrere der Lebersegmente wird entfernt). Zur unterstützenden Operationsplanung und zur besseren Orientierung des Chirurgen während des Eingriffs wurde in dieser Arbeit ein Software-Tool entwickelt, welches patientenspezifische Leber(sub)segmente aus präoperativen CT Daten mit möglichst wenig User-Interaktion anhand von Abstraktionen der Lebergefäße berechnet und visualisiert.
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Nouak, Alexander; Hahn, Volker
Access Control and Surveillance
Nouak, Alexander; Hahn, Volker
Access Control and Surveillance
Bullinger, Hans-Jörg (Ed.): Technology Guide : Principles, Applications, Trends. Berlin, Heidelberg, New York: Springer, 2009, pp. 522-527
In recent years, the growing threat of international terrorism and the increasing networking of organised crime have led to a worldwide boom in surveillance technology. In Great Britain alone, where video control has been pioneered since the eighties, more than one million security cameras are in use today in the private and public spheres. In London alone, several thousand cameras are deployed in underground stations, buses, football stadiums and other public places. In other countries, too, surveillance technology is making progress. Application areas are predominantly the monitoring of objects, i. e. buildings, public spaces, stations, public transport and stadiums, as well as traffic control. The increasing use of security cameras also poses new challenges for operators. Although the installation costs of the camera systems have become rather low by now, using them is labour-intensive. Due to the great number of existing cameras there is a flood of video data that can only be mastered with high labour costs. This is raising the question of how special software for automatic analysis of video content might automate surveillance to reduce work for the users.
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Polin, Dmitrij; Gerth, Maik (Betreuer)
Interaktive Konstruktion von Prothesengerüsten für die Zahnmedizin
Polin, Dmitrij; Gerth, Maik (Betreuer)
Interaktive Konstruktion von Prothesengerüsten für die Zahnmedizin
Darmstadt, TU, Diplomarbeit, 2009
Ausgehend aus der Situation im Patientenmund, repräsentiert durch die Zahnfleisch- und Pfeilermodelle, wurden in dieser Arbeit Algorithmen zur interaktiven Konstruktion von Prothesengerüsten sogennanten Stegen entwickelt. Der Stegverlauf wurde aus der Position der Pfeiler mittels Splineinterpolation bestimmt. Das Oberflächenmodell wurde durch das Propagieren eines Querschnittes entlang dieser Linie und anschließende Triangulierung erstellt. Zuerst wurden Stegsegmente, die zwischen den Pfeilern liegen und sie nicht durchdringen, erzeugt. Nachdem sie entsprechend den Einstellungen an die Situation angepasst wurden, fand ihre Fusion mit den Stegpfeilern statt. Da jeder Pfeiler mit zwei Stegsegmenten benachbart ist, bestimmte sich die Verbindung aus den Verläufern der beiden Segmenten. Entlang der Verbindung stellte man Schnittpunkte mit dem Pfeiler fest, die später zum Ausschneiden eines vom Steg nicht verdeckten Pfeilerbereiches verwendet wurden. Der ausgeschnittener Bereich wurde dann durch die Triangulierung mit den Stegsegmenten verbunden.
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Rizou, Despoina; Sachpazidis, Ilias; Salvatore, Luca; Sakas, Georgios
TraumaStation: A Portable Telemedicine Station
Rizou, Despoina; Sachpazidis, Ilias; Salvatore, Luca; Sakas, Georgios
TraumaStation: A Portable Telemedicine Station
IEEE Engineering in Medicine and Biology Society (EMBS): Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology : EMBC 2009 [CD-ROM]. New York: IEEE Press, 2009, pp. 1254-1257
Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) <31, 2009, Minneapolis, MN, USA>
TraumaStation is a portable medical device which covers the mobility of the medical doctors as well as integrates the diversity of telemedicine devices. Many portable telemedicine devices have been developed the last years in order to help patients in remote areas or in emergency situationns. The medical TraumaStation is a light portable tele-medical first-aid device, which provides the physicians with an ultrasound, electrocardiogram, blood pressure, oxygen meter apparatus all in a suitcase. In addition, the portable device is equipped with all available telecommunication gateways (e.g. GSM, UMTS, ISDN, DSL, Satellite) providing a great communication convenience to the physicians utilizing XMMP instant messaging protocols and real time video conference.
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Sachpazidis, Ilias; Callejo, Elica; Sakas, Georgios
T@HIS: A Satellite Based Telemedicine Network for Imaging Teleconsultations
Sachpazidis, Ilias; Callejo, Elica; Sakas, Georgios
T@HIS: A Satellite Based Telemedicine Network for Imaging Teleconsultations
Latin American Journal of Telehealth [online], Vol.1 (2009), 1, pp. 105-122
T@His is an ESA (European Space Agency) project for the deployment of a telemedical network connecting physicians and hospitals over a new-generation satellite network based on the AmerHis payload on the Hispasat Amazonas satellite. The consortium is formed by Thales Alenia Space España (Spain), Fraunhofer IGD (Germany) and CETA (Center of Excellence in Advanced Technology of Rio Grande do Sul in Brazil). The project objectives are to extend current medical network connecting isolated areas in Amazon over satellite communication. The project involved three remote sites in isolated areas and one site in urban area. Intotal four satellite terminals have been deployed at Porto Alegre (referral hospital in southern Brazil), Breves, Portel and Gurupá. All three spokes are located in Pará state, in northern Brazil.
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Sachpazidis, Ilias; Kontaxakis, George; Sakas, Georgios
A Portable Medical Unit for Medical Imaging Telecollaboration
Sachpazidis, Ilias; Kontaxakis, George; Sakas, Georgios
A Portable Medical Unit for Medical Imaging Telecollaboration
Association for Computing Machinery (ACM): Proceedings of the 2nd ACM International Conference on PErvasive Technologies Related to Assistive Environments : PETRA 2009. New York: ACM, 2009
ACM International Conference on PErvasive Technologies Related to Assistive Environments (PETRA) <2, 2009, Corfu, Greece>
In this paper, we are going to introduce a multimodal portable medical device for both medical imaging tele-collaboration and monitoring of vital parameters. The introduced portable unit offers diversity of medical devices and is in position to acquire ultrasound images, ECG 12 leads, and blood pressure and be able to measure oxygen level in the blood. In addition, the portable unit is equipped with all available telecommunication gateways (e.g. GSM, UMTS, ISDN, DSL, Satellite) providing a great communication convenience to the physicians utilizing XMMP instant messaging protocols.
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Sakas, Georgios; Grimm, Marcus; De Beni, Stefano; Solbiati, Luigi
Closed Loop: A Classification Framework for Interventional Procedures
Sakas, Georgios; Grimm, Marcus; De Beni, Stefano; Solbiati, Luigi
Closed Loop: A Classification Framework for Interventional Procedures
Dössel, Olaf (Ed.) et al.: World Congress on Medical Physics and Biomedical Engineering 2009. Proceedings DVD-ROM. Berlin, Heidelberg, New York: Springer, 2009. (IFMBE Proceedings 25), IFMBE 25/IV; pp. 704-707
World Congress on Medical Physics and Biomedical Engineering (WC) <11, 2009, Munich, Germany>
We present a closed-loop taxonomy framework for interventional procedures assisting to understand and locate an increasing number of "buzzword driven" techniques within the workflow of the interventionalist. Our framework applies equally for open and minimally invasive techniques and emphasizes the fact that all steps within an interventional procedure act as a closed chain, thus none of them can be regarded separately from all others. We give a concrete example of one of the first soft tissue navigation systems introduced to clinical routine since 2002.
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Sakas, Georgios; Karangelis, Grigorios; Pommert, Andreas
Advanced Applications of Volume Visualization Methods in Medicine
Sakas, Georgios; Karangelis, Grigorios; Pommert, Andreas
Advanced Applications of Volume Visualization Methods in Medicine
Stergiopoulos, Stergios (Ed.): Advanced Signal Processing : Theory and Implementation for Sonar, Radar, and Non-Invasive Medical Diagnostic Systems. Boca Raton: Taylor & Francis, CRC Press, 2009. (The Electrical Engineering and Signal Processing Series), 147-219
This chapter summarizes the state-of-the-art application of techniques developed over the recent years for visualising volumetric medical data acquired by modern medical imaging modalities such as CT, MRA, MRI, Nuclear Medicine, 3D-Ultrasound, Laser Confocal Microscopy etc. Although all of the modalities provide "slices of the body", significant differences exist between the image content of each modality. The focus of the Report is less in explaining algorithms and rendering techniques, but rather to point out their applicability, benefits, and potential in the medical environment. In the first part, fundamentals of medical image processing and methods for all steps of the volume visualisation pipeline from data preprocessing to object display are reviewed, with special emphasis on data structures, segmentation, and surface- and volume-based rendering. Furthermore, volume registration, intelligent visualisation, intervention rehearsal, and aspects of image quality are discussed. In the second part, applications are illustrated from the areas of craniofacial surgery, traumatology, neurosurgery, radiotherapy, and medical education. Further, some new applications of volumetric methods are presented: 3D ultrasound, laser confocal datasets, and 3D-reconstruction of cardiological datasets, i.e. vessels as well as ventricles. These new volumetric methods are currently under development but due to their enormous application potential they are expected to be clinically accepted within the next years.
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Schmidt, Carola; Erdt, Marius (Betreuer)
Atlasbasierte Segmentierung mittels elastischer Registrierung
Schmidt, Carola; Erdt, Marius (Betreuer)
Atlasbasierte Segmentierung mittels elastischer Registrierung
Koblenz/Landau, Univ., Diplomarbeit, 2009
Die vorliegende Arbeit beschäftigt sich mit atlasbasierter Segmentierung von CT-Datensätzen mit Hilfe von elastischen Registrierungsmethoden. Ziel atlasbasierter Segmentierung ist die vollautomatische Segmentierung eines beliebigen Eingabedatensatzes durch Registrierung mit einem vorsegmentierten Referenzdatensatz - dem Atlanten. Ein besonderes Augenmerk liegt dabei auf der Implementierung und Evaluation elastischer Registrierungsverfahren, da rigide Registrierungsmethoden besonders in Bereichen hoher anatomischer Varianzen keine genaue Segmentierung gewährleisten. Im Vordergrund steht zunächst die Generierung zweier Atlanten, die als durchschnittliche Referenzdatensätze Informationen über die anatomische Varianz männlicher und weiblicher Bevölkerungsgruppen enthalten. Des Weiteren werden vier etablierte elastische Registrierungsarten: BSpline- Registrierung, Demons-Registrierung, Level-Set-Motion-Registrierung und FEMRegistrierung implementiert und im Hinblick auf eine atlasbasierte Segmentierung der wichtigen Organe des menschlichen Torsos evaluiert. Robustheit und Genauigkeit der implementierten Verfahren wurden anhand von Lungen- und Abdomedatensätzen sowohl intra- als auch interpatientenspezifisch ausgewertet. Es wird gezeigt, dass vor allem die elastische BSpline-Registrierung hier genauere Segmentierungsergebnisse liefern kann, als es mit einer rigiden Registrierung möglich ist.
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Steger, Sebastian; Erdt, Marius; Chiari, Gianfranco; Sakas, Georgios
Feature Extraction from Medical Images for an Oral Cancer Reoccurrence Prediction Environment
Steger, Sebastian; Erdt, Marius; Chiari, Gianfranco; Sakas, Georgios
Feature Extraction from Medical Images for an Oral Cancer Reoccurrence Prediction Environment
Dössel, Olaf (Ed.) et al.: World Congress on Medical Physics and Biomedical Engineering 2009. Proceedings DVD-ROM. Berlin, Heidelberg, New York: Springer, 2009. (IFMBE Proceedings 25), IFMBE 25/V; pp. 97-100
World Congress on Medical Physics and Biomedical Engineering (WC) <11, 2009, Munich, Germany>
We present the concept of a novel image feature extraction approach that will be used to predict oral cancer reoccurrence in the scope of the NeoMark project. Based on current clinical practice, we propose several numeric image features that characterize tumors and lymph nodes. In order to (semi) automatically extract those features we introduce the following approach which is independent from human subjectivity: Registration and supervised segmentation of CT/MR images forms the base of the automated extraction of geometric and texture features of tumors and lymph nodes. In order to reduce the amount of user interaction during follow ups we incorporate the segmentation results of the previous examinations. The robustness and the numeric manner of the extracted features make them ideally suited as input for a sophisticated adaptive prediction environment that estimates the likelihood of oral cancer reoccurrence and assists the clinician to develop a treatment plan.
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Wittenberg, Thomas; Drechsler, Klaus; Kaltenbacher, Dominik; Friedl, Sven; Rotinat-Libersa, Christine; Reis, C.; Di Betta, Marie; Sakas, Georgios; Perrot, Yann; Stallkamp, Jan; Kondruweit, Markus
'MISS Heart': Assisting Systems for Minimal Invasive Smart Suturing in Cardiac Surgery - A Conceptually Closed-Loop Approach
Wittenberg, Thomas; Drechsler, Klaus; Kaltenbacher, Dominik; Friedl, Sven; Rotinat-Libersa, Christine; Reis, C.; Di Betta, Marie; Sakas, Georgios; Perrot, Yann; Stallkamp, Jan; Kondruweit, Markus
'MISS Heart': Assisting Systems for Minimal Invasive Smart Suturing in Cardiac Surgery - A Conceptually Closed-Loop Approach
Dössel, Olaf (Ed.) et al.: World Congress on Medical Physics and Biomedical Engineering 2009. Proceedings DVD-ROM. Berlin, Heidelberg, New York: Springer, 2009. (IFMBE Proceedings 25), IFMBE 25/IV; pp. 445-448
World Congress on Medical Physics and Biomedical Engineering (WC) <11, 2009, Munich, Germany>
The project MISS (Minimal invasive smart suture) provides solutions and concepts for several key issues within cardiac surgery. These issues include pre-operative imagebased stenosis detection and planning, intra-operative semiautomatic registration and dynamically adapting of video and angiography data, as well as the presentation of two novel concepts for bypass connection. The proposed solutions are conceptually parts of a closed-loop surgical interaction process and will in the mid-term be connected accordingly.
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Berckmann, Eva; Sakas, Georgios (Betreuer); Steinbrecher, Tillmann (Betreuer)
Entwicklung eines Software Artikulators zur Simulation von Kieferbewegungen
Berckmann, Eva; Sakas, Georgios (Betreuer); Steinbrecher, Tillmann (Betreuer)
Entwicklung eines Software Artikulators zur Simulation von Kieferbewegungen
Aachen, RWTH, Diplomarbeit, 2008
Ziel dieser Arbeit war die Implementierung eines Software-Artikulators zur Simulation von Unterkieferbewegungen. Dazu wurden 3D-Modelle des mechanischen Artikulators genutzt (triangulierte 3D-Scandaten), die in einen 3D-Viewer eingefügt wurden, wobei die Positionen der Artikulatormodelle entsprechend der Abmessung des mechanischen Artikulators gewählt wurden. Für die Bewegungssimulation wurde ein vereinfachtes physikalisches Modell der im Artikulator auftretenden Kräfte entwickelt und implementiert. Weiterhin wurde ein robuster Algorithmus entwickelt, der die Gleitbewegung einer Fläche auf einer Kugel simuliert. Mit diesem Verfahren wurde eine genaue Simulation aller Bewegungstypen des Artikulators ermöglicht. In der Auswertung bestätigte sich, dass die Bewegungssimulation sehr genau durchgeführt werden kann. Die Bedingungen, die am mechanischen Artikulator vorgegeben waren, konnten vollständig umgesetzt werden. Dazu kann der Benutzer die Bewegungssimulation anhand von Standardwerten oder individuellen Patientendaten durchführen.
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Binotto, Alécio Pedro Delazari; Avila, Flávio; Pereira, Carlos Eduardo; Iochpe, Cirano; Sachpazidis, Ilias; Sakas, Georgios
PO@HEALTH - A Medical Training Telemedicine Case Study Based on Ultrasound Images Over an Hybrid Power Line Network
Binotto, Alécio Pedro Delazari; Avila, Flávio; Pereira, Carlos Eduardo; Iochpe, Cirano; Sachpazidis, Ilias; Sakas, Georgios
PO@HEALTH - A Medical Training Telemedicine Case Study Based on Ultrasound Images Over an Hybrid Power Line Network
Azevedo, Luís (Ed.) et al.: Proceedings of the First International Conference on Health Informatics. Volume 1 : HEALTHINF 2008, p. 28-33
International Conference on Health Informatics (HEALTHINF) <1, 2008, Funchal, Portugal>
The growth of fast internet, including the recent advance on using PLC (Power Line Communication) for reaching rural and remote areas in Brazil, and the state-of-the-art of image compression methods allowed rapid teleconsultations and medical training based on medical images. At the present time, one of the challenging problems in telemedicine is the real-time teleconsultation in case of emergency and for the medical training at remote regions where the internet access is precarious. In this paper, we present the kick-off of the applied project PO@Health, which merges the European-Latin American T@lemed Project (telemedicine based on ultrasound images) and the Brazilian PLC Restinga Project (communication via Power Line in a remote district). The platform used for medical teleconsultations and residents training is able to perform both on-line (in real-time) and off-line image-based teleconsultations over the Internet connection. For the ultrasound cases, the platform is being adapted to work with the DICOM medical images synchronized with the physician hand position images of the examination in order to increase the diagnosis precision. In addition, we describe the hybrid network over PLC that is being used by the telemedical platform.
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Erdt, Marius; Raspe, Matthias; Suehling, Michael
Automatic Hepatic Vessel Segmentation Using Graphics Hardware
Erdt, Marius; Raspe, Matthias; Suehling, Michael
Automatic Hepatic Vessel Segmentation Using Graphics Hardware
Dohi, Takeyoshi (Ed.) et al.: Medical Imaging and Augmented Reality. Proceedings : 4th International Workshop. Berlin; Heidelberg; New York: Springer, 2008. (Lecture Notes in Computer Science (LNCS) 5128), pp. 403-412
International Workshop Medical Imaging and Augmented Reality (MIAR) <4, 2008, Tokyo, Japan>
The accurate segmentation of liver vessels is an important prerequisite for creating oncologic surgery planning tools as well as medical visualization applications. In this paper, a fully automatic approach is presented to quickly enhance and extract the vascular system of the liver from CT datasets. Our framework consists of three basic modules: vessel enhancement on the graphics processing unit (GPU), automatic vessel segmentation in the enhanced images and an option to verify and refine the obtained results. Tests on 20 clinical datasets of varying contrast quality and acquisition phase were carried out to evaluate the robustness of the automatic segmentation. In addition the presented GPU based method was tested against a CPU implementation to demonstrate the performance gain of using modern graphics hardware. Automatic segmentation using graphics hardware allows reliable and fast extraction of the hepatic vascular system and therefore has the potential to save time for oncologic surgery planning.
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Firle, Evelyn; Encarnação, José L.; Sakas, Georgios
Automatische multimodale nicht-elastische Registrierung und Visualisierung medizinischer 2D, 3D und 4D Datensätze
Firle, Evelyn; Encarnação, José L.; Sakas, Georgios
Automatische multimodale nicht-elastische Registrierung und Visualisierung medizinischer 2D, 3D und 4D Datensätze
Bildgebende Verfahren bilden die Basis für die medizinische Diagnostik sowie für die Planung, Durchführung und Kontrolle unterschiedlichster Therapien. Heutzutage werden immer detailliertere Daten durch stetig verbesserte Bildaufnahmeverfahren erreicht. Sowohl die räumliche als auch die zeitliche Auflösung erfahren eine permanente Steigerung, so dass Bildstapel mit mehreren tausend Schichten keine Seltenheit mehr sind. Eine vornehmlich automatisierte Unterstützung bei der Betrachtung und Überlagerung unterschiedlicher Modalitäten ist daher geboten. Unter Zuhilfenahme von Software macht es sich die medizinische Bildverarbeitung zur Aufgabe, bei der Extraktion relevanter Informationen aus klinischen drei- und vierdimensionalen Bilddaten unterstützend zur Seite zu stehen. Neben der geeigneten Visualisierung und Vorverarbeitung der Bilddaten steht hierbei vornehmlich eine Qualitätssteigerung und Erreichung einer reduzierten Benutzerabhängigkeit im Bereich der Diagnostik und Therapieplanung im Vordergrund. Manuelle Verfahren sind vor allem für den Bereich der Registrierung und Fusion multipler Datensätze nicht präzise durchführbar. Auch eine mentale Zusammenführung ist gemessen an heutigen wissenschaftlichen Standards nicht realistisch. Dies liegt neben der Dimensionalität und Größe der unterschiedlichen Bilddaten auch an zumeist auftretenden Lageveränderungen zwischen den diversen Aufnahmezeitpunkten. Eine ganzheitliche Betrachtung des Themenbereiches der Registrierung und Visualisierung medizinischer Bilddaten steht daher im Vordergrund dieser Arbeit. Zur Erreichung einer möglichst hohen Stabilität und Reproduzierbarkeit zum Einsatz in der klinischen Praxis werden automatische Methoden betrachtet und eine Beschleunigung dieser Verfahren angestrebt. Es werden zunächst neue Methoden bezüglich der Oberflächenextraktion und Vorverarbeitung von Prostata Ultraschalldaten zur effektiven Registrierung von sowohl Phantom- als auch Patientendaten entwickelt. Der Schwerpunkt der Arbeit liegt jedoch im Bereich der Registrierungsmethoden basierend auf der statistischen Maßzahl Mutual Information. In diesem Rahmen werden zwei Modelle eingeführt und diskutiert, die vor allem zur Registrierung von Ganzkörperdatensätzen respektive im intra-operativen Einsatz ihre Anwendung finden. Hierbei hat der Benutzer die Möglichkeit bei Anwendung der Registrierung zu entscheiden, ob der Schwerpunkt auf geringe Verarbeitungszeit oder auf hohe Genauigkeit gelegt werden soll. Weiterhin wird eine Anwendung der Registrierungsmethoden im dynamischen Bereich, d.h. zur Registrierung vierdimensionaler Bilddaten erarbeitet. Hierzu wird eine Entwicklung zur temporalen Adaption anhand eines Deformationsmodells vorgestellt und zur anschließenden Registrierung kardiologischer Cine MRT Daten eingesetzt. Um eine praxisnahe Anwendung zu ermöglichen, sind intuitive und effiziente Möglichkeiten zur Exploration multi- und monomodaler Überlagerungen notwendig. In diesem Kontext werden unterschiedliche Methoden vorgestellt, erarbeitet und diskutiert. Neben der multimodalen Schichtbilddarstellung wird ein innovativer Ansatz zur Multi-Volumenvisualisierung basierend auf Spatialized Transfer Functions entwickelt.
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Friebe, M.; Sachtler, D.; Hellwig, S.; Schlüter, M.; Sakas, Georgios; Jorczyck, U.
Autonomous Navigation Assistant for MRI Guided Interventions
Friebe, M.; Sachtler, D.; Hellwig, S.; Schlüter, M.; Sakas, Georgios; Jorczyck, U.
Autonomous Navigation Assistant for MRI Guided Interventions
Kronreif, Gernot (Ed.) et al.: SMIT 2008. 20th International Conference of the Society for Medical Innovation and Technology : Electronic Proceedings [DVD-ROM]. PROFACTOR Research and Solutions, 2008, 4 p.
International Conference of the Society for Medical Innovation and Technology (SMIT) <20, 2008, Vienna, Austria>
Interventions, like biopsies, tumor therapy, injection of drugs, placements of intravascular implants (stents, coils, etc.) and many more are performed image guided. MRI would be the preferred guidance device due to the fact that it provides the best soft tissue contrast and comes with no or little negative side effects for the human body. Several known problems have to be overcome while working in or around a MRI system, mainly related to the strong magnetic and electric fields, which require the use of special materials and special shielding. Interventions are also limited due to the relatively small openings of the horizontal magnet systems (bore diameter of 60 cm to 70 cm). Open scanners facilitate the access to the patient much better, but they also use lower magnetic field strength and therefore do not provide equally good image quality. Interventions are therefore usually performed outside of the magnet bore. This requires moving the patient in and out of the magnet as the actual position of a medical instrument has to be frequently updated through newly acquired images. Workflow and quality of intervention - in the case of a needle therapy for example - could be significantly improved, if the physician would know where to penetrate skin, in which angle to hold the instrument and what the distance from skin to target (organ, tumor, etc.) is. Devices inside the MRI bore could mark the penetration point including the required angle with a laser on the patient's skin after the intervention was planned by a physician on the previously obtained MR images. Also, a mechanical apparatus could be aligned by such a device, through which the instrument can be inserted into the body. Several of such systems have been proposed, but all are complicated, very expensive, and further limit the available space inside the bore. The goal was therefore to develop an innovative and inexpensive navigation assistant, to be placed inside the bore of the MRI system (reduced size) - but with the option to also use it outside the magnet - which is able to identify (with e.g. a laser diode) the desired entry position (point of skin penetration and angle of penetration) for the intervention/therapy on the patients body.
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Heinrich, Gregor; Leitner, Michael; Jung, Christoph; Logemann, Fabian; Hahn, Volker
A Platform for Audiovisual Telepresence Using Model- and Data-Based Wave-Field Synthesis
Heinrich, Gregor; Leitner, Michael; Jung, Christoph; Logemann, Fabian; Hahn, Volker
A Platform for Audiovisual Telepresence Using Model- and Data-Based Wave-Field Synthesis
Audio Engineering Society (AES): 125th Audio Engineering Society Convention. Convention Papers [CD-ROM]. New York: AES and Mira Publishing Inc., 2008, 14 p.
Audio Engineering Society Convention <125, 2008, San Francisco, CA, USA>
We present a platform for real-time transmission of immersive audiovisual impressions using model- and data- based audio wave-field analysis/synthesis and panoramic video capturing/projection. The audio subsystem considered in this paper is based on microphone arrays with different element counts and directivities as well as weakly directional loudspeaker arrays. We report on both linear and circular setups that feed different wave-field synthesis systems. In an attempt to extend this, we present first findings for a data-based approach derived using experimental simulations. This data-based wave-field analysis/synthesis (WFAS) approach uses a combination of cylindrical-harmonic decomposition of cardioid array signals and enforces causal plane wave synthesis by angular windowing and a directional delay term. Specifically, our contributions include (1) a high-resolution telepresence environment that is omnidirectional in both the auditory and visual modality, as well as (2) a study of data-based WFAS realistic microphone directivities as a contribution towards for real-time holophonic reproduction.
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Jähne, Marion; Lacalli, Christina; Wesarg, Stefan
Novel Techniques for Automatically Enhanced Visualization of Coronary Arteries in MSCT Data and for Drawing Direct Comparisons to Conventional Angiography
Jähne, Marion; Lacalli, Christina; Wesarg, Stefan
Novel Techniques for Automatically Enhanced Visualization of Coronary Arteries in MSCT Data and for Drawing Direct Comparisons to Conventional Angiography
Institute for Systems and Technologies of Information, Control and Communication (INSTICC): VISIGRAPP 2008. Proceedings : International Joint Conference on Computer Vision and Computer Graphics Theory and Applications [CD-ROM]. INSTICC Press, 2008, pp. 290-296
International Conference on Computer Vision Theory and Applications (VISAPP) <3, 2008, Funchal, Madeira, Portugal>
The new generation of multi-slice computed tomography (MSCT) scanners enables the radiologist to assess the coronary arteries in a non-invasive way. The question of particular interest is whether the quality of the findings based on MSCT data can compete with the gold standard - the coronary angiography. In this work we present novel automated methods for a reliable visualization of coronary arteries and for drawing direct visual side-by-side comparisons to conventional angiograms. Our approach comprises a new method for automatically extracting the heart from cardiac CT data and an advanced masking method for eliminating large cardiac cavities to obtain a better visibility of the coronary arteries in the rendered CT data. For drawing direct side-by-side comparisons we present a novel approach for simulating the conventional coronary angiography in an easy-to-handle manner. The new methods have been developed for and tested with contrast-enhanced cardiac CT datasets.
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Kaftan, Jens N.; Kiraly, Atilla P.; Erdt, Marius; Suehling, Michael; Aach, Til
Fuzzy Pulmonary Vessel Segmentation Using Optimized Vessel Enhancement Filtering
Kaftan, Jens N.; Kiraly, Atilla P.; Erdt, Marius; Suehling, Michael; Aach, Til
Fuzzy Pulmonary Vessel Segmentation Using Optimized Vessel Enhancement Filtering
Brown, Matthew (Ed.) et al.: The First International Workshop on Pulmonary Image Analysis. New York, 2008, pp. 233-242
The First International Workshop on Pulmonary Image Analysis <1, 2008, New York, USA>
Vessel segmentation within pulmonary images serves as a basis for a variety of applications, including PE detection and visualization, lung nodule detection, assistance in bronchoscopic navigation, lobe segmentation, and surgical planning. Although applications have different segmentation requirements, speed and accuracy is a clear benefit. A new approach combining a single parameter vessel enhancement filter and fuzzy connectedness is presented. The advantages of vessel filtering are brought to bear with a minimal impact on time by limiting the scales. Vesselness and intensity features are combined within a fuzzy segmentation framework, reducing the number of required scales and avoiding some of the drawbacks of each feature alone. Validation was performed on five datasets and Dice Similarity Coefficients (DSC) demonstrate an improvement of 9% (from 81% to 90%) on average for small vessels without influencing the accuracy for large vessels (95%) compared to an intensity-based method alone.
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Klein, Konrad; Sakas, Georgios; Teschner, Matthias; Goesele, Michael
Automatisierung der 3D-Rekonstruktion aus mehreren Tiefenbildern durch Optimierung prädizierter Qualitätsgewinne
Klein, Konrad; Sakas, Georgios; Teschner, Matthias; Goesele, Michael
Automatisierung der 3D-Rekonstruktion aus mehreren Tiefenbildern durch Optimierung prädizierter Qualitätsgewinne
Mit Methoden der optischen Meßtechnik können die Oberflächen realer Objekte abschnittsweise flächenhaft digitalisiert werden. Die Planung, Umsetzung und Integration der Teilaufnahmen zur vollständigen Vermessung von Objekten erfordert jedoch viel Zeit und Erfahrung. Daher bilden Verfahren zur automatischen Aufnahmeplanung unter Berücksichtigung der Datenqualität (vor allem im Sinne der Abtastdichte) den Gegenstand der vorliegenden Dissertation. Als Ergebnis ermöglichen die vorgeschlagenen Verfahren die vollautomatische Digitalisierung initial unbekannter Objekte mit Hilfe geeigneter Roboter. Es werden Lösungen für die beiden zentralen Teilprobleme der Aufnahmeplanung vorgeschlagen: nämlich für die Repräsentation des erst teilweise vermessenen Objekts, sowie für die Ableitung einer geeigneten Zielsetzung für die Aufnahmeplanung. Letztere nutzt die vorliegende Objektrepräsentation zur Prädiktion des Qualitätsgewinns, der von einem zusätzlichen Aufnahmevorgang zu erwarten ist. Dabei wird gezeigt, wie sich die intrinsischen Eigenschaften des Sensors unter Verwendung computergraphischer Verfahren zur Planung nutzen lassen, indem gerenderte Darstellungen der Objektrepräsentation analysiert werden. Ergänzend wird eine Methodik zur Evaluation der Ergebnisse vorgeschlagen. Ergebnisse aus dem Bereich der Gebäudevermessung und der Objektdigitalisierung vervollständigen die Arbeit.
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Lacalli, Christina; Jähne, Marion; Wesarg, Stefan
Automatisierte Verfahren zur verbesserten Visualisierung der Koronararterien in MSCT-Daten und für die direkte Vergleichbarkeit zur Angiographie
Lacalli, Christina; Jähne, Marion; Wesarg, Stefan
Automatisierte Verfahren zur verbesserten Visualisierung der Koronararterien in MSCT-Daten und für die direkte Vergleichbarkeit zur Angiographie
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2008. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2008. (Informatik aktuell), pp. 283-287
Workshop Bildverarbeitung für die Medizin (BVM) <11, 2008, Berlin, Germany>
In diesem Beitrag stellen wir neue, automatisierte Verfahren zur Visualisierung der Koronararterien einerseits und für eine direkte Vergleichbarkeit mit konventionellen Angiogrammen andererseits vor. Unser Ansatz umfasst Methoden für die automatische Extraktion des Herzens aus kontrastverstärkten CT-Daten, sowie für die Maskierung grosser kontrastmittelgefüllter Kavitäten des Herzens, um die Sichtbarkeit der Koronararterien bei der Darstellung mittels Volumenrendering zu verbessern. Für den direkten Vergleich zur konventionellen Angiographie haben wir ein Verfahren zur automatischen Generierung von - den Angiogrammen entsprechenden - Projektionsansichten aus den CTDaten entwickelt.
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Menary, Wayne; Sachpazidis, Ilias; Rizou, Despoina
Telemedicine via Satellite: Linking eHealth and Development in Rural Peru and Brazil
Menary, Wayne; Sachpazidis, Ilias; Rizou, Despoina
Telemedicine via Satellite: Linking eHealth and Development in Rural Peru and Brazil
Asociación Argentina de Informática Médica (AAiM): Actas de Congreso INFOLAC 2008 [online]. [cited 23 January 2009] Available from: http://aaim.com.ar/index.php?option=com content&view=article&id=58&Itemid=65&lang=en, 2008, 5 p.
Congreso Latinoamericano de Informática Médica <3, 2008, Buenos Aires, Argentina>
Access to health care services is extremely difficult for many rural and underserved regions of Latin America, particularly in rural Peru and Brazil. MEDNET attempts to redress this issue by developing a medical health network in selected sites in rural Peru and Brazil with the help of the collaboration medical application TeleConsult. The medical applications vary from gynaecology, paediatric, cardiology to typical infectious diseases for the region such as malaria and tuberculosis. The examinations will involve ultrasound examination, ECG test and blood test and blood test imaging for automation diagnosis. All the patient information, extracted from the examinations will be stored a health care database, along with the demographic information and medication prescription. The expected benefits will be improved support for medics in the field, reduction of patient referrals, reduction in number of emergency interventions and improved times for medical diagnosis. Importantly, the project has the full support of regional political and health authorities and, importantly, full local community support.
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Menary, Wayne; Sachpazidis, Ilias; Rizou, Despoina; Cardenas, J.; Cabrera, C.
MEDical NETwork: MedNET Helps Rural Peru Access Health Care Services with Telemedicine via Satellite
Menary, Wayne; Sachpazidis, Ilias; Rizou, Despoina; Cardenas, J.; Cabrera, C.
MEDical NETwork: MedNET Helps Rural Peru Access Health Care Services with Telemedicine via Satellite
eHealth Magazine [online], Vol.3 (2008), 8, pp. 31-34
Currently, patients in rural Peru and Brazil travel long distances just to arrive at a rural health centre. Upon arrival, due to a chronic dearth of medical equipment at these health facilities, a patient receives only basic primary care. Access to specialist physicians is rare. If the physician is uncertain and decides to refer the patient for further consultation and/or examination, only approximately 5% of patients undertake the journey. Consequently, large sections of the community in these regions are effectively disenfranchised from the health service. MedNET, an initiative part funded under the Seventh Framework Programme of the European Community (EC), is attempting to tackle this problem of improving access to a quality health care service by enhancing social inclusion for outlying, under-served regions. MedNet will be deployed in both Peru and Brazil and will enable doctors to constantly monitor patients, assisted by an automated infrastructure which promotes the sharing of knowledge and resources between doctors in remote areas and specialists in urban centres and by providing access to medical applications in a range of fields from gynaecology, paediatrics and cardiology to region-specific diseases such as malaria and tuberculosis. Additionally, patient information from examinations will be stored in a secure database along with information concerning demographics and medication prescribed.
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Rizou, Despoina; Sachpazidis, Ilias; Selby, Peter
Broadband Health Care Network in Brazil and Peru
Rizou, Despoina; Sachpazidis, Ilias; Selby, Peter
Broadband Health Care Network in Brazil and Peru
Silva, Leila M.A. (Ed.) et al.: Euro American Conference on Telematics and Information Systems. Proceedings : EATIS 2008 Proceedings [CD-ROM]. New York: ACM, 2008, 5 p.
Euro American Conference on Telematics and Information Systems (EATIS) <3, 2008, Aracaju-Sergipe, Brazil>
This paper will present a medical network in Latin America. This network will provide in rural and isolated areas an appropriate health care from distance. The medical applications will vary from gynaecology, paediatrics, cardiology to typical infectious diseases for the region such as malaria and tuberculosis. The examinations will involve ultrasound examinations, electrocardiogram and blood imaging when applicable. Our medical tele-consulting tool will be used for that purpose. The medical network aims to connect isolated areas in Amazon over European satellite technology providing broadband communication and quality of services (QoS) for real-time data transmission and video/audio conference.
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Sachpazidis, Ilias; Encarnação, José L.; Sakas, Georgios
Image and Medical Data Communication Protocols for Telemedicine and Teleradiology
Sachpazidis, Ilias; Encarnação, José L.; Sakas, Georgios
Image and Medical Data Communication Protocols for Telemedicine and Teleradiology
Telemedicine is currently being used to bridge the physical distance between patients in remote areas and medical specialists around the world. Distributed client-server applications have become very popular with the explosive growth of the Internet. These distributed applications provide an inexpensive and fast way to access medical information and also provide good accessibility and availability of medical service. Telemedicine applications are a client/server applications where medical and patient information is stored in a server and the information is made accessible to doctors and medical personnel at a distant site. In addition, depending on the type and the needs of the medical application different type of communication protocols and medical devices are utilized making interoperability and communication over different communication channels quite difficult. In my dissertation I analyzed first a range of telemedicine systems already used and I concluded that telemedicine systems can be categorized according to on three different features (layers): - Transportation protocol layer - Medical devices layer - Application layer The outcome of the analysis was that on the application layer, there exists a wide variety of different telemedical applications, each one supporting a special and focused medical application case. Thus, on the application layer a heterogeneous environment of medical use cases exists and it not possible to homogenize due to the particularities of each medical situation. Regarding the device layer, a plurality of different medical devices is used for each medical application supporting different functionality. As an example, one uses ECG devices for monitoring heard activity, blood pressure devices to measure the diastolic and systolic arterial pressure, ultrasound, CT, MRI devices for medical imaging analyzing physiological structures and so on. Nevertheless, although the individual devices will have to remain separate, I propose here an interfacing scheme enabling connection of the various devices to a unique data interface, enabling their individual data to be transferred and handled in a unique, transparent way. By this I integrated a wide variety of medical devices offering flexible solutions covering large number of home care, emergency and radiology applications. On the transportation layer I concluded that a number of various telecommunication protocols are utilized and miscellaneous types of data types and data sizes are to be exchanged, depending on their application. In addition, I concluded that all the communication protocols applied today show common problems emerging from firewalls and network address translation servers. I also concluded that the applied communication protocols do not support presence awareness of the users. Based on the aforementioned observations, I propose an instant messaging protocol able to homogenize the communication and transportation layer and support any data type and any data size while solving all of the existing problems at once. In this way I unified the various protocols, replacing them by only one, at the same time overcoming common problems arising from firewalls, NATs and mobility of the users. Traumastation shows exemplarily the correctness of my approach and demonstrates how several different medical devices can be integrated on one single case and support a wide variety of applications utilising thereby one single data transportation protocol.
