TY - CHAP A1 - Seim, Heiko A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Bindernagel, Matthias A1 - Malinowski, Jana A1 - Zachow, Stefan ED - v. Ginneken, B. T1 - Model-based Auto-Segmentation of Knee Bones and Cartilage in MRI Data T2 - Proc. MICCAI Workshop Medical Image Analysis for the Clinic Y1 - 2010 SP - 215 EP - 223 ER - TY - GEN A1 - Ehlke, Moritz A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Efficient projection and deformation of volumetric shape and intensity models for accurate simulation of X-ray images T2 - Eurographics Workshop on Visual Computing for Biomedicine (NVIDIA best poster award) Y1 - 2012 ER - TY - JOUR A1 - Ramm, Heiko A1 - Kahnt, Max A1 - Zachow, Stefan T1 - Patientenspezifische Simulationsmodelle für die funktionelle Analyse von künstlichem Gelenkersatz JF - Computer Aided Medical Engineering (CaMe) Y1 - 2012 VL - 3 IS - 2 SP - 30 EP - 36 ER - TY - CHAP A1 - Kahnt, Max A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan ED - Levine, Joshua A. ED - Paulsen, Rasmus R. ED - Zhang, Yongjie T1 - Feature-Preserving, Multi-Material Mesh Generation using Hierarchical Oracles T2 - Proc. MICCAI Workshop on Mesh Processing in Medical Image Analysis (MeshMed) Y1 - 2012 VL - 7599 SP - 101 EP - 111 ER - TY - CHAP A1 - Ramm, Heiko A1 - Zachow, Stefan ED - Niederlag, Wolfgang ED - Lemke, Heinz ED - Peitgen, Heinz-Otto ED - Lehrach, Hans T1 - Computergestützte Planung für die individuelle Implantatversorgung T2 - Health Academy Y1 - 2012 VL - 16 SP - 145 EP - 158 ER - TY - JOUR A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Seim, Heiko A1 - Zachow, Stefan T1 - Multi-object segmentation of head bones JF - MIDAS Journal Y1 - 2009 ER - TY - CHAP A1 - Seim, Heiko A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - A System for Unsupervised Extraction of Orthopaedic Parameters from CT Data T2 - GI Workshop Softwareassistenten - Computerunterstützung für die medizinische Diagnose und Therapieplanung Y1 - 2009 SP - 1328 EP - 1337 CY - Lübeck, Germany ER - TY - CHAP A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Seim, Heiko A1 - Zinser, Max A1 - Zachow, Stefan ED - Yang, Guang-Zhong ED - J. Hawkes, David ED - Rueckert, Daniel ED - Noble, J. Alison ED - J. Taylor, Chris T1 - Automatic Extraction of Mandibular Nerve and Bone from Cone-Beam CT Data T2 - Proceedings of Medical Image Computing and Computer Assisted Intervention (MICCAI) Y1 - 2009 SP - 76 EP - 83 CY - London, UK ER - TY - CHAP A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - An Articulated Statistical Shape Model for Accurate Hip Joint Segmentation T2 - EBMC 2009. Int. Conf. of the IEEE Eng. in Med. and Biol. Society (EMBC) Y1 - 2009 SP - 6345 EP - 6351 CY - Minneapolis, USA ER - TY - CHAP A1 - Seim, Heiko A1 - Kainmüller, Dagmar A1 - Heller, Markus O. A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - Automatic Extraction of Anatomical Landmarks from Medical Image Data: An Evaluation of Different Methods T2 - Proc. of IEEE Int. Symposium on Biomedical Imaging (ISBI) Y1 - 2009 SP - 538 EP - 541 CY - Boston, MA, USA ER - TY - JOUR A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Multi-object Segmentation with Coupled Deformable Models JF - Annals of the British Machine Vision Association (BMVA) Y1 - 2009 VL - 5 SP - 1 EP - 10 ER - TY - JOUR A1 - Zachow, Stefan A1 - Muigg, Philipp A1 - Hildebrandt, Thomas A1 - Doleisch, Helmut A1 - Hege, Hans-Christian T1 - Visual Exploration of Nasal Airflow JF - IEEE Transactions on Visualization and Computer Graphics Y1 - 2009 U6 - https://doi.org/10.1109/TVCG.2009.198 VL - 15 IS - 8 SP - 1407 EP - 1414 ER - TY - JOUR A1 - Zachow, Stefan A1 - Deuflhard, Peter T1 - Computergestützte Planung in der kraniofazialen Chirurgie JF - Face 01/08, Int. Mag. of Orofacial Esthetics Y1 - 2008 SP - 43 EP - 49 PB - Oemus Journale Leipzig ER - TY - CHAP A1 - Zilske, Michael