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Sachpazidis, Ilias; Rizou, Despoina; Menary, Wayne
Satellite Based Health Network in Peru and Brazil
Sachpazidis, Ilias; Rizou, Despoina; Menary, Wayne
Satellite Based Health Network in Peru and Brazil
IEEE Engineering in Medicine and Biology Society (EMBS): 5th International Conference on Information Technology and Applications in Biomedicine. Proceedings CD-ROM. Los Alamitos, Calif.: IEEE Computer Society, 2008, pp. 309-314
International Conference on Information Technology and Applications in Biomedicine (ITAB) <5, 2008, Shenzhen, China>
This paper will present a medical network in Latin America. This network will provide in rural and underserved areas an appropriate health care from distance. The medical applications will vary from gynaecology, paediatrics, cardiology to typical infectious diseases for the region such as malaria and tuberculosis. The examinations will involve ultrasound examination, electrocardiogram and blood imaging when applicable. Our medical tele-consulting tool will be used for that purpose. The medical network aims to connect isolated areas in Amazon over European satellite technology providing broadband communication and quality of services (QoS) for real-time data transmission and video/audio conference.
mehr mehr
Sachpazidis, Ilias; Sakas, Georgios
Medication Intake Assessment
Sachpazidis, Ilias; Sakas, Georgios
Medication Intake Assessment
Association for Computing Machinery (ACM): Proceedings of the 1st ACM International Conference on PErvasive Technologies Related to Assistive Environments : PETRA 2008. New York: ACM, 2008. (ACM International Conference Proceedings Series 282), 4 p.
ACM International Conference on PErvasive Technologies Related to Assistive Environments (PETRA) <1, 2008, Ahtens, Greece>
Today, more than 430 million people worldwide are estimated to be suffering at any given time from mental disorders. Surprisingly, there is limited awareness that mental disorders are a major cause of lost healthy years of life. According to the World Health Organisation, Affective Disorders (depression and manicdepression or bipolar disorder), Schizophrenia and related conditions are among the top ten leading causes of disability worldwide. This evidence shows how important it is to respond to the growing global burden of mental illness. Europe is taking a leading role in this field with a number of initiatives aiming to improve the mental well-being and reduce the level of social exclusion and disability amongst the mentally ill. Recent years have seen a dramatic increase in our understanding of the biological, psychological and social determinants of mental illness and this has led to the development of many effective medicines. However, we also know that the quality of treatment delivery is of paramount importance. Prescribed medication becomes a truly effective intervention if it is coupled with efficient service delivery. In such circumstances patients have the opportunity to realize their potential and to become functioning and productive members of their communities. Key components of efficient service delivery are timely detection of non-adherence to medication and rapid response by mental health professionals to any signs of impeding relapse. In this paper, we are going to describe a home care application for medication adherence monitoring and assessment.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Selective X-Ray Reconstruction and Registration for Pose Estimation in 6 Degrees of Freedom
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Selective X-Ray Reconstruction and Registration for Pose Estimation in 6 Degrees of Freedom
International Society for Photogrammetry and Remote Sensing (ISPRS): ISPRS Congress Beijing 2008, Proceedings of Commission V : The International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5, pp. 799-804
International Society for Photogrammetry and Remote Sensing Congress (ISPRS) <21, 2008, Beijing, China>
Particle beams in radiological cancer treatment provide high accuracy in dose delivery. Thus approaches from image-guided radiotherapy (IGRT) are used to overcome accuracy limitations caused by the patient misalignment in the treatment device. By comparing stereoscopic X-ray images of the patient in treatment position to a reference Computed Tomography (CT) scan, a correction of the initial patient set-up can be computed. Automatic registration of the X-ray images with digital reconstructed radiographs (DDRs) from the CT and back-projection of the transformation gives a pose correction in 5 degrees of freedom (DOF). To obtain a 6 DOF correction, DDRs have to be generated for a large amount of hypothetical alignments to find the optimal match the X-ray images. To accelerate this time consuming process and to reduce the disturbing influence of image contents that do not match correctly, we automatically exclude regions that may not improve the resulting pose correction from the rendering as well as from the matching process. Therefore these regions are identified in the X-ray images and transferred into the plane of the respective DDR. We then perform the radon transform for DDR generation only for a subset of possible pixel values and exclude the missing information from the registration process. As a result of this approach, the time needed for a full automatic pose correction computation in 6 DOF is decreased by means of 4 and more and additionally misregistrations caused by unsuitable image contents can be avoided.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Patient Alignment Estimation in Six Degrees of Freedom Using a CT-scan and a Single X-ray Image
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Patient Alignment Estimation in Six Degrees of Freedom Using a CT-scan and a Single X-ray Image
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2008. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2008. (Informatik aktuell), pp. 127-132
Workshop Bildverarbeitung für die Medizin (BVM) <11, 2008, Berlin, Germany>
Particle beam treatment allows accurate dose delivery onto carcinogen tissue. The reachable accuracy is limited by patient alignment errors relative to the beam source. Errors can be corrected manually or by automatic comparison of two X-ray images to a CT-scan but correction mostly does not cover all degrees of freedom (DoF). In this contribution we present a solution that makes use of one X-ray image and computes full 6 DoF alignment correction by gray value based comparison to a CT. By using regions of interest, we are able to increase performance and reliability.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Reconstruction and Registration of Multispectral X-ray Images for Reliable Alignment Correction in Radiation Treatment Devices
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Reconstruction and Registration of Multispectral X-ray Images for Reliable Alignment Correction in Radiation Treatment Devices
Reinhardt, Joseph M. (Ed.) et al.: Medical Imaging 2008: Image Processing. Part 1 : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 9, No. 31. Bellingham: SPIE Press, 2008. (Proceedings of SPIE 6914), 9 p.
SPIE Medical Imaging Symposium <2008, San Diego, CA, USA>
To align patients in radiation devices in six degrees of freedom (DoF), image-guided approaches perform the task of correction computation for the patient position. Digital radiography (DR) images are compared to projections of a CT series to estimate misalignments. A problem is that digital reconstructed radiographs (DRRs) have to be created from the CT to be registered with the DRs. Depending on the X-ray tube energy, detector sensitivity and body part involved, DRRs and DRs may look very different and often cannot be registered. We present a method that reconstructs multi-spectral DRRs for different X-ray settings, which can be registered to real X-ray images. As short rendering times are crucial, multiple spectra of a DRR are generated in one ray-tracing process. We register our multi-spectral DRR with the DR and add a further DoF to find a best match not only for the translations and in-plane rotation, but also the best fitting spectral planes. The results are used to identify patient misalignments and show that higher reliability can be achieved compared to conventional approaches. Misalignments can be identified even if ineligible X-ray settings have been used. As our approach allows application of lower X-ray energies for DR creation, an additional benefit is the reduction of the delivered dose.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Internal Evaluation of Registration Results for Radiographic Images
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Internal Evaluation of Registration Results for Radiographic Images
Institute of Electrical and Electronics Engineers (IEEE): The 19th International Conference on Pattern Recognition. Proceedings : ICPR 2008. Madison, WI, USA: Omnipress, 2008, 4 p.
International Conference on Pattern Recognition (ICPR) <19, 2008, Tampa, Florida, USA>
This work focuses on internal gray level based evaluation of image registration results. The motivation is to provide an approach for self-diagnosis in the scope of a patient alignment system based on rigid registration of real and reconstructed X-ray images. As an automatic system should provide expressive indicators for the correctness of the outcome, we propose a method to estimate the probability for the resulting transformations to lie within a predefined window of acceptable values. Based purely on image gray values, the approach is independent from previous knowledge about the image. By registration of corresponding fragments of both images we generate redundancy and define the probability density of the resulting transformations. The proposed method is tested comparing digital reconstucted radiographs (DRRs) to X-ray images. By introducing geometric and radiometric deviations we show that a reliable self-diagnosis is possible.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Stilla, Uwe
Geometry Calibration for X-ray Equipment in Radiation Treatment Devices and Estimation of Remaining Patient Alignment Errors
Selby, Peter; Sakas, Georgios; Walter, Stefan; Stilla, Uwe
Geometry Calibration for X-ray Equipment in Radiation Treatment Devices and Estimation of Remaining Patient Alignment Errors
Hsieh, Jiang (Ed.) et al.: Medical Imaging 2008: Physics of Medical Imaging : Progress in Biomedical Optics and Imaging. Proceedings Issue. Vol. 9, No. 30. Bellingham: SPIE Press, 2008. (Proceedings of SPIE 6913), 11 p.
SPIE Medical Imaging Symposium <2008, San Diego, CA, USA>
Positioning a patient accurately in treatment devices is crucial for radiological treatment, especially if accuracy vantages of particle beam treatment are exploited. To avoid sub-millimeter misalignments, X-ray images acquired from within the device are compared to a CT to compute respective alignment corrections. Unfortunately, deviations of the underlying geometry model for the imaging system degrade the achievable accuracy. We propose an automatic calibration routine, which bases on the geometry of a phantom and its automatic detection in digital radiographs acquired for various geometric device settings during the calibration. The results from the registration of the phantom's X-ray projections and its known geometry are used to update the model of the respective beamlines, which is used to compute the patient alignment correction. The geometric calibration of a beamline takes all nine relevant degrees of freedom into account, including detector translations in three directions, detector tilt by three axes and three possible translations for the X-ray tube. Introducing a stochastic model for the calibration we are able to predict the patient alignment deviations resulting from inaccuracies inherent to the phantom design and the calibration. Comparisons of the alignment results for a treatment device without calibrated imaging systems and a calibrated device show that an accurate calibration can enhance alignment accuracy.
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Steinbrecher, Tillmann; Gerth, Maik
Dental Inlay and Onlay Construction by Iterative Laplacian Surface Editing
Steinbrecher, Tillmann; Gerth, Maik
Dental Inlay and Onlay Construction by Iterative Laplacian Surface Editing
Computer Graphics Forum, Vol.27 (2008), 5, pp. 1441-1447
Eurographics Symposium on Geometry Processing (SGP) <6, 2008, Copenhagen, Denmark>
We propose a new method for automatic construction of inlays and onlays. Mesh models from a small tooth library are adapted to the remaining healthy surface of the patient's tooth. In the area above the cavity, the general morphology of the model tooth (fissures, cusp tips, etc) is preserved, but precisely adjusted to the intra-oral situation. Our approach uses iterative Laplacian Surface Editing to deform the model tooth. This allows the automatic generation of highly individual, functional and anatomically correct inlays/onlays, without having to resort to a large library of different tooth shapes.
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Tulchiner, Roman; Erdt, Marius (Betreuer)
Volumetrische Organ-Segmentierung mithilfe von Semantically Shape Constrained Deformable Models
Tulchiner, Roman; Erdt, Marius (Betreuer)
Volumetrische Organ-Segmentierung mithilfe von Semantically Shape Constrained Deformable Models
Darmstadt, TU, Master Thesis, 2008
Die nachfolgende Arbeit beschäftigt sich mit einem der zentralen Themen aus dem Gebiet medizinischer Bildverarbeitung - der Organsegmentierung. Da ein rein manueller Segmentierungsprozess oft sehr zeitaufwendig ist, wurde eine Vielzahl computergestützter Segmentierungsverfahren entwickelt. Diese liefern aber häufig deutlich schlechtere Ergebnisse als die manuelle Segmentierung. Die grundlegende Problematik liegt hier unter anderem in der sehr hohen anatomischen Varianz menschlicher Organe, den teilweise sehr ähnlichen Absorptionsraten des benachbarten Gewebes sowie den kaum vermeidbaren Bildartefakten in den mit bildgebenden Verfahren der Medizin bezogenen Daten. Ein automatisiertes Verfahren, das schnelle, robuste und exakte Segmentierung medizinischer Daten ermöglicht, ist also weiterhin Gegenstand aktueller Forschung. In dieser Arbeit wird das modellbasierte Verfahren der Organsegmentierung verfolgt. Bei diesem Verfahren wird Vorwissen, zum Beispiel über die Beschaffenheit und die Form des Organs, durch ein explizites Organmodell gegeben. Der in der vorliegenden Abschlussarbeit entwickelte Ansatz erweitert das modellbasierte Verfahren um Vorwissen über die Nachbarschaftsverhältnisse und die Varianz der Gewebebeschaffenheit an bestimmten Organstellen. Dazu werden im Modell gebietsspezifische Anpassungskriterien definiert. Dadurch soll eine bessere lokale Anpassung des Modells sowohl an die Organstellen mit hoher Strukturvarianz als auch an die Bereiche mit geringer Absorptionswertabweichung des Nachbargewebes erreicht werden. Anschließend wird das entwickelte Verfahren mit Hilfe von Datensätzen der linken Niere und der Milz gegen die manuelle Segmentierung evaluiert.
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Vellaramkalayil, Teena George; Steinbrecher, Tillmann (Betreuer)
3D-Modellierung von Zahnoberflächen unter Berücksichtigung der Kieferbewegung
Vellaramkalayil, Teena George; Steinbrecher, Tillmann (Betreuer)
3D-Modellierung von Zahnoberflächen unter Berücksichtigung der Kieferbewegung
Darmstadt, TU, Master Thesis, 2008
Am Fraunhofer IGD wird seit über 15 Jahren Dental CAD-Software im Rahmen von verschiedenen Forschungs- und Industrieprojekten entwickelt. Ausgehend von 3D-Scans der Situation im Patientenmund erlaubt diese Software die Konstruktion von Zahnersatz (Kronen, Brücken, Inlays). Dabei ist gerade die sorgfältige Kauflächengenerierung besonders wichtig, um gesundheitliche Schäden beim Patienten zu vermeiden. Für funktional optimale Kauflächen muss jedoch der Antagonist stärker berücksichtigt werden. Insbesondere für größere Rekonstruktionen sollten auch Kieferbewegungen, wie sie z.B. durch einen Software-Artikulator simuliert werden, beachtet werden ("dynamische Okklusion"). Diese Arbeit soll, ausgehend von registriertem Antagonisten und Bewegungssimulation durch einen Software-Artikulator, den vorhandenen Konstruktionsvorschlag der Dental CAD-Software an die intraorale Situation anpassen. Dazu werden im ersten Teil Methoden zur Ermittlung der maximalen "Durchdringung" zwischen Konstruktionsvorschlag und Gegenbiss während des Kauvorgangs entwickelt. Die Anpassung an den Gegenbiss erfolgt dann zunächst durch Simulation von Abrasion. Im zweiten Teil werden schließlich Möglichkeiten zur Anpassung an den Antagonisten unter Erhaltung der anatomischen Grundform des Zahns entwickelt und untersucht. Dazu wird ein hierfür geeignetes Meshverformungsverfahren, das Laplacian Surface Editing, verwendet.
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Wesarg, Stefan; Khan, M. Fawad; Jähne, Marion; Lacalli, Christina
Automatisierte Analyse der Koronararterien basierend auf MSCT-Daten
Wesarg, Stefan; Khan, M. Fawad; Jähne, Marion; Lacalli, Christina
Automatisierte Analyse der Koronararterien basierend auf MSCT-Daten
Deutsche Zeitschrift für klinische Forschung: DZKF, Vol.11 (2008), 3/4, pp. 28-33
Ein frühzeitiges Erkennen von Gefäßverengungen ist von großer Wichtigkeit für die Diagnose Koronarer Herzkrankheiten. Durch automatisierte Koronaranalysen können zuverlässige Ergebnisse nun bei einem deutlich reduzierten Zeitaufwand geliefert werden.
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Wesarg, Stefan; Lacalli, Christina
Computation and Visualization of Asynchronous Behavior of the Heart
Wesarg, Stefan; Lacalli, Christina
Computation and Visualization of Asynchronous Behavior of the Heart
Botha, C. P. (Ed.) et al.: Eurographics Workshop on Visual Computing for Biomedicine : EG VCBM 2008. Aire-la-Ville: Eurographics Association, 2008, pp. 29-36
Eurographics Workshop on Visual Computing for Biomedicine (VCBM) <1, 2008, Delft, Netherlands>
Nowadays, computer-aided diagnosis is widely used in the analysis of cardiac image data. Especially, for the investigation of the dynamic behavior of the heart, automated analysis tools for 4D data sets have been developed. A small set of descriptors of the heart's dynamics are established and used in the clinical routine. However, there exists a whole lot more of such parameters that can be extracted by analyzing 4D data sets. But, many of them are not used due to several reasons: time-consuming computation, no intuitive meaning, little clinical relevance, etc.. In this work we propose a novel descriptor for the dynamic behavior of the heart that can easily be computed from 4D data sets. It describes to which extent the heart exhibits an asynchronous movement. This novel descriptor ASYNCHRONISM is based on the already established measures WALL MOTION and WALL THICKENING, but reveals new, valuable information that is not available when relying only upon the two aforementioned parameters. The ASYNCHRONISM has an intuitive meaning, since it corresponds to the clinical classification scheme of wall motion abnormalities. Beyond its computation we present in this work also methods for its visualization as well as first preliminary results for 4D cardiac magnetic resonance image data.
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Baltas, Dimos; Sakas, Georgios; Steckenreiter, O.; Karabis, A.; Giannouli, S.; Sauvonet, B.; Zamboglou, N.
2D-3D and 3D-3D Fusion Imaging (US & CT/MR): Interventional US Applied to Prostate Brachytherapy
Baltas, Dimos; Sakas, Georgios; Steckenreiter, O.; Karabis, A.; Giannouli, S.; Sauvonet, B.; Zamboglou, N.
2D-3D and 3D-3D Fusion Imaging (US & CT/MR): Interventional US Applied to Prostate Brachytherapy
Zoumboulis, P. (Ed.): 8o Panellinio Synedrio Yperixografias = 8th Greek Ultrasonography Conference. MD Congress Press, 2007, pp. 239-240
Greek Ultrasonography Conference <8, 2007, Athens, Greece>
Ultrasound imaging offers a fast, inexpensive, radiation-free and portable image processing method. In the field of prostate cancer treatment, ultrasound imaging can be used for diagnosis and therapy guidance.
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Basdogan, Cagatay; Sedef, Mert; Harders, Matthias; Wesarg, Stefan
VR-Based Simulators for Training in Minimally Invasive Surgery
Basdogan, Cagatay; Sedef, Mert; Harders, Matthias; Wesarg, Stefan
VR-Based Simulators for Training in Minimally Invasive Surgery
IEEE Computer Graphics and Applications, Vol.27 (2007), 2, pp. 54-66
Simulation-based training using VR techniques is a promising alternative to traditional training in minimally invasive surgery (MIS). Simulators let the trainee touch, feel, and manipulate virtual tissues and organs through the same surgical tool handles used in actual MIS while viewing images of tool-tissue interactions on a monitor as in real laparoscopic procedures.
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Bullinger, Hans-Jörg; Encarnação, José L.; Unbescheiden, Matthias; Nouak, Alexander; Hahn, Volker
Technologieführer: Grundlagen - Anwendungen - Trends
Bullinger, Hans-Jörg; Encarnação, José L.; Unbescheiden, Matthias; Nouak, Alexander; Hahn, Volker
Technologieführer: Grundlagen - Anwendungen - Trends
ISBN: 3540337881
ISBN: 9783540337881
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De Beni, S.; Grimm, Marcus; Maccio, M.; Sakas, Georgios; Solbiati, L.
2D-3D Fusion Imaging (US & CT/MR): Interventional US Applied to Liver RF Ablation
De Beni, S.; Grimm, Marcus; Maccio, M.; Sakas, Georgios; Solbiati, L.
2D-3D Fusion Imaging (US & CT/MR): Interventional US Applied to Liver RF Ablation
Zoumboulis, P. (Ed.): 8o Panellinio Synedrio Yperixografias = 8th Greek Ultrasonography Conference. MD Congress Press, 2007, pp. 241-242
Greek Ultrasonography Conference <8, 2007, Athens, Greece>
Image guidance is essential in the treatment of liver tumours using percutanous ablative techniques. Apart from careful pre-procedure planning and elaborate post-procedure evaluation, accurate intraprocedure targeting, monitoring, and controlling play a critical role in the success of the technique. Radiofrequency (RF) ablation is most commonly performed under ultrasound (U/S) guidance, with computed tomography (CT) guidance being reserved for lesions inconspicuous on US. However, there are occasions when the liver lesion is only optimally visualized on contrast-enhanced CT, making targeting and monitoring difficult due to lack of real-time imaging guidance. In this scenario, it would be desirable to co-register information from different imaging modalities (e.g., US and CT) and such multimodality matching have been utilized in nuclear medicine, radiotherapy, and neurosurgery.
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Dold, Christian; Bockholt, Ulrich; Roth, Marcus; Heussel, Claus Peter; Gosepath, Jan; Sakas, Georgios
Segmentation and Navigation Support of Clinical Data Sets to Simulate the Bronchoscopy and Rhinoscopy
Dold, Christian; Bockholt, Ulrich; Roth, Marcus; Heussel, Claus Peter; Gosepath, Jan; Sakas, Georgios
Segmentation and Navigation Support of Clinical Data Sets to Simulate the Bronchoscopy and Rhinoscopy
Buzug, Thorsten M. (Ed.): Advances in Medical Engineering. Berlin, Heidelberg, New York: Springer, 2007. (Springer Proceedings in Physics 114), pp. 145-150
Workshop of Medical Robotics, Navigation and Visualization (MRNV) <2, 2007, Remagen, Germany>
A training and simulation system for therapy planning is developed based on patient specific imaging data. A real endoscope is used for navigation through the virtual patient. For this purpose sensors were built in the endoscope in order to track the translation, rotation and the angle of the distal end. Pre-processing (segmentation, tissue characterization) speeds-up the volume rendering up to real-time. Collision detection enables a realistic fly through the virtual patient.
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Dold, Christian; Bockholt, Ulrich; Roth, Marcus; Heussel, Claus Peter; Gosepath, Jan; Sakas, Georgios
Simulations- und Trainingsystem für die Bronchoskopie / Rhinoskopie durch klinische Datensätze
Dold, Christian; Bockholt, Ulrich; Roth, Marcus; Heussel, Claus Peter; Gosepath, Jan; Sakas, Georgios
Simulations- und Trainingsystem für die Bronchoskopie / Rhinoskopie durch klinische Datensätze
Deutsche Gesellschaft für Biomedizinische Technik im VDE (DGBMT): BMT 2007. Proceedings [CD-ROM]. 41. Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik (DGBMT) im VDE : Biomedizinische Technik - Biomedical Engineering, Vol. 52 (2007) Ergänzungsband. Berlin: de Gruyter, 2007, 2 pp.
Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik im VDE (BMT) <41, 2007, Aachen, Germany>
Auf Grundlage patientenspezifischer Bilddaten wurde ein Trainings- und Simulationssystem entwickelt, mit dem eine anstehende Therapie vorbereitet werden kann. Zur Navigation durch die Bilddaten wird ein echtes Endoskop benutzt. Hierzu wurden Sensoren im Endoskop eingebaut die die Translation, Rotation und den Winkel des distalen Endes abgreifen. Ein label file, generiert aus dem Segmentierungsergebnis, und ein Kollisisons Detektions Algorithmus unterstützen die Navigation indem die Position der relativen Sensoren bei Kollision angepasst wird.
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Firle, Evelyn; Keil, Matthias
Multi-volume Visualization Using Spatialized Transfer Functions: Gradient- versus Multi-intensity-based Approach
Firle, Evelyn; Keil, Matthias
Multi-volume Visualization Using Spatialized Transfer Functions: Gradient- versus Multi-intensity-based Approach
Lemke, Heinz U. (Ed.) et al.: CARS 2007. Computer Assisted Radiology and Surgery : Proceedings of the 21st International Congress and Exhibition : International Journal of Computer Assisted Radiology and Surgery, Vol. 2 (2007), Supplement 1. Berlin, Heidelberg, New York: Springer, 2007, pp. S121-S123
Computer Assisted Radiology and Surgery (CARS) <21, 2007, Berlin, Germany>
Using medical imaging techniques physicians and scientists got insight into the human body. A combined presentation of registered three-dimensional data sets of the same object, which were acquired with different imaging modalities (multimodal visualization), enables the use of the advantages of the individual imaging techniques. Furthermore it compensates their disadvantages. In addition complementary information, which results from the specific characteristics of the imaging techniques, can be presented together. The last few years, the image acquisition has gone through a tremendous quality improvement and therefore the amount of image data, i.e. slices through the visualized body, has increased immense. Physicians deal with up to 300 slices when scanning through the images. But when considering more than one image modality at the same time the physicians usually reach the boundaries of their imagination - especially when the images are viewed side by side and fused only mentally. A three-dimensional visualization also offers a natural view of the object. For this purpose we present an efficient multimodal volume visualization system for threedimensional visualization of pre-registered medical data sets based on Spatialized Transfer Functions. Two different approaches were realized - a gradient- and a multiintensity based method - and their advantages and disadvantages compared.
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Hirschbach, Henning; Steinbrecher, Tillmann; Gerth, Maik
Tangential anliegene Verbinder für Brückengerüste
Hirschbach, Henning; Steinbrecher, Tillmann; Gerth, Maik
Tangential anliegene Verbinder für Brückengerüste
Deutsche Gesellschaft für Biomedizinische Technik im VDE (DGBMT): BMT 2007. Proceedings [CD-ROM]. 41. Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik (DGBMT) im VDE : Biomedizinische Technik - Biomedical Engineering, Vol. 52 (2007) Ergänzungsband. Berlin: de Gruyter, 2007, 2 pp.
Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik im VDE (BMT) <41, 2007, Aachen, Germany>
Für die Stabilität von Gerüsten für Dentalbrücken spielt die Form der Konnektoren, die einzelne Brückenelemente verbinden, eine wichtige Rolle. Wir präsentieren ein Verfahren zur algorithmischen Generierung von Verbindern, die tangential an den zu verbindenden Brückengliedern anliegen, und deren Form anhand verschiedener Parametern nach den Wünschen des CAD-Benutzers angepasst werden kann.
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Pommer, Mira; Dold, Christian (Betreuer)
Planung und Kontrolle von Operationen und Interventionen anhand der Computertomographie
Pommer, Mira; Dold, Christian (Betreuer)
Planung und Kontrolle von Operationen und Interventionen anhand der Computertomographie
Darmstadt, TU, Diplomarbeit, 2007
Die Behandlung eines Bronchialkarzinoms (Lungenkrebs) erfolgt häufig durch einen chirurgischen Eingriff. Dabei wird immer mehr dazu übergegangen, durch anspruchsvolle Operationstechniken, so genannte Manschetten- oder Keilresektionen, möglichst viel gesundes Lungengewebe zu erhalten, anstatt komplette Lungenlappen oder sogar einen ganzen Lungenflügel zu entfernen. Die dadurch entstandenen Verbindungsstellen (Anastomosen) bedürfen einer besonderen Planung sowie einer postoperativen Kontrolle. Diese Arbeit präsentiert eine semiautomatische Analyse von Bronchialsegmenten, dabei wird der Durchmesserund Lumenverlauf des betrachteten Segmentes orthogonal zur Bronchus-Achse berechnet. Diese Berechnungen werden auf dem originalen Grauwertvolumen basierend auf einer Kombination der ersten und zweiten Ableitung berechnet. Zusätzlich werden zur Bronchus-Achse parallele Längs- und Querschnitte erzeugt, um durch den Verlauf des Gefäßes zu navigieren und diesen so besser beurteilen zu können.
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Ried, Malte; Cavet, René (Betreuer)
Generative Programmierung für Datenbanken am Beispiel MediaSeeker
Ried, Malte; Cavet, René (Betreuer)
Generative Programmierung für Datenbanken am Beispiel MediaSeeker
Gießen-Friedberg, FH, Diplomarbeit, 2007
Arbeiten mehrere Personen an einem Projekt, das auf eine Datenbank zugreift, so kommt es häufig vor, dass verschiedene Entwickler auf unterschiedliche Weise auf die Datenbank zugreifen. Durch die verschiedenen Lösungsansätze ist jedoch die Wartung des Codes schwierig. Auch wenn an dem Schema der Datenbank Änderungen vorgenommen werden, so müssen oft zahlreiche Stellen im Code angepasst werden. Um diese Probleme zu umgehen, kann ein Generator verwendet werden, der mit Hilfe des Datenbankschemas Quellcode erzeugt. Der im Zuge der Diplomarbeit entwickelte Generator DBCodeGen ist in der Lage, ein beliebiges Datenbankschema aus einer Microsoft SQLServer Datenbank auszulesen und einem oder mehreren Ausgabe-Plugins zur Verfügung zu stellen. Diese werden zur Laufzeit geladen und verwaltet. Das für DBCodeGen geschriebene Ausgabe-Plugin DBCodeExporter ist in der Lage, aus Templates und dem Datenbankschema Texte zu generieren. Die Templates verwenden dafür eine spezielle Sprache, die von DBCodeExporter interpretiert wird. Die Sprache ermöglicht Schleifen über zum Beispiel alle Tabellen oder Sichten, Abfragen, ob zum Beispiel eine Spalte als Primärschlüssel fungiert und das Einfügen fester Werte wie zum Beispiel den Datenbanknamen. Aller Text, der nicht in der Sprache definiert ist, wird in die Ausgabe kopiert. Es ist möglich, jeden beliebigen Text zu generieren, zum Beispiel Quellcode, Dokumentation oder HTML-Seiten. Der in dieser Arbeit vorgestellte Code zum Zugriff auf die Datenbank ist vollständig mit DBCodeGen und DBCodeExporter generiert worden. Durch einige Maßnahmen ist es nur noch sehr schwer möglich, Code zu schreiben, der zur Laufzeit Probleme, wie zum Beispiel falsche Typen, erzeugt. Diese werden alle bereits beim Compilieren abgefangen.
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Sakas, Georgios; Grimm, Marcus
Freehand 3D/4D Ultrasound: Extending Existing U/S Devices
Sakas, Georgios; Grimm, Marcus
Freehand 3D/4D Ultrasound: Extending Existing U/S Devices
Zoumboulis, P. (Ed.): 8o Panellinio Synedrio Yperixografias = 8th Greek Ultrasonography Conference. MD Congress Press, 2007, pp. 243-244
Greek Ultrasonography Conference <8, 2007, Athens, Greece>
3D ultrasound is the extension of 2D ultrasound to the third dimension. In case of acquiring heat motion, we speak about 4D (3 spatial and one temporal dimension). Our 3D/4D approach uses a 2D transducer in a free-scan technique where the transducer movement (performed by the physician) is measured by an additional tracking device. Freehand acquisition requires no intervention in the ultrasound devices and is therefore an upgrade possibility for nearly every conventional 2D device.
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Sakas, Georgios; Muller, M.
MiniPACS Implementation in Telemedicine
Sakas, Georgios; Muller, M.
MiniPACS Implementation in Telemedicine
Zoumboulis, P. (Ed.): 8o Panellinio Synedrio Yperixografias = 8th Greek Ultrasonography Conference. MD Congress Press, 2007, pp. 245-246
Greek Ultrasonography Conference <8, 2007, Athens, Greece>
MedCom MiniPACS offers access, management, archiving and easy transfer of medical images.Importing U/S, CT, MR and many other DICOM Images is possible. Especially important is a variance offering miniPACS functionality for existing U/S devices.
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Selby, Peter; Sakas, Georgios; Walter, Stefan
3D Alignment Correction for Proton Beam Treatment
Selby, Peter; Sakas, Georgios; Walter, Stefan
3D Alignment Correction for Proton Beam Treatment
Deutsche Gesellschaft für Biomedizinische Technik im VDE (DGBMT): BMT 2007. Proceedings [CD-ROM]. 41. Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik (DGBMT) im VDE : Biomedizinische Technik - Biomedical Engineering, Vol. 52 (2007) Ergänzungsband. Berlin: de Gruyter, 2007, 2 p.
Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik im VDE (BMT) <41, 2007, Aachen, Germany>
The Bragg Peak of proton beams allows applying treatment doses onto carcinogen tissue with accuracy much below 1.0 mm and decreases the dose applied on surrounding tissue. The possible accuracy is limited by set-up errors from the initial patient alignment in respect of the particle beam nozzle. In this contribution a solution is presented, that allows overcoming these limitations. Two X-ray images acquired from within the treatment machine are compared to digitally reconstructed radiographs (DRRs) from a CT series. The system automatically determines initial set-up errors and computes a position correction in either 5 or 6 degrees of freedom (DoF). For 5 DoF we increase performance by reducing the number of DRRs that have to be rendered from the CT series by combining several 2D offset corrections. The DRRs are then iteratively adapted to the corrected 3D geometry. To achieve full 6 DoF alignment correction, the X-ray images are directly compared to respective DRRs for an assumed patient position and the image correlation is maximized to find the best fitting patient alignment.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, U.
Pose Estimation of Eyes for Particle Beam Treatment of Tumors
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, U.
Pose Estimation of Eyes for Particle Beam Treatment of Tumors
Horsch, Alexander (Ed.) et al.: Bildverarbeitung für die Medizin 2007. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2007. (Informatik aktuell), pp. 368-374
Workshop Bildverarbeitung für die Medizin (BVM) <10, 2007, München, Germany>
To assure a correct position and orientation of the patient's eye in radiation treatment, a new approach in image-guided radiotherapy is used to determine the misalignment of the eye and the respective correction for the patient support devices. New methods allow correcting the misalignment of the patient's eye full-automatically. Therefore, metallic clips attached to the patient's eyeball are detected in a CT and in two digital X-ray images. Corresponding pairs of clip positions found in the X-ray images are then transferred into the 3D space of the CT volume via inverse projection and compared to the clips found in the CT slices. If several combinations of correspondences are possible, we use a temporary pre-registration to assure that the correct back-projections will be obtained. A rigid, point-set based 6 degrees of freedom registration of the back-projected clip positions with the CT clips allows determining the misalignment of the eye tumor which consists of three shifts and three rotations. These transformations are transformed into parameters for a treatment chair and an eye fixation designated to control placement and orientation of the eye during treatment.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Detection of Pose Changes for Spatial Objects from Projective Images
Selby, Peter; Sakas, Georgios; Walter, Stefan; Groch, W.-D.; Stilla, Uwe
Detection of Pose Changes for Spatial Objects from Projective Images
Stilla, Uwe (Ed.) et al.: PIA07 - Photogrammetric Image Analysis : Part A, Papers Accepted on the Basis of Peer-Reviewed Full Manuscripts. München: Institute of Photogrammetry and Cartography, 2007. (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences 36, Part 3/W49A), pp. 105-110
Photogrammetric Image Analysis (PIA) <2007, Munich, Germany>
Numerous fields of application effort the detection of pose changes for 3 dimensional objects in six degrees of freedom (6 DoF). Automatic procedures that exploit 2D images for the detection of pose changes can be used for example for tracking object movements, for quality control or for the verification of the alignment of patients in radiation treatment devices. In this contribution we present two different solutions for the detection of pose changes that base on the comparison of two 2D images resulting from the projection of an object in the new pose and a 3D volume of the same object in a known reference alignment. Whereas for the first solution we use an object where we can clearly extract landmarks useable as reference positions for the determination of the object's alignment, we provide a second solution for objects where these landmarks cannot be extracted, which is involved automatically if necessary. In this case grey value based pose estimation is conducted by registering the computationally projected reference 3D volume to the 2D images. As reference data for the object with known alignment, CT slices will be used, as they are provided for the alignment of patients in radiation treatment devices. Two X-ray images of the same object in an unknown pose can then be compared to the reference data to determine the respective pose change, which may consist of 3 rotations and 3 translations. Using both approaches to determine patient misalignments in treatment devices shows, that both methods result in highly accurate pose detections and that the second method, despite being less accurate and more time consuming, is an appropriate solution in cases where landmark detection fails.
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Selby, Peter; Sakas, Georgios; Walter, Stefan; Stilla, Uwe
Geometry Calibration for X-Ray Equipment in Radiation Treatment Devices
Selby, Peter; Sakas, Georgios; Walter, Stefan; Stilla, Uwe
Geometry Calibration for X-Ray Equipment in Radiation Treatment Devices
Tavares, João Manuel R.S. (Ed.) et al.: Computational Vision and Medical Image Processing : VipIMAGE 2007. London: Taylor & Francis, 2007, pp. 247-252
ECCOMAS Thematic Conference on Computational Vision and Medical Image Processing (VipIMAGE) <1, 2007, Porto, Portugal>
It is essential for radiological tumor treatment to position a patient very accurate in the treatment device. To avoid sub-millimetre misalignments for a patient in the treatment facility, X-ray images acquired from within the device can be compared to the planning CT. But as slight displacements of the treatment beam nozzle, the digital X-ray panels and the X-ray tubes may arise over time and with movements of the dynamic parts of the treatment device, the underlying geometry model for the patient set-up correction may become inaccurate. To solve this problem, an automatic calibration routine is proposed, which bases on the known geometry of a calibration phantom and X-ray images acquired during the calibration routine. The result from the registration of the X-ray projections of the phantom and its known geometry is used to update the geometric model of the respective beamlines to enable accurate alignment correction.
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Stapf, Tobias; Steinbrecher, Tillmann (Betreuer)
Bearbeitung von dreidimensionalen Daten in der Zahnmedizin unter Berücksichtigung statischer Okklusion
Stapf, Tobias; Steinbrecher, Tillmann (Betreuer)
Bearbeitung von dreidimensionalen Daten in der Zahnmedizin unter Berücksichtigung statischer Okklusion
Darmstadt, Hochschule, Master Thesis, 2007
ViRus ist ein CAD/CAM-System zur Rekonstruktion von Zahndefekten. Das System verfügt über zahnmedizinisches Wissen in Form einer Zahnbibliothek, die für jede vorkommende Zahnform ein geometrisch verformbares Modell enthält. Für die Restauration eines zerstörten Zahns wird zunächst die fehlende Oberfläche rekonstruiert. Derzeit wird diese lediglich anhand des präparierten Zahns und seiner Nachbarzähne angepasst; eine genaue Berücksichtigung des Gegenbisses erfolgt nicht - obwohl entsprechende Daten (3D-Scans der gegenüberliegenden Zähne, der sog. "Antagonisten") in der Regel vorliegen. Diese Arbeit soll die Basis dafür schaffen, eine Anpassung des zu restaurierenden Zahns an seinen Gegenbiss zu ermöglichen. Die Anpassung an den Antagonisten soll zunächst statisch anhand von Kontaktpunkten erfolgen. Hierzu müssen zunächst die Zahnmodelle der Bibliothek überarbeitet werden, so dass sie Informationen bezüglich der "optimalen" Kontaktpunkte enthalten. Des Weiteren müssen auf den Scans des Gegenbisses die dazugehörigen Kontaktpunkte gefunden werden. Hierbei werden zuerst einzelne Zähne auf dem Antagonistenmodell über verschiedene Segmentierungsverfahren bestimmt. Somit kann ein Zahnmodell darauf platziert werden, um Flächen auf den einzelnen Zähnen des Antagonistenmodells zu markieren. Die Bestimmung und Überprüfung von Kontaktpunkten ist somit möglich. Dadurch sind alle Voraussetzungen getroffen, um eine Anpassung an den Antagonisten vorzunehmen. Dies erfolgt über einen iterativen Prozess, welcher das Zahnmodell verformt und danach jeweils die neuen Kontaktpunkte zwischen Zahn und Antagonisten überprüft. Abschließend kann gesagt werden, dass die Anpassung des restaurierten Zahns an den Antagonisten in den meisten Fällen erfolgreich durchgeführt werden kann.
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Terörde, Steffen; Hahn, Volker (Betreuer)
Konzeption und Realisierung eines Kameraclusters zur Erzeugung von Videopanoramen
Terörde, Steffen; Hahn, Volker (Betreuer)
Konzeption und Realisierung eines Kameraclusters zur Erzeugung von Videopanoramen
Darmstadt, Hochschule, Master Thesis, 2007
Telepräsenzsysteme bieten ihrem Benutzer die Möglichkeit, die Sinneseindrücke eines entfernten Ortes wahrzunehmen und so an diesem Ort "präsent" zu sein. Oft erfolgt auch eine Interaktion des Benutzers mit der entfernten Umgebung, beispielsweise durch die wechselseitige Übertragung von Sprache und Bild in Telekonferenz-Systemen oder durch Fernsteuerung von medizinischen Geräten bei komplizierten Operationen in der Telemedizin. Das am Fraunhofer IGD in Darmstadt entwickelte Videopanoramasystem Telepresence, das den Projektrahmen für diese Arbeit bietet, erzeugt ein 360°-Videopanorama in Bild und Ton und überträgt das aufgenommene Video auf eine zylinderförmige Leinwand mit entsprechendem Lautsprecher-Array, in deren Mitte sich der Betrachter befindet. Das Thema der vorliegenden Arbeit ist die Konzeption und Realisierung der Bildaufnahmekomponente des Videopanoramasystems. Es werden Bilder von sieben ringförmig angeordneten Videokameras synchron aufgenommen und an die Bildverarbeitungskomponente zum Zusammensetzen (Stitching) des Panoramavideobildes weitergeleitet. Inhalt dieser Arbeit ist neben der synchronen Aufnahme die nötige Vorverarbeitung für das Stitching, dies beinhaltet das Rekonstruieren von Farbbildern aus den Kameradaten durch Bayer-Demosaicing, die Korrektur der Verzeichnung der Kameraoptik sowie die Anpassung der Bildgeometrie zur Anpassung der Projektionen der einzelnen Kameras zueinander. Die Vorgehensweise beim Stitching des Videopanoramas ist nicht Teil dieser Arbeit. Zunächst wurde eine Software-Komponente zur Feststellung der Verzeichnung erstellt. Eine Grabbingkomponente ermöglicht die synchrone Aufnahme der sieben Kamerabilder und stellt diese zur Weiterverarbeitung zur Verfügung. Bayer-Demosaicing und Verzeichnungskorrektur erfolgen auf der Grafikkarte durch ein entsprechendes Fragment Shader-Programm. Die Anpassung der Bildgeometrie geschieht anschließend durch Projektion der korrigierten Farbbilder auf einen entsprechenden Korrekturkörper.
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Wald, Diana; Wesarg, Stefan; Nowak, Stefanie
Quantifizierung und Visualisierung von Narbenbereichen des Myokards
Wald, Diana; Wesarg, Stefan; Nowak, Stefanie
Quantifizierung und Visualisierung von Narbenbereichen des Myokards
Horsch, Alexander (Ed.) et al.: Bildverarbeitung für die Medizin 2007. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2007. (Informatik aktuell), pp. 323-327
Workshop Bildverarbeitung für die Medizin (BVM) <10, 2007, München, Germany>
In diesem Beitrag wird ein automatisches Verfahren zur Quantifizierung von Narbenbereichen des Myokards aus MRT-Daten vorgestellt. Spezielles Augenmerk wird dabei auf die automatische Berechnung und die praxisnahe Präsentation der Analysedaten gelegt. Weiterhin werden dem Anwender verschiedene Möglichkeiten geboten, die Ergebnisse auf ihre Korrektheit zu überprüfen und wenn nötig zu korrigieren, um Fehldiagnosen zu vermeiden.
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Wesarg, Stefan; Fellner, Dieter W.; Giannitsis, Evangelos
Automatisierte Analyse und Visualisierung der Koronararterien und großen Kavitäten des Herzens für die klinische Anwendung
Wesarg, Stefan; Fellner, Dieter W.; Giannitsis, Evangelos
Automatisierte Analyse und Visualisierung der Koronararterien und großen Kavitäten des Herzens für die klinische Anwendung
Es werden verschiedene Verfahren zur Analyse von Bilddaten des kardiovaskulären Systems behandelt. Damit wird eine Verbesserung sowohl der Diagnose als auch der Planung von eventuell notwendigen Eingriffen erreicht. Die beschriebenen Verfahren zeichnen sich durch eine hohe Automatisierung und Reproduzierbarkeit der Analyseergebnisse sowie ihre klinische Anwendbarkeit aus. Augenmerk wird vor allem auf die auf der Oberfläche des Herzens liegenden Herzkranzgefäße und die den Hauptteil des Herzens bildenden Kavitäten - das linke und rechte Ventrikel gelegt. Hier werden verschiedene im Rahmen dieser Arbeit entwickelte, neue Segmentierungs- und Analyseverfahren vorgestellt und diskutiert. Im Falle der Herzkranzgefäße sind das trackingbasierte Segmentierungsansätze, die die Basis bilden für eine Analyse des Gefäßes hinsichtlich - der Detektion und Vermessung von Stenosen - des Vorhandenseins von harten Arterienverkalkungen - der Zusammensetzung des umliegenden Gewebes Desweiteren wird ein Verfahren vorgestellt, das es ermöglicht, die damit erreichten Ergebnisse mit der Koronarangiographie - dem Gold-Standard - zu vergleichen. Für eine angepaßte Präsentation der Analyseergebnisse werden speziell entwickelte Verfahren für deren optimale Visualisierung als auch die der Bilddaten selbst vorgestellt. Letztere betreffend wird ein automatisches Verfahren eingeführt, mit dessen Hilfe sich Strukturen wie der Brustkorb ausmaskieren lassen, die die direkte Sicht auf das Herz stören. Für die Analyse von linkem (LV) und rechtem Ventrikel (RV) werden automatisierte Segmentierungsverfahren vorgestellt, aus deren Ergebnis sich die die Dynamik der Ventrikel beschreibenden physikalischen Parameter ableiten lassen. Für das LV wird eine umfassende, automatische und detaillierte Analyse der Wandbewegung, Wanddickenzunahme und Volumenänderung vorgestellt. Als neuer Deskriptor für die Dynamik wird die Asynchronität eingeführt. Die für das LV entwickelten Analyseverfahren werden auf das RV übertragen und ermöglichen so eine ganz neue Qualität dessen Analyse. Die Präsentation der berechneten Parameter erfolgt in einer standardisierten Weise entsprechend den Empfehlungen der American Heart Association. Als Erweiterung dieser Darstellungsmöglichkeit wird die direkte Visualisierung dieser Größen zusammen mit einem 3D-Rendering des LV eingeführt. Dies fließt ein in eine kombinierte Darstellung von dynamischen Parametern und Infarktbereichen des Herzens. Letztere werden zudem automatisch quantifiziert. Die wesentlichen Fortschritte dieser Arbeit sind: 1. die Entwicklung zweier neuer trackingbasierter Algorithmen für die Segmentierung von Koronararterien in kontratverstärkten CT-Daten, 2. die Einführung neuer Visualisierungsmethoden für die Präsentation der Ergebnisse der Koronaranalyse, 3. die Schaffung direkter Vergleichsmöglichkeiten zwischen CT-Angiographie und konventioneller Angiographie, 4. die Kombination bestehender Segmentierungstechniken mit anatomischer Kenntnis für eine automatisierte Extraktion von linkem und rechtem Ventrikel, 5. die Etablierung von umfassenden Analyseverfahren für die Dynamik des linken Ventrikels, 6. die erstmalige Anwendung dieser Ansätze auf die Dynamik des rechten Ventrikels, 7. die Einführung eines das asynchrone Verhalten von Bereichen des Ventrikels beschreibenden neuen Parameters in die LV-Analyse und 8. die Erweiterung der Diagnostik von Infarktbereichen um eine automatische Narbenquantifizierung und neue Visualisierungsmethoden.
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Balwierz, Matthias; Sakas, Georgios (Betreuer)
Interaktives hybrides Rendering mit Schnittoperationen
Balwierz, Matthias; Sakas, Georgios (Betreuer)
Interaktives hybrides Rendering mit Schnittoperationen
Darmstadt, TU, Bachelor Thesis, 2006
Diese Bachelorarbeit befasst sich mit der hybriden Darstellung von Volumen und Polygondaten mit Schnittoperationen. Das Ziel war es ein System zu entwickeln, welches Schnitte zwischen dynamischen Polygondaten und Volumen in Echtzeit bewerkstelligen kann. Zunächst werden aktuelle Darstellungsverfahren von Volumen auf aktueller Grafikhardware untersucht. Für die Beschleunigung der Darstellung von Volumen beim Volume-Slicing wird ein neues Verfahren entwickelt welches einen geschlossenen Kantenzug aus dem Schnitt einer Ebene und einem 3D-Modell in linearer Zeit berechnet. Anschließend wird ein Verfahren zur gemischten Darstellung von Polygonen und Volumen auf der Grafikhardware vorgestellt und dieses um CSG-Operationen erweitert. Mit einem Szenegraphen ergibt sich zum Schluss ein System, welches mehrere Volumen und konkave 3D-Modelle in Echtzeit mischen und gegeneinander schneiden kann.
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Binotto, Alecio; Torres, Marcio Soares; Sachpazidis, Ilias; Gomes, Ricardo; Pereira, Carlos Eduardo
T@lemed: um Estudo de Caso de Tele-saúde Baseado em Imagens de Ultra-som
Binotto, Alecio; Torres, Marcio Soares; Sachpazidis, Ilias; Gomes, Ricardo; Pereira, Carlos Eduardo
T@lemed: um Estudo de Caso de Tele-saúde Baseado em Imagens de Ultra-som
Sociedade Brasileira de Informática em Saúde: Congresso Brasileiro de Informática em Saúde (CBIS) 2006. Proceedings, pp. 1273-1277
Congresso Brasileiro de Informática em Saúde (CBIS) <10, 2006, Florianópolis, Brazil>
O crescimento da Internet rápida (a cabo e também sem fios, inclusive por satélite) no Brasil e o recente avanço de métodos de compressão de imagem permitiram a execução de tele-consultas interativas baseadas em imagens médicas. Atualmente, um dos problemas desafiadores em tele-medicina é a teleconsulta em tempo-real em casos de emergência. Neste artigo, descreve-se o Projeto T@lemed no Estado do Rio Grande do Sul e os resultados preliminares em dois anos de operação. Além disso, apresenta-se a extensão do projeto no Estado do Pará, através de comunicação via satélite. A plataforma de tele-medicina usada pode realizar tele-consultas baseadas em imagens do tipo on-line (tele-consulta em tempo-real) ou off-line.
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Dold, Christian; Bockholt, Ulrich; Sakas, Georgios; Roth, Marcus
Virtuelle Analyse und Simulation im Bereich der Bronchoskopie und Rhinoskopie mit echten Patientendaten
Dold, Christian; Bockholt, Ulrich; Sakas, Georgios; Roth, Marcus
Virtuelle Analyse und Simulation im Bereich der Bronchoskopie und Rhinoskopie mit echten Patientendaten
Schenk, Michael (Ed.): 9. IFF-Wissenschaftstage 2006. Tagungsband : Virtual Reality and Augmented Reality zum Planen, Testen und Betreiben technischer Systeme. Magdeburg: Fraunhofer IFF, 2006, pp. 163-170
IFF-Wissenschaftstage <9, 2006, Magdeburg, Germany>
Auf Grundlage patientenspezifischer Bilddaten wird ein Trainings- / Simulationssystem entwickelt, mit dem eine anstehende Therapie vorbereitet werden kann. Die untersuchten Fälle können gleichzeitig zum Aufbau einer Trainingsdatenbank herangezogen werden.
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Dold, Christian; Paruchuri, Ramakrishna; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Segmentation of Human Lung CT Scans Using Hybrid Method
Dold, Christian; Paruchuri, Ramakrishna; Fraunhofer-Institut für Graphische Datenverarbeitung (IGD)
Segmentation of Human Lung CT Scans Using Hybrid Method
The purpose of this thesis work is to segment Human Lung CT Scans. Segmentation is the process of collecting image pixels or voxels based on the criteria of similarities and homogeneity in an image region. There are varying approaches to achieve this aim. As a part of this work combination of 'Region Growing' and 'Fuzzy Connected' methods are implemented as 'Hybrid Segmentation' method. These methods are based on the filters available in the 'Insight Segmentation and Registration Toolkit' (ITK). This thesis is divided in to three parts: as image acquisition plays an important role in the segmentation process, in part one of this thesis work history of different medical imaging technologies are explained along with the reasons why I was motivated to work in this direction. In the beginning of part two, basic structure and methods available for viewing medical images using Medical Imaging Platform (MIP, a platform developed at Fraunhofer Institute for the analysis of medical images) are explained. After that different steps involved in 'Pre-Processing' and 'Hybrid Segmentation' method of medical images are presented. In part three, the basic algorithm or pipeline is introduced, its implementation is explained, improved and finally tested with medical image data. In the testing phase, the algorithm is first tried with different datasets like 'water flask', 'Human Head CT Scan' and 'Human Lung CT Scan'. Finally, the results in each case of the algorithm or pipeline are presented and analysed to draw conclusions about the working procedure of this 'Hybrid Segmentation' method.
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Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Advantages and Limitations of Prospective Head Motion Compensation for MRI Using an Optical Motion Tracking Device
Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Advantages and Limitations of Prospective Head Motion Compensation for MRI Using an Optical Motion Tracking Device
Academic Radiology, Vol.13 (2006), 9, pp. 1093-1103
Patient motion remains a significant problem in many magnetic resonance (MR) imaging (MRI) applications, including functional MRI (fMRI) (1 and 2) and cardiac and abdominal imaging, as well as conventional acquisitions. Many techniques are available to reduce or compensate for bulk motion effects, such as physiological gating, phase-encode reordering, fiducial markers (3), special algorithms (4), fast acquisitions, image volume registration, or such alternative data-acquisition strategies as projection reconstruction, spiral, and Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction (PROPELLER) (5 and 6). Navigator echoes are used to measure motion with one or more degrees of freedom (df) (7). The motion then is compensated for either retrospectively or prospectively. An orbital navigator (ONAV) echo captures data in a circle in some plane of k-space, centered at the origin (8, 9 and 10). These data can be used to detect rotational and translational motion in this plane and correct for this motion. However, multiple orthogonal ONAVs are required for general three-dimensional (3D) motion determination, and the accuracy of a given ONAV is affected adversely by motion out of its slice. Methods capable of correcting for head motion in all 6 df have been proposed for human positron emission tomography brain imaging (11). These methods rely on accurate measurement of head motion in relation to the reconstruction coordinate frame. Implementing a similar technique in MRI presents additional challenges. Foremost, the tracking system and MRI system have to be compatible. High magnetic fields of 1.5 Tesla or greater in MRI systems require that the tracking camera system be positioned at sufficient distance from the MRI system to ensure proper function and safety. Additionally, efforts need to be taken to ensure radiofrequency (RF) screening on the tracking hardware. fMRI also proves challenging because of the high spatial accuracy (root mean square [RMS] < 0.3 mm) required by the complete measurement chain with a small latency time of the tracking system. A precise relationship between spatially varying magnetic field gradients and spatial tracking information is necessary to compensate for motion artifacts. Our initial trials using an external tracking system to compensate for movement artifacts in MRI are published elsewhere (12, 13, 14, 15 and 16).
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Heinrich, Gregor; Teresniak, Sven; Witschel, Hans Friedrich
Entwicklung von Testkollektionen für P2P Information Retrieval
Heinrich, Gregor; Teresniak, Sven; Witschel, Hans Friedrich
Entwicklung von Testkollektionen für P2P Information Retrieval
Hochberger, Christian (Ed.) et al.: Informatik 2006. Informatik für Menschen. Band 1 : Beiträge zur 36. Jahrestagung der Gesellschaft für Informatik e.V.. Bonn: Gesellschaft für Informatik, 2006. (GI-Edition - Lecture Notes in Informatics (LNI) P-93), pp. 20-27
Informatik 2006 - Jahrestagung der Gesellschaft für Informatik e.V. (GI) <36, 2006, Dresden, Germany>
Dieser Beitrag stellt laufende Arbeiten an Testkollektionen vor, die für die realistische Simulation semantischer Suche in P2P-Netzwerken verwendet werden können. Er entwickelt eine allgemeine Vorgehensweise für die Erstellung solcher Simulationsdaten. Mithilfe eines probabilistischen Modells wird die semantische Verteilung von Peer-Dokumentenbeständen und Suchanfragen abgedeckt, wobei die verwendeten Dokumente keine Vorklassifizierung benötigen.
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Khan, M. Fawad; Dogan, Selami; Maataoui, Adel; Wesarg, Stefan; Gurung, Jessen; Ackermann, Hanns; Schiemann, Mirko; Wimmer-Greinecker, Gerhard; Vogl, Thomas J.
Navigation-Based Needle Puncture of a Cadaver Using a Hybrid Tracking Navigational System
Khan, M. Fawad; Dogan, Selami; Maataoui, Adel; Wesarg, Stefan; Gurung, Jessen; Ackermann, Hanns; Schiemann, Mirko; Wimmer-Greinecker, Gerhard; Vogl, Thomas J.
Navigation-Based Needle Puncture of a Cadaver Using a Hybrid Tracking Navigational System
Investigative Radiology, Vol.41 (2006), 10, pp. 713-720
Purpose: The purpose of this study was to determine the puncture accuracy of a navigational system, Medarpa, in a soft tissue environment using augmented overlay imaging. Materials and Methods: Medarpa is an optical electromagnetic tracking system, which allows tracking of instruments, the radiologist's head position, and the transparent display. The display superimposes a computed tomography scan of a cadaver chest on a human cadaver in real time. In group A, needle puncture was performed using the Medarpa system. Three targets located inside the cadaver chest were selected. In group B, the same targets were used to perform standard computed tomography-guided puncture using a single-slice technique. A total of 42 punctures were performed in each group. Postpuncture computed tomography scans were made to verify needle tip positions. Results: Mean deviation from targets was 8.42 mm ± 1.78 mm for group A and 8.90 mm ± 1.71 mm for group B. No significant difference was found between group A and B in any target (P > 0.05). No significant difference was found between the targets of the same group (P > 0.05). Procedural time for 42 punctures was 160 minutes in group A versus 289 minutes in group B (P < 0.05). Conclusion: Needle puncture in a soft tissue environment using the navigational system Medarpa can be reliably performed and matches the accuracy achieved by a computed tomography-guided puncture technique.
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Khan, M. Fawad; Wesarg, Stefan; Gurung, Jessen; Dogan, Selami; Maataoui, Adel; Brehmer, Boris; Herzog, Christopher; Ackermann, Hanns; Aßmus, Birgit; Vogl, Thomas J.
Facilitating Coronary Artery Evaluation in MDCT Using a 3D Automatic Vessel Segmentation Tool
Khan, M. Fawad; Wesarg, Stefan; Gurung, Jessen; Dogan, Selami; Maataoui, Adel; Brehmer, Boris; Herzog, Christopher; Ackermann, Hanns; Aßmus, Birgit; Vogl, Thomas J.
Facilitating Coronary Artery Evaluation in MDCT Using a 3D Automatic Vessel Segmentation Tool
European Radiology, Vol.16 (2006), 8, pp. 1789 - 1795
The purpose of this study was to investigate a 3D coronary artery segmentation algorithm using 16-row MDCT data sets. Fifty patients underwent cardiac CT (Sensation 16, Siemens) and coronary angiography. Automatic and manual detection of coronary artery stenosis was performed. A 3D coronary artery segmentation algorithm (Fraunhofer Institute for Computer Graphics, Darmstadt) was used for automatic evaluation. All significant stenoses (>50%) in vessels >1.5 mm in diameter were protocoled. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of coronary angiography. Sensitivity and specificity were determined for automatic and manual detection as well as was the time for both CT-based evaluation methods. The overall sensitivity and specificity of the automatic and manual approach were 93.1 vs. 95.83% and 86.1 vs. 81.9%. The time required for automatic evaluation was significantly shorter than with the manual approach, i.e., 246.04±43.17 s for the automatic approach and 526.88±45.71 s for the manual approach (P<0.0001). In 94% of the coronary artery branches, automatic detection required less time than the manual approach. Automatic coronary vessel evaluation is feasible. It reduces the time required for cardiac CT evaluation with similar sensitivity and specificity as well as facilitates the evaluation of MDCT coronary angiography in a standardized fashion.
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Kontaxakis, George; Pozo, Miguel Angel; Ohl, Roland; Visvikis, Dimitris; Sachpazidis, Ilias; Ortega, Fernando; Guerra, Pedro; Cheze-Le Rest, Catherine; Selby, Peter; Pan, Leyun; Diaz, Javier; Dimitrakopoulou-Strauss, Antonia; Santos, Andres; Strauss, Ludwig; Sakas, Georgios
European Health Telematics Networks for Positron Emission Tomography
Kontaxakis, George; Pozo, Miguel Angel; Ohl, Roland; Visvikis, Dimitris; Sachpazidis, Ilias; Ortega, Fernando; Guerra, Pedro; Cheze-Le Rest, Catherine; Selby, Peter; Pan, Leyun; Diaz, Javier; Dimitrakopoulou-Strauss, Antonia; Santos, Andres; Strauss, Ludwig; Sakas, Georgios
European Health Telematics Networks for Positron Emission Tomography
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol.569 (2006), 2, pp. 626-630
International Conference on Imaging Technologies in Biomedical Sciences (ITBS) <3, 2005, Milos Island, Greece>
A pilot network of positron emission tomography centers across Europe has been setup employing telemedicine services. The primary aim is to bring all PET centers in Europe (and beyond) closer, by integrating advanced medical imaging technology and health telematics networks applications into a single, easy to operate health telematics platform, which allows secure transmission of medical data via a variety of telecommunications channels and fosters the cooperation between professionals in the field. The platform runs on PCs with Windows 2000/XP and incorporates advanced techniques for image visualization, analysis and fusion. The communication between two connected workstations is based on a TCP/IP connection secured by secure socket layers and virtual private network or jabber protocols. A teleconsultation can be online (with both physicians physically present) or offline (via transmission of messages which contain image data and other information). An interface sharing protocol enables online teleconsultations even over low bandwidth connections. This initiative promotes the cooperation and improved communication between nuclear medicine professionals, offering options for second opinion and training. It permits physicians to remotely consult patient data, even if they are away from the physical examination site.
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Kontaxakis, George; Sakas, Georgios; Walter, Stefan
Mobile Tele-Echography Systems - Teleinvivo: A Case Study
Kontaxakis, George; Sakas, Georgios; Walter, Stefan
Mobile Tele-Echography Systems - Teleinvivo: A Case Study
Istepanian, Robert (Ed.) et al.: M-Health : Emerging Mobile Health Systems. Berlin; Heidelberg; New York: Springer, 2006. (International Topics in Biomedical Engineering), pp 445-460
Telemedicine, defined as practice of medicine at a distance, has been performed ever since humans learned to communicate: a messenger carrying over a medical advice from a distant expert to the bed of a patient has been always practicing telemedicine. By definition, therefore, telemedicine does not imply any technological breakthrough. It is however in the present days, with the breathtaking advancement in medicine, information technology, telecommunications, and biomedical sciences, that the term telemedicine emerged as one designating a new health care service, firmly related to the cutting edge of scientific and technological progression in these fields. By minimizing or even eliminating the effect of distance, telemedicine comes to establish new basements for the delivery of health services worldwide. One of the major application areas is the provision of skilled medical care to patients who are in some way isolated from the specialized care they need. This is specially the case of isolated areas (rural regions, remote islands) and of crisis situation areas (ecological disaster, military conflict, etc.). Residents of these areas often have substandard access to specialty health care, primarily because specialist physicians are more likely to be located in areas of concentrated population. Access to these services is only achieved with the use of applications that allow remote expert consultation providing a faster response in emergency and crisis situations. Tele-echography is a telemedicine modality preferred by many for its low-cost and non-invasive characteristics of capturing dynamic images of human body organs in real time. TeleInViVo is an international and intercontinental tele-echography project, which proved in practice that mobile tele-echography could dramatically improve the medical and health care provided to every person worldwide.
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Kontaxakis, George; Visvikis, Dimitris; Ohl, Roland; Sachpazidis, Ilias; Suarez, Juan Pablo; Selby, Peter; Cheze-Le Rest, Catherine; Santos, Andres; Ortega, Fernando; Diaz, Javier; Pan, Leyun; Strauss, Ludwig; Dimitrakopoulou-Strauss, Antonia; Sakas, Georgios; Pozo, Miguel Angel
Integrated Telemedicine Applications and Services for Oncological Positron Emission Tomography
Kontaxakis, George; Visvikis, Dimitris; Ohl, Roland; Sachpazidis, Ilias; Suarez, Juan Pablo; Selby, Peter; Cheze-Le Rest, Catherine; Santos, Andres; Ortega, Fernando; Diaz, Javier; Pan, Leyun; Strauss, Ludwig; Dimitrakopoulou-Strauss, Antonia; Sakas, Georgios; Pozo, Miguel Angel
Integrated Telemedicine Applications and Services for Oncological Positron Emission Tomography
Oncology Reports: An International Journal devoted to Fundamental and Applied Research in Oncology, Vol.15 (2006), Special Issue, pp. 1091-1100
TENPET (Trans European Network for Positron Emission Tomography) aims to evaluate the provision of integrated teleconsultation and intelligent computer supported cooperative work services for clinical positron emission tompgraphy (PET) in Europe at its current stage, as it is a multi-centre project financially supported by the European Commission (Information Society, eTEN Program). It addresses technological challenges by linking PET Centres and developing supporting services that permit remote consultation between professionals in the field. The technological platform (CE-marked) runs on WIN2000/NT/XP systems and incorporates advanced techniques for image visualization, analysis and fusion, as well as for interactive communication and message handling for off-line communications. Four PET Centres from Spain, France and Germany participate to the pilot system trials. The performance evaluation of the system is carried out via log files and userfilled questionnaires on the frequency of the teleconsultations, their duration and efficancy, quality of the images received, user satisfaction. as well as on privacy, ethical and security issues. TENPET promotes the co-opertation and improved communication between PET practitioners that are miles away from their peers or on mobile units, offering options for second opinion and training and permitting physicians to remotely consult paptient data if they are away from their centre. It is expected that TENPET will have a significant impact in the development of new skills by PET professionals and will support the establishment of peripheral PET units. To our knowledge, TENPET is the first telemedicine service specifically designed for oncological PET. This report presents the technical innovations incorporated in the TENPET platform and the initial pilot studies at real and diverse clinical environments in the field of oncology.
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Lacalli, Christina; Wesarg, Stefan (Betreuer)
Matching von Angiographiebildern mit tomographischen Volumendaten
Lacalli, Christina; Wesarg, Stefan (Betreuer)
Matching von Angiographiebildern mit tomographischen Volumendaten
Koblenz/Landau, Univ., Diplomarbeit, 2006
Die Koronararterien sind verantwortlich für die Versorgung des Herzmuskels mit Sauerstoff und Nährstoffen. Verengungen oder Verstopfungen dieser Gefäße können Herz-Kreislauf-Erkrankungen bis hin zum Herzinfarkt auslösen. Gegenwärtig stellt die invasive Koronarangiographie den Goldstandard innerhalb der Diagnostik dieser Erkrankungen dar. Eine alternative, nicht-invasive Untersuchungsmöglichkeit ist durch die Mehrschicht-Spiral-Computertomographie (MSCT) gegeben. Seit Einführung dieses Verfahrens 1998 ist die Fragestellung nach der Korrelation der aus den Volumendaten gewonnen Informationen über die Koronararterien mit denen aus der Koronarangiographie aufgekommen. In dieser Arbeit wurde ein Matchingverfahren entwickelt, das es dem Mediziner erstmals ermöglicht, mit geringem Zeitaufwand und minimaler Interaktion, einzelne Angiogramme mit entsprechenden CT-Datensätzen des Thorax in Deckung zu bringen, um so Informationen über das Koronararteriensystem aus beiden bildgebenden Verfahren direkt miteinander vergleichen zu können. Das Verfahren basiert auf der Generierung künstlicher Projektionsbilder aus CT-Datensätzen des Thorax, sogenannter Digitally Reconstructed Radiographies (DRRs), und einer anschließenden Registrierung dieser mit den entsprechenden Koronarangiogrammen. Das entwickelte Verfahren umfasst darüberhinaus einen neuen Ansatz, um kontrastverstärkte Herzstrukturen, die die Sicht auf die Koronararterien in den Projektionsbildern stören, auszumaskieren. Dieser vorverarbeitende Schritt bildet eine wesentliche Grundlage, um eine anschließende Registrierung überhaupt durchführen zu können. Die Visualisierung der Ergebnisse erfolgt durch eine fusionierte Darstellung der beiden Bildmodalitäten, sowie durch eine Parallelansicht der registrierten Datensätze.
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Nowak, Stefanie; Wesarg, Stefan (Betreuer)
4D Narbendarstellung des Herzens Visualisierung und Modellierung der Dynamik und Funktion des linken Ventrikels
Nowak, Stefanie; Wesarg, Stefan (Betreuer)
4D Narbendarstellung des Herzens Visualisierung und Modellierung der Dynamik und Funktion des linken Ventrikels
Siegen, Univ., Diplomarbeit, 2006
Über medizinische Bildgebungsverfahren ist es Ärzten möglich, einen Einblick in den menschlichen Körper und seine komplexen Vorgänge zu erhalten und so Diagnose und Behandlungsplanung zu erstellen. Besonders nach einem Herzinfarkt ist eine Abschätzung des Ausmaßes der Beeinträchtigung der Herzfunktion notwendig. Dafür, aber auch für eine prophylaktische Einschätzung der Herztätigkeit, können Parameter berechnet werden, die die Funktion des Herzens beschreiben. Aufgrund der Masse an Bilddaten, die für eine solche Berechnung anfallen, sind automatische, intuitiv bedienbare Applikationen notwendig, um den Arzt bei seiner Diagnose zu unterstützen. Die vorliegende Arbeit beschäftigt sich mit der drei- und vierdimensionalen Darstellung der Funktion und Deformation des linken Ventrikels bei Herzinfarktpatienten. Eine Visualisierung der Ventrikelfunktion mit Überlagerung des vernarbten Gewebes illustriert die durch den Infarkt hervorgerufenen Bewegungsstörungen. Untersucht wurde der Zusammenhang der Lokalisierung des vernarbten Gewebes zu Bereichen mit kritischen Funktionsparametern. Dazu wurde ein automatisches Verfahren entwickelt, dass ein dreidimensionales, die Funktionsparameter farbkodierendes Modell des linken Ventrikels zu jeder Herzphase erstellt und zudem einen Satz von Bewegungsvektoren über den Herzzyklus ableitet. Die Deformationsfelder werden für eine künstliche Deformation auf den nur zu einem Zeitpunkt im Herzzyklus vorhandenen statischen Datensatz (late enhancement) angewendet. Es zeigt sich, dass neben einer intuitiven Erkenntnis der Bewegungsstörungen durch den in einer Animation simulierten Pumpvorgang, die überlagerte Visualisierung der Deformation des Narbendatensatzes dem Arzt eine kompakte Informationsdarstellung bietet. Über direkte Visualisierungstechniken wird der Narbenbereich zufrieden stellend hervorgehoben visualisiert. Für eine Darstellung und Beurteilung der Qualtät des entwickelten Verfahrens, wurde es an Daten von 12 Herzinfarktpatienten getestet und ausgewertet.
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Sachpazidis, Ilias; Kiefer, Stephan; Selby, Peter; Ohl, Roland; Sakas, Georgios
A Medical Network for Teleconsultations in Brazil and Colombia
Sachpazidis, Ilias; Kiefer, Stephan; Selby, Peter; Ohl, Roland; Sakas, Georgios
A Medical Network for Teleconsultations in Brazil and Colombia
Pinciroli, F. (Ed.): Proceedings of the Second IASTED International Conference on Telehealth. Anaheim, Calgary, Zurich: IASTED/ACTA Press, 2006, pp. 16-21
IASTED International Conference on Telehealth <2, 2006, Banff, Canada>
Access to medical care is sometimes very difficult to be reached from people living in rural and underserved areas. That problem is very well known in rural areas in Brazil and Colombia. Citizens have no access to health care. They have to travel hundred of kilometres to receive a medical diagnosis. In this paper we will propose a medical network based on state-of-the-art medical applications that address the problems of providing health care from a distance. Additionally, we are going to show preliminarily results of the first year of the system deployment and utilization in undeserved regions in Brazil and Colombia.
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Sachpazidis, Ilias; Konnis, George; Kiefer, Stephan; Rohm, Kerstin; Lozano, Alfonso; Yunda, Leonardo; Selby, Peter; Binotto, Alecio; Messina, Luiz Ary; Sakas, Georgios
T@LEMED: Medical Imaging Tele-cooperation Technologies Providing Medical Services in Latin America
Sachpazidis, Ilias; Konnis, George; Kiefer, Stephan; Rohm, Kerstin; Lozano, Alfonso; Yunda, Leonardo; Selby, Peter; Binotto, Alecio; Messina, Luiz Ary; Sakas, Georgios
T@LEMED: Medical Imaging Tele-cooperation Technologies Providing Medical Services in Latin America
IEEE Engineering in Medicine and Biology Society (EMBS): ITAB 2006. Proceedings CD-ROM. Ioannina, 2006, 5 p.
International Special Topic Conference on Information Technology in Biomedicine (ITAB) <2006, Ioannina, Greece>
Developing countries have very high patients-perdoctor ratios that are a common indicator of the amount of healthcare that exists in a region. As a point of comparison, developed countries such as the US have one doctor for every 200 to 500 people, while developing countries in East Africa have as little as one doctor for every 40,000 people. In Brazil and Colombia the situation is not completely different according to WHO charts. The state of health of a population is a direct determinant of its development, and investment in health is a prerequisite to economic and social progress. Developing countries need low cost, sustainable solutions for the local delivery of primary healthcare and efficient access to medical expertise when needed. T@LEMED project introduces an e-health model to the provision of health services in strongly underserved regions in Colombia and Brazil. The implementation of this model is supported on telehealth technologies as well as on evidence based medicine. The target clinical applications include typical infectious diseases for the region such as malaria and tuberculosis, and general ultrasound applications such as pregnancy control, urology and cardiovascular diagnosis. In this paper we are going to provide information about the deployed medical network and utilization information for the field trials in Brazil and Colombia.
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Sachpazidis, Ilias; Majadas, Maria
A Medication Adherence Monitoring System Based on HL7 Messages
Sachpazidis, Ilias; Majadas, Maria
A Medication Adherence Monitoring System Based on HL7 Messages
The Journal on Information Technology in Healthcare, Vol.4 (2006), 1, pp. 49-58
A Medication Adherence Monitoring System (MAMS) system has been designed based on Health Level 7 (HL7) messages. MAMS is a practical and patient-friendly solution that has the potential to both improve medication adherence and monitoring adherence in any group of patients. The proposed system can be easily integrated into any hospital administration system by providing an HL7 interface for seamless integration.
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Sachpazidis, Ilias; Ohl, Roland; Binotto, Alecio; Torres, Mario Soares; Messina, Luiz Ary; Sales, Alexandre; Gomes, Ricardo; Sakas, Georgios
T@lemed: Ehealth Applications Applied to Underserved Areas in Latin America
Sachpazidis, Ilias; Ohl, Roland; Binotto, Alecio; Torres, Mario Soares; Messina, Luiz Ary; Sales, Alexandre; Gomes, Ricardo; Sakas, Georgios
T@lemed: Ehealth Applications Applied to Underserved Areas in Latin America
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol.569 (2006), 2, pp. 635-639
International Conference on Imaging Technologies in Biomedical Sciences (ITBS) <3, 2005, Milos Island, Greece>
Access to medical care is sometimes very difficult to be reached from people living in rural and underserved areas. This problem is very well known in rural areas in Brazil. Citizens have no access to health care. They have to travel hundreds of kilometres to receive medical care. In this paper, we will propose a medical network based on state-of-the-art medical imaging application that addresses the problems of providing health care from a distance. Additionally, we are going to show preliminarily results of the first year of the system deployment and utilization in undeserved regions in Brazil. The total number of patients submitted to ultrasound examinations, during the 10 months of projects' medical trials, is 321. The exams have begun with the elderly people (hypertension and diabetes cases) with 90% above 50-years-old. Fifty-four percent were male and 46% were female. From those exams, 67 exams (21%) needed a second medical opinion and were transmitted to Santa Casa hospital in Porto Alegre, Brazil, one of the referral medical centres. From those second opinions of Santa Casa, 12 exams had to be repeated since the acquired images were not sufficient to give a correct diagnosis. The Lagoa Tres Cantos medical doctor performed also preventive exams with patients who had not presented any symptoms (70%).
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Sachpazidis, Ilias; Ohl, Roland; Kontaxakis, George; Sakas, Georgios
TeleHealth Networks: Instant Messaging and Point-to-point Communication Over the Internet
Sachpazidis, Ilias; Ohl, Roland; Kontaxakis, George; Sakas, Georgios
TeleHealth Networks: Instant Messaging and Point-to-point Communication Over the Internet
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol.569 (2006), 2, pp. 631-634
International Conference on Imaging Technologies in Biomedical Sciences (ITBS) <3, 2005, Milos Island, Greece>
This paper explores the advantages and disadvantages of a medical network based on point-to-point communication and a medical network based on Jabber instant messaging protocol. Instant messaging might be, for many people, a convenient way of chatting over the Internet. We will attempt to illustrate how an instant messaging protocol could serve in the best way medical services and provide great flexibility to the involved parts. Additionally, the directory services and presence status offered by the Jabber protocol make it very attractive to medical applications that need to have real time and store and forward communication. Furthermore, doctors connected to Internet via high-speed networks could benefit by saving time due to the data transmission acceleration over Jabber.
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Sachpazidis, Ilias; Selby, Peter; Binotto, A.; Sakas, Georgios; Pereira, Carlos Eduardo
Enhanced Medical Services in Amazon over AmerHis Satellite
Sachpazidis, Ilias; Selby, Peter; Binotto, A.; Sakas, Georgios; Pereira, Carlos Eduardo
Enhanced Medical Services in Amazon over AmerHis Satellite
University of Patras: 5th European Symposium on Biomedical Engineering. Proceedings CD-ROM, 4 p.
European Symposium on Biomedical Engineering (ESBME) <5, 2006, Patras, Greece>
In this paper we are going to present a tele-medical network connecting physician/hospitals over satellite based on DVB-RCS over AmerHis satellite. The medical applications include general obstetric, and gynaecology examinations. The applied platform handles any imagining modality and particularly DICOM formatted data. The dominant type of images transferred over the system is ultrasound images, acquired from portable or stationary ultrasound devices. The state of Pará presents the rate of general mortality of 3,65 deaths in 1.000 inhabitants. The main reasons are the blood circulation diseases and birth associated diseases. The aim of the current medical implementation will be the improvement of accessing of medical resource available only to rural cities from the isolated areas in Amazon in Para prefecture.
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Sakas, Georgios; Bockholt, Ulrich
Simulators and Closed Interaction Loops: Guest Editors' Introduction
Sakas, Georgios; Bockholt, Ulrich
Simulators and Closed Interaction Loops: Guest Editors' Introduction
IEEE Computer Graphics and Applications, Vol.26 (2006), 6, pp. 22-23
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Sakas, Georgios; Pommert, Andreas
Processing and Segmentation of 3D Images
Sakas, Georgios; Pommert, Andreas
Processing and Segmentation of 3D Images
Schlegel, Wolfgang (Ed.) et al.: New Technologies in Radiation Oncology. Berlin, Heidelberg, New York: Springer, 2006. (Medical Radiology - Radiation Oncology), pp.17-25
The article summarises the technological developments of the recent years in the area of Processing and segmentation of 3D Images. It reviews the established method in the areas of Pre-processing, Segmentation, Classification, Edge Detection, 3D Boundary Tracking, Geodesic Active Contours, Extraction of Tubular Objects, Atlas Registration and Interactive Segmentation.
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Sakas, Georgios; Pommert, Andreas
3D Visualization
Sakas, Georgios; Pommert, Andreas
3D Visualization
Schlegel, Wolfgang (Ed.) et al.: New Technologies in Radiation Oncology. Berlin, Heidelberg, New York: Springer, 2006. (Medical Radiology - Radiation Oncology), pp. 26-40
After segmentation, the choice of which rendering technique to use must be made. The more traditional surface-based methods first create an intermediate surface representation of the object to be shown. It may then be rendered with any standard computer graphics method. More recently, volume-based methods have been developed which create a 3D view directly from the volume data. These methods use the full gray-level information to render surfaces, cuts, or transparent and semi-transparent volumes. As a third way, transform-based rendering methods may be used.
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Volmer, Stephan; Encarnação, José L.; Fellner, Dieter W.
Inhaltsbasierte Bildsuche mittels visueller Merkmale
Volmer, Stephan; Encarnação, José L.; Fellner, Dieter W.
Inhaltsbasierte Bildsuche mittels visueller Merkmale
Die ständig wachsende Menge an verfügbaren digitalen Daten erfordert neuartige Methoden, die einen gezielten Zugriff auf relevante Information ermöglichen. Eine zentrale Rolle spielt in diesem Zusammenhang die automatische Erschließung bildlicher Information in digitalen Bilddaten. Der klassische Ansatz - die manuelle Annotation des Bildinhaltes mittels alphanumerischer Texte - hat sich in der Vergangenheit als zu fehleranfällig und zu kostenintensiv erwiesen. Im Rahmen dieser Arbeit wird ein alternativer Ansatz entwickelt, der es ermöglicht, große Mengen von digitalen Bilddaten mittels merkmalsbasierter Verfahren zu erschließen. Dies geschieht unter der Annahme, dass das zugrundeliegende Bildmaterial weder aufgrund seines Erscheinungsbildes, noch aufgrund seiner Bedeutung irgendeiner Einschränkung unterliegt. Zunächst wird ein allgemeingültiges Modell für die merkmalsbasierte Suche nach visuellen Inhalten in digitalen Bildern definiert. Dieses Modell stellt den formalen Rahmen für die Entwicklung und Kombinierung neuartiger Algorithmen zur Merkmalsextraktion und -indexierung dar. Das Modell ermöglicht eine inhaltsbasierte Bildsuche auf der Basis eines Systems mit einheitlicher Architektur und standardisierten Schnittstellen. Ein solches System kann durch die Entwicklung einzelner anwendungsspezifischer Bausteine für eine bestimmte Problemstellung erweitert werden. Startpunkt für die Entwicklung eines Algorithmus zur Merkmalsextraktion ist die sinnvolle Interpretation der Farben einzelner diskreter Bildpunkte. Der Mensch unterscheidet im Gegensatz zur technischen Darstellung nur zwischen einer handvoll verschiedener Farben. Daher wird im Rahmen dieser Arbeit die neuartige Farbrepräsentation vorgestellt, die die Farbinformation eines Bildes auf der Basis von - für den Menschen bedeutungsvollen - Farbnamen zugänglich macht. Das zugrundeliegende mathematische Gerüst ermöglicht einen einfachen und schnellen Vergleich von Farben. Eine solche Interpretation von Farbinformation kann nahezu für jede Aufgabe im Bereich der digitalen Bildverarbeitung nutzbringend eingesetzt werden. Auf dieser Farbrepräsentation aufbauend werden einige universelle Extraktionsalgorithmen vorgestellt, die gewisse visuelle Aspekte eines digitalen Bildes kompakt beschreiben. Große Datenmengen bedingen entsprechend lange Verarbeitungszeiten bei der Suche nach Information. Daher wird im letzten Teil der Arbeit ein Indexierungsverfahren vorgestellt, dass die proportionale Beziehung zwischen Datenmenge und Verarbeitungszeit aufbricht. Das Indexierungsverfahren basiert auf der Lokaliserung der Suche in der unmittelbaren Umgebung der Suchanfrage im Merkmalsraum. Durch das Eingrenzen des Suchraums kann eine signifikante Beschleunigung der Suche erreicht werden. Da ein solches Verfahren immanent mit einer gewissen Ungenauigkeit behaftet ist, werden experimentelle Ergebnisse präsentiert, die den Nutzen des Verfahrens im praktischen Einsatz dokumentieren.
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Wald, Diana; Wesarg, Stefan (Betreuer)
Quantifizierung und Visualisierung von Narbenbereichen des Myokards
Wald, Diana; Wesarg, Stefan (Betreuer)
Quantifizierung und Visualisierung von Narbenbereichen des Myokards
Koblenz/Landau, Univ., Diplomarbeit, 2006
Die vorliegende Diplomarbeit thematisiert die quantitative Analyse und die Visualisierung von Infarktgewebe des linken Herzmuskels. Im Mittelpunkt der Untersuchung steht das Ausmaß der Narbe und deren Deformation über den Herzzyklus. Für die Narbenausdehnung stehen so genannte Late-Enhancement-Daten zur Verfügung, die das avitale Gewebe durch ein Kontrastmittel hervorheben. Anhand von automatisierten Verfahren wird die Narbe aus den Bilddaten extrahiert und auf ihre Größe, Lokalisation und Transmuralität quantifiziert. Die Transmuralität gibt dabei das lokale Verhältnis zwischen der Herzwand- und der Narbenbreite an. Des Weiteren wird die Narbe für die Beurteilung der Beschaffenheit dreidimensional in dem Analysefenster dargestellt. Der Mediziner kann durch das entwickelte Verfahren innerhalb kürzester Zeit Aussagen über das Ausmaß und den Ursprung des Herzinfarktes treffen und zudem die Ergebnisse durch verschiedene visuelle Darstellungen kontrollieren. Die Deformation des Narbengewebes über den Herzzyklus und deren Integration mit den dynamischen Cine-Daten wurde bereits in einer vorangegangenen Diplomarbeit umgesetzt. Im Rahmen dieser Arbeit wird eine visuelle Verbesserung der Deformationsergebnisse angestrebt, die das Narbengewebe aus den Volumendaten extrahiert. Das avitale Gewebe wird durch das Eliminieren von uninteressanten Bildinformationen hervorgehoben und verbessert somit die visuelle Analyse der Narbendeformation über den Herzzyklus. Beide Verfahren liefern eine detaillierte und eindeutige Analyse des Infarktgewebes, die die manuelle Untersuchung in der klinischen Praxis ergänzen kann.
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Wesarg, Stefan; Khan, M. Fawad; Firle, Evelyn
Localizing Calcifications in Cardiac CT Data Sets Using a New Vessel Segmentation Approach
Wesarg, Stefan; Khan, M. Fawad; Firle, Evelyn
Localizing Calcifications in Cardiac CT Data Sets Using a New Vessel Segmentation Approach
Journal of Digital Imaging, Vol.19 (2006), 3, pp. 249-257
The new generation of multislice computed tomography (CT) scanners allows for the acquisition of high-resolution images of the heart. Based on that image data, the heart can be analyzed in a noninvasive way-improving the diagnosis of cardiovascular malfunctions on one hand, and the planning of an eventually necessary intervention on the other. One important parameter for the evaluation of the severeness of a coronary artery disease is the number and localization of calcifications (hard plaques). This work presents a method for localizing these calcifications by employing a newly developed vessel segmentation approach. This extraction technique has been developed for, and tested with, contrast-enhanced CT data sets of the heart. The algorithm provides enough information to compute the vessel diameter along the extracted segment. An approach for automatically detecting calcified regions that combines diameter information and gray value analysis is presented. In addition, specially adapted methods for the visualization of these analysis results are described.
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Wesarg, Stefan; Nowak, Stefanie
An Automated 4D Approach for Left Ventricular Assessment in Clinical Cine MR Images
Wesarg, Stefan; Nowak, Stefanie
An Automated 4D Approach for Left Ventricular Assessment in Clinical Cine MR Images
Hochberger, Christian (Ed.) et al.: Informatik 2006. Informatik für Menschen. Band 1 : Beiträge zur 36. Jahrestagung der Gesellschaft für Informatik e.V.. Bonn: Gesellschaft für Informatik, 2006. (GI-Edition - Lecture Notes in Informatics (LNI) P-93), pp. 483-490
Informatik 2006 - Jahrestagung der Gesellschaft für Informatik e.V. (GI) <36, 2006, Dresden, Germany>
CineMagnetic Resonance (MR) imaging has become the method-of-choice for the examination of the dynamic behaviour of the heart. An assessment of the left ventricle can reveal regions of myocardial dysfunction and their severeness. The scope of this work is a complete analysis of the left ventricular dynamics for the usage in a clinical environment. For that purpose, endocardial and epicardial borders are automatically extracted in 3D cine data in a first step. This is followed by a segmentation of the endocardium and the myocardium into 17 segments following the recommendations of the American Heart Association and the computation of common global volumetric values (stroke volume, ejection fraction etc.) and parameters that describe the left ventricular dynamics (wall motion, wall thickening). A retrospective analysis of cardiac cine MR image data from 20 patients (healthy ones, patients with abnormal wall motion, and patients who suffered an infarction) has been done. That image data has been acquired in the clinical routine at two different hospitals. The here presented automated approach led to a successful segmentation and assessment of the left ventricle for all data sets. The pathological cases could be identified easily due to their characteristic change of the motion pattern. The main advantage of our approach is the reproducibility of the assessment results and the gain in time for the cardiologist who has to analyse the huge amount of cine data.
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Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Real Time Prospective Motion Correction for High Resolution In Vivo MRI Using an Optical Motion Tracking System
Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Real Time Prospective Motion Correction for High Resolution In Vivo MRI Using an Optical Motion Tracking System
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM 14th Scientific Meeting : Proceedings of the International Society for Magnetic Resonance in Medicine, p. 2978
ISMRM Scientific Meeting <14, 2006, Seattle, Washington, USA>
Even small subject motions can degrade the image quality especially in high-resolution MRI. For head imaging the overall imaging time is limited by the subject.s ability to maintain the same head position. This time is on the order of minutes and may be dramatically reduced in a case of pathology. Projection reconstruction(1) or PROPELLER(2) methods are known to be less prone to motion artefacts. The sensitivity of standard 2D and 3D imaging methods to motion may be reduced by use of the navigator echoes, such as orbital (3) or spherical (4) navigator methods. Navigators, however, not only lengthen the measurement, but also require additional excitation RF pulses to be incorporated into the sequence, which disturbs the steady state. Here we demonstrate the possibility of interfacing the MR scanner with an external optical motion tracking system, capable of determining object.s position with sub-millimetre accuracy at high update rate. The proposed approach uses this motion information to update in real time the position of the imaging volume during the acquisition of k-space data. Such methods have previously been proposed for fMRI. The purpose of the study is to evaluate the applicability of prospective motion correction for high-resolution brain imaging in the presence of strong subject motion.
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Zaitsev, Maxim; Dold, Christian; Henning, J.; Speck, Oliver
Integration of an External Motion Tracking System with the MR Scanner for Highly Accurate Real-Time Prospective Motion Correction
Zaitsev, Maxim; Dold, Christian; Henning, J.; Speck, Oliver
Integration of an External Motion Tracking System with the MR Scanner for Highly Accurate Real-Time Prospective Motion Correction
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM 14th Scientific Meeting : Proceedings of the International Society for Magnetic Resonance in Medicine, p. 1355
ISMRM Scientific Meeting <14, 2006, Seattle, Washington, USA>
Image quality in MRI may be critically disturbed by subject motion. A number of MR-based approaches, such that orbital(1) or spherical(2) navigators, has been developed to reduce the motion sensitivity of the standard 2D and 3D imaging techniques. Navigators, however, are not compatible with every imaging method because of possible steady state perturbations and measurement time considerations. Employing external motion tracking hardware for motion correction in MRI(3-7) is a promising approach. However, up to now it failed to meet the requirements on both the accuracy placed by high resolution imaging and the overall system latency to enable prospective corrections. The goal of this work was to seamlessly integrate a high-end motion tracking system with the MR scanner and to optimise its accuracy by the development of a novel cross-calibration method. In addition, a method to determine experimentally the total latency of the measurement system is proposed.
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Zaitsev, Maxim; Dold, Christian; Sakas, Georgios; Hennig, Jürgen; Speck, Oliver
Magnetic Resonance Imaging of Freely Moving Objects: Prospective Real-time Motion Correction Using an External Optical Motion Tracking System
Zaitsev, Maxim; Dold, Christian; Sakas, Georgios; Hennig, Jürgen; Speck, Oliver
Magnetic Resonance Imaging of Freely Moving Objects: Prospective Real-time Motion Correction Using an External Optical Motion Tracking System
NeuroImage, Vol.31 (2006), 3, pp.1038-1050
Subject motion and associated artefacts limit the applicability of MRI and the achievable quality of the images acquired. In this paper, a fully integrated method for prospective correction of arbitrary rigid body motion employing an external motion tracking device is demonstrated for the first time. The position of the imaging volume is updated prior to every excitation of the spin system. The performance of the available tracking hardware and its connection to the MR imager is analyzed in detail. With the introduction of a novel calibration procedure the accuracy of motion correction is improved compared to previous approaches. Together with the high geometry update rate even freely moving objects can be imaged without motion related artefacts. The high performance and image quality improvement in case of subject motion are demonstrated for various imaging techniques such as gradient and spin echo, as well as echo planar imaging.
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Dold, Christian; Tingelhoff, Kathrin; Wesarg, Stefan; Firle, Evelyn
LV-Segmentation and Rotation Analysis Based on MRI Data
Dold, Christian; Tingelhoff, Kathrin; Wesarg, Stefan; Firle, Evelyn
LV-Segmentation and Rotation Analysis Based on MRI Data
Boenick, U. (Ed.) et al.: Medical Physics Vol. 1 : Proceedings of the Jointly Held Congresses ICMP and BMT. Berlin: Schiele & Schön, 2005. (Biomedizinische Technik 50, Suppl. 1), pp. 70-71
International Conference of Medical Physics of the International Organization for Medical Physics (IOMP) <14, 2005, Nuremberg, Germany>
Heart diseases often imply cardiac motion anomalies, so a number of heart diseases can be diagnosed by analysing cardiac volume and motion during one cardiac cycle. We propose a method for extracting complex left ventricle motion which consists of different components as a sinking motion caused by respiration, contraction and reverse rotation at cardiac basis and apex. The reverse rotation is determined by following landmarks over one cardiac cycle. An algorithm to detect automatically landmarks in CT and MRI data for complete heart motion analysis is the long term objective.
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Dold, Christian; Wesarg, Stefan; Firle, Evelyn; Seitel, Mathias
4D-Segmentierung des linken Ventrikels basierend auf Region Growing und einer speziellen Bildaufbereitung angewendet auf CT, MR und U/S
Dold, Christian; Wesarg, Stefan; Firle, Evelyn; Seitel, Mathias
4D-Segmentierung des linken Ventrikels basierend auf Region Growing und einer speziellen Bildaufbereitung angewendet auf CT, MR und U/S
Meinzer, Hans-Peter (Ed.) et al.: Bildverarbeitung für die Medizin 2005. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2005. (Informatik aktuell), pp. 133-137
Workshop Bildverarbeitung für die Medizin (BVM) <2005, Heidelberg, Germany>
Es wurde eine Softwareplattform entwickelt, die 4D-Datensätze von CT-, MR- und Ultraschalldaten segmentieren kann. Dabei ist sie sehr leicht zu bedienen und auf die unterschiedlichen Modalitäten anpassbar. Bei der Herzanalyse wird enorm viel Zeit gespart, da lediglich die Region-of-Interest, ein Seedpunkt und die Ober-/ Untergrenze des Grauwertes angegeben werden muß, um eine 4D-Segmentierung vorzunehmen. Die Daten müssen nicht, wie üblich, in der Kurzachsenaufnahme zur Verfügung stehen, da sie beliebig vom Radiologen mit der Software ausgerichtet werden können. Auch ist das Ergebnis nicht mehr von der zu bedienenden Person abhängig sondern reproduzierbar.
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Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Prospective Head Motion Compensation for MRI by Updating the Gradients and Radio Frequency During Data Acquisition
Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Prospective Head Motion Compensation for MRI by Updating the Gradients and Radio Frequency During Data Acquisition
Duncan, James S. (Ed.) et al.: Medical Image Computing and Computer-Assisted Intervention - MICCAI 2005 Proceedings. Part 1 : 8th International Conference. Berlin, Heidelberg, New York: Springer, 2005. (Lecture Notes in Computer Science (LNCS) 3749), pp.482-489
International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI) <8, 2005, Palm Springs, CA, USA>
Subject motion appears to be a limiting factor in numerous magnetic resonance imaging (MRI) applications. For head imaging the subject's ability to maintain the same head position for a considerable period of time places restrictions on the total acquisition time. For healthy individuals this time typically does not exceed 10 minutes and may be considerably reduced in case of pathology. In particular, head tremor, which often accompanies stroke, may render certain high-resolution 2D and 3D techniques inapplicable. Several navigator techniques have been proposed to circumvent the subject motion problem. The most suitable for head imaging appears to be the orbital or spherical navigator methods. Navigators, however, not only lengthen the measurement because of the time required for acquisition of the position information, but also require additional excitation radio frequency (RF) pulses to be incorporated into the sequence timing, which disturbs the steady state. Here we demonstrate the possibility of interfacing the MR scanner with an external optical motion tracking system, capable of determining the object's position with sub-millimeter accuracy and an update rate of 60Hz. The movement information on the object position (head) is used to compensate the motion in real time. This is done by updating the field of view (FOV) by recalculating the gradients and the RF-parameter of the MRI tomograph during the acquisition of k-space data based on the tracking data. Results of rotation phantom, in vivo experiments and the implementation in two different MRI sequences are presented.
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Drossel, Alexander; Hirschbach, Henning (Betreuer)
Ein 3D-Glättungsalgorithmus für die Zahnrekonstruktion
Drossel, Alexander; Hirschbach, Henning (Betreuer)
Ein 3D-Glättungsalgorithmus für die Zahnrekonstruktion
Darmstadt, FH, Bachelor Thesis, 2005
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Frangou, S.; Sachpazidis, Ilias; Stasinakis, A.; Sakas, Georgios
Telemonitoring of Medication Adherence in Patients with Schizophrenia
Frangou, S.; Sachpazidis, Ilias; Stasinakis, A.; Sakas, Georgios
Telemonitoring of Medication Adherence in Patients with Schizophrenia
Telemedicine Journal and E-Health, Vol.11 (2005), 6, pp. 675-683
Nonadherence to medication is a widespread problem in schizophrenia and is associated with poor clinical outcomes and inappropriate management and utilization of resources. The aim of the current investigation was to assess the impact of telemonitoring of medication adherence on symptomatology and service use in patients with schizophrenia. A total of 108 schizophrenia patients were randomized into three equal groups according to the approaches used to assess medication adherence; self-report, pill counting, and telemonitoring. Telementoring was achieved through an innovative new platform called @HOME. This platform offers clinicians early warnings about impeding nonadherence as well as information about the pattern of medication taking. Patient's adherence was observed over an 8-week period, during which patient's clinical status and service use were recorded. In comparison to the other two groups, patients using @HOME showed improvement in the Global Clinical Impression Scale and a significant reduction in emergency visits and medical appointments. The @HOME platform was highly acceptable by patients, caregivers, and professionals, and required minimal training for implementation. The results of the study suggest that the use of telemonitoring in psychiatric settings was both feasible and acceptable and may be associated with significant clinical and service related benefits.
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Grimm, Andreas G.; Dold, Christian (Betreuer)
Segmentierung des Myokards aus Datensätzen der Kernspintomographie
Grimm, Andreas G.; Dold, Christian (Betreuer)
Segmentierung des Myokards aus Datensätzen der Kernspintomographie
Darmstadt, FH, Master Thesis, 2005
Eine der häufigsten Todesursachen in wohlhabenden Ländern ist der Herzinfarkt. 8,2% der Sterbefälle 2002 in der BRD erfolgten durch einen solchen. Aus Aufnahmen der Kernspintomographie können Informationen gewonnen werden, die zur Prophylaxe eines Herzinfarkts eingesetzt werden können. Zu dieser Informationsgewinnung können (unter anderem) Segmentierungen des Herzmuskels (Myokard) eingesetzt werden. Die Herausforderung bei dieser Segmentierung stellt der teilweise nicht vorhandene Grauwertunterschied des Myokards mit der Umgebung im MRT-Bild dar. In dieser Arbeit wurden zwei Verfahren zur Segmentierung des Myokards aus Datensätzen der Kernspintomographie konzipiert und innerhalb der Plattform MIP realisiert. Ein Ansatz basiert auf einer Geodesic Active Contours (GAC)-Segmentierung, der andere auf einem neuen Verfahren: Der Measure and Estimate (MAE)-Segmentierung. Für den GAC-Ansatz wurde von einer bereits bestehenden GAC-Segmentierungskette ausgegangen, die zur Lebersegmentierung erfolgreich eingesetzt wurde, aber für die Myokardsegmentierung ungeeignet ist. Diese Kette wurde bezüglich des speziellen Segmentierungsziels optimiert. Besonderheiten der so erzielten Filterkette sind das automatische Setzen der Vielzahl von notwendigen Seedpoints für den verwendeten Fast Marching-Filter und die Verwendung von Region Growing-Segmentierungen des Myokards und des Ventrikels in der Vorverarbeitung. Der MAE-Ansatz basiert auf einem Teil der Vorverarbeitung der optimierten GAC-Segmentierungskette, variiert aber in der eigentlichen Segmentierung vollständig. Nach der Vorverarbeitung der Bilder erfolgt eine in dieser Arbeit konzipierte Analyse, in der bestimmt wird, welche Teile der Myokardkontur bestimmbar sind und welche abgeschätzt werden müssen. Die innere Kontur wird anhand einer Region Growing-Segmentierung des Ventrikels bestimmt. Die Detektion der äußeren Kontur geschieht basierend auf einer Region Growing-Segmentierung des Myokards. Hierbei wird erkannt welche Bereiche der äußeren Kontur bestimmt werden können und welche abgeschätzt werden müssen. Die Abschätzung erfolgt anschließend. Auf Basis dieses gesammelten Wissens resultiert die eigentliche Segmentierung.
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Hohlfeld, Oliver; Sachpazidis, Ilias (Betreuer)
Entwicklung eines Instant Messaging basierten Kommunikationsmoduls für telemedizinische Anwendungen
Hohlfeld, Oliver; Sachpazidis, Ilias (Betreuer)
Entwicklung eines Instant Messaging basierten Kommunikationsmoduls für telemedizinische Anwendungen
Darmstadt, FH, Bachelor Thesis, 2005
Durch Telemedizin kann in schwach besiedelten Regionen oder Krisengebieten vielmals die medizinische Versorgung der Bevölkerung verbessert werden. In unklaren Fällen kann der behandelnde Arzt Aufnahmen, beispielsweise Ultraschallbilder, anfertigen und per Computer innerhalb kürzester Zeit an einen Spezialisten schicken. Hierfür muss der Patient keine lange Reise antreten. Ein solches telemedizinisches Projekt des Fraunhofer IGD ist das TeleInViVo-System. Die Kommunikationsschicht beruht dabei auf direkten TCP-Verbindungen, die durch Firewallsysteme zunehmend Schwierigkeiten bekommt. Des Weiteren erweist sich die Adressierung der Ärzte über IP-Adressen in der Praxis als umständlich. Diese sind schwer zu merken und erlauben durch häufige IP Wechsel nur eine ungenügende Mobilität. Die vorliegende Bachelorarbeit untersucht einen Instant Messaging basierten Ansatz für die Kommunikationsschicht des TeleInViVo-Projektes. Wesentliche Ziele dieser Arbeit sind es Firewallbarrieren weitestgehend zu umgehen und die, für Ärzte, mühsame Adressierung über IP-Adressen zu lösen. Als Instant Messaging-Protokoll wird das freie Jabber/XMPP-Protokoll verwendet. Die Adressierung erfolgt nun über Jabber-Adressen, die im Wesentlichen keine Änderungen erfahren und für Ärzte einfacher zu handhaben sind. Die sensiblen Patientendaten werden auf der Übertragungsebene durch das SSL/TLS-Protokoll geschützt. Firewallbarrieren werden durch den Einsatz von zentralen Instant Messaging-Servern und Proxy-Technologien weitestgehend umgangen. Durch das HTTP-Polling Jabber-Zusatzprotokoll genügt eine einfache HTTP-Verbindung zum Datenaustausch. Ein Schwerpunkt dieser Arbeit liegt in der Auswahl, Bewertung und Spezifizierung von Protokollen für den Austausch von medizinischen Daten über Jabber/XMPP. Hierbei sind zum einen Daten, wie beispielsweise Ultraschallbilder oder Laborwerte und zum anderen Mausaktionen, wie Mausklicks oder Mausbewegungen zu übertragen. Für die Datenübertragung wird ein bestehendes Protokoll erweitert und für die Übertragung von Mausaktionen ein neues Protokoll spezifiziert. Einige der vorgestellten Konzepte werden anschließend implementiert, getestet und bewertet.
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Huber, Andrea; Cavet, René (Betreuer)
Automatische Erkennung von Bildschirmteilung in digitalen Videoströmen
Huber, Andrea; Cavet, René (Betreuer)
Automatische Erkennung von Bildschirmteilung in digitalen Videoströmen
Furtwangen, FH, Diplomarbeit, 2005
Tausende von Stunden von Video werden täglich auf der ganzen Welt im Fernsehen gezeigt. Gerade im Bereich der Marktforschung wäre es deshalb sehr interessant, die Möglichkeit zu haben, diese Inhalte genauer analysieren zu können. Aus diesem Grund wurde am Fraunhofer Institut für Graphische Datenverarbeitung in Darmstadt das MediaSeeker System entwickelt, das in Echtzeit eine automatische Analyse der Videoinhalte durchführt. Dabei wird die zu untersuchende Aufnahme mit vorhandenem Videomaterial verglichen, das in einer Datenbank gespeichert ist. Die Analyse von Videomaterial wird derzeit auf Basis des gesamten Bildinhaltes durchgeführt. In letzter Zeit wird jedoch bei allen deutschen Fernsehsendern die so genannte Splitscreen-Technik eingesetzt, um mehrere Handlungsabläufe gleichzeitig in einem Bild darzustellen. Die beliebte Split-Screen-Werbung zeigt im überwiegenden Teil des Bildschirmes die Werbefilme, während in einer Ecke weiterhin die Sendung, der Abspann oder die Programmvorschau gezeigt wird. Wird ein Video analysiert, das Bildschirmteilungen beinhaltet, so werden daher keine Übereinstimmungen gefunden, da sich der Gesamtbildinhalt aus mehreren Bereichen unterschiedlichen Inhaltes zusammensetzt. Stattdessen wäre es sinnvoll, die gleichzeitig dargestellten Handlungsabläufe getrennt analysieren zu können. Für diese getrennt Analyse muss jedoch die Größe und Position der einzelnen Bildschirmbereiche bekannt sein. Aus diesem Grund ist es notwendig ein System zu entwickeln, das im Video vorhandene Bildschirmteilungen automatisch detektiert und deren Position, Größe und Dauer zurückgibt.
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Jähne, Marion; Wesarg, Stefan (Betreuer)
Automatische Extraktion des Herzens aus kontrastverstärkten Schichtaufnahmen des Thorax
Jähne, Marion; Wesarg, Stefan (Betreuer)
Automatische Extraktion des Herzens aus kontrastverstärkten Schichtaufnahmen des Thorax
Darmstadt, TU, Diplomarbeit, 2005
In der Herzchirurgie bietet der Einsatz computerunterstützer Verfahren erheblich verbesserte Möglichkeiten zur Planung und Durchführung einer Operation. Die Segmentierung des Herzens bildet dabei einen Vorverarbeitungsschritt für die nachfolgende Visualisierung oder problemorientierte Segmentierung. Durch die Segmentierung des Herzens aus den Thorax-Aufnahmen werden Strukturen, die die Sicht auf das Herz stören, unterdrückt, so dass man eine uneingeschränkte Sicht auf die Herzstrukturen erhält. In dem hier entworfenen Verfahren erfolgt die Segmentierung des Herzens durch Kombination aus einem Schwellwertverfahren (Otsu-Verfahren), mit dem der Datensatz vorsegmentiert wird, und einem 2D-Suchstrahl-Verfahren zur Erkennung der Herzoberfläche in den axialen Schichten. Die Suchstrahlen finden die klaren hell-dunkel Übergänge vom Herzen zum umliegenden Gewebe. An den Stellen, an denen das Herz an das Brustbein oder die Aorta grenzt, werden die zu langen Suchstrahlen interpoliert. Das Verfahren wurde auf 25 CT- und 2 MR-Datensätzen ausgewertet. Die durchschnittliche Bearbeitungszeit beträgt auf einem dualen AMD Athlon mit 2 GHz je nach Größe des Datensatzes zwischen 5 und 9 Sekunden.
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Keil, Matthias; Firle, Evelyn (Betreuer); Wesarg, Stefan (Betreuer)
Entwurf eines multimodalen Volumenvisualisierungssystems
Keil, Matthias; Firle, Evelyn (Betreuer); Wesarg, Stefan (Betreuer)
Entwurf eines multimodalen Volumenvisualisierungssystems
Magdeburg, Univ., Diplomarbeit, 2005
Durch medizinische Bildgebung ist es den Ärzten und Forschern möglich geworden, Einblick ins Innere des menschlichen Körpers zu bekommen. Eine gemeinsame Darstellung von registrierten Volumendatensätzen des gleichen Objektes, welche zudem mit verschiedenen Modalitäten aufgenommen wurden (multimodale Visualisierung), ermöglicht die Nutzung der Vorteile der einzelnen bildgebenden Verfahren und ebenso eine Kompensation der Nachteile. Weiterhin können komplementäre Informationen, die sich aus den speziellen Abbildungseigenschaften der Verfahren ergeben, gemeinsam präsentiert werden. Eine dreidimensionale Visualisierung bietet zudem einen natürlichen Blick auf das Objekt. Für diesen Zweck wurde ein multimodales Volumenvisualisierungssystem für die dreidimensionale Darstellung registrierter medizinischer Datensätze entworfen und implementiert. Für die Darstellung der Bilddaten wurde eine direkte Volumenvisualisierung mittels mehrdimensionalen Transferfunktionen (TFs) für Farbe und Transparenz gewählt. Die Grundlage für mehrdimensionale TFs bilden Histogramme über die Intensität und den Gradientenbetrag der Bilddaten. Durch die Verwendung von Spatialized Transfer Functions und die damit verbundene halbautomatische Klassifikation des 2D-Histogramms in Bereiche, welche Strukturen im Volumendatensatz repräsentieren, gelang es den Spezifikationsaufwand für den Nutzer auf die Auswahl dieser Bereiche zu reduzieren. Das Konzept des Visualisierungssystems umfasst zwei Ansätze. Im sogenannten multiintensitätsbasierten Ansatz definiert der Nutzer eine gemeinsame TF für die beiden darzustellenden Volumen. Diese TF ist über die Intensitätswerte der beiden Datensätze definiert. Im gradientenbasierte Ansatz wird für jedes Volumen eine eigene TF spezifiziert und somit zwei separate Volumenvisualisierungen erzeugt, welche anschließend zu einer gemeinsamen multimodalen Visualisierung fusioniert werden können. Der gradientenbasierte Ansatz erlaubt eine interaktive Änderung der Transformation, welche die Registrierung der Datensätze beschreibt. Mit dem implementierten Volumenvisualisierungssystem wurden erfolgreich multimodale Visualisierungen erzeugt mit denen die Kommunikation von Diagnoseergebnissen erleichtert wird. Weiterhin konnten die Registrierungsergebnisse anhand der Visualisierungen überprüft werden.
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Khan, M. Fawad; Dogan, Selami; Maataoui, Adel; Gurung, Jessen; Schiemann, Mirko; Ackermann, Hanns; Wesarg, Stefan; Sakas, Georgios; Vogl, Thomas J.
Accuracy of Biopsy Needle Navigation Using the Medarpa System-computed Tomography Reality Superimposed on the Site of Intervention
Khan, M. Fawad; Dogan, Selami; Maataoui, Adel; Gurung, Jessen; Schiemann, Mirko; Ackermann, Hanns; Wesarg, Stefan; Sakas, Georgios; Vogl, Thomas J.
Accuracy of Biopsy Needle Navigation Using the Medarpa System-computed Tomography Reality Superimposed on the Site of Intervention
European Radiology, Vol.15 (2005), 11, pp. 2366-2374
The aim of this work was to determine the accuracy of a new navigational system, Medarpa, with a transparent display superimposing computed tomography (CT) reality on the site of intervention. Medarpa uses an optical and an electromagnetic tracking system which allows tracking of instruments, the radiologist and the transparent display. The display superimposes a CT view of a phantom chest on a phantom chest model, in real time. In group A, needle positioning was performed using the Medarpa system. Three targets (diameter 1.5 mm) located inside the phantom were punctured. In group B, the same targets were used to perform standard CT-guided puncturing using the single-slice technique. The same needles were used in both groups (15 G, 15 cm). A total of 42 punctures were performed in each group. Post puncture, CT scans were made to verify needle tip positions. The mean deviation from the needle tip to the targets was 6.65±1.61 mm for group A (range 3.54-9.51 mm) and 7.05± 1.33 mm for group B (range 4.10-9.45 mm). No significant difference was found between group A and group B for any target (p>0.05). No significant difference was found between the targets of the same group (p>0.05). The accuracy in needle puncturing using the augmented reality system, Medarpa, matches the accuracy achieved by CT-guided puncturing technique.
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Kiefer, Stephan; Sachpazidis, Ilias
Telemedicine in Developing Countries, Optimizing Health Care Resources by Telehealth Platforms, an Example from Latin-America
Kiefer, Stephan; Sachpazidis, Ilias
Telemedicine in Developing Countries, Optimizing Health Care Resources by Telehealth Platforms, an Example from Latin-America
National Academy of Sciences of Belarus (NAS of Belarus): Proceedings of the International Conference on Advanced Information and Telemedicine Technology for Health. Vol.1, pp. 241-246
International Conference on Advanced Information and Telemedicine Technology for Health (AITTH) <2005, Minsk, Belarus>
An e-health model to the provision of health services is introduced in underserved rural regions in Colombia and Brazil in the European Latin-American telemedicine demonstration project T@lemed. The implementation of this model is supported on current telehealth technologies of Fraunhofer and its partners as well as on evidence based medicine. The target clinical applications include typical infectious diseases for the region such as malaria, and general ultrasound applications such as pregnancy control, urology and cardiovascular diagnosis. The implemented telehealth networks connect high-level health care resources available in large cities with low-level health care facilities in underserved regions. The trial of this model, reflected in the deployment and pilot tests of the telehealth platforms TOPCARE and TeleConsult, demonstrates local health authorities the benefits of information technologies for health provision and social development. As a result, it is expected that this model will be incorporated into health services of both government health authorities and private health providers.
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Kontaxakis, George; Guerra, P.; Ohl, Roland; Sachpazidis, Ilias; Strauss, L.G.; Ortega, F.; Visvikis, D.; Diaz, J.; Cheze-Le Rest, C.; Dimitrakopoulou-Strauss, A.; Pan, L.; Santos, A.; Sakas, Georgios; Pozo, M.A.
Redes Telemáticas Transeuropeas para la Tomografía por Emisión de Positrones: el Proyecto TENPET
Kontaxakis, George; Guerra, P.; Ohl, Roland; Sachpazidis, Ilias; Strauss, L.G.; Ortega, F.; Visvikis, D.; Diaz, J.; Cheze-Le Rest, C.; Dimitrakopoulou-Strauss, A.; Pan, L.; Santos, A.; Sakas, Georgios; Pozo, M.A.
Redes Telemáticas Transeuropeas para la Tomografía por Emisión de Positrones: el Proyecto TENPET
Kontaxakis, George (Ed.) et al.: Proceedings of the CASEIB 2005, pp. 215-218
Annual Congress of the Spanish Society of Biomedical Engineering (CASEIB) <23, 2005, Madrid, Spain>
El proyecto TENPET (Trans European Networks for Positron Emission Tomography) tiene como objetivo evaluar el impacto en la practica clínica de servicios integrados de teleconsulta y trabajo cooperativo para la tomografía por emisión de positrones. Este proyecto aborda distintos desafíos tecnológicos, enlazando distintos centros PET a los que se les proporciona servicios que permiten la consulta remota entre expertos de la materia. La plataforma tecnológica está basada en Windows (Win2000/NT/XP) e incorpora técnicas avanzadas para la visualización, análisis y fusión de imágenes, así como para la comunicación interactiva y la gestión de mensajería. TENPET promueve la cooperación y mejora la comunicación entre médicos nucleares separados entre sí, bien con el objeto de pedir una segunda opinión o bien con el de formar especialistas a distancia. Además, un especialista que se encuentre fuera de su centro de trabajo puede acceder a los datos de sus pacientes.
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Meub, Jürgen; Klein, Konrad (Betreuer)
Bewertung und Optimierung von Aufnahmekonfigurationen bei der 3D-Digitalisierung mit Lichtschnittsensoren
Meub, Jürgen; Klein, Konrad (Betreuer)
Bewertung und Optimierung von Aufnahmekonfigurationen bei der 3D-Digitalisierung mit Lichtschnittsensoren
Darmstadt, FH, Diplomarbeit, 2005
Die vorliegende Arbeit befasst sich mit dem Problem der Aufnahmeplanung im Bereich der 3D-Rekonstruktion von Alltagsgegenständen. Je nach Komplexität der Objekte nimmt der Zeitaufwand, der für eine vollständige manuelle Vermessung benötigt wird stark zu. Zusätzlich wird vom Anwender ein hohes Maß an Erfahrung im Umgang mit dem System gefordert. Das Ziel der Arbeit war daher die Entwicklung eines Verfahrens zur vollständigen Automatisierung der Aufnahmeplanung. Die zur Planung und Rekonstruktion benötigten Daten werden dabei von einem auf Lichtschnittsensorik basierenden Scanner-System geliefert. Die Positionierung dieses Scanners wird wiederum von einem Gelenkarmroboter durchgeführt, was eine große Bewegungsfreiheit ermöglicht. Das Verfahren basiert auf den vom Scanner-System zurückgelieferten Tiefenbildern. Diese Tiefenbilder müssen auf eine geeignete Weise qualitativ analysiert werden um mögliche neue Aufnahmepositionen zu ermitteln. Dabei mussten zwei zentrale Problemstellungen gelöst werden: Die Wahl einer geeigneten Repräsentation der unvermessenen Objektbereiche sowie die Entwicklung eines Verfahrens zur Bewertung von Ansichten. Der entwickelte Algorithmus zielt dabei zunächst auf das Schließen von Lücken im Objekt und versucht danach eine vom Anwender vorgegebene Abtastdichte der Oberflächen zu erreichen. Weiterhin wird gezeigt wie sich die Berechnungen durch trickreiche Verwendung des diffusen OpenGL Beleuchtungsmodells vereinfachen und beschleunigen lassen. Die Ergebnisse zeigen, dass das Verfahren in der Lage ist auch komplexere Objekte effektiv zu vermessen.
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Müller, Matthias Peter; Sakas, Georgios (Betreuer)
Detektion von Merkmalen in sequentiellen medizinischen Bildern
Müller, Matthias Peter; Sakas, Georgios (Betreuer)
Detektion von Merkmalen in sequentiellen medizinischen Bildern
Darmstadt, TU, Diplomarbeit, 2005
Diese Diplomarbeit beschreibt ein Verfahren zur Fusion von realen und virtuellen Bronchoskopiebildern. Das Verfahren geht von einer bekannten Startposition aus, von der aus es die Bewegung der realen Bronchoskopiekamera in Echtzeit verfolgt. Die Bewegungsverfolgung wird durch Merkmale realisiert, die in den Kamerabildern erkannt und verfolgt werden. Die virtuelle Bronchoskopie wird hierbei ausgenutzt, indem aus CT-Daten die räumliche Tiefe zu den Merkmalen bestimmt wird. Mit Hilfe der räumlichen Merkmalskoordinaten wird die Position der Kamera nach ihrer Bewegung berechnet. Von dieser Position aus kann ein virtuelles Bild der Bronchien erzeugt werden und mit dem Kamerabild überlagert werden. Die Arbeit wurde mit einem Video aus einem Bronchienmodell und dessen CT-Daten getestet. Es wurden gute Ergebnisse bei gleichmäßigen Bewegungen des Bronchoskops erzielt und es konnte zu 15 Bildern pro Sekunde die Kameraposition berechnet werden, welches der Echtzeitanforderung genügt.
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Sachpazidis, Ilias; Hohlfeld, Oliver
Instant Messaging Communication Gateway for Medical Applications
Sachpazidis, Ilias; Hohlfeld, Oliver
Instant Messaging Communication Gateway for Medical Applications
Jennett, P. (Ed.) et al.: Proceedings of the IASTED International Conference on Telehealth. Anaheim, Calgary, Zurich: IASTED/ACTA Press, 2005, pp. 12-16
IASTED International Conference on Telehealth <1, 2005, Banff, Canada>
Internet has changed the way of how people communicate and exchange information. Enduringly, more and more doctors are getting familiar with internet and the offered capabilities. Hospitals are interconnected, making use of internet, forming medical information networks. The doctors exchange information with the help of internet. A very common way of communication is the electronic email even when a doctor looks for a second opinion from another expert doctor. In the market, various medical applications for tele-consultation can be found. Some of them are web based and others are stand alone applications. In this paper we will propose a comminication gateway, based on Jabber instant massaging protocol, for modern and demanding medical applications, focusing on teleconsultations applications. The proposed gateway is able to handle connections restricted by firewalls and makes use of potential available proxies inside of a network. In addition, we will address the problems related to firewalls and proxies and will proposed a new way of communication for medical applications based on Jabber an instant massaging protocol. Furthermore, in order to handle binary data transmission to an offline entity over a Jabber network, we proposed an extension to In-Band Byte streams communication protocol.
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Sachpazidis, Ilias; Hohlfeld, Oliver; Ohl, Roland
Implementation of a Jabber-Based Medical Tele-Consulting Application
Sachpazidis, Ilias; Hohlfeld, Oliver; Ohl, Roland
Implementation of a Jabber-Based Medical Tele-Consulting Application
Furnell, Steven M. (Ed.) et al.: INC 2005. Proceedings of the 5th International Network Conference. University of the Aegean, 2005, pp. 527-534
International Network Conference (INC) <5, 2005, Samos, Greece>
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Sachpazidis, Ilias; Majadas, Maria
Medication Adherence Monitoring System Elaborating HL7 Messages
Sachpazidis, Ilias; Majadas, Maria
Medication Adherence Monitoring System Elaborating HL7 Messages
Kioulafas, Kyriakos Em. (Ed.) et al.: Proceedings of the 3rd International Conference on Information Communication Technologies in Health : Telemedicine and eHealth in Recent Years: Meeting the Challenges. Athens: National and Kapodistrian University of Athens, 2005, pp. 216-225
International Conference on Information Communication Technologies in Health (ICICTH) <3, 2005, Samos, Greece>
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Sachpazidis, Ilias; Ohl, Roland; Polanczyk, C.A.; Torres, M.S.; Messina, Luiz Ary; Sales, A.; Sakas, Georgios
Applying Telemedicine to Remote and Rural Underserved Regions in Brazil Using eMedical Consulting Tool
Sachpazidis, Ilias; Ohl, Roland; Polanczyk, C.A.; Torres, M.S.; Messina, Luiz Ary; Sales, A.; Sakas, Georgios
Applying Telemedicine to Remote and Rural Underserved Regions in Brazil Using eMedical Consulting Tool
IEEE Engineering in Medicine and Biology Society (EMBS): 27th Annual Conference of the 2005 IEEE Engineering in Medicine and Biology. Proceedings CD-ROM : Innovation from Biomolecules to Biosystems. New York: IEEE Press, 2005, 5 p.
Annual International Conference on the IEEE Engineering in Medicine and Biology Society (EMBC) <27, 2005, Shanghai, China>
In this paper, we are going to depict a medical tele-consultation network for medical imaging that has been deployed in Brazil. Preliminary outcomes of the medical network will be presented. In addition, the medical application used for tele-consultations will be shown. Eighty nine ultrasound acquisitions took place in the period of five months of the operation of the medical network and five hundred fifty six medical consultations performed.
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Sakas, Georgios; Bockholt, Ulrich
Anwendungen der Virtuellen und Erweiterten Realität in der Medizin
Sakas, Georgios; Bockholt, Ulrich
Anwendungen der Virtuellen und Erweiterten Realität in der Medizin
Schulze, Thomas (Ed.) et al.: Simulation und Visualisierung 2005. Proceedings. Erlangen: SCS-European Publishing House, 2005, pp. 383-392
Simulation und Visualisierung (SimVis) <16, 2005, Magdeburg>
Rechnergestützte Verfahren beginnen den medizinischen Alltag und die chirurgische Praxis zu revolutionieren. Insbesondere Techniken aus den Bereichen "Virtuelle Realität und Erweiterte Realität" bergen große Potentiale für medizinische Ausbildung, Diagnose, Operationsvorbereitung und intraoperative Unterstützung. Dabei versteht man unter "Virtueller Realität" eine 3D-Datenwelt, in die der Benutzer eintauchen und mit Hilfe neuer Interaktionsmechanismen intuitiv und effizient interagieren kann. Mit dem Begriff "Erweiterte Realität" wird die Technologie bezeichnet, in der die reale Umgebung mit computergenerierten Darstellungen bereichert und überlagert wird. Am Fraunhofer Institut für Graphische Datenverarbeitung werden medizinische Trainingssimulatoren entwickelt, mit denen angehende Chirurgen die Handhabung von Endoskop und chirurgischen Instrumenten üben. Darauf aufbauend wurden Projekte im Bereich der patientenspezifischen Therapieplanung durchgeführt: Dreidimensionale Modelle der anatomischen Strukturen können aus dem Tomographiedatensatz der Patienten rekonstruiert werden, mit Hilfe eines Planungssystems wird der bevorstehende Eingriff exakt spezifiziert. So wird sichergestellt, dass der optimale Ansatz für eine bevorstehende Operation vorbereitet wird. Die Ergebnisse der Operationsplanung werden mit Hilfe von Verfahren aus dem Bereich "Augmented Reality" intraoperativ visualisiert, um eine Navigationsunterstützung zu geben, die eine exaktes Umsetzen des Therapieplans garantiert.
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Sakas, Georgios; Bockholt, Ulrich
Chirurgisches Training mit Technologien der Virtuellen Realität
Sakas, Georgios; Bockholt, Ulrich
Chirurgisches Training mit Technologien der Virtuellen Realität
Endoskopie heute, Vol.18 (2005), 3, pp. 105-107
Rechnergestützte Verfahren beginnen den medizinischen Alltag und die chirurgische Praxis zu revolutionieren. Insbesondere Techniken aus den Bereichen "Virtuelle Realität" und "Erweiterte Realität" bergen große Potentiale für medizinische Ausbildung, Diagnose, Operationsvorbereitung und intraoperative Unterstützung. Dabei versteht man unter "Virtueller Realität" eine 3D-Datenwelt, in die der Benutzer eintauchen und mit Hilfe neuer Interaktionsmechanismen intuitiv und effizient interagieren kann. Mit dem Begriff "Erweiterte Realität" wird die Technologie bezeichnet, in der die reale Umgebung mit computergenerierten Darstellungen bereichert und überlagert wird. Am Fraunhofer Institut für Graphische Datenverarbeitung werden medizinische Trainingssimulatoren entwickelt, mit denen angehende Chirurgen die Handhabung von Endoskop und chirurgischen Instrumenten üben. Darauf aufbauend wurden Projekte im Bereich der patientenspezifischen Therapieplanung durchgeführt: Dreidimensionale Modelle der anatomischen Strukturen können aus dem Tomographiedatensatz der Patienten rekonstruiert werden, mit Hilfe eines Planungssystems wird der bevorstehende Eingriff exakt spezifiziert. So wird sichergestellt, dass der optimale Ansatz für eine bevorstehende Operation vorbereitet wird. Die Ergebnisse der Operationsplanung werden mit Hilfe von Verfahren aus dem Bereich "Augmented Reality" intraoperativ visualisiert, um eine Navigationsunterstützung zu geben, die eine exaktes Umsetzen des Therapieplans garantiert.
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Schosser, Andreas; Wesarg, Stefan (Betreuer)
Visualisierung medizinischer Bilddaten unter Verwendung von Transferfunktionen für Farbe und Transparenz
Schosser, Andreas; Wesarg, Stefan (Betreuer)
Visualisierung medizinischer Bilddaten unter Verwendung von Transferfunktionen für Farbe und Transparenz
Gießen-Friedberg, FH, Diplomarbeit, 2005
Die Darstellung der mit Hilfe bildgebender Verfahren wie der Magnetresonanztomographie oder der Computertomographie gewonnenen medizinischen Daten erfolgt üblicherweise durch Grauwertbilder. Da beim Sehen nicht nur Helligkeitsempfindungen, sondern auch Farbton und Farbsättigung unterschieden werden, ist das farbliche Auflösungsvermögen des menschlichen Auges deutlich höher als die Auflösung unterscheidbarer Grauwert- bzw. Helligkeitseindrücke. Derzeitige Bestrebungen in der medizinischen Bildverarbeitung versuchen daher, sinnvolle Zuordnungen von Farbwerten zu den medizinischen Bilddaten zu finden. Im Rahmen dieser Arbeit konnten für verschiedene akquirierte Bilddaten medizinisch sinnvolle farbliche Darstellungen definiert werden. Dazu wurde in Anlehnung an die kommerzielle Anwendung VolView Volume Visualization eine interaktive Benutzerschnittstelle entwickelt, die eine flexible und intuitive Definition von Transferfunktionen erlaubt. Mit Hilfe der realisierten Visualisierungssteuerungskomponenten wird ein allgemeines Vorgehen für eine experimentelle Bestimmung medizinisch sinnvoller Farb- und Opazitätszuordnungen ermittelt und beschrieben. Ausgehend von den verwendeten bildgebenden Verfahren werden für verschiedene Körperbereiche individuelle Farbzuordnungen bestimmt und an konkrete medizinische Problemstellungen angepasst. Wie an verschiedenen Beispielen gezeigt wird, ist dadurch eine verbesserte Darstellung bestimmter Erkrankungen, Verletzungen und anderer Anomalien möglich.
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Schröer, Torsten; Sakas, Georgios (Betreuer); Wesarg, Stefan (Betreuer)
Segmentierung von Strukturen mit unscharfen Rändern in medizinischen Bilddaten: Implementierung, Validierung und Erweiterung des Region Growing Verfahrens nach Hojjatoleslami und Kittler
Schröer, Torsten; Sakas, Georgios (Betreuer); Wesarg, Stefan (Betreuer)
Segmentierung von Strukturen mit unscharfen Rändern in medizinischen Bilddaten: Implementierung, Validierung und Erweiterung des Region Growing Verfahrens nach Hojjatoleslami und Kittler
Heilbronn, FH, Diplomarbeit, 2005
Gegenstand der Arbeit bildet ein 2D Region Growing Verfahren, welches sich durch die Behandlung von Objekten mit unscharfen Rändern auszeichnet, allerdings mit zunehmender Größe des zu segmentierenden Gebiets für den täglichen Einsatz zu langsam wird. Zunächst wurde daher ein 2D Prototyp auf Basis des Insight Segmentation and Registration Toolkit (ITK) erstellt, um das Verfahren, wie es in der Literatur beschrieben wird, zu validieren. Mit dem Prototypen konnten viel versprechende Ergebnisse, allerdings in unakzeptabler Zeit, produziert werden. Im folgenden wurde daher versucht, das Verfahren zu beschleunigen und auf einen 3D Algorithmus zu erweitern. Hierbei wurden unterschiedliche Datenstrukturen und Algorithmen eingesetzt und die Auswirkung auf die Geschwindigkeit des Algorithmus untersucht. Des weiteren werden zwei Multi Resolution Ansätze vorgestellt, die das Verfahren so weit beschleunigen, dass ein praktischer Einsatz auch für große Datensätze möglich wird. Da eine Beschränkung auf eine Modalität oder einen konkreten Anwendungsfall nicht gegeben war, wurde das Verfahren an unterschiedlichen Modalitäten getestet. Unter anderem wurden Computertomograhie-, Magnetzresonanz- und Ultraschalldaten verschiedener Körperregion ausgewählt, das Region Growing durchgeführt und die Ergebnisse qualitativ beurteilt bzw. mit Standard Region Growing Verfahren verglichen. Zusätzlich wurde ein Modell zur quantitativen Analyse des Algorithmus entwickelt. Das Modell wurde in Tests auf allen implementierten Varianten des Region Growings angewandt. Die Ergebnisse wurden verglichen und beurteilt. Es konnte gezeigt werden, dass alle 3D-Erweiterungen des Algorithmus auf unterschiedlichen medizinischen Bilddaten einsatzfähig sind. Dabei sind besonders die einfache Bedienung im Vergleich zu Standard Region Growing Verfahren (hoher Grad an Automatisierung) und die gute Behandlung von Kanten mit Gauß-verteilten Grauwertverfäufen hervorzuheben.
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Steinbrecher, Tillmann; Cavet, René (Betreuer)
Efficient Similarity Search in Large Video Databases
Steinbrecher, Tillmann; Cavet, René (Betreuer)
Efficient Similarity Search in Large Video Databases
Darmstadt, TU, Diplomarbeit, 2005
Today, the main source of income for most TV stations are paid advertisements. In Germany alone, billions of Euros are spent each year on TV ads. Substantial commercial interest lies in the question how exactly this money is being spent - i.e., which ad clips played on which channel, at which time. TV stations do not disclose this data to the public; therefore it has to be gathered by content-based retrieval, from recorded TV broadcasts. In order to cope with the large amounts of data involved (a single TV station generates about 30GB of MPEG2 data per day), highly efficient methods for video similarity search must be available. In the context of this diploma thesis, a fast video detection system that relies on feature-based frame similarity calculations was developed. The system is robust to temporal/spatial modifications in the source video, as well as missing frames - to the extent that decoding only the I-frames of the analyzed stream will suffice for good detection results. Different image features were compared and evaluated. For speed and scalability improvement, an index-based search that relies on clusters in feature space was implemented. The video detector does not aim for perfect accuracy in the sense that the results are free of false positives. Instead, its purpose is to find candidates for detection as quickly as possible, in order to reduce the search domain for downstream processing stages, which use slower, but more accurate methods.
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Terörde, Steffen; Hahn, Volker (Betreuer)
Detektion von Werbeflächen in Einzelbildern aus Sport-Videosequenzen
Terörde, Steffen; Hahn, Volker (Betreuer)
Detektion von Werbeflächen in Einzelbildern aus Sport-Videosequenzen
Darmstadt, FH, Bachelor Thesis, 2005
Firmen, die Geld in das Sponsoring von Sportveranstaltungen investieren, sind daran interessiert, inwieweit sich ihre Investition in das Sportmarketing für sie positiv auszahlt. Um den für sie entscheidenden "Return on Invest" zu quantifizieren lassen sich dabei verschiedene, objektiv messbare Faktoren ermitteln, die für die Häufigkeit des Auftretens und das Image einer bestimmten Marke von Bedeutung sind. So ist beim Sponsoring eines Fussballspiels z.B. das Auftreten der von einer bestimmten Firma finanzierten Werbebanden in der Fernsehübertragung interessant. Dabei kann es eine Rolle spielen, wie oft, wie lange, in welcher Größe und in welchem inhaltlichen Kontext diese Werbebanden zu sehen sind. Die Erfassung dieser Daten wird heute von Marktforschungsdienstleistern für die werbetreibenden Kunden manuell durchgeführt. Diese Vorgehensweise birgt allerdings eine hohe Arbeitsintensität, so dass sich durch eine automatische bzw. semiautomatische Erfassung der Werbebanden ein hohes Einsparpotential bietet. Mit dieser Thematik beschäftigt sich auch das internationale, von der Europäischen Union geförderte Forschungsprojekt "Direct Info - Media Monitoring and Multimodal Analysis for Time Critical Decisions", an dem die Abteilung A7 des IGD beteiligt ist. Eine Erkennung der Werbebanden kann heute mit Hilfe von Computern durch Matchingverfahren durchgeführt werden, was aber aufgrund der Komplexität der Verfahren einen hohen Rechenaufwand beinhaltet. Eine einfache Methode die Laufzeit der Matchingverfahren zu verringern ist die Vorverarbeitung des zu prüfenden Bildmaterials, um durch die Detektion von potentiellen Zielregionen die zu prüfende Bilddatenmenge zu verringern. Die in dieser Bachelorarbeit vorgestellten Verfahren haben zum Ziel, Werbebanden in Fussballübertragungen zu detektieren um damit die für das nachfolgende Matchingverfahren zu untersuchenden Bilddaten zu reduzieren. Hierzu werden verschiedene Verfahren vorgestellt und die bei der Implementierung der Verfahren auftretenden Schwierigkeiten diskutiert.
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Tingelhoff, Kathrin; Dold, Christian (Betreuer); Wesarg, Stefan (Betreuer)
Tracking von Herzbewegungen aus Tomographiebildern
Tingelhoff, Kathrin; Dold, Christian (Betreuer); Wesarg, Stefan (Betreuer)
Tracking von Herzbewegungen aus Tomographiebildern
Koblenz/Landau, Univ., Diplomarbeit, 2005
Herzerkrankungen äußern sich in vielen Fällen durch eine Veränderung der Herzbewegung. Sofern sich die Bewegung bestimmen lässt, kann man diese für die Diagnose von Herzerkrankungen verwenden. In dieser Diplomarbeit wurde die Herzbewegung aus CT- und MR-Bilddaten bestimmt, damit unterscheidet sich das eigene von den meisten bisher publizierten Verfahren, in denen datensatzspezifische Algorithmen entwickelt wurden. Auf der Grundlage einer ausführlichen Literaturrecherche wurden drei Konzepte entwickelt von denen eins im Rahmen dieser Arbeit implementiert und getestet wurde. Die berechneten Bewegungsparameter sind: Längsachsenkontraktion, globale Sack- und Kippbewegung des Herzens und eine Drehbewegung, die im apikalen und im basalen Bereich des Herzens entgegengesetzt ist. Die Bewegungsparameter wurden durch einen semiautomatischen Algorithmus bestimmt. Zur Berechnung der Längsachsenkontraktion und der Sack- und Kippbewegung wurde eine linke Ventrikel-Achse approximiert, deren Bewegung während eines Herzzyklus bestimmt und verfolgt wurde. Zur Bestimmung der Drehbewegung werden Landmarken händisch markiert, aus denen eine 3D Bewegung abgeleitet werden kann. Das entwickelte Verfahren wurde in die Medical Imaging Platform, ein in der Abteilung für Cognitive Computing and Medical Imaging entwickeltes Software-Toolkit integriert. Für die Implementierung wurden die open source Bibliotheken VTK, ITK, wxWidgets und boost verwendet. Das entwickelte Verfahren wurde mit CT- und MR-Bilddaten getestet und ausgewertet und es konnte gezeigt werden, dass durch das Verfahren medizinisch relevante Ergebnisse erzielt werden.
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Wesarg, Stefan
AHA Conform Analysis of Myocardial Function Using and Extending the Toolkits ITK and VTK
Wesarg, Stefan
AHA Conform Analysis of Myocardial Function Using and Extending the Toolkits ITK and VTK
Lemke, Heinz U. (Ed.) et al.: Computer Assisted Radiology and Surgery. Proceedings : CARS 2005. Amsterdam: Elsevier, 2005. (International Congress Series 1281), pp. 44-49
Computer Assisted Radiology and Surgery (CARS) <19, 2005, Berlin, Germany>
Modern dynamic image acquisition techniques allow for a non-invasive imaging of the beating heart. Thus, ischemic areas of the heart's wall can be detected by anlyzing the left ventricular myocardial function. For a standardization of that task the American Heart Association (AHA) has published recommendations for the myocardial segmentation and nomenclature. We propose in this paper a comprehensive, fully automatic, and AHA conform analysis of the myocardial function that is based on the segmentation results of the left ventricular cavity for the whole cardiac cycle. The physical values wall motion, ejection fraction, and wall thickening are computed and visualized employing and extending the toolkits ITK and VTK. First test results using dynamic MRI data are presented.
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Wesarg, Stefan
Supporting the TECAB Grafting Through CT Based Analysis of Coronary Arteries
Wesarg, Stefan
Supporting the TECAB Grafting Through CT Based Analysis of Coronary Arteries
Frangi, Alejandro F. (Ed.) et al.: Functional Imaging and Modeling of the Heart. Proceedings. Berlin, Heidelberg, New York: Springer, 2005. (Lecture Notes in Computer Science (LNCS) 3504), pp. 133-142
International Workshop, Functional Imaging and Modeling of the Heart (FIMH) <3, 2005, Barcelona, Spain>
Calcified coronary arteries can cause severe cardiac problems and may provoke an infarction of the heart's wall. An established treatment method is the bypass operation. The usage of a telemanipulation system allows for the execution of that operation as a totally endoscopic coronary artery bypass (TECAB) grafting. This relatively new method narrows the surgeon's view and does not permit the palpation of the vessel in order to detect calcifications (hard plaques). A planning based on contrast enhanced, cardiac CT data sets can compensate for that problem. This work presents analysis methods for coronary arteries. Hard plaques are detected using a tracking-based vessel segmentation technique. In addition, the vessel's neighborhood is analyzed in order to decide whether it is surrounded by tissue or fat, or if it is freely accessible for the surgeon's instruments. Furthermore, well adapted methods for the visualization of these analysis results are presented.
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Wesarg, Stefan; Dold, Christian; Tadge, Tonio; Seitel, Mathias
Analyse des linken Ventrikels nach AHA-Richtlinien unter Verwendung von VTK
Wesarg, Stefan; Dold, Christian; Tadge, Tonio; Seitel, Mathias
Analyse des linken Ventrikels nach AHA-Richtlinien unter Verwendung von VTK
Meinzer, Hans-Peter (Ed.) et al.: Bildverarbeitung für die Medizin 2005. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2005. (Informatik aktuell), pp. 16-20
Workshop Bildverarbeitung für die Medizin (BVM) <2005, Heidelberg, Germany>
Die Analyse des linken Ventrikels basierend auf dynamischen 4D-Bilddaten (3D-Volumen + Zeit) stellt für die Kardiologie eine wichtige Methode zur Diagnose von Herzproblemen dar. Durch eine Untersuchung der Wandbewegung und der damit verbundenen Volumenänderung lassen sich ischämische Bereiche des Herzens erkennen. Zur einheitlichen Darstellung der Ergebnisse hat die American Heart Association (AHA) die Verwendung eines Bull's-Eye-Displays empfohlen. Diese Arbeit präsentiert eine vollautomatische Analyse des linken Ventrikels basierend auf dessen Segmentierung. Dabei werden die die Wandbewegung und die Volumenänderung beschreibenden Größen aus den Ergebnissen einer vorangehenden Segmentierung des Ventrikels berechnet und AHA-konform dargestellt. Zur Visualisierung wird dabei das Toolkit VTK verwendet, das um ein Bull's-Eye-Display-Widget erweitert wird.
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Wesarg, Stefan; Firle, Evelyn
CT-basierte Analyse von Koronararterien zur Unterstützung eines TECAB-Grafting
Wesarg, Stefan; Firle, Evelyn
CT-basierte Analyse von Koronararterien zur Unterstützung eines TECAB-Grafting
Meinzer, Hans-Peter (Ed.) et al.: Bildverarbeitung für die Medizin 2005. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2005. (Informatik aktuell), pp. 26-30
Workshop Bildverarbeitung für die Medizin (BVM) <2005, Heidelberg, Germany>
Verkalkungen der Herzkranzgefäße können zu Erkrankungen des kardio-vaskulären Systems bis hin zu einem Herzinfarkt führen. Eine gängige Behandlungsmethode ist die Bypaß-Operation, welche mit Hilfe moderner Telemanipulator-Systeme minimal-invasiv durchgeführt werden kann. Dies ist allerdings mit Einschränkungen für den Chirurgen bezüglich der Sicht auf die Koronararterien und des Zugang zu selbigen verbunden. Diese Arbeit beschreibt neuartige Methoden für die Unterstützung eines TECAB-Grafting, einer speziellen Form einer minimal-invasiven Bypaß-Operation. Basierend auf einer Segmentierung des Herzkranzgefäßes werden harte Arterienverkalkungen automatisch detektiert und die Umgebung des Gefäßes analysiert. Zudem werden speziell entwickelte Methoden für die Visualisierung der Analyseergebnisse vorgestellt.
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Bockholt, Ulrich; Encarnação, José L.; Sakas, Georgios
Rechnergestützte Therapie unter Berücksichtigung patientenspezifischer Biomechanik
Bockholt, Ulrich; Encarnação, José L.; Sakas, Georgios
Rechnergestützte Therapie unter Berücksichtigung patientenspezifischer Biomechanik
Computer-assisted methods have emerged in medical diagnosis and therapy planning. Thereby the planning often relies on a 3D model of the anatomical structures reconstructed from medical image data (CT, MRT, US). Within this dissertation the diagnostic possibilities are enhanced by combining the model generation of with a simulation of the patient specific biomechanics. Not only image data also biomechanical parameters are considered in the simulation. The pathologic function can be analyzed within the simulation, this analysis is combined with a description of the planned intervention and it results in a prediction of the therapy outcome and the change of functionality caused by the planned intervention. Using this approach different biomechanical phenomena have been examined in different medical application fields: Static analyses have been performed to specify an optimal prosthesis for the implantation of an artificial knee joint, a simulation of the patient specific jaw movement helps to detect occlusions and to verify the design of onlays and crowns in dental diagnostics. Stress-strain simulation is applied in spine surgery and flow simulation has been used in ENT medicine to analyze the patient-specific air flow in the nose. For the presented approaches not only the diagnostic method is presented also an evaluation strategy is outlined that can be applied to proof the significance of the simulation. The presented work results in an approach registering biomedical parameters in real-time and considering these parameters in a Virtual Reality based method for whiplash therapy.
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Cavet, René
Visuelle Klassifikation von digitalen Videoströmen zur automatischen Metadatenextraktion
Cavet, René
Visuelle Klassifikation von digitalen Videoströmen zur automatischen Metadatenextraktion
Fernseh- und Kinotechnische Gesellschaft e.V.: Fernsehen und Film, ein interaktives Überall-Medium?! Proceedings : Die 21. Tagung der Fernseh- und Kinotechnischen Gesellschaft (FKTG)
Tagung der Fernseh- und Kinotechnischen Gesellschaft (FKTG) <21, 2004, Koblenz>
Der Zuwachs von multimedialen Dokumenten lässt sich nur mit Content-Management-Systemen bewältigen. Die Art und Weise, wie man Informationen in solchen Dokumenten effizient erschließt, sucht und findet, muss jedoch neu überdacht werden. Multimediale Objekte bestehen aus abstrakten Daten, die im Wesentlichen die Signale eines technischen Sensorsystems repräsentieren. Diese Sensorinformationen können aber nicht unmittelbar vom Menschen interpretiert werden. Deshalb wurde mit dem Metadaten-Standard MPEG-7 eine einheitliche Beschreibungssprache für Mediendaten zur Verfügung gestellt, aber für eine semantisch sinnvolle Beschreibung der Dokumente ist heutzutage immer noch die sehr zeitaufwendige und kostenintensive manuelle Annotierung notwendig. Im Rahmen des vom BMBF geförderten Fraunhofer-Verbundprojekts PiAVlda wurden verschiedene Verfahren und Ansätze zur automatisierten Erschließung, Segmentierung und Klassifizierung von multimedialen Datenströmen (Text, Audio, Video/TV/Film) entwickelt. Darunter befindet sich ein neues Verfahren zur automatischen Klassifikation von visuellen Datenströmen in semantisch sinnvolle Kategorien, das am Beispiel von aufgezeichneten Nachrichtensendungen und den IPTC-Klassen (Politik, Wirtschaft, Arbeit, Justiz, Werbung, usw.) erprobt wurde. Das Verfahren basiert auf MPEG-7-kompatiblen syntaktischen und semiotischen Audio-, Video- und Sprachmerkmalen, die automatisch aus den Videoströmen extrahiert und dem Klassifikationssystem zur Verfügung gestellt werden. Das entwickelte Klassifikationssystem arbeitet in zwei Stufen: In der Lernphase wird mit manuell annotierten Daten sowie den automatisch extrahierten Merkmalen das System trainiert, um dann in der zweiten Stufe unbekannte Daten automatisch in die trainierten semantischen Kategorien zuordnen zu können. Diese Vorgehensweise erreicht in verschiedenen Kategorien Ergebnisse, die mit der manuellen semantischen Klassifikation vergleichbar sind. Die Integration der entwickelten Techniken in Produktionsumgebungen, sowie umfassendes Training, hat das Potenzial als Vorverarbeitung verschiedene Arbeitsschritte zu vereinfachen als auch kosteneffektiver zu gestalten und ermöglicht die Realisierung einer Fülle von automatisierten Anwendungen in den Bereichen Werbung, TV-Analyse, digitale Archivierung, Trend- und Nachrichtenanalyse.
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Cavet, René; Bouffier, Alexandre
Color Normalization for the Robust Recognition of Television Broadcasts
Cavet, René; Bouffier, Alexandre
Color Normalization for the Robust Recognition of Television Broadcasts
Villanueva, J.J. (Ed.): Proceedings of the Fourth IASTED International Conference on Visualization, Imaging, and Image Processing. Anaheim: ACTA Press, 2004, 3 p.
IASTED International Conference on Visualization, Imaging, and Image Processing <4, 2004, Marbella, Spain>
This paper presents a new procedure for the correction of color information in the context of the automatic recognition of video sequences on television. From its acquisition by a camera to its reproduction on a screen, lots of arti- ficial influences can lead to changes of the image. Since algorithms for the determination of visual correspondences usually work on basis of the color information of images, color distortions represent an important factor concerning the recognition accuracy. Purpose of the presented Color Gamut Sphering (CGS) procedure is to reduce distortions in the color information and therewith, to minimize the negative effect on the recognition reliability. It is a color normalization procedure, which works without any prior information on the content of video sequences and that is based on a color transformation that has proved to remove dependency on small brightness and saturation distortions. Its efficiency has been evaluated in comparison with wellknown color correction algorithms.
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Cavet, René; Volmer, Stephan; Leopold, Edda; Kindermann, Jörg; Paaß, Gerhard
Revealing the Connoted Visual Code: A New Approach to Video Classification
Cavet, René; Volmer, Stephan; Leopold, Edda; Kindermann, Jörg; Paaß, Gerhard
Revealing the Connoted Visual Code: A New Approach to Video Classification
Computers & Graphics, Vol.28 (2004), 3, pp. 361-369
In this paper, we present a new approach for classifying video content into semantic classes at a high level of abstraction by exploiting the connoted visual code. The method is based on the concept of supervised learning algorithms that have already been applied for the classification of written text and spoken language quite successfully. In order to extend this approach for classifying video content, a visual analog to words is constructed from signal-level visual features. A common bag-of-words approach is applied in order to represent video documents. Subsequently, support vector machines are trained to categorize the documents into known classes by using the proposed visual words. Experimental results indicating the classification performance are given and discussed.
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Dold, Christian; Firle, Evelyn
Prospektive Kompensation von Kopfbewegungen mit den Gradienten des MR-Tomographen
Dold, Christian; Firle, Evelyn
Prospektive Kompensation von Kopfbewegungen mit den Gradienten des MR-Tomographen
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2004. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2004. (Informatik aktuell), pp. 90-94
Workshop Bildverarbeitung für die Medizin (BVM) <2004, Berlin, Germany>
Enorm wichtig bei der Aufnahme des Kopfes ist die Eliminierung von Artefakten hervorgerufen durch Bewegungen. Einige Navigator Techniken wurden publiziert, um diese Bewegungsartefakte zu eliminieren. Diese verlängern jedoch die Untersuchungszeit, welche notwendig ist, um die Bewegungsinformation zu detektieren und stören die Erregerfrequenzen in ihrem zeitlichen Ablauf bzw. stören den Steady State der magnetischen Anregung. Eine Möglichkeit dies zu umgehen, ist die externe Messung der Bewegung mit einem optischen Trackingsystem. Entsprechend der Bewegungsänderung werden die Gradienten des MRT nachgeführt und somit sämtliche Bewegungsartefakte kompensiert. Eine "Volume to Volume" Korrektur als auch eine "Slice to Slice" Korrektur ist möglich. Erste Ergebnisse mit Phantomen und Personen werden näher erläutert.
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Dold, Christian; Firle, Evelyn; Sakas, Georgios; Zaitsev, Maxim; Speck, Oliver; Hennig, Jürgen; Schwald, Bernd
Prospective Head Motion Compensation by Updating the Gradients of the MRT
Dold, Christian; Firle, Evelyn; Sakas, Georgios; Zaitsev, Maxim; Speck, Oliver; Hennig, Jürgen; Schwald, Bernd
Prospective Head Motion Compensation by Updating the Gradients of the MRT
Buzug, Thorsten M. (Ed.) et al.: Perspective in Image-Guided Surgery : Proceedings of the Scientific Workshop on Medical Robotics, Navigation and Visaulization. Singapore; New Jersey: World Scientific, 2004, pp. 160-167
Scientific Workshop on Medical Robotics, Navigation and Visualization (MRNV) <2004, Remagen, Germany>
Subject motion appears to be a limiting factor in numerous magnetic resonance imaging applications. For head imaging the subject's ability to maintain the same head position for a considerable period of time places restrictions on the total acquisition time. For healthy individuals this time typically does not exceed 10 minutes and may be considerably reduced in case of pathology. In particular, head tremor, which often accompanies stroke, may render certain high-resolution 2D and 3D techniques inapplicable. Several navigator techniques have been proposed to circumvent the subject motion problem. The most suitable for head imaging appear to be the orbital or spherical navigator methods. Navigators, however, not only lengthen the measurement because of the time required for acquisition of the position information, but also require additional excitation RF pulses to be incorporated into the sequence timing, which disturbs the steady state. Here we demonstrate the possibility of interfacing the MR scanner with an external optical motion tracking system, capable of determining the object's position with sub- millimeter accuracy and an update rate of 25Hz. The information on the object position is used without time penalty to update the position of the imaging volume during the acquisition of k-space data. Results of rotation phantom and in vivo experiments and the implementation in one MRI sequence are shown.
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Dold, Christian; Younis, Waheed; Winter, Jeff; Sakas, Georgios; Firle, Evelyn; Stergiopoulos, Stergios
The Compensation of Head Motion Artifacts Using an Infrared Tracking System and a New Algorithm for fMRI
Dold, Christian; Younis, Waheed; Winter, Jeff; Sakas, Georgios; Firle, Evelyn; Stergiopoulos, Stergios
The Compensation of Head Motion Artifacts Using an Infrared Tracking System and a New Algorithm for fMRI
Westwood, James D. (Ed.) et al.: Medicine Meets Virtual Reality 2004. Proceedings : Building a Better You: The Next Tools for Medical Education, Diagnosis, and Care. Amsterdam: IOS Press; Ohmsha, 2004. (Studies in Health Technology and Informatics 98), pp. 75-81
Medicine Meets Virtual Reality (MMVR) <12, 2004, Newport Beach, CA, USA>
We aim to provide a next generation magnetic resonance imaging (MRI) system technology with an integrated solution for reducing motion artifacts in brain imaging applications. New developments in the field of MRI are revolutionizing the diagnostic capabilities e.g. of functional (fMRI) of the technique. Unfortunately, motion artifacts are eminent problems in cerebral MRI images, especially in difficult patient populations (ie. chronic pain, children, neonates). Patient motion artifacts are present in 2D sequences but are extremely detrimental in multi-slice 3D sequences often employed in fMRI. The problem of motion compensation in MRI technology deals with: - Identification of the source as well as pattern of motion. - Obtaining a mathematical model of motion that can be used to identify and then compensate the motion effects. - Optimizing the image acquisition sequence in order to minimize, or even eliminate, the effect of motion. We propose a method to obtain a quantitative measure of the movement of the head between different data acquisition points in both MRI, and functional MRI examination.
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Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Updating of MRI Gradients Using a Infrared Tracking System to Compensate Motion Artifacts
Dold, Christian; Zaitsev, Maxim; Speck, Oliver; Firle, Evelyn; Hennig, Jürgen; Sakas, Georgios
Updating of MRI Gradients Using a Infrared Tracking System to Compensate Motion Artifacts
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM Twelfth Scientific Meeting 2004. Proceedings CD-ROM, p. 742
ISMRM Scientific Meeting <12, 2004, Kyoto, Japan>
Functional MRI (fMRI) is a non-invasive imaging technique that is used to investigate cerebral function. Patient motion remains a significant problem in many MRI applications, including fMRI, cardiac and abdominal imaging, and conventional long TR acquisitions. Many techniques are available to reduce or to compensate for bulk motion effects, such as physiological gating, phase-encode reordering, fiducial markers, fast acquisitions, image volume registration, or alternative data acquisitions strategies such as projection reconstruction, spiral and PROPELLER. Navigator echoes are used to measure motion with one or more degrees of freedom; the motion is then compensated for either retrospectively or prospectively. Implementing a similar technique in MRI presents additional challenges. Foremost the tracking system and the MRI system have to be compatible. High magnetic fields >= 1.5 Tesla in magnetic resonance imaging systems require that the tracking camera system be positioned a sufficient distance from the MRI system to ensure proper function and safety. Functional MRI also proves challenging because of the high spatial accuracy (RMS <0,3mm) required by the complete measurement chain with a small latency time (<30ms) of the tracking system. The coordinate system of a MRI scanner is controlled using magnetic field gradients and frequencies in the sequence. Determining a precise relationship between the spatial varying magnetic field gradients and the spatial tracking information is necessary to compensate for motion artifacts.
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Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Beschleunigte automatische CT/PET-Registrierung basierend auf partiellem Volumen-Matching und Mutual Informations
Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Beschleunigte automatische CT/PET-Registrierung basierend auf partiellem Volumen-Matching und Mutual Informations
Tolxdorff, Thomas (Ed.) et al.: Bildverarbeitung für die Medizin 2004. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2004. (Informatik aktuell), pp. 473-477
Workshop Bildverarbeitung für die Medizin (BVM) <2004, Berlin, Germany>
Die Berücksichtigung mehrerer tomographischer Bildgebungsmodalitäten nimmt eine zunehmend bedeutendere Rolle im Bereich der Diagnose und Therapieplanung ein. Hierdurch können vermehrt die Stärken der einzelnen Modalitäten genutzt werden. Insbesondere im Bereich der Krebsbehandlung bietet die Kombination von CT - zur Darstellung der Knochenstruktur -- und PET -- zur Visualisierung der funktionellen Information - etliche Vorteile. Das statistische Maß der Mutual Information ist eine Möglichkeit zur Bestimmung der für die Registrierung benötigten Transformation. Die hier vorgestellte Entwicklung beschäftigt sich mit dem Problem rigider Registrierung von CT- und PET-Volumina basierend auf Mutual Information. Es wird ein neuer Ansatz zur Beschleunigung des Matching-Prozesses unter gleichzeitiger Erhaltung der Genauigkeit und Robustheit dieser Methode vorgestellt.
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Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Mutual Information Based Registration for Ultrasound and CT Datasets
Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Mutual Information Based Registration for Ultrasound and CT Datasets
The International Society for Optical Engineering (SPIE): Medical Imaging 2004: Image Processing. Part 2. Bellingham: SPIE Press, 2004. (Proceedings of SPIE 5370), pp. 1130-1138
SPIE Medical Imaging Symposium <2004, San Diego, CA, USA>
In many applications for minimal invasive surgery the acquisition of intra-operative medical images is helpful if not absolutely necessary. Especially for Brachytherapy imaging is critically important to the safe delivery of the therapy. Modern computed tomography (CT) and magnetic resonance (MR) scanners allow minimal invasive procedures to be performed under direct imaging guidance. However, conventional scanners do not have realtime imaging capability and are expensive technologies requiring a special facility. Ultrasound (U/S) is a much cheaper and one of the most .exible imaging modalities. It can be moved to the application room as required and the physician sees what is happening as it occurs. Nevertheless it may be easier to interpret these 3D intra-operative U/S images if they are used in combination with less noisier preoperative data such as CT. The purpose of our current investigation is to develop a registration tool for automatically combining pre-operative CT volumes with intra-operatively acquired 3D U/S datasets. The applied alignment procedure is based on the information theoretic approach of maximizing the mutual information of two arbitrary datasets from di.erent modalities. Since the CT datasets include a much bigger .eld of view we introduced a bounding box to narrow down the region of interest within the CT dataset. We conducted a phantom experiment using a CIRS Model 53 U/S Prostate Training Phantom to evaluate the feasibility and accuracy of the proposed method.
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Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Fast CT/PET Registration Based on Partial Volume Matching
Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Fast CT/PET Registration Based on Partial Volume Matching
Lemke, Heinz U. (Ed.) et al.: Computer Assisted Radiology and Surgery 2004. Proceedings : CARS 2004. Amsterdam: Elsevier, 2004. (International Congress Series 1268), pp. 31-36
Computer Assisted Radiology and Surgery (CARS) <18, 2004, Chicago, USA>
Combining CT representing bone structures and PET visualizing functional information reveals many advantages in the area of cancer diagnosis and treatment. Here, fully automatic registration is desired but very time-consuming when considering big datasets. We present a technique to register CT and PET datasets based on the "Mutual Information" criterion. To overcome the speed problem, we developed a new approach for the matching based on partial volumes introducing a "3D cross model".
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Gürke, Sven; Encarnação, José L.; Sakas, Georgios
Verfahren zur modellbasierten Restauration von Zahndefekten
Gürke, Sven; Encarnação, José L.; Sakas, Georgios
Verfahren zur modellbasierten Restauration von Zahndefekten
Berichte aus der Informatik
ISBN: 3832226850
ISSN: 0945-0807
Modeling of the occlusal surface of teeth is an important problem in computer-aided design of dental restorations. The designed shape must fit the existing individual anatomy of the patient. Also, the design process must be fast to be practical in clinical applications. To fulfil these requirements a new technique for automatic adaptation of the occlusal surface for the restoration of teeth has been developed. By introducing free function assignment in the control points and an dimensional independency the basic concept of geometrically deformable models has been generalized. The presented approach handles also the problem of model generation und interactive model modifications. Further tests on synthetically produces images and real medical records proved its accuracy and many-sidedness.
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Hirschbach, Henning; Klein, Konrad (Betreuer)
Segmentierung und Vereinfachung von Dreiecksnetzen durch Detektion theoretischer Kanten
Hirschbach, Henning; Klein, Konrad (Betreuer)
Segmentierung und Vereinfachung von Dreiecksnetzen durch Detektion theoretischer Kanten
Darmstadt, FH, Master Thesis, 2004
Das Ziel der 3D-Rekonstruktion ist es, möglichst genaue und gleichzeitig wenig komplexe Repräsentanten von realen Objekten zu erstellen. In der Regel werden die vermessenen Modelle durch Dreiecksnetze repräsentiert. Beim Erstellungsvorgang der Dreiecksnetze werden jedoch scharfe Kanten des zu vermessenden Modells wegen des Abtasttheorems leicht abgerundet wiedergegeben. Die abgerundete Repräsentation der scharfen Modellkanten ist nicht korrekt und erhöht wegen der höheren Zahl von Stützstellen und Facetten zusätzlich den Speicherbedarf der Dreiecksnetze. Das Ziel dieser Masterthesis ist es, die nicht korrekt wiedergegebenen Modellkanten ausfindig zu machen und gezielt zu rekonstruieren. Um die Modellkanten zu finden werden die Dreiecksnetze segmentiert und die Segmente durch geeignete Flächenprimitive angenähert. Die Modellkanten ergeben sich schließlich aus den Schnittkurven benachbarter Flächenprimitive. Für die erste Segmentierung wird die Oberflächenkrümmung der Dreiecksnetze genutzt. Anschließend optimiert ein iterativer Prozess die Segmentierung des Dreiecksnetzes, den Approximationsfehler der Flächenprimitive, und fasst falls möglich benachbarte Flächenprimitive zusammen. Der Benutzer kann schließlich die so gefundenen Modellkanten im Dreiecksnetz rekonstruieren. Zur Bestimmung der Oberflächenkrümmung und der Segmentierung der Dreiecksnetze werden verschiedene Methoden vorgestellt, bewertet, und die geeignetste ausgewählt. Die erreichten Ergebnisse werden ausführlich dargestellt und diskutiert. Ferner werden geeignete Methoden zur Approximation der Segmente durch Flächenprimitive sowie zur Berechnung und Repräsentation der gefundenen Kanteninformation vorgestellt und deren Ergebnisse diskutiert. Schließlich werden zwei Ansätze zur Rekonstruktion der Modellkanten vorgestellt und ihre Ergebnisse verglichen.
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Karangelis, Grigorios; Encarnação, José L.; Sakas, Georgios
3D Simulation of External Beam Radiotherapy
Karangelis, Grigorios; Encarnação, José L.; Sakas, Georgios
3D Simulation of External Beam Radiotherapy
Radiation therapy treatment is a very demanding cancer treatment process. The aim of the treatment is to cure or to limit the disease using high-energy radiation dose, having as minimum as possible damage on healthy tissues. In order to have the wanted results, the process is composed from several steps that are highly depended to each other. One could separate them into three different categories; the treatment planning and evaluation, the planning verification before and after treatment and finally the treatment itself. This work is a contribution in the chain of the radiotherapy process from the medical software application point of view. In principle the 3-Dimensional digital patient data are used instead of the physical patient, in order to perform the geometric planning (3D-Simulation), and partly the evaluation steps of the radiation therapy process. This thesis introduces the fully 3D definition of volumetric structures, offering higher degree of freedom to the clinicians for investigating the 3D information of the digital volumes. Also presents the semi-automatic segmentation of the spine, which is an essential tool used daily for the extraction of the spine volume. Main advantages of the methods are the increased efficiency and the improved time rates during volume segmentation. An interesting part of this work is the compensation of breathing artifacts as they are recorded and reconstructed on the surfaces of the acquired computed tomography medical volumes. This kind of artifacts is a source for potential errors during treatment planning and treatment evaluation. In this work we present a method for eliminating these inaccuracies and thus improving the treatment outcome. Further more using as basis the volume rendering pipe-line of the 3D-Simulation system reconstruction techniques have been established, to display anatomical volumes from specific body regions with sensitive structures. These methods require the minimum user interaction. Finally this thesis deals with a very essential issue related to the treatment planning verification. This is by presenting methods for the 3D visualization of the dose distribution in relation to the standard patient anatomy and the segmented anatomical structures.
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Merkert, Danyel; Klein, Konrad (Betreuer)
Messverfahren zur 3D-Patientenlagebestimmung mit CCD-Kameras basierend auf Laserebenen
Merkert, Danyel; Klein, Konrad (Betreuer)
Messverfahren zur 3D-Patientenlagebestimmung mit CCD-Kameras basierend auf Laserebenen
Gießen-Friedberg, FH, Diplomarbeit, 2004
Im Rahmen dieser Diplomarbeit wurde ein dreidimensionales Messverfahren für die Patientenpositonierung bei der Strahlentherapie entwickelt. Das Verfahren basiert auf der Beobachtung des Laser-Postionionierungskreuzes mit einer CCD-Kamera. Durch Triangulation wird hierbei die exakte Position der beiden Laserlinien im dreidimensionalen Raum berechnet. Man erhält so zwei senkrecht zueinander stehende, gekrümmte Linien im Raum, die die 3D-Kontur des Patienten an den Stellen der Laserlinien wiedergibt. Das entwickelte Messverfahren zeichnet sich durch eine hohe Messgenauigkeit sowie eine kurze Ansprechzeit auf Patientenbewegungen aus. Ferner wurde das Grundprinzip eines zweidimensionalen Messverfahrens beschrieben, welches durch alleinige Distanzmessung von Positionierungskreuz und Hautmarkierung im Kamerabild die Lageänderung des Patienten bestimmen soll. Als weiterführende Arbeit sollte man die Einsetzbarkeit des entwickelten Messverfahrens für die Patientenpositionierung näher untersuchen. Es sollte hierbei nach Verfahren für die Distanzbestimmung zwischen den berechneten dreidimensionalen Linien von aufeinanderfolgenden Kamerabildern gesucht werden. Dies sollte dann eine Beurteilung der Patienten-Bewegungen zwischen den einzelnen Kamerabildern erlauben. Wie im letzten Kapitel erwähnt, haben starke Helligkeitsunterschiede des Hintergrunds starke Auswirkungen bei der Positionsbestimmung der Laserpixel. Für eine Weiterentwicklung des Messverfahrens wäre es deshalb denkbar, bei der Positionsbestimmung den Hintergrund des Lasers zu rekonstruieren. Dies könnte entweder durch Zuhilfenahme angrenzender Hintergrundpixel oder durch Filterung der Laserlinien aus dem Kamerabild geschehen. Durch Berücksichtigung der Hintergrunds könnte man den Messfehler an diesen Stellen reduzieren. Weiterhin steht noch eine Implementierung des chamfering-Algorithmus (siehe Abschnitt 5.2) für die Positionsbestimmung der Hautmarkierungen aus.
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Paloc, Céline; Carrasco, Eduardo; Macía, Iván; Gómez, Rubén; Barandiarán, Iñigo; Jiménez, José Manuel; Rueda, Oskar; de Urbina, Jorge Ortiz; Valdivieso, Andrés; Sakas, Georgios
Computer Aided Surgery Based on Auto-Stereoscopic Augmented Reality
Paloc, Céline; Carrasco, Eduardo; Macía, Iván; Gómez, Rubén; Barandiarán, Iñigo; Jiménez, José Manuel; Rueda, Oskar; de Urbina, Jorge Ortiz; Valdivieso, Andrés; Sakas, Georgios
Computer Aided Surgery Based on Auto-Stereoscopic Augmented Reality
Banissi, Ebad (Ed.) et al.: Eighth International Conference on Information Visualization. Proceedings : IV 2004. Los Alamitos, Calif.: IEEE Computer Society, 2004, pp. 189-193
IEEE International Conference on Information Visualization (IV) <8, 2004, London, UK>
Although Augmented Reality (AR) promises to provide valuable means for Computer-Aided Surgery, the underlaying technologies often create a cumbersome work environment that is inadequate for clinical employment. A great deal of research is still needed to develop comfortable and easy-to-use tools providing an augmented view of the patient and its main internal structures. In this paper we propose to develop an AR system for enhanced visualization of the liver that involves minimal annoyance for both the surgeon and the patient. The ultimate application of our system is to assist the surgeon in oncological liver surgery.
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Sachpazidis, Ilias; Fragou, Sofia; Sakas, Georgios
Medication Adherence System Using SMS Technology
Sachpazidis, Ilias; Fragou, Sofia; Sakas, Georgios
Medication Adherence System Using SMS Technology
Institute of Electrical and Electronics Engineers (IEEE): Proceedings of the 2004 Intelligent Sensors, Sensor Networks & Information Processing Conference [CD-ROM], pp. 571-575
International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP) <1, 2004, Melbourne, Australia>
Adherence is the degree to which patients conform to a given treatment plan. Despite the potential for serious psychiatric or medical consequences, patients do not always adhere to their prescribed medication regimen. In this paper, we will introduce a GSM based system improving the medication adherence of the patients.
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Sachpazidis, Ilias; Ohl, Roland; Sakas, Georgios
Instant Messaging: A Communication Layer for Medical Applications
Sachpazidis, Ilias; Ohl, Roland; Sakas, Georgios
Instant Messaging: A Communication Layer for Medical Applications
Systems & Biomedical Engineering Department (SBME): Biomedical Enginnering Conference 2004. CD-ROM : CIBEC 2004 [CD-ROM]. Cairo: Cairo University, Faculty of Engineering, 2004, 3 p.
International Biomedical Engineering Conference (CIBEC) <2, 2004, Cairo, Egypt>
Instant messaging has been used for communication among users even in wireless or wire line networks. In this paper we are going to propose architecture, integrating instant messaging service with medical applications. Particularly, we are going to evolve a medical imaging platform used for teleconsultation among doctors in rural and underserved areas.
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Schwald, Bernd; Seibert, Helmut; Schnaider, Michael; Wesarg, Stefan; Röddiger, Sandra; Dogan, Selami
Implementation and Evaluation of an Augmented Reality System Supporting Minimal Invasive Interventions
Schwald, Bernd; Seibert, Helmut; Schnaider, Michael; Wesarg, Stefan; Röddiger, Sandra; Dogan, Selami
Implementation and Evaluation of an Augmented Reality System Supporting Minimal Invasive Interventions
Workshop AMI-ARCS 2004. Online Proceedings : Augmented Environments for Medical Imaging [online]. [cited 4 February 2005] Available from: http://ami2004.loria.fr/ 2004, pp. 41-48
Workshop AMI-ARCS <2004, Rennes, France>
Minimal invasive surgery and interventions promise a number of advantages for the patient. The biggest one is a reduced trauma for the patient, at the cost of a limited view for the physician. The project MEDARPA offers Augmented Reality (AR) technology to enhance the real view of the surgeon with pre-operatively acquired medical data from 3D imaging modalities. During the last three years, a group of clinical, medical engineering and research partners has designed and implemented a prototype of an AR-enhanced navigation support system for minimal invasive interventions. It comprises of a transparent display device 'AR window', a hybrid tracking system, navigation support and a volume rendering system for medical 3D images. The system has been designed for a variety of medical applications. For the proof of concept cardiosurgery, radio oncology and pneumology scenarios have been considered. This paper gives an overview of the system design and its evaluation.
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Tadge, Tonio; Wesarg, Stefan (Betreuer)
Segmentierung und Analyse von Herzgefäßen in CT-Daten
Tadge, Tonio; Wesarg, Stefan (Betreuer)
Segmentierung und Analyse von Herzgefäßen in CT-Daten
Darmstadt, FH, Master Thesis, 2004
Jedes Jahr erleiden Millionen Menschen in den industrialisierten Nationen einen Herzinfarkt. Die Ursache hierfür ist oft eine Verengung (Stenose) der Herzkranzgefäße. Deshalb ist die Vermessung und Abschätzung der Geometrie der Herzkranzgefäße eine sehr wichtige Aufgabe bei der Diagnose von Erkrankungen. Es gab zwar schon längere Zeit die Möglichkeit, 3D-Aufnahmen zu erzeugen mit Hilfe der konventionellen Computertomographie (CT), aber erst die Erhöhung der räumlichen Auflösung auf 0.5 mm Kantenlänge pro Voxel und der Einsatz von Kontrastmitteln hat diese für die Kardiologie interessant gemacht. In dieser Arbeit wurden verschiedene Verfahren zur Segmentierung und Analyse von Herzkranzgefäßen untersucht und in die Medical Imaging Platform (MIP) des Fraunhofer Institut für Graphische Datenverarbeitung Darmstadt integriert. Dabei wurden nach einer Literaturrecherche drei Verfahren zur Segmentierung ausgewählt und implementiert und zusammen mit einem in dieser Arbeit entwickelten Verfahren hinsichtlich Robustheit, Geschwindigkeit, Genauigkeit und Benutzerfreundlichkeit getestet und verglichen. Dabei konnten die Verfahren Confidence Connected (Flächenwachstumsverfahren) und Freezing Fast Marching (Modellbasiertes Verfahren) wegen ihrer Ungenauigkeit bei der Segmentierung nicht überzeugen. Dagegen lieferten die Algorithmen Resample Verdonck (Verfolgungsverfahren [tracking based]) und der neu entwickelte Vessel Cutter brauchbare Ergebnisse. Für die Analyse von Herzkranzgefäßen wurde ein die Krümmungen der Gefäßwand betrachtendes Verfahren für die Klassifizierung von Stenosen und Aneurysmen ausgewählt und implementiert. Da die Ergebnisse dieser Analyse eher zweifelhaft waren, wurden zusätzlich zwei Charakteristika zur Klassifizierung verwendet. Das war der Querschnitt des Gefäßes und ein Gradienten-basiertes Kriterium im Resample Verdonck- und Vessel Cutter- Verfahren. Zusammenfassend läßt sich sagen, dass der Einsatz der in dieser Arbeit beschriebenen Verfahren auf die dreidimensionalen, hochaufgelösten CT-Daten wertvolle und neue Erkenntisse für die Diagnose der relativ kleinen und schwer zu erkennenden Herzkranzgefäße gebracht hat.
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Villalba Mora, Elena; Sachpazidis, Ilias (Betreuer)
Development of Software Tools for Reading, Writing and Interchanging Electrocardiograms and Medical Files According to SCP-ECG
Villalba Mora, Elena; Sachpazidis, Ilias (Betreuer)
Development of Software Tools for Reading, Writing and Interchanging Electrocardiograms and Medical Files According to SCP-ECG
Darmstadt, TU, Diplomarbeit, 2004
This project focuses on the development of tools for managing with the interchanging of electrocardiograms and medical files according to the Standard Communication Protocol for Computer-assisted Electrocardiography (SCP-ECG). The standard SCP-ECG is described in the document prEN 1064:2002 prepared by the European Committee for Standardization of Health Informatics (CEN/TC 251) The project contains applications for reading and creating SCP-files as well as for interchanging them. Within the dissertation, the state of art is described. Then, the implementation of the project is explicated. To conclude, future possible extensions are explained.
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Wesarg, Stefan; Firle, Evelyn
Localizing Calcifications in Cardiac CT Data Sets Using a New Vessel Segmentation Approach
Wesarg, Stefan; Firle, Evelyn
Localizing Calcifications in Cardiac CT Data Sets Using a New Vessel Segmentation Approach
Society for Computer Applications in Radiology (SCAR): SCAR 2004 : Extended Abstracts. Great Falls, Virginia: Society for Computer Applications in Radiology, 2004, pp. 14-16
Annual Meeting of the Society for Computer Applications in Radiology (SCAR) <21, 2004, Vancouver, BC, Canada>
The new generation of multislice CT scanners allows for the acquisition of high-resolution images of the heart. In cardiac surgery this image data is often the basis for interventional methods like the bypass grafting. In case of executing those interventions as minimal invasive procedures, it is mandatory to have a detailed knowledge about the position of calcifications in the coronary arteries. This work presents a method for localizing these calcifications by employing a newly developed vessel segmentation approach. That extraction technique has been developed for and tested with contrast-enhanced CT data sets of the heart. The algorithm provides enough information to compute the vessel's diameter along the extracted segment. An approach for automatically detecting calcified regions based on this information is presented.
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Wesarg, Stefan; Firle, Evelyn
Segmentation of Vessels: The Corkscrew Algorithm
Wesarg, Stefan; Firle, Evelyn
Segmentation of Vessels: The Corkscrew Algorithm
The International Society for Optical Engineering (SPIE): Medical Imaging 2004: Image Processing. Part 3. Bellingham: SPIE Press, 2004. (Proceedings of SPIE 5370), pp. 1609-1620
SPIE Medical Imaging Symposium <2004, San Diego, CA, USA>
Medical imaging is nowadays much more than only providing data for diagnosis. It also links 'classical' diagnosis to modern forms of treatment such as image guided surgery. Those systems require the identification of organs, anatomical regions of the human body etc., i. e. the segmentation of structures from medical data sets. The algorithms used for these segmentation tasks strongly depend on the object to be segmented. One structure which plays an important role in surgery planning are vessels that are found everywhere in the human body. Several approaches for their extraction already exist. However, there is no general one which is suitable for all types of data or all sorts of vascular structures. This work presents a new algorithm for the segmentation of vessels. It can be classified as a skeleton-based approach working on 3D data sets, and has been designed for a reliable segmentation of coronary arteries. The algorithm is a semi-automatic extraction technique requirering the definition of the start and end the point of the (centerline) path to be found. A first estimation of the vessel's centerline is calculated and then corrected iteratively by detecting the vessel's border perpendicular to the centerline. We used contrast enhanced CT data sets of the thorax for testing our approach. Coronary arteries have been extracted from the data sets using the 'corkscrew algorithm' presented in this work. The segmentation turned out to be robust even if moderate breathing artifacts were present in the data sets.
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Wesarg, Stefan; Firle, Evelyn; Schwald, Bernd; Seibert, Helmut; Zogal, Pawel; Röddiger, Sandra
Accuracy of Needle Implantation in Brachytherapy Using a Medical AR System - a Phantom Study
Wesarg, Stefan; Firle, Evelyn; Schwald, Bernd; Seibert, Helmut; Zogal, Pawel; Röddiger, Sandra
Accuracy of Needle Implantation in Brachytherapy Using a Medical AR System - a Phantom Study
The International Society for Optical Engineering (SPIE): Medical Imaging 2004: Visualization, Image-guided Procedures, and Display. Bellingham: SPIE Press, 2004. (Proceedings of SPIE 5367), pp. 341-352
SPIE Medical Imaging Symposium <2004, San Diego, CA, USA>
Brachytherapy is the treatment method of choice for patients with a tumor relapse after a radiation therapy with external beams or tumors in regions with sensitive surrounding organs-at-risk, e. g. prostate tumors. The standard needle implantation procedure in brachytherapy uses pre-operatively acquired image data displayed as slices on a monitor beneath the operation table. Since this information allows only a rough orientation for the surgeon, the position of the needles has to be verified repeatedly during the intervention. Within the project Medarpa a transparent display being the core component of a medical Augmented Reality (AR) system has been developed. There, pre-operatively acquired image data is displayed together with the position of the tracked instrument allowing a navigated implantation of the brachytherapy needles. The surgeon is enabled to see the anatomical information as well as the virtual instrument in front of the operation area. Thus, the Medarpa system serves as 'window into the patient'. This paper deals with the results of first clinical trials of the system. Phantoms have been used for evaluating the achieved accuracy of the needle implantation. This has been done by comparing the output of the system (instrument positions relative to the phantom) with the real positions of the needles measured by means of a verification CT scan.
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Wesarg, Stefan; Seitel, Mathias; Firle, Evelyn; Dold, Christian
AHA Conform Visualization of Conventionally Acquired Cardiac CT Data Using the Toolkits itk and vtk
Wesarg, Stefan; Seitel, Mathias; Firle, Evelyn; Dold, Christian
AHA Conform Visualization of Conventionally Acquired Cardiac CT Data Using the Toolkits itk and vtk
Lemke, Heinz U. (Ed.) et al.: Computer Assisted Radiology and Surgery. Proceedings : CARS 2004. Amsterdam: Elsevier, 2004. (International Congress Series 1268), pp. 1096-1101
Computer Assisted Radiology and Surgery (CARS) <18, 2004, Chicago, USA>
Several modalities like CT, MRI, or U/S are used for the imaging of the myocardium and the adjacent cavity. The American Heart Association (AHA) has published recommenda- tions for the heart's orientation in cross-sectional slices for a better comparability of data from di erent imaging modalities. We present and compare techniques for the generation of such conform slices from conventionally acquired cardiac CT data sets by employing the toolkits vtk and itk for visualization as well as image processing purposes.
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Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Prospective Real-Time Slice-by-Slice 3D Motion Correction for EPI Using an External Optical Motion Tracking System
Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Prospective Real-Time Slice-by-Slice 3D Motion Correction for EPI Using an External Optical Motion Tracking System
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM Twelfth Scientific Meeting 2004. Proceedings CD-ROM, p. 517
ISMRM Scientific Meeting <12, 2004, Kyoto, Japan>
The need for motion correction in functional MRI (fMRI) time series has been well recognised. This correction may be performed in two ways: either retrospectively, by image registration after the time series has been fully collected,(1) or prospectively, when the motion parameters are measured during the time series acquisition and the corresponding changes are made to the imaging parameters. Prospective techniques differ in the way they acquire the position information. Navigator techniques(2,3) include additional pulse sequences, capable of object position determination. Image-based methods(4) perform co-registration of the measured volume data to extract motion parameters during the acquisition of the time series. Both these approaches are, however, not without problems. Navigator-based techniques slow the acquisition process considerably and perturb the steady-state because of the additional excitation RF pulses. Image-based methods require volume coverage in order to extract position information and considerable computational effort, which introduces delays. Both navigator and image-based corrections typically update positions of the slice packet once per measured volume, which may not be valid, if motion occurs while the slice packet is being acquired. Here we demonstrate a possibility of slice-by-slice 3D prospective motion correction of EPI time series using an external optical motion tracking system.
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Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Imaging of Freely Moving Objects by Means of Real-Time Image Coordinates Update Using an External Optical Motion Tracking System: E-Poster
Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Imaging of Freely Moving Objects by Means of Real-Time Image Coordinates Update Using an External Optical Motion Tracking System: E-Poster
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM Twelfth Scientific Meeting 2004: E-Posters on DVD, 6 p.
ISMRM Scientific Meeting <12, 2004, Kyoto, Japan>
Subject motion appears to be a limiting factor in numerous magnetic resonance imaging applications. For head imaging the subject's ability to maintain the same head position for a considerable period of time places restrictions on the total acquisition time. For healthy individuals this time typically does not exceed 10 minutes and may be considerably reduced in case of pathology. In particular, head tremor, which often accompanies stroke, may render certain high-resolution 2D and 3D techniques inapplicable. Several navigator techniques have been proposed to circumvent the subject motion problem. Navigators, however, not only lengthen the measurement because of the time required for acquisition of the position information, but also require additional excitation RF pulses to be incorporated into the sequence timing, which disturbs the steady state. Here we demonstrate the possibility of interfacing the MR scanner with an external optical motion tracking system, capable of determining the object's position with sub-millimeter accuracy and an update rate of 25Hz. The information on the object position is used without time penalty to update the position of the imaging volume during the acquisition of k-space data. Results of rotation phantom and in vivo experiments and the implementation in two different MRI sequences are shown.
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Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Imaging of Freely Moving Objects by Means of Real-Time Image Coordinates Update Using an External Optical Motion Tracking System
Zaitsev, Maxim; Dold, Christian; Hennig, Jürgen; Speck, Oliver
Imaging of Freely Moving Objects by Means of Real-Time Image Coordinates Update Using an External Optical Motion Tracking System
International Society for Magnetic Resonance in Medicine (ISMRM): ISMRM Twelfth Scientific Meeting 2004. Proceedings CD-ROM, p. 2668
ISMRM Scientific Meeting <12, 2004, Kyoto, Japan>
Subject motion appears to be a limiting factor in numerous magnetic resonance imaging applications. For head imaging the subject's ability to maintain the same head position for a considerable period of time places restrictions on the total acquisition time. For healthy individuals this time typically does not exceed 10 minutes and may be considerably reduced in case of pathology. In particular, head tremor, which often accompanies stroke, may render certain high-resolution 2D and 3D techniques inapplicable. Several navigator techniques have been proposed to circumvent the subject motion problem. Navigators, however, not only lengthen the measurement because of the time required for acquisition of the position information, but also require additional excitation RF pulses to be incorporated into the sequence timing, which disturbs the steady state. Here we demonstrate the possibility of interfacing the MR scanner with an external optical motion tracking system, capable of determining the object's position with sub-millimeter accuracy and an update rate of 25Hz. The information on the object position is used without time penalty to update the position of the imaging volume during the acquisition of k-space data. Results of rotation phantom and in vivo experiments and the implementation in two different MRI sequences are shown.
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Zamboglou, Nikolaos; Karangelis, Grigorios; Nomikos, Ioannis; Zimeras, Stelios; Kolotas, Christos; Baltas, Dimos; Sakas, Georgios
Virtual CT-3D Simulation Using Exomio: With Special Reference to Prostate Cancer
Zamboglou, Nikolaos; Karangelis, Grigorios; Nomikos, Ioannis; Zimeras, Stelios; Kolotas, Christos; Baltas, Dimos; Sakas, Georgios
Virtual CT-3D Simulation Using Exomio: With Special Reference to Prostate Cancer
Nowotwory Journal of Oncology, Vol.54 (2004), 6, p. 547-554
The paper describes a new CT based 3D virtual simulator system called EXOMIO that has been developed at the Institut für Graphische Datenverarbeitung [Fraunhofer IGD] in collaboration with the Department of Radiation Oncology of the Klinikum Offenbach. The system is based on low cost and widely available hardware [PC]: unlike the other commercially available systems that depend on expensive workstations. It provides high quality and high performance visualisation tools. It can be connected via a network to any DICOM supporting CT or MR scanner and via DICOM-RT supplements it enables support for a treatment planning system and for a verification system for linear accelerators. Finally, a prostate cancer case history is given as an example of a clinical application of EXOMIO.
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Bouffier, Alexandre; Volmer, Stephan (Betreuer)
Color Normalization for the Robust Recognition of Video Sequences
Bouffier, Alexandre; Volmer, Stephan (Betreuer)
Color Normalization for the Robust Recognition of Video Sequences
Darmstadt, TU, Studienarbeit, 2003
In this work two new procedures for the correction of color information, called color normalization procedures, are proposed and evaluated in the context of the automatic recognition of video sequences. In the transmission chain from the original sequence to its reproduction on the screen, lots of different influences can lead to changes in the color information of the image. Since algorithms for the determination of visual correspondences usually work on basis of the color information of the image, the color correctness represents a critical factor concerning the recognition accuracy. Purpose of the presented procedures is to correct such changes in the color information and to minimize their negative effect on the recognition reliability. The first procedure --- called Color Gamut Sphering --- is a heuristic color normalization. It works without any prior information on the content of the video sequence, and is based on a projection of the color distribution in the RGB color space on a subspace, in which the dependency on small brightness and saturation distortions becomes negligible. The second procedure --- called Channel Color Profile --- is an optimized color normalization that supposes the knowledge of both the original spot --- the so-called master --- and the broadcaster. It corrects the distorted versions of the videos specifically in terms of common image transformations. Two learning step are therefore necessary, first to characterize the standard color transformations and second to model each channel's specific distortion in terms of these color transformations. The efficiency of the proposed methods has been evaluated in comparison with well-known color correction algorithms.
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Braun, Tim; Cavet, René (Betreuer)
Automatische Lokalisierung von Gesichtern in digitalen Videoströmen
Braun, Tim; Cavet, René (Betreuer)
Automatische Lokalisierung von Gesichtern in digitalen Videoströmen
Darmstadt, TU, Diplomarbeit, 2003
In der vorliegenden Diplomarbeit wurde ein Verfahren entwickelt, das annähernd frontal abgebildete Gesichter in digital aufgezeichneten, farbigen Videodaten lokalisiert. Die gelieferten Informationen über die Position und Größe der vorkommenden Gesichter können zur Klassifikation der Aufzeichnung in verschiedene Genres verwendet werden oder als Grundlage für weitere Verarbeitungsschritte dienen, wie zum Beispiel dem Erkennen der gezeigten Personen mittels biometrischer Verfahren. Das als Eingabe verwendete Videomaterial unterliegt keinerlei Einschränkungen bezüglich Aufnahmebedingungen oder -umgebung. Daher wurde die Entwicklung eines besonders robusten Lokalisationsverfahrens angestrebt, das mit der zu erwartenden hohen Variabilität der Eingabedaten gut umgehen kann. Die anfallende große Datenmenge bei Videos führt zusätzlich zur Forderung einer möglichst kurzen Laufzeit des Verfahrens. Um beide Ziele zu erreichen, wird als Basis zum Erkennen von Gesichtsmustern das als sehr robust angesehene Mustererkennungsverfahren der Support Vector Machine (SVM) verwendet. Die inakzeptable Geschwindigkeit der normalen SVM bei der Bildanalyse wird durch Einsatz einer schnell auswertbaren angenäherten SVM und einer iterativen Verbesserungsstrategie der Näherung stark erhöht, ohne auffällige Auswirkungen auf die Genauigkeit der Gesichtslokalisation zu haben. Eine weitere Beschleunigung des Verfahrens wird durch Analyse der Farbinformation des Videos erzielt; die ebenfalls enthaltenen Bewegungsinformation wird zum Ausschluss von Fehldetektionen und damit zur Erhöhung der Erkennungsgenauigkeit verwendet. Durch die Kombination eines robusten Basisverfahrens mit Komponenten zur Geschwindigkeitssteigerung konnte ein Gesichtslokalisationsverfahren entwickelt werden, das Gesichter in einem weiten Bereich von unterschiedlichen (Frontal-)Posen, Beleuchtungen, Farbverfälschungen und Qualitätsschwankungen finden kann, und dabei dennoch eine Bearbeitungsgeschwindigkeit von mehreren Videoframes pro Sekunde aufweist.
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Diakopoulos, Nicholas; Volmer, Stephan
Temporally Tolerant Video Matching
Diakopoulos, Nicholas; Volmer, Stephan
Temporally Tolerant Video Matching
ACM SIGIR: Multimedia Information Retrieval Workshop 2003. [cited 24 August 2005] Available from: http://km.doc.ic.ac.uk/mmir2003/ 2003
Multimedia Information Retrieval Workshop (MM IR) <3, 2003, Toronto, Canada>
A temporally tolerant notion of visual similarity for videos is defined in the domain of television advertisements. This notion encompasses robustness to channel and encoding noise, encoding rate, and reediting of the advertisements. Using a color-based visual feature as a basis for describing the frames of the video, a sub-shot segmentation of the video that is consistent across encoding rates and extensible to streaming media is produced. This segmentation is subsequently utilized in a similarity matrix based matching algorithm that effectively matches temporally reencoded and reedited videos. Experimental matching results for the situation of discrete video files are given. The method is developed to be fully extensible to any domain with a continuous media stream.
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Dold, Christian; Firle, Evelyn
Aufnahme von Kopfbewegungen in Echtzeit zur Korrektur von Bewegungsartefakten bei fMRI
Dold, Christian; Firle, Evelyn
Aufnahme von Kopfbewegungen in Echtzeit zur Korrektur von Bewegungsartefakten bei fMRI
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2003. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2003. (Informatik aktuell), pp. 141-145
Workshop Bildverarbeitung für die Medizin (BVM) <2003, Erlangen, Germany>
Eine Schlüsselstelle bei der funktionellen Kernspintomographie (fMRI) ist die Eliminierung von Artefakten, hervorgerufen durch Kopfbewegungen. In diesem Paper wird gezeigt, wie mit einem optischen Trackingsystem und speziellen Markerbefestigungen am Schädelknochen die 6 Freiheitsgrade (6 Degrees Of Freedom, DOF) mit einer Genauigkeit von ~100µm und einer Latenzzeit von ~17ms bestimmt werden können. Bei der prospektiven Technik sendet das MRI-System ein Triggersignal an das Trackingsystem. Dieses antwortet mit den aktuellen 6 DOF und das Messkoordinatensystem des Scanners wird entsprechend nachgeführt, sodass Bewegungsartefakte direkt eliminiert werden können und somit keine nachträgliche Bewegungskorrektur mehr erforderlich ist. Ebenso ist eine retrospektive Bewegungskorrektur mit einer getriggerten Aufnahme der beiden Modalitäten (Tracking-System und Kernspintomograph) möglich.
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Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Registrierung und Visualisierung von 3D U/S und CT Datensätzen der Prostata
Firle, Evelyn; Wesarg, Stefan; Dold, Christian
Registrierung und Visualisierung von 3D U/S und CT Datensätzen der Prostata
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2003. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2003. (Informatik aktuell), pp. 26-30
Workshop Bildverarbeitung für die Medizin (BVM) <2003, Erlangen, Germany>
Brachytherapie ist eine Strahlentherapie, welche u. a. mit Hochenergie-Strahlenquellen in Hohlnadeln, die in den Körper des Patienten eingestochen werden, durchgeführt wird. Die präzise Konturierung des zu bestrahlenden Gewebes, sowie die genaue Plazierung der Hohlnadeln an den Positionen, welche durch das "Pre-Planing" vorgegeben werden, sind hierbei wichtige Arbeitsschritte. Bisher basiert die Behandlung des Prostatakarzionoms mittels Brachytherapie vornehmlich auf CT Aufnahmen, welche aber keine Echtzeit-Visualisierung während der Implantation der Katheter zulassen. Sind sowohl CT als auch 3D U/S Aufnahmen vorhanden, können diese registriert und fusioniert werden, um somit die Vorteile beider Modalitäten zu nutzen. Im folgenden werden die Untersuchungen zur Registrierung sowie Möglichkeiten zur Evaluierung dargestellt.
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Firle, Evelyn; Wesarg, Stefan; Karangelis, Grigorios; Dold, Christian
Validation od 3D Ultrasound - CT Registration of Prostate Images
Firle, Evelyn; Wesarg, Stefan; Karangelis, Grigorios; Dold, Christian
Validation od 3D Ultrasound - CT Registration of Prostate Images
Sonka, Milan (Ed.) et al.: Medical Imaging 2003: Image Processing. Proceedings. Bellingham: SPIE Press, 2003. (Proceedings of SPIE 5032), pp. 354-362
SPIE Medical Imaging Symposium <2003, San Diego, CA, USA>
All over the world 20% of men are expected to develop prostate cancer sometime in his life. In addition to surgery - being the traditional treatment for cancer - the radiation treatment is getting more popular. The most interesting radiation treatment regarding prostate cancer is Brachytherapy radiation procedure. For the safe delivery of that therapy imaging is critically important. In several cases where a CT device is available a combination of the information provided by CT and 3D Ultrasound (U/S) images o.ers advantages in recognizing the borders of the lesion and delineating the region of treatment. For these applications the CT and U/S scans should be registered and fused in a multi-modal dataset. Purpose of the present development is a registration tool (registration, fusion and validation) for available CT volumes with 3D U/S images of the same anatomical region, i.e. the prostate. The combination of these two imaging modalities interlinks the advantages of the high-resolution CT imaging and low cost real-time U/S imaging and o.ers a multi-modality imaging environment for further target and anatomy elineation. This tool has been integrated into the visualization software "InViVo" which has been developed over several years in Fraunhofer IGD in Darmstadt.
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Karangelis, Grigorios; Firle, Evelyn; Zamboglou, N.; Sakas, Georgios; Borman, Ulrich
Fast Smoothing of Superficial Respiratory Artifacts on Medical Surfaces
Karangelis, Grigorios; Firle, Evelyn; Zamboglou, N.; Sakas, Georgios; Borman, Ulrich
Fast Smoothing of Superficial Respiratory Artifacts on Medical Surfaces
IEEE Computer Society: Seventh International Conference on Information Visualization. Proceedings : An International Conference on Computer Visualization & Graphics Applications. Los Alamitos, Calif.: IEEE Computer Society, 2003, pp. 344-349
International Conference on Information Visualization (IV) <7, 2003, London, England>
Respiratory artifacts appear very often in medical volumes when the subject under examination is in free respiration conditions. Such artifacts cause a severe deformation to the external body anatomy and are visible and enhanced during the 3D reconstruction of the patient surface. We present a dedicated approach for suppressing the respiratory artifacts on planar body contours. The proposed technique leads to an efficient mechanism, which enables the qualitative and quantitative improvement of the respiratory waves on the final reconstructed mesh while preventing the original anatomical features of the body. We show examples and statistical measurements, which demonstrate the effectiveness and robustness of our approach for different CT cases.
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Malerczyk, Cornelius; Klein, Konrad; Wiebesiek, Torsten
3D Reconstruction of Sports Events for Digital TV
Malerczyk, Cornelius; Klein, Konrad; Wiebesiek, Torsten
3D Reconstruction of Sports Events for Digital TV
Skala, Vaclav (Ed.): Journal of WSCG Volume 11 No. 2. Proceedings. Plzen: University of West Bohemia, 2003, pp. 306-313
International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <11, 2003, Plzen, Czech Republic>
As the capabilities of video standards and receiver hardware are increasing towards integrated 3d animations, generating realistic content is now becoming a limiting factor. In this paper we present a new technique of generating 3D content from reality, i.e. from video sequences acquired with normal TV cameras. The major aim is to provide the TV viewer with animated 3D reconstructions of athletic events in MPEG-4 over Digital Video Broadcast (DVB), which allows for an immersive experience via free navigation and interaction on the receiver side. As intervention in the actual scene, e.g. by markers, is often prohibited, markerless computer vision techniques are used on the images from normal broadcasting cameras for the accurate estimation of an athlete's movements. The paper focuses on the key components for the realistic reconstruction of 3D geometric features, which are the calibration of moving TV cameras and the modelling of the moving athlete in its environment.
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Sakas, Georgios
Unterstützung der Krebstherapie: 3D-Simulationsprogramm EXOMIO
Sakas, Georgios
Unterstützung der Krebstherapie: 3D-Simulationsprogramm EXOMIO
PraxisComputer, Vol.19 (2003), 4, pp. 12-14
Das weltweit zugelassene Simulationsverfahren EXOMIO erhöht die Präzision und Qualität einer Strahlentherapie und gestaltet den Behandlungsprozess schonend für den Patienten und flexibel für den Arzt.
mehr mehr
Sakas, Georgios
Unterstützung der Krebstherapie: 3D-Simulationsprogramm
Sakas, Georgios
Unterstützung der Krebstherapie: 3D-Simulationsprogramm
Deutsches Ärzteblatt, Vol.100 (2003), 40, pp. 2170-2172
Das weltweit zugelassene Simulationsverfahren EXOMIO erhöht die Präzision und Qualität einer Strahlentherapie und gestaltet den Behandlungsprozess schonend für den Patienten und flexibel für den Arzt.
mehr mehr
Seitel, Mathias; Gläser, H. (Betreuer); Dold, Christian (Betreuer)
Segmentierung von 3D-MRI-Volumendatensätzen
Seitel, Mathias; Gläser, H. (Betreuer); Dold, Christian (Betreuer)
Segmentierung von 3D-MRI-Volumendatensätzen
Furtwangen, FH, Diplomarbeit, 2003
Hintergrund Diese Arbeit befasst sich mit der Konzeption und Implementierung einer Anwendung zur Segmentierung medizinischer Volumendatensätze. Die zu entwickelnde Software (MIP - Medical Imaging Platform) wird als Test- und Entwicklungsplattform für allgemeine Problemstellungen der medizinischen Bildverarbeitung entworfen. Zur Ermittlung elementarer Produktanforderungen wird ein typischer Anwendungsfall genauer untersucht: Zeitaufgelöste Serien dreidimensionaler Kernspintomographie-Aufnahmen des menschlichen Herzens sollen segmentiert und im Hinblick auf verschiedene kardiologisch interessante Merkmale analysiert werden. Methoden und Tools Planung und Entwurf der Anwendung orientieren sich an den üblichen Richtlinien des Software-Engineering. Auf Basis der Anforderungsanalyse wird ein objektorientiertes Analysemodell entwickelt. In der Entwurfsphase wird dieses verfeinert und schließlich in der Programmiersprache C++ umgesetzt. Dabei kommen verschiedene Software-Bibliotheken zum Einsatz: Das Toolkit ITK (Insight Segmentation & Registration Toolkit) bildet die Basis für die zu implementierende Bildverarbeitungsfunktionalität. Die Visualisierung der Bilddatensätze erfolgt mittels des Toolkits VTK (Visualization Toolkit). Zur Realisierung der graphischen Benutzerschnittstelle wird das Framework wxWindows verwendet. Ergebnisse Um eine einfache Erweiterbarkeit um neue Anwendungsbereiche sicherzustellen, werden verschiedene Ansätze zur effektiven Organisation und Handhabung von Bilddaten untersucht. Da in der medizinischen Bildverarbeitung eine Vielzahl von Bildtypen existiert, wird dabei dem Kriterium Typflexibilität eine besondere Rolle beigemessen. Der daraus resultierende Ansatz spiegelt sich im Konzept der gesamten Anwendung wieder, welche vollständig über typunabhängige Schnittstellen gesteuert werden kann. Dies betrifft nicht nur die Verwaltung beliebiger Bildtypen, sondern auch die Steuerung von Bildverarbeitungsverfahren. Als hilfreich erweist sich dabei der Einsatz objektorientierter Entwurfsmuster. Bildverarbeitung umfasst im Allgemeinen die sukzessive Filterung von Bilddaten. Zu diesem Zweck werden Filterketten gebildet, wobei die Ausgabe eines Filters als Eingabe seines Nachfolgers dient. Diese in ITK bereits integrierte Grundfunktionalität wird erweitert, um eine konsistente Verarbeitung von Bildserien zu ermöglichen. Filter werden in Klassen gekapselt und können über eine einheitliche, typunabhängige Schnittstelle parametriert werden. Zwei Segmentierungsverfahren, Region Growing Connected Threshold und Geodesic Active Contours, werden implementiert und auf die vorliegenden Datensätze angewendet. Der Entwurf der graphischen Benutzerschnittstelle orientiert sich an den Bedürfnissen des Software-Entwicklers. So bietet sie größtmögliche Kontrolle über die integrierten Bildverarbeitungsalgorithmen. Dialoge zur Konfiguration von Filtern und zur Steuerung des Datenflusses werden automatisch erzeugt. Die dazu benötigten Informationen lassen sich über einheitliche Schnittstellen der jeweiligen Klassenhierarchien ermitteln. Schlussfolgerung Die entwickelte Software ist als Grundlage für die Implementierung und Untersuchung verschiedenster Anwendungen der medizinischen Bildverarbeitung vorgesehen. Dazu wurde insbesondere auf eine konsistente Handhabung des Datenflusses sowie größtmögliche Typflexibilität geachtet. Grundfunktionen wie das Laden und Visualisieren von Bilddaten sowie die graphische Benutzerschnittstelle wurden im Hinblick auf einfache Erweiterbarkeit realisiert.
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Volmer, Stephan; Diakopoulos, Nicholas
Contextually Meaningful Representation of Color for the Description of Visual Content
Volmer, Stephan; Diakopoulos, Nicholas
Contextually Meaningful Representation of Color for the Description of Visual Content
Knowledge Systems Institute: The Ninth International Conference on Distributed Multimedia Systems. Proceedings. Skokie: Knowledge Systems Institute, 2003, pp. 403-409
International Conference on Visual Information Systems (VISUAL) <6, 2003, Miami, FL, USA>
A flexible framework for color representation is developed with the goal of lending perceptual or context specific meaning to visual content. Any given color representation in this framework consists of a set of definable base colors chosen from an underlying tri-chromatic color system. The mathematical foundation of the framework allows for a simple yet powerful assessment of visual similarity. A specific color representation within this framework is devised with the objective of enhancing content-based retrieval applications involving photographic content. Examples are presented and discussed.
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Zamboglou, N.; Karangelis, Grigorios; Nomikos, Ioannis; Zimeras, Stelios; Helfmann, T; Uricchio, R.; Martin, Thomas; Röddiger, Sandra; Kolotas, Christos; Baltas, Dimos; Sakas, Georgios
EXOMIO Virtual Simulation: Oropharynx, Prostate and Breast Cancers
Zamboglou, N.; Karangelis, Grigorios; Nomikos, Ioannis; Zimeras, Stelios; Helfmann, T; Uricchio, R.; Martin, Thomas; Röddiger, Sandra; Kolotas, Christos; Baltas, Dimos; Sakas, Georgios
EXOMIO Virtual Simulation: Oropharynx, Prostate and Breast Cancers
Mould, R.F. (Ed.): Progress in CT-3D Simulation. Bochum: Medical Innovative Technology, 2003, pp. 1-18
International EXOMIO Conference <1, 2002, Limassol, Cyprus>
Simulators are medical devices used in the oncology clinics to perform the simulation for the external beam radiotherapy treatment. Unlikely for a clinic to obtain a real Simulator is a high investment in terms of money, space and personnel. The alternative here can be a Virtual Simulator (VS). The CT simulators are system-software that can perform the simulation process using the Computed Tomography (CT) data set of the patient, including the external patient's skin landmarks, instead of the physical patient. In this paper we present a new high performance CT based virtual simulation system running on a low cost widely available PC hardware - EXOMIO. The implemented high-end visualization techniques allow the users to simulate every function of the real simulator including the mechanical component movements, radiation beam projection and fluoroscopy. Further more this virtual simulation concept provides the physicians with ergonomic volume definition and navigation tools. Our clinical experience is described using three patient examples: Neck cancer, prostate cancer and breast cancer. The advantages of virtual simulation system over classical simulation are stated and its clinical effectiveness is emphasized.
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Chen, Wei; Firle, Evelyn
Geometry Transformation Consideration in Free-Hand Navigation System for Brachytherapy
Chen, Wei; Firle, Evelyn
Geometry Transformation Consideration in Free-Hand Navigation System for Brachytherapy
Skala, Vaclav (Ed.) et al.: WSCG 2002. Conference Proceedings: CD-ROM. Plzen: University of West Bohemia, 2002, File B71
International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <10, 2002, Plzen, Czech Republic>
In this paper, we summarize the geometry transformation relations among volume dataset, the volume rendering and the tracker system in free-hand navigation for high dose rate brachytherapy application. Subsequently, three algorithms during free-hand navigation: the calibration of needle tip, registration and active immobilization are proposed.
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Chen, Wei; Firle, Evelyn
Realistic and Dynamic Simulation of Needle Implantation in Brachytherapy
Chen, Wei; Firle, Evelyn
Realistic and Dynamic Simulation of Needle Implantation in Brachytherapy
Meiler, M. (Ed.) et al.: Bildverarbeitung für die Medizin 2002. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2002. (Informatik aktuell), pp. 89-92
Workshop Bildverarbeitung für die Medizin (BVM) <2002, Leipzig, Germany>
We present a realistic and dynamic simulation method of the needle implantation in brachytherapy. The needle is firstly modeled as a polygon model and then its position and orientation are dynamically and automatically located using a magnetic tracking technology. Two buffers that reserve the result of the volumetric rendering and geometric rendering are mixed in the context of image-level hybrid volume rendering. Thereafter pre-planning of virtual catheters and the interactive and vivid simulation of needle implantation in brachytherapy are carried out. The realistic enhancement ways such as depth weight, shadow and 3D cutting view are also proposed in this paper.
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Chen, Wei; Sakas, Georgios; Peng, Qunsheng
A Free Hand Navigation System for Brachytherapy: (in Chinese)
Chen, Wei; Sakas, Georgios; Peng, Qunsheng
A Free Hand Navigation System for Brachytherapy: (in Chinese)
Jisuanji-fuzhu-sheji-yu-tuxingxue-xuebao = Journal of Computer-Aided Design & Computer Graphics, Vol.14 (2002), 9
This paper describes a free hand navigation system for high-dose-rate brachytherapy. The whole system pipeline consists of four steps, namely, pre-processing, pre-operational planning, intra-operational navigation and post-operational planning. During pre-processing, the uses can decide the positions of operational catheters and draw contouring of the target volumes interactively. For intra-operational free hand navigation, the catheters are tracked by 6-DOF magnetic-tracking technology preciously and accurately. At the same time the high-quality volume visualization techniques guide the users implant the catheters to pre-defined poses. Thereafter the dose calculation and optimization are carried out after the implantations of catheters are fulfilled. Finally, the radioactive sources are inserted and dwelled by using the afterloader to implement the radiation. According to our preliminary experiments, this system achieves encouraging 2-3 times accuracy improvement compared to the trial-and-error manual implantation method. Moreover, the operational time is saved dramatically which decreases the painfulness of the patients.
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Delépine, Ghislain; Volmer, Stephan (Betreuer)
Automatische Lokalisierung von Gesichtern in Videobildern
Delépine, Ghislain; Volmer, Stephan (Betreuer)
Automatische Lokalisierung von Gesichtern in Videobildern
Darmstadt, TU, Diplomarbeit, 2002
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Demiris, Athanasios M.; Walczak, Krzysztof; Wingbermühle, Jochen; Malerczyk, Cornelius; Traka, Maria; Kerbiriou, Paul; Curet, Dominique; Klein, Konrad; Reusens, Emmanuel; Boyle, Eammon; Garcia, Christophe; Ioannidis, Nikos
Sprinting along with the Olympic Champions: Personalized, Interactive Broadcasting using Mixed Reality Techniques and MPEG-4
Demiris, Athanasios M.; Walczak, Krzysztof; Wingbermühle, Jochen; Malerczyk, Cornelius; Traka, Maria; Kerbiriou, Paul; Curet, Dominique; Klein, Konrad; Reusens, Emmanuel; Boyle, Eammon; Garcia, Christophe; Ioannidis, Nikos
Sprinting along with the Olympic Champions: Personalized, Interactive Broadcasting using Mixed Reality Techniques and MPEG-4
Abramowicz, Witold (Ed.): Business Information Systems. Proceedings 2002. CD-ROM
International Conference on Business Information Systems (BIS) <5, 2002, Poznan, Poland>
Interactivity and Personalization are the main aspects of the next generation TV. In this paper, we introduce concepts for the creation of enhanced content in sports broadcasting and its consumption on next generation media terminals allowing interactive and personalized viewing. The underlying architecture is designed within the framework of the EU funded IST project PISTE (Personalized, Immersive Sports TV Experience). PISTE introduces a series of tools for the easy creation and handling of enhanced content during the broadcasting of sports events, focusing on computer vision techniques that create a mixed reality view of the athletes attempt in MPEG-4 enabling free navigation. PISTE also allows to create, broadcast and interactively display supplementary visual information, such as measurements and comparison of different attempts that provide enhanced viewing experience.
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Firle, Evelyn; Chen, Wei; Wesarg, Stefan
Registration of 3D U/S and CT Images of the Prostate
Firle, Evelyn; Chen, Wei; Wesarg, Stefan
Registration of 3D U/S and CT Images of the Prostate
Lemke, Heinz U. (Ed.) et al.: Computer Assisted Radiology and Surgery 2002. Proceedings. Berlin, Heidelberg, New York: Springer, 2002, pp. 527-532
Computer Assisted Radiology and Surgery (CARS) <16, 2002, Paris, France>
Radiotherapy is a rapidly growing cancer treatment technique. In brachytherapy - one radiotherapy treatment technique - pre- and post-planning is usually carried out using CT imaging. As CT scanners cannot easily be moved from one operation room to an other and as CT does not have real-time imaging capability, alternative imaging modalities are needed to realize the vision of image guided surgery. Ultrasound (U/S) is such an alternative imaging modality. For the comparison of U/S and CT image fusion is very useful. After volume segmentation (see ref. 1) the volumes have to be registered, and afterwards the fused volume can be displayed. In this paper we investigate the registration part. We present two different approaches for the 3D registration of CT and U/S volumes. They are compared regarding accuracy and speed of calculation. The resulting fused volumes are visualized using the "InViVo" software where the registration routines have been integrated into.
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Großkopf, Stefan; Encarnação, José L.; Sakas, Georgios
Realitätsnahe Modellierung und Visualisierung dynamischer medizinischer Bilddaten mittels aktiver Konturen, aktiver Regionen und deformierbarer Modelle
Großkopf, Stefan; Encarnação, José L.; Sakas, Georgios
Realitätsnahe Modellierung und Visualisierung dynamischer medizinischer Bilddaten mittels aktiver Konturen, aktiver Regionen und deformierbarer Modelle
In der Medizin werden sensible Entscheidungen zunehmend in allen Phasen der Behandlung (Diagnose, Planung, Durchführung und Kontrolle der Therapie) auf der Grundlage von Bild-material getroffen. Die Präzision, mit der medizinisches Bildmaterial die Anatomie und darüber hinaus physiologische und dynamische Prozesse des menschlichen Körpers abbildet, konnte aufgrund der technologischen Entwicklung der Bildgebung seit Entdeckung der Rönt-genstrahlen erheblich verbessert werden. Damit erfolgte gleichzeitig ein tiefgreifender Wan-del im klinischen Alltag. Andererseits hat sich die Form der Bewertung der Bilddaten seit Einführung der Computer-tomographie in der Mitte der 70er Jahre nur wenig verändert. Trotz der Verfügbarkeit digita-ler Bilddaten über Breitbandnetzwerke werden Bilder häufig schichtweise betrachtet und ausgewertet. Die Genauigkeit, mit der anatomische Details in Original-Schichtbildern zu er-kennen sind, scheint durch andere Methoden der Visualisierung bisher unerreicht. Bei einer schichtweisen Betrachtung des Bildmaterials muss jedoch die eigentlich in 3D vorliegende, sich dynamisch ändernde Anatomie des Patienten mental rekonstruiert werden. Erstrebenswert ist eine dynamische Visualisierung von 3D-Modellen der Anatomie, mit der darüber hin-aus verbesserte Möglichkeiten der Therapieplanung und Kontrolle direkt in 3D realisiert werden können. Eine Reihe von Anwendungen, die den Stand der Technik darstellen, haben sich trotz enger Kooperationen mit medizinischen Partnern insgesamt noch wenig im klinischen Alltag durchsetzen können. Die vorliegende Arbeit möchte einen Beitrag zur Verbesserung der Situation durch neue Methoden der realitätsnahen Modellierung, der Visualisierung und der Analyse dynamischer medizinischer Bilddaten leisten. Durch die Integration der Verfahren und Verfahrensketten in Pilotapplikationen für die Onkologie, Kardiologie und Zahnmedizin sowie einer nicht-medizinischen Anwendung werden deren Genauigkeit und Effizienz demonstriert und evaluiert. Durch den Einsatz aktiver Konturen, aktiver Regionen und deformierbarer Modelle ist der Anwender dabei in der Lage, in allen Phasen die Genauigkeit der Modelle und Visualisierung zu kontrollieren. Darüber hinaus ermöglichen sie eine genaue Selektion für die Visualisierung nur derjenigen Daten, die für eine Diagnose von Bedeutung sind. Durch den Einsatz von Methoden der Statistik, der mathematischen Morphologie und der topologischen Analyse können in dieser Arbeit signifikante Fortschritte gegenüber zuvor in der Literatur vorgestellten Techniken erzielt werden. Es werden neue Verfahren und Verfahrensketten zur Rekonstruktion, Segmentierung, Triangulation und direkten Volumenvisualisierung sowie ein Verfahren zur Formanalyse von 3D-Modellen entwickelt und anhand von realen medizinischen Bilddaten unterschiedlicher Patienten evaluiert. Im Anschluss an eine Zusammenfassung des Standes der Technik in der Bildakquisition werden zunächst zwei Verfahren zur Rekonstruktion aus dynamischen, angiographischen Projektionen präsentiert. Die Angiographie ist in der Kardiologie aufgrund der hohen Auflösung in Raum und Zeit und der guten Verfügbarkeit der Goldstandard. Insofern stellen die entwickelten Verfahren der photogrammetrischen Rekonstruktion (für die Rekonstruktion von Koronargefäßen) und ein Verfahren der Rückprojektion (für die Rekonstruktion des linken Ventrikels) eine Wertsteigerung dieser verbreiteten Bildgebungstechnik mit einem großem Anwendungspotential dar. Für die Segmentierung, auf der ein Schwerpunkt dieser Arbeit liegt, werden nach einer Analyse der Einzelkomponenten aktiver Konturen (Repräsentation, Constraints, Energiedefinition, Extremalsuche) verschiedene Ansätze aktiver Konturen und Regionen gegenübergestellt. Hierzu zählen die Level Set-Methode, das Verfahren des Region Competition, sowie ein eigener Ansatz einer aktiven Kontur, der eine gerichtete Distanztransformation zur Propagierung von Bildkonturen in den Bildraum verwendet. Des weiteren wird eine aktive Region, die auf der Simulation Lagrangescher Dynamik basiert, und ein Ansatz des Kontur-Trackings durch das zur Videokompression eingesetzte Blockmatching präsentiert und bewertet. Als ein Beitrag zur geometrischen Modellierung durch Triangulationen wird das Verfahren des Tracing Cube vorgestellt. Es verfolgt genau eine Oberfläche von einem vorgegebenen Startpunkt aus und ist dadurch in der Lage, einen rekonstruierten Ventrikel von Ghostings der Rückprojektion zu isolieren. Durch einen Ansatz zur Dreiecksreduktion basierend auf einem geometrisch deformierbaren Modell können Dreiecksnetze mit einer optimalen Anzahl von Dreiecken generiert werden, da ihre Dreiecksgröße lokal adaptiv aufgrund der Oberflä-chenkrümmung gewählt wird. Die Genauigkeit der Approximation einer implizit definierten Oberfläche kann dabei gegenüber einem zuvor angewendeten Vergleichsverfahren etwa um den Faktor fünf gesteigert werden. Für die Formanalyse wird ein Verfahren vorgestellt, das zunächst das zu analysierende Objekt (z. B. einen Gefäßbaum) bis auf sein Skelett verdünnt, um Verzweigungsstellen, Endpunkte und Stenosen mit Hilfe einer zusätzlich durchgeführten Distanztransformation zu identifizieren. Im weiteren werden zwei Verfahren der direkten Volumenvisualisierung vorgestellt und diskutiert: selektive Volumenvisualisierung, die globale Segmentierungsinformation nutzt, um interessierende Objektoberflächen aus dem Datensatz herauszuschälen und eine durch die Quantillenanalyse verbesserte Maximums- (Minimums-) Intensitätsprojektion. Mit Hilfe der letzteren ist es z. B. möglich, durch Selektion eines Grauwertebereiches Liquorgefüllte Hirn-ventrikel aus CT-Datensätzen zu visualisieren. Für eine abschließende Bewertung werden die eingangs erwähnten Pilotapplikationen vor-gestellt, die aus den Bereichen Onkologie, Kardiologie und Zahnmedizin stammen. Für sie wird jeweils eine Demonstrationssoftware beschrieben, die eine Evaluierung der Technologi-en ermöglicht und die z. T. bereits Einzug in den Alltag gefunden haben. Darüber hinaus wird das vorstehend erwähnte Verfahren zur Dreiecksreduktion auch für eine technische Applika-tion angewendet: Für eine Rekonstruktion von Objektoberflächen auf der Basis mehrerer 2,5D-Scans.
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Gómez Zardaín, Jorge; Firle, Evelyn (Betreuer)
Automatic Registration of PET and CT resp. PET and MRT Volume Data
Gómez Zardaín, Jorge; Firle, Evelyn (Betreuer)
Automatic Registration of PET and CT resp. PET and MRT Volume Data
Darmstadt, TU, Diplomarbeit, 2002
Motivation: There are millions of people which suffer from tumors and their harmful consequences. All the methods to face up tummors require the most accurate determination of their position and extension. Nowadays, several techniques are available for resolving how the tumors are. Three of the most important medical imaging techniques are Computed Tomography (CT), Magnetic Resonance Tomography (MRT), and Positron Emission Tomography (PET). The first two ones are anatomical modalities, that is to say, they represent the physical structures inside the body. The latter represents they way an organ is functioning. It is a functional medical modality. Task: The aim of this work is the registration of CT and PET as well as MRT and PET. The registration consists of situating the two modalities together so that the specialist can extract the advantages of visualizing them at the same time. That is why complementary modalities are selected. These registration is performed in an automatic way. It does not need the interaction of a user. It only needs the information of the voxels, so the determination of contours, segmentations, or any other preprocess step are not necessary. The implemented method is valid for datasets with different resolutions, different voxel sizes, and different orientations.
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Klein, Konrad; Malerczyk, Cornelius; Wiebesiek, Torsten; Wingbermühle, Jochen
Creating a "Personalised, Immersive Sports TV Experience" via 3d Reconstruction of Moving Athletes
Klein, Konrad; Malerczyk, Cornelius; Wiebesiek, Torsten; Wingbermühle, Jochen
Creating a "Personalised, Immersive Sports TV Experience" via 3d Reconstruction of Moving Athletes
Abramowicz, Witold (Ed.): Business Information Systems. Proceedings 2002. CD-ROM
International Conference on Business Information Systems (BIS) <5, 2002, Poznan, Poland>
As the capabilities of video standards and receiver hardware are increasing towards integrated 3d animations, generating realistic content is now becoming a limiting factor. In this paper we present a new technique of generating 3d content from reality, i.e. from video sequences acquired with normal TV cameras. The major aim is to provide the TV viewer with animated 3d reconstructions of athletic events in MPEG-4 over Digital Video Broadcast (DVB), which allows for an immersive experience via free navigation and interaction on the receiver side. As intervention in the actual scene, e.g. by markers, is often prohibited, markerless computer vision techniques are used on the images from normal broadcasting cameras for the accurate estimation of an athlete's movements. The paper focuses on the key components for the realistic reconstruction of 3d geometric features, which are the calibration of moving TV cameras and the modelling of the moving athlete in its environment.
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Maier, Stefan Michael; Volmer, Stephan (Betreuer)
Automatische Erkennung von eingeblendetem Text in Videostreams
Maier, Stefan Michael; Volmer, Stephan (Betreuer)
Automatische Erkennung von eingeblendetem Text in Videostreams
Darmstadt, TU, Diplomarbeit, 2002
Eine effiziente Organisation von Videodaten innerhalb einer Datenbank erfordert Information über den Inhalt der Videoströme. Im Gegensatz zu gespeicherten Dokumenten liefern die abstrakten binären Videodaten explizit keine Information. Die Videoströme werden deshalb bei ihrer Archivierung manuell um Annotationen, d.h. weitergehende Information, ergänzt, die zur Verwaltung der Videodaten herangezogen werden können. Auf Grund der mit einer manuellen Bearbeitung verbundenen hohen Kosten und des großen Zeitaufwandes ist es kaum möglich, die stark wachsende Zahl vorliegender digitaler Videos zu indizieren. Eben diese Masse der digital vorliegenden Videodaten verlangt nach einer Automatik, um die benötigten Annotationen erzeugen zu können. Diese Diplomarbeit beschreibt ein Verfahren zur automatischen Extraktion von Information aus Videobildern. Extrahiert wird künstlich eingeblendeter Text, der in der Nachbearbeitungsphase bei der Produktion des Videos ergänzt wurde und im Allgemeinen eine grundlegende Informationsquelle bezüglich der Semantik und des Inhaltes eines Videos darstellt. Dieser Text eignet sich dadurch hervorragend zur automatischen Annotation des Videoinhaltes. Das entwickelte Texterkennungssystem gliedert sich in einen Analyseteil, in welchem der eingeblendete Text durch ein Segmentierungsverfahren sowie eine Frequenzanalyse im Videobild lokalisiert wird, und einen Aufbereitungsteil, in dem die gewonnenen Bildausschnitte durch eine OCR-Software in alphanumerische Zeichen umgesetzt werden. Diese extrahierten Zeichen können schließlich dem Videostrom als Annotationen hinzugefügt werden.
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Sachpazidis, Ilias
@HOME: A modular telemedicine system
Sachpazidis, Ilias
@HOME: A modular telemedicine system
Koop, Andreas (Ed.) et al.: Mobile Computing in Medicine. Proceedings 2002. Bonn: Gesellschaft für Informatik, 2002. (GI-Edition - Lecture Notes in Informatics (LNI) P-15), pp.87-95
International Workshop on Mobile Computing in Medicine <2, 2002, Heidelberg>
In that paper we will describe a system for remotely monitoring of patients at home from the doctors at the hospital. In general, the @Home system can measure, collect, analyze and record health care data at a patient's home and the subsequently send these data to the hospital using the global system for mobile communications (GSM) or PSTN telephone line. The paper is organized as follows: In section 1, a brief introduction of the @home project is exposed. In section2, the overall architecture of the system is shown. Finally, the paper concludes in section 3, stating the clinical trials and the benefits of the project.
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Sachpazidis, Ilias
@Home: A system for real time monitoring of patients' vital parameters
Sachpazidis, Ilias
@Home: A system for real time monitoring of patients' vital parameters
Kim, Myoung-Hee (Ed.) et al.: Advanced Medical Image Processing. Proceedings 2002. Germany, 2002
Korea-Germany Joint Workshop on Advanced Medical Image Processing <6, 2002, Heidelberg>
In this paper we are going to describe a robust platform for real-time remote monitoring of patients at their home by doctors at the hospital. The platform is based on both state-of-the-art medical sensors - Bluetooth & DECT enabled sensors - and telecommunication system - GSM/UMTS. The system provides a user-friendly co-operative distributed environment, which enables the following functionalities: Health monitoring sensors which have the capability to measure quick and easy vital parameters such as blood pressure, pulse rate, temperature, oxygen saturation (SpO2), as well as ECG 12 leads. Additionally, an advantage of the platform is that all the sensors are wearable and the patient is able to walk around in the house or go for a walk. Moreover, the sensors are able to convey the recorded data over Bluetooth, a short range wireless communication, to any Bluetooth enabled device such as Desktop computer or a Pocket PC. A real time remote monitoring of patient. The recordings from each medical sensor are immediately transmitted to the clinic over GSM/UMTS. This allows the clinic to monitor the patient in real time and take action if something goes wrong. Conserving safety issues. A Virtual Private Network (VPN) is set up during data transfer between the patient's personal computer and the central server at the clinic. The User Interface (GUI). From a clinical point of view, the GUI enables complete control of the system by the operator. From the patient's side, his records are available for access via Internet, by making use of a password provided by the clinic.
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Sachpazidis, Ilias; Stassinakis, A.; Memos, D.; Fragou, Sofia; Vamvatsikos, A.; Stavropoulou, A.; Fonseca, M.; Mgalhães, R.; Valente, B.; D'Aquila, A.; Ferreira, J.; Aguiar, C.
@Home - Ein neues EU-Projekt zum Tele Home Care
Sachpazidis, Ilias; Stassinakis, A.; Memos, D.; Fragou, Sofia; Vamvatsikos, A.; Stavropoulou, A.; Fonseca, M.; Mgalhães, R.; Valente, B.; D'Aquila, A.; Ferreira, J.; Aguiar, C.
@Home - Ein neues EU-Projekt zum Tele Home Care
Niederlag, Wolfgang (Ed.) et al.: Telemonitoring und Tele Home Care : Methodische Grundlagen, technische Voraussetzungen, organisatorische Konzepte, praktische Erfahrungen, medizintechnische Produkte. Dresden-Friedrichstadt: General Hospital, 2002. (Health Academy 1/2002), pp. 124-127
@Home ist eine robuste Plattform für das gleichzeitige Remotemonitoring von Patienten in ihren Häusern durch Ärzte in Krankenhäusern. Gesundheit überwachende Sensore, haben die Fähigkeit lebenswichtige Parameter wie Blutdruck, Pulsschlag, Temperatur, Sauerstoff Sättigung (SpO2), sowie ECG 12 (...) schnell und einfach zu messen. Zusätzlich ist ein Vorteil der Plattform, daß alle Sensoren wearable sind und der Patient kann herum zuhause oder draußen tragen. Außerdem sind Sensore dazu fähig, gespeicherte Daten über Bluetooth, ein short-range drahtlos Kommunikation, zu irgendeinem Bluetooth aktivierten Schreibtisch Computer oder einem Taschen- PC zu übertragen.
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Sakas, Georgios
Trends in Medical Imaging: From 2D to 3D
Sakas, Georgios
Trends in Medical Imaging: From 2D to 3D
Computers & Graphics, Vol.26 (2002), 4, pp. 577-587
In recent years, three important new developments have dominated the world of medical imaging: ''better diagnosis alone'' is not desired by end users if there is no impact on the therapy procedure; interventional procedures are gaining importance as compared to pure diagnostics; and a general shift from 2Dslices to 3Dmodels of organs has been observed. These trends influence all existing imaging modalities. In this article, we review some aspects of this tendency on applications from CT, MRI/MRA, angiography, 3Dultrasound, cancer treatment, simulation and training, and VR/AR in navigation. We expect that intraoperative imaging and surgical applications, including operation planning, pre-operative simulation and intraoperative navigation, will shape the future of medical imaging and introduce new applications in the field.
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Schnaider, Michael; Seibert, Helmut; Schwald, Bernd; Weller, Tanja; Wesarg, Stefan; Zogal, P.
Medarpa - Ein Augmented Reality System für Minimal-Invasive Interventionen
Schnaider, Michael; Seibert, Helmut; Schwald, Bernd; Weller, Tanja; Wesarg, Stefan; Zogal, P.
Medarpa - Ein Augmented Reality System für Minimal-Invasive Interventionen
Bundesministerium für Bildung und Forschung (BMBF): Internationale Statustagung "Virtuelle und Erweiterte Realität". [cited 20 July 2005] Available from: http://informatiksysteme.pt-it.de/vr-ar-2/tagungscd.html 2002, 9 pp.
Internationale Statustagung Virtuelle und Erweiterte Realität (VR/AR) <2, 2002, Leipzig, Germany>
Minimal-invasive Operationstechniken erfreuen sich in den letzten Jahren einer zunehmenden Akzeptanz und Verbreitung. Sie bieten dem Patienten offensichtliche Vorteile wie ein geringes Trauma, kürze Behandlungszeiten, etc. Gleichzeitig steigen mit diesen Techniken aber auch die Herausforderungen an die Chirurgen, die sich nun mit einer stark eingeschränkten optischen Wahrnehmung des Operationsbereiches konfrontiert sehen. In diesem Beitrag wird ein neuartiger Ansatz für die Computer-unterstützte Chirurgie vorgestellt, der die Techniken der Visualisierung und der erweiterten Realität (AR - Augmented Reality) mit einem neuartigen Ausgabegerät, dem AR-Fenster, kombiniert. Das Forschungsprojekt Medarpa beschäftigt sich mit der Entwicklung eines medizinischen AR-Systems, das ein im Projekt entwickeltes halb-transparentes Display nutzt, welches - über den Körper des Patienten geschwenkt - dem Chirurgen eine Sicht in den Patientenkörper ermöglicht. Es werden auf dem halb-transparenten Display im Vorfeld aufgenommene medizinische 3D-Bildmodalitäten eingeblendet, Anatomien dargestellt und in den Patientenkörper eingeführte Operationsinstrumente visualisiert. Der Chirurg erhält eine erweitere Darstellung der Realität, die ihm in seiner Aufgabe unterstützt. Es wurde ein erstes prototypisches Gesamtsystem entwickelt, dessen Funktionsüberprüfung in ersten Testläufen bei den klinischen Partnern bereits erfolgreich durchgeführt werden konnte. Dabei wurde bereits während der ersten Entwicklungsphasen auf die Berücksichtigung der Anforderungen eines realen klinischen Einsatzes Wert gelegt.
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Straßmann, Gerd; Heyd, Reinhard; Cabillic-Engenhart, Rita; Kolotas, Christos; Walter, Stefan; Sakas, Georgios; Richter, Detlef; Zamboglou, Nikolaos
Accuracy of 3-D Needle Navigation in Interstitial Brachytherapy in Various Body Regions
Straßmann, Gerd; Heyd, Reinhard; Cabillic-Engenhart, Rita; Kolotas, Christos; Walter, Stefan; Sakas, Georgios; Richter, Detlef; Zamboglou, Nikolaos
Accuracy of 3-D Needle Navigation in Interstitial Brachytherapy in Various Body Regions
Strahlentherapie und Onkologie, Vol.178 (2002), 11, p. 644-647
Background: Precise immobilisation of a patient during extracranial stereotactic 3-D navigation is essential in order to minimize the patient's movement during CT data recording and needle application. In this paper we report the first results of needle positioning accuracy in various body regions, using a 3-D navigation system for brachytherapy and a new patient immobilisation system. Patients and Methods: Six patients with different manifestations of neoplastic diseases were immobilized by a special vacuum system and treated with stereotactic 3-D navigational interstitial brachytherapy. Results: The comparison of the simulated stereotactic needle positions with the actual needle positions resulted in a mean positioning deviation varying from 3.4 to 6.5 mm for 29 needles. The maximum positioning deviation lay between 5.7 and 13 mm. Conclusion: The results of our study show that, despite effective patient immobilisation, an increase in needle positioning accuracy is limited by the method of stereotactic 3-D navigation. Effects such as modification of body shape caused by the needle application, morphologic alterations, and inherent inaccuracies within the navigation system have an important influence upon accuracy, which it is not yet possible to calculate.
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Volmer, Stephan
Fast Approximate Nearest-Neighbour Queries in Metric Feature Spaces by Buoy Indexing
Volmer, Stephan
Fast Approximate Nearest-Neighbour Queries in Metric Feature Spaces by Buoy Indexing
Chang, Shi-Kuo (Ed.) et al.: Recent Advances in Visual Information Systems. Berlin, Heidelberg, New York: Springer, 2002. (Lecture Notes in Computer Science (LNCS) 2314), pp. 36-49
International Conference on Visual Information Systems (VISUAL) <5, 2002, Hsin Chu, Taiwan>
A novel indexing scheme for solving the problem of nearest neighbor queries in generic metric feature spaces for content-based image retrieval is proposed aiming to break the "dimensionality curse." The basis for the proposed method is the partitioning of the feature dataset into clusters that are represented by single buoys. Upon submission of a query request, only a small number of clusters whose buoys are close to the query object are considered for the approximate query result, effectively cutting down the amount of data to be processed enormously. Results concerning the retrieval accuracy from extensive experimentation with a real image archive are given. The influence of control parameters is investigated with respect to the tradeoff between retrieval accuracy and computational cost.
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Wesarg, Stefan; Ebert, Matthias; Bortfeld, Thomas
Parker Weights Revisited
Wesarg, Stefan; Ebert, Matthias; Bortfeld, Thomas
Parker Weights Revisited
Medical Physics, Vol.29 (2002), 3, pp. 372-378
The short-scan case in fan-beam computed tomography requires the introduction of a weighting function to handle redundant data. Parker introduced such a weighting function for a scan over pi plus the opening angle of the fan. In this article we derive a general class of weighting functions for arbitrary scan angles between pi plus fan angle and 2pi (over-scan). These weighting functions lead to mathematically exact reconstructions in the continuous case. Parker weights are a special case of a weighting function that belongs to this class. It will be shown that Parker weights are not generally the best choice in terms of noise reduction, especially when there is considerable overscan. We derive a new weighting function that has a value of 0.5 for most of the redundant data and is smooth at the boundaries.
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Wünstel, Michael; Schumann, Hagen
Automatic 3D- Reconstruction of the Ocular Fundus from Stereo Images
Wünstel, Michael; Schumann, Hagen
Automatic 3D- Reconstruction of the Ocular Fundus from Stereo Images
Lemke, Heinz U. (Ed.) et al.: Computer Assisted Radiology and Surgery 2002. Proceedings. Berlin, Heidelberg, New York: Springer, 2002, pp. 456-460
Computer Assisted Radiology and Surgery (CARS) <16, 2002, Paris, France>
The methods of computer vision allow the 3D-reconstruction of an object from 2D stereo image pairs. The EU-Project Glaucad studies the glaucoma disease regarding appropriate geometric characterizations. Our task within this project is to develop a module for automatic 3D-reconstruction of the ocular fundus out of the uncalibrated stereo images. These reconstructions will be used to analyze the changes of the ocular fundus of glaucoma patients. Using methods of computer vision two main demands turned out to produce precise results: A good image preprocessing to compensate the partly changing and difficult recording conditions and a precise registration as prerequisite for the later calculation steps.
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Zarcero Garcia-Risco, Maria del Carmen; Karangelis, Grigorios (Betreuer)
Computer-Based Methods for Matching and Comparison of Portal Image and Digitally Reconstructed Radiograph
Zarcero Garcia-Risco, Maria del Carmen; Karangelis, Grigorios (Betreuer)
Computer-Based Methods for Matching and Comparison of Portal Image and Digitally Reconstructed Radiograph
Darmstadt, TU, Diplomarbeit, 2002
The Radiotherapy is the clinical and scientific discipline devoted to the management of patients with cancer by the use of ionizing radiation or high energy X-ray. One of the most important steps in the Radiotherapy Process will be the Simulation Phase. This considers in first place the Treatment Planning which main tasks are the radiation dose calcultions and the beams placements. And in second place the Treatment Verification which considers the verification that the target coverage and the irradiation of healthy tissues agree with the Treatment Planning. The accurate patient positioning and beams alignment becomes crucial components in the Treatment Verification. This introduces an element of urgency in the developement of a computer model to permit the ability to set up accurately the patient just before the Treatment Delivery. This work proposes a computer model for the direct comparison of the Portal Image and the Mega voltage Digitally Reconstructed Radiograph of the corresponding Treatment Plan. The portal image represents the patient positioning in the moment of the treatment by the use of Electronic Portal Imaging Devices. For this purpose, the following steps are achieved: 1. Reconstruction of Digitally Reconstructed Radiographs at different energies from keV to MeV. 2. Importation of Electronic Portal Image to the Simulator software. 3. Development of image enhancement and filtering tools (e.g. contrast enhancement and edge detection ) to assist the management of Portal Images. 4. Development of methods for Spatial Transformations (e.g. rotation, scaling, translation). 5. Point Registration in the case of Open Field beams. 6. Contour Registration in the case of Field beams with blocks. 7. Blending of the Mega voltage Digitally reconstructed Radiograph and the Transformed Portal Image in the Fusion Image.
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Zimeras, Stelios; Karangelis, Grigorios; Firle, Evelyn; Lauer, Tobias
Shape Reconstruction Using Computer-assisted Segmentation Tools
Zimeras, Stelios; Karangelis, Grigorios; Firle, Evelyn; Lauer, Tobias
Shape Reconstruction Using Computer-assisted Segmentation Tools
Kim, Myoung-Hee (Ed.) et al.: Advanced Medical Image Processing. Proceedings 2002. Germany, 2002
Korea-Germany Joint Workshop on Advanced Medical Image Processing <6, 2002, Heidelberg>
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Adolph, Sabine; Gürke, Sven
Modeling of a Fitting Inlay from Various Information
Adolph, Sabine; Gürke, Sven
Modeling of a Fitting Inlay from Various Information
Ertl, Thomas (Ed.) et al.: Vision, Modeling, and Visualization 2001. Proceedings : VMV 2001. Amsterdam; Berlin: IOS Press, 2001, pp. 309-316
Vision, Modeling, and Visualization (VMV) <6, 2001, Stuttgart, Germany>
Automatic occlusal surface reconstruction for all kinds of tooth restorations is an important ongoing research topic. It is undisputed that an automation of the restoration process is only possible if the typical geometry of teeth is known by the system. One realizable approach is the restoration of the occlusal surface by adapting an appropriate tooth model. A first prototype that was developed at our institute is based on this idea. The main goal of this approach is the explicit use of dental knowledge in the form of a small number of tooth models that have the ability to adapt to the patient's anatomy automatically. In this paper, we present the steps necessary to get from the adapted model to the surface representation of the fitting inlay. By analyzing the adapted tooth model together with the scanned reparation, the border of the cavity within the model is detected automatically. The resulting three dimensional line is used to cut the inlay out of the model and the scanned cavity. The latter has to be triangulated in order to get the bottom of the cavity. Having generated both meshes, top and bottom of the cavity, the only task left is to glue these two meshes together.
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Banks, Jasmine
A Framework for a Dense Matching Algorithm - Results Using Matching Metrics and Order Statistic Filters
Banks, Jasmine
A Framework for a Dense Matching Algorithm - Results Using Matching Metrics and Order Statistic Filters
Giagourta, Venetia (Ed.) et al.: International Conference on Augmented, Virtual Environments and Three-Dimensional Imaging. Proceedings 2001, pp. 224-227
International Conference on Augmented, Virtual Environments and Three-Dimensional Imaging (EUROIMAGE ICAV3D) <2001, Mykonos, Greece>
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Banks, Jasmine; Bennamoun, Mohammed
Reliability Analysis of the Rank Transform for Stereo Matching
Banks, Jasmine; Bennamoun, Mohammed
Reliability Analysis of the Rank Transform for Stereo Matching
IEEE Transactions on Systems, Man, and Cybernetics, Vol.31 (2001), 6, pp. 870-880
The rank transform is a nonparametric technique which has been recently proposed for the stereo matching problem. The motivation behind its application to this problem is its invariance to certain types of image distortion and noise, as well as its amenability to real-time implementation. This paper derives one constraint which must be satisfied for a correct match. This has been termed the rank constraint. Experimental work has shown that this constraint is capable of resolving ambiguous matches, thereby improving matching reliability. A novel matching algorithm incorporating the rank constraint has also been proposed. This modified algorithm consistently resulted in an increased percentage of correct matches, for all test imagery used. Furthermore, the rank constraint has been used to devise a method of identifying regions of an image where the rank transform, and hence matching outcome, is more susceptible to noise. Experimental results have shown that the errors predicted using this technique are consistent with the actual errors which result when images are corrupted with noise. Such a method could be used to identify matches which are likely to be incorrect and/or provide a measure of confidence in a match.
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Banks, Jasmine; Corke, Peter
Quantitative Evaluation of Matching Methods and Validity Measures for Stereo Vision
Banks, Jasmine; Corke, Peter
Quantitative Evaluation of Matching Methods and Validity Measures for Stereo Vision
The International Journal of Robotics Research, Vol.20 (2001), 7, pp. 512-532
The authors present a qualitative and quantitative comparison of various similarity measures that form the kernel of common area-based stereo-matching systems. The authors compare classical difference and correlation measures as well as nonparametric measures based on the rank and census transforms for a number of outdoor images. For robotic applications, important considerations include robustness to image defects such as intensity variation and noise, the number of false matches, and computational complexity. In the absence of ground truth data, the authors compare the matching techniques based on the percentage of matches that pass the left-right consistency test. The authors also evaluate the discriminatory power of several match validity measures that are reported in the literature for eliminating false matches and for estimating match confidence. For guidance applications, it is essential to have an estimate of confidence in the three-dimensional points generated by stereo vision. Finally, a new validity measure, the rank constraint, is introduced that is capable of resolving ambiguous matches for rank transform-based matching.
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Boyle, Eammon; Demiris, Athanasios M.; Curran, Thomas; Klein, Konrad; Garcia, Christophe; Malerczyk, Cornelius; Bouville, Christian
The creation of MPEG-4 content and its delivery over DVB infrastructure
Boyle, Eammon; Demiris, Athanasios M.; Curran, Thomas; Klein, Konrad; Garcia, Christophe; Malerczyk, Cornelius; Bouville, Christian
The creation of MPEG-4 content and its delivery over DVB infrastructure
IEE The Institute of Electrical Engineering: First Joint IEI/IEE Symposium on Telecommunications Systems Research, F5.pdf
Joint IEI/IEE Symposium on Telecommunications Systems Research <1, 2001, Dublin, Ireland>
With the advent of Broadcast Digital TV (BDT), the advances in 3D visualisation, image processing and emergence of standards such as MPEG-4, which facilitates the efficient communication of rich multimedia content including video, audio and synthetic visual objects, the potential exists to revolutionise TV viewing. This paper describes the PISTE (Personalised Immersive Sports TV Experience) system, which is designed to address the complete needs of both broadcasters and viewers. In the development of such a system it is intended to provide large amount of novel applications. These include image processing techniques that provide augmentation of real events. Tools to provide the viewers with a deeper understanding of sports events through the use of textual overlays and athlete profiles, available whenever the viewer desires. The creation of MPEG-4 content, which is not standardised, but is essential for the acceptance of MPEG-4. The use of DVB (Digital Video Broadcast) which is central for the delivery of MPEG-4 content within MPEG-2 streams. In addition, this paper focuses on the creation of 3D animated MPEG-4 content through the use of an animation package. This content will be stored in BIFS (Binary Format for Scenes); the scene description language in MPEG-4 and the animation data is stored in BIFS-Anim.
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Cai, Wenli; Encarnação, José L.; Sakas, Georgios; Shi, Jiaoying
Interactive Volume Visualization in the Context of Virtual Radiotherapy Treatment Planning
Cai, Wenli; Encarnação, José L.; Sakas, Georgios; Shi, Jiaoying
Interactive Volume Visualization in the Context of Virtual Radiotherapy Treatment Planning
ISBN: 3631374135
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Chen, Wei; Cai, Wenli; Firle, Evelyn; Wang, Min; Peng, Qunsheng
A Hardware Assisted LDI Building Algorithm with Application to Hybrid Volume Rendering
Chen, Wei; Cai, Wenli; Firle, Evelyn; Wang, Min; Peng, Qunsheng
A Hardware Assisted LDI Building Algorithm with Application to Hybrid Volume Rendering
Peng, Qunsheng (Ed.) et al.: CAD/Graphics 2001. Proceedings of the Seventh International Conference on Computer Aided Design and Computer Graphics : Proceedings of the Seventh International Conference on Computer Aided Design and Computer Graphics. Beijing, China: International Academic Publishers, 2001, pp. 225 - 232
International Conference on Computer Aided Design and Computer Graphics <7, 2001, Kunming, China>
This paper proposes a new hardware-assisted LDI Building algorithm with application to hybrid volume rendering. It works by creating Layered Depth Image (LDI) using OpenGL. Together with LDI, the scene can be rendered by intermixing segmented volume data and stored depth lists easily. The highlight of our algorithm is that it creates a z-sorting list simply by using depth and stencil buffer in OpenGL. We discussed the implementations, the performance, as well as the accurancy and the optimization of hybrid volume rendering. As z-sorting is the essential problem of visibility in computer graphics, our method is also useful to visibility decision for a large scale polygon environment and IBR-relative application.
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Chen, Wei; Firle, Evelyn
Active Patient Immobilization in Brachytherapy
Chen, Wei; Firle, Evelyn
Active Patient Immobilization in Brachytherapy
Center of Advanced European Studies and Research (CAESAR): Third Caesarium on Computer Aided Medicine : Handouts. Bonn, 2001
Caesarium <3, 2001, Bonn>
This paper describes a method in brachytherapy for an adequate active immobilization of the patient, through which the computer guided free-hand needle insertion, implantation and the navigation procedure can achieve an acceptable level of accurancy and reproducibility.
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Demiris, Athanasios M.; Diamantakos, George; Walczak, Krzysztof; Reusens, Emmanuel; Kerbiriou, Paul; Klein, Konrad; Garcia, Christophe; Marchal, Isabelle; Wingbermühle, Jochen; Boyle, Eammon; Cellary, Wojtech; Ioannidis, Nicos
PISTE: Mixed Reality for Sports TV
Demiris, Athanasios M.; Diamantakos, George; Walczak, Krzysztof; Reusens, Emmanuel; Kerbiriou, Paul; Klein, Konrad; Garcia, Christophe; Marchal, Isabelle; Wingbermühle, Jochen; Boyle, Eammon; Cellary, Wojtech; Ioannidis, Nicos
PISTE: Mixed Reality for Sports TV
European Association for Speech, Signal and Image Processing (EURASIP): International Workshop on Very Low Bitrate Video Coding. Proceedings : Theme: Visual Content Representation and Analysis [online]. [cited 20 July 2005] Available from: http://www.image.ece.ntua.gr/vlbv01/proceedings/start.pdf 2001, 2 p.
International Workshop on Very Low Bitrate Video Coding (VLBV) <2001, Athens, Greece>
In this poster we present the architecture of an application that will address the needs of viewers and broadcasters for enhanced content and interaction by means of mixed reality for sports broadcasting. The presented system aims at the fast creation of visual enhancements and their embedding in the footage of sports events either in real-time (as they are being transmitted) or near real-time, in the so called "replay mode". The goal of the work is the creation of the complete chain from production to the viewing, covering aspects like transmission, encoding/decoding etc. The basis for the representation of the content and the interaction is the MPEG-4 standard, while for the metadata accompanying the content and allowing for personalization MPEG-7 is used. The work presented here is carried out in the framework of the project PISTE funded by the European Commission.
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Demiris, Athanasios M.; Traka, Maria; Reusens, Emmanuel; Walczak, Krzysztof; Garcia, Christophe; Klein, Konrad; Malerczyk, Cornelius; Kerbiriou, Paul; Bouville, Christian; Boyle, Eammon; Ioannidis, Nicos
Enhanced Sports Broadcasting by Means of Augmented Reality in MPEG-4
Demiris, Athanasios M.; Traka, Maria; Reusens, Emmanuel; Walczak, Krzysztof; Garcia, Christophe; Klein, Konrad; Malerczyk, Cornelius; Kerbiriou, Paul; Bouville, Christian; Boyle, Eammon; Ioannidis, Nicos
Enhanced Sports Broadcasting by Means of Augmented Reality in MPEG-4
Giagourta, Venetia (Ed.) et al.: International Conference on Augmented, Virtual Environments and Three-Dimensional Imaging. Proceedings 2001, pp. 10-13
International Conference on Augmented, Virtual Environments and Three-Dimensional Imaging (EUROIMAGE ICAV3D) <2001, Mykonos, Greece>
In this paper we present the architecture of an application that will address the needs of viewers and broadcasters for enhanced content creation, viewing and interaction by means of augmented reality for sports broadcasting. The presented system aims at the fast creation of visual enhancements and their embedding in the footage of sports events either in real-time (as they are being transmitted) or near real-time, in the so called replay mode . The goal of the work is the creation of the complete chain from production to the viewing, covering aspects like motion detection, image analysis, generation of 3D scenery, transmission, encoding/decoding, viewer interaction etc. The basis for the representation of the content and the interaction is the MPEG-4 standard. The infrastructure used for the transmission of such content is DVB. The work presented here is carried out in the framework of the IST project PISTE funded by the European Commission.
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Dhanantwari, Amar C.; Stergiopoulos, Stergios; Zamboglou, Nikolaos; Baltas, Dimos; Vogt, Hans-Georg; Karangelis, Grigorios
Correcting Organ Motion Artifacts in X-ray CT Systems Based on Tracking of Motion Phase by the Spatial Overlap Correlator. II. Experimental study
Dhanantwari, Amar C.; Stergiopoulos, Stergios; Zamboglou, Nikolaos; Baltas, Dimos; Vogt, Hans-Georg; Karangelis, Grigorios
Correcting Organ Motion Artifacts in X-ray CT Systems Based on Tracking of Motion Phase by the Spatial Overlap Correlator. II. Experimental study
Medical Physics, Vol.28 (2001), 8, pp. 1577-1596
This paper presents the experimental part of an investigation on tracking and eliminating organ motion artifacts in x-ray CT cardiac applications with emphasis on imaging coronary calcification. The system methodology consists of a software implementation of the spatial overlap correlator (SSOC) concept in x-ray CT scanners to track the net amplitude and phase of organ motion during the CT data acquisition process. A coherent sinogram synthesis (CSS) method is then used to identify the repeated phases of a periodic organ motion from the information provided by the SSOC process and hence synthesize a new sinogram with no motion effects. Since the SSOC scheme is capable of tracking cardiac motion, it identifies also the projection points associated with minimum amplitude cardiac motion effects. These points are used to identify a 180 degrees plus the fan angle sinogram for image reconstruction. This leads to a retrospective gating (RG) scheme that is based on the output of the SSOC process. Performance comparison of the proposed methodology with the retrospective ECG gating using real data sets with phantoms and human patients provides a performance assessment of the merits of the proposed methods. Real results demonstrate that the new methodology eliminates the requirement for ECG gating. Moreover, the CSS and the new RG methods do not require breath holding and they can be implemented in x-ray CT scanners to image coronary calcification and the heart's ventricles.
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Encarnação, José L.; Firle, Evelyn; Malkewitz, Rainer; INI-GraphicsNet
Selected Readings in Computer Graphics 2000. CD-ROM
Encarnação, José L.; Firle, Evelyn; Malkewitz, Rainer; INI-GraphicsNet
Selected Readings in Computer Graphics 2000. CD-ROM
Selected Readings in Computer Graphics. CD-ROM 11
ISBN: 381675886X
ISSN: 1611-0234
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Firle, Evelyn
Semi-automatische Segmentierung der Prostata mit Hilfe von 3D Ultraschallaufnahmen
Firle, Evelyn
Semi-automatische Segmentierung der Prostata mit Hilfe von 3D Ultraschallaufnahmen
Handels, H. (Ed.) et al.: Bildverarbeitung für die Medizin 2001. Proceedings : Algorithmen, Systeme, Anwendungen. Heidelberg: Springer, 2001. (Informatik aktuell), pp. 262-266
Workshop Bildverarbeitung für die Medizin (BVM) <2001, Lübeck, Germany>
Die Konturierung der Prostata ist ein sehr wichtiger Schritt in der Behandlung des Prostatakarzionoms mittels Brachytherapie. Diese Strahlentherapie wird u.a. mit Hochenergie-Strahlenquellen in Hohlnadeln, die in den Körper des Patienten eingestochen werden, durchgeführt. Ein wichtiger Arbeitsschritt hierbei ist die schnelle und genaue Segmentierung des zu bestrahlenden Gewebes, d.h. in diesem Falle der Prostata, und der umliegenden Organe. Die bisherige Arbeitsweise, bei der das Prostatavolumen manuell Schicht für Schicht ermittelt wird, ist sehr arbeits- und zeitaufwendig. Die hier vorgestellte Entwicklung ermöglicht eine semi-automatische Segmentierung des kompletten Prostatavolumens basierend auf einem aktiven-Konturen Modell.
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Firle, Evelyn; Chen, Wei
Semi-Automatic Registration for MR and CT Datasets
Firle, Evelyn; Chen, Wei
Semi-Automatic Registration for MR and CT Datasets
Center of Advanced European Studies and Research (CAESAR): Third Caesarium on Computer Aided Medicine : Handouts. Bonn, 2001
Caesarium <3, 2001, Bonn>
In this paper we present a method for the automatic identification of markers in MR datasets, registration of datasets from different modalities - based on the automatically selected markers in MR and manually selected fiducials in other modalities and display of the fused datasets in 2D and 3D.
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Großkopf, Stefan
Evaluating Deformable Models for Segmentation of Cardiac Images
Großkopf, Stefan
Evaluating Deformable Models for Segmentation of Cardiac Images
Kim, Myoung-Hee (Ed.) et al.: Advanced Medical Image Processing. Proceedings 2001. Seoul, 2001
Korea-Germany Joint Workshop on Advanced Medical Image Processing <5, 2001, Seoul, Korea>
For diagnosis and treatment planning of heart diseases temporal series of tomographic images (EB-CT, MRI) are acquired. Their evaluation can be simplified by segmenting the images and enable the measurement of several medical indicators (ejection fraction, end-diastolic volume, end-systolic volume). This paper presents three different active contour model based techniques applied to segmentation of cardiac images. In order to find the ventricle contours different image features are used. In addition this paper discusses methods for evaluation of the accuracy of segmentation results.
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Hong, Helen; Großkopf, Stefan; Kim, Myoung-Hee
Ventricular Shape Visualization Using Selective Volume Rendering of Cardiac Datasets
Hong, Helen; Großkopf, Stefan; Kim, Myoung-Hee
Ventricular Shape Visualization Using Selective Volume Rendering of Cardiac Datasets
Computers in Biology and Medicine, Vol.31 (2001), 6, pp. 481-498
In this paper, we present a novel technique of improving volume rendering quality and speed by integrating original volume data and global model information attained by segmentation. The segmentation information prevents object occlusions that may appear when volume rendering is based on local image features only. Thus the presented visualization technique provides meaningful visual results that enable a clear understanding of complex anatomical structures. In the 7rst part, we describe a segmentation technique for extracting the region of interest based on an active contour model. In the second part, we propose a volume rendering method for visualizing the selected portions of fuzzy surfaces extracted by local image processing methods. We show the results of selective volume rendering of left and right ventricle based on cardiac datasets from clinical routines. Our method o:ers an accelerated technique to accurately visualize the surfaces of segmented objects.
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Karangelis, Grigorios; Grimm, Marcus
Advances in CT-Simulation of External Beam Radiotherapy
Karangelis, Grigorios; Grimm, Marcus
Advances in CT-Simulation of External Beam Radiotherapy
Kim, Myoung-Hee (Ed.) et al.: Advanced Medical Image Processing. Proceedings 2001. Seoul, 2001
Korea-Germany Joint Workshop on Advanced Medical Image Processing <5, 2001, Seoul, Korea>
Computed tomography (CT)-Simulators are system-software and they belong to one of the most significant advances in radiation oncology in the past 15-20 years. They aim to simulate the external beam treatment process using the digital computed tomography data of the patient instead the real patient. A very high percentage of patient cases (about 90%) can be simulated using the CT-Simulator replacing the conventional Simulator. Although the idea of the CT-Simulation is old and mature systems can be found in the market, there are still areas for improvements. In this work we present a number of advanced features implemented on a CT-Simulator, named EXOMIO. These features involve interactive techniques on field delineation and advanced visualization-navigation techniques.
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Karangelis, Grigorios; Zamboglou, N.
CT based virtual simulation for external beam radiation therapy
Karangelis, Grigorios; Zamboglou, N.
CT based virtual simulation for external beam radiation therapy
Lemke, Heinz U. (Ed.): Computer Assisted Radiology and Surgery (CARS) 2001. Proceedings. Amsterdam; Lausanne: Elsevier, 2001. (International Congress Series 1230), pp. 465-470
Computer Assisted Radiology and Surgery (CARS) <15, 2001, Berlin>
Computed tomography (CT)-Simulators are system-software and they belong to one of the most significantadvances in radiation oncology in the past 15-20 years. They aim to simulate the external beam treatment process using the digital computed tomography data of the patient instead the real patient. A very high percentage of patient cases (about 90%) can be simulated using the CT-Simulator replacing the conventional Simulator. Although the idea of the CT-Simulation is old and mature systems can be found in the market, there are still areas for improvements. In this work we present a number of advanced features implemented on a CT-Simulator, named EXOMIO. These features involve interactive techniques on field delineation and advanced visualization-navigation techniques.
mehr mehr
Karangelis, Grigorios; Zamboglou, Nikolaos; Baltas, Dimos; Sakas, Georgios
Exomio: A 3D Simulator for External Beam Radiotherapy
Karangelis, Grigorios; Zamboglou, Nikolaos; Baltas, Dimos; Sakas, Georgios
Exomio: A 3D Simulator for External Beam Radiotherapy
Mueller, Klaus (Ed.) et al.: Volume Graphics 2001 : Proceedings of the Joint IEEE TCVG and Eurographics Workshop in Stony Brook, New York, USA. Wien; New York: Springer, 2001. (Springer Computer Science), pp. 351-362
International Workshop on Volume Graphics (VG) <2001, New York, NY, USA>
Simulators are medical devices used in the oncology clinics to perform the simulation procedure for the external beam radiotherapy treatment. Unlikely for a clinic to obtain a real Simulator is a high investment in terms of money, space and personnel. The alternative here can be a Virtual Simulator (VS). The VSs are system-software that can perform the simulation process using the Computed Tomography (CT) data set of the patient, including the external patient s skin landmarks, instead of the physical patient. In this paper we present EXOMIO, a 3D VS which supports high-end visualization techniques. As a result we can simulate every function of the real Simulator including component movement, light field projection and fluoroscopy. Further more we can provide the physicians with ergonomic volume definition and navigation tools.
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Karangelis, Grigorios; Zimeras, Stelios; Firle, Evelyn; Wang, Min; Sakas, Georgios
Volume Definition Tools for Medical Imaging Applications
Karangelis, Grigorios; Zimeras, Stelios; Firle, Evelyn; Wang, Min; Sakas, Georgios
Volume Definition Tools for Medical Imaging Applications
Niessen, Wiro J. (Ed.) et al.: Medical Image Computing and Computer-Assisted Intervention - MICCAI 2001 Proceedings. : 4th International Conference. Berlin, Heidelberg, New York: Springer, 2001. (Lecture Notes in Computer Science (LNCS) 2208), pp. 1295-1297
International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI) <4, 2001, Utrecht, Netherlands>
The definition of structures and the extraction of organ's shape are essential parts of medical imaging applications. These might be applications like diagnostic imaging, image guided surgery or radiation therapy. The aim of the volume definition process is to delineate a specific shape of an organ on a digital image as accurate as possible. This can be done, either by manual user interaction or applying imaging processing techniques for the automatic detection of specific structures in the image. In this work we present a set of tools that are implemented on several computer based medical application. Central focus of this work, are techniques used to improve time and interaction needed for a user when defining one or more structures. These techniques involve interpolation methods for the manual volume definition and methods for the semiautomatic organ shape extraction.
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Klein, Konrad; Sequeira, Vitor
View Planning for Unknown Indoor Scenes Based on a Cost Benefit Analysis
Klein, Konrad; Sequeira, Vitor
View Planning for Unknown Indoor Scenes Based on a Cost Benefit Analysis
Radig, Bernd (Ed.) et al.: Pattern Recognition 2001. Proceedings : 23rd DAGM Symposium. Berlin, Heidelberg, New York: Springer, 2001. (Lecture Notes in Computer Science (LNCS) 2191), pp. 313-320
DAGM Symposium <23, 2001, Munich>
From the task of automatically reconstructing real world scenes using range images, the problem of planning the image acquisition arises. Although solutions for small objects in known environments are already available, these approaches lack scalability to large scenes and to a high number of degrees of freedom. In this paper, we present a new planning algorithm for initially unknown, large indoor environments. Using a surface representation of seen and unseen parts of the environment, we propose a method based on the analysis of occlusions. In addition to previous approaches, we take into account both a quality criterion and the cost of the next acquisition. Results are shown for two large indoor scenes -- an artificial scene and a real world room -- with numerous self occlusions.
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Morsdorf, Felix; Volmer, Stephan
LIVE@WEB.COM - Using CBIR Technology in Interactive Web-TV
Morsdorf, Felix; Volmer, Stephan
LIVE@WEB.COM - Using CBIR Technology in Interactive Web-TV
Jorge, Joaquim A. (Ed.) et al.: 6th Eurographics Workshop on Multimedia 2001. Preliminary Proceedings : Proceedings of the Eurographics Workshop. Wien: Springer-Verlag, 2001. (Springer Computer Science), pp. 165-173
Eurographics Workshop on Multimedia (EGMM) <6, 2001, Manchester, UK>
The increasing amount of internet based television broadcasts has lead to new approaches to interactivity in TV programs. We developed a system which is able to supply the viewer of the program upon interaction with information relating to the program, only based on the low -level visual content of the scde. This aim is achieved by comparing signatures describing the visual content of single frames of the video with a remote database of signatures derived from known videos. The database actually links the visual information contained in the signatures to some second-level information interesting for the user. Two main problems in extending CBIR technology to videos must be overcome, one is the extraction of the visual information out of the highly redundant video material, and the other is reducing the matching time of the system enough to allow for web-based interactivity.
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Neugebauer, Peter Johannes; Encarnação, José L.; Liedtke, Claus Eberhard; Sakas, Georgios
3D-Digitalisierung und Rekonstruktion realer Objekte unter Berücksichtigung der Sensorgeometrie
Neugebauer, Peter Johannes; Encarnação, José L.; Liedtke, Claus Eberhard; Sakas, Georgios
3D-Digitalisierung und Rekonstruktion realer Objekte unter Berücksichtigung der Sensorgeometrie
Berichte aus der Informatik
ISSN: 0945-0807
ISBN: 3826596064
Die dreidimensionale Modellierung realer Objekte inklusive ihrer Textur stellt trotz der heute verfügbaren 3D-Sensoren immer noch eine herausfordernde Aufgabe dar, da die Objekte zu ihrer vollständigen Digitalisierung aus unterschiedlichen Ansichten dreidimensional vermessen und photographisch erfasst werden müssen. Das Ziel der Arbeit besteht deshalb darin, Objekte inklusive ihrer Textur durch Mehrbildintegration von Tiefenbildern und Photographien komplett zu erfassen und bis ins Detail zu modellieren. Dabei dürfen sowohl die 3D-Aufnahmen als auch die Photographien zur Erleichterung der Aufnahmesituation aus wahlfreien Aufnahmepositionen aufgenommen werden. Ausgangspunkt der Arbeit bildet die Betrachtung der bildgebenden 3D-Sensoren, die als Ergebnis des Meßprozesses eine geordnete Punktewolke liefern. Die 3D-Sensoren werden abstrakt durch die in der Arbeit definierte Sensorgeometrie beschrieben. Mittels der Sensorgeometrie kann jedem Meßpunkt nicht nur ein Tiefenwert sondern zusätzlich auch eine individuelle Aufnahmerichtung zugeordnet werden. Unter spezieller Berücksichtigung der Sensorgeometrie wird in der Arbeit eine komplette Verfahrenskette zur Rekonstruktion realer Objekte entworfen. Die entwickelte Verfahrenskette setzt sich aus folgenden Schritten zusammen: 3D-Digitalisierung, Registrierung von Punktewolken in ein gemeinsames Koordinatensystem, Herstellung der Datenkonsistenz innerhalb eines Bildverbunds, Definition der Objektoberfläche, Gewinnung einer Oberflächentriangulation und Texturierung der 3D-Modelle aus unregistrierten Photographien.
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Ristow, Bernhard; Encarnação, José L.; Sakas, Georgios
Gewinnung semantischer 3D-Modelle aus Fotographien
Ristow, Bernhard; Encarnação, José L.; Sakas, Georgios
Gewinnung semantischer 3D-Modelle aus Fotographien
Berichte aus der Informatik
ISBN: 3826592123
ISSN: 0945-0807