A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Adaptive Remeshing of Non-Manifold Surfaces T2 - Eurographics 2008 Annex to the Conf. Proc. Y1 - 2008 SP - 207 EP - 211 ER - TY - CHAP A1 - Seim, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Segmentation of Bony Structures with Ligament Attachment Sites T2 - Bildverarbeitung für die Medizin 2008 Y1 - 2008 U6 - https://doi.org/10.1007/978-3-540-78640-5_42 SP - 207 EP - 211 PB - Springer ER - TY - CHAP A1 - Neugebauer, Mathias A1 - Janiga, Gabor A1 - Zachow, Stefan A1 - Krischek, Özlem A1 - Preim, Bernhard ED - Hauser, Helwig T1 - Generierung qualitativ hochwertiger Modelle für die Simulation von Blutfluss in zerebralen Aneurysmen T2 - Proc. of Simulation and Visualization 2008 Y1 - 2008 SP - 221 EP - 235 ER - TY - CHAP A1 - Dornheim, Jana A1 - Born, Silvia A1 - Zachow, Stefan A1 - Gessat, Michael A1 - Wellein, Daniela A1 - Strauß, Gero A1 - Preim, Bernhard A1 - Bartz, Dirk ED - Hauser, Helwig T1 - Bildanalyse, Visualisierung und Modellerstellung für die Implantatplanung im Mittelohr T2 - Proc. of Simulation and Visualization 2008 Y1 - 2008 SP - 139 EP - 154 ER - TY - JOUR A1 - Steinmann, Alexander A1 - Bartsch, Peter A1 - Zachow, Stefan A1 - Hildebrandt, Thomas T1 - Breathing Easily: Simulation of airflow in human noses can become a useful rhinosurgery planning tool JF - ANSYS Advantage Y1 - 2008 VL - Vol. II, No. 1 SP - 30 EP - 31 ER - TY - JOUR A1 - Weiser, Martin A1 - Zachow, Stefan A1 - Deuflhard, Peter T1 - Craniofacial Surgery Planning Based on Virtual Patient Models JF - it - Information Technology Y1 - 2010 U6 - https://doi.org/10.1524/itit.2010.0600 VL - 52 IS - 5 SP - 258 EP - 263 PB - Oldenbourg Verlagsgruppe ER - TY - CHAP A1 - Zachow, Stefan A1 - Hahn, Horst A1 - Lange, Thomas ED - Schlag, Peter ED - Eulenstein, Sebastian ED - Lange, Thomas T1 - Computerassistierte Chirugieplanung T2 - Computerassistierte Chirurgie Y1 - 2010 SP - 119 EP - 149 PB - Elsevier ER - TY - CHAP A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Seim, Heiko A1 - Zachow, Stefan A1 - Hege, Hans-Christian ED - Navab, Tianzi ED - P. W. Pluim, Josien ED - Viergever, Max T1 - Improving Deformable Surface Meshes through Omni-directional Displacements and MRFs T2 - Proc. Medical Image Computing and Computer Assisted Intervention (MICCAI) Y1 - 2010 U6 - https://doi.org/10.1007/978-3-642-15705-9_28 VL - 6361 SP - 227 EP - 234 PB - Springer ER - TY - CHAP A1 - Zachow, Stefan A1 - Kubiack, Kim A1 - Malinowski, Jana A1 - Lamecker, Hans A1 - Essig, Harald A1 - Gellrich, Nils-Claudius T1 - Modellgestützte chirurgische Rekonstruktion komplexer Mittelgesichtsfrakturen T2 - Proc. BMT, Biomed Tech 2010 Y1 - 2010 VL - 55 (Suppl 1) SP - 107 EP - 108 PB - Walter de Gruyter-Verlag ER - TY - CHAP A1 - Lamecker, Hans A1 - Kainmüller, Dagmar A1 - Seim, Heiko A1 - Zachow, Stefan T1 - Automatische 3D Rekonstruktion des Unterkiefers und der Mandibulärnerven auf Basis dentaler Bildgebung T2 - Proc. BMT, Biomed Tech Y1 - 2010 VL - 55 (Suppl. 1) SP - 35 EP - 36 PB - Walter de Gruyter-Verlag ER - TY - JOUR A1 - Dworzak, Jalda A1 - Lamecker, Hans A1 - von Berg, Jens A1 - Klinder, Tobias A1 - Lorenz, Cristian A1 - Kainmüller, Dagmar A1 - Seim, Heiko A1 - Hege, Hans-Christian A1 - Zachow, Stefan T1 - 3D Reconstruction of the Human Rib Cage from 2D Projection Images using a Statistical Shape Model JF - Int. J. Comput. Assist. Radiol. Surg. Y1 - 2010 U6 - https://doi.org/10.1007/s11548-009-0390-2 SN - 1861-6410 VL - 5 IS - 2 SP - 111 EP - 124 PB - Springer ER - TY - GEN A1 - Kamer, Lukas A1 - Noser, Hansrudi A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Wittmers, Antonia A1 - Kaup, Thomas A1 - Schramm, Alexander A1 - Hammer, Beat T1 - Three-dimensional statistical shape analysis - A useful tool for developing a new type of orbital implant? Y1 - 2006 SP - 20 EP - 21 PB - AO Development Institute, New Products Brochure 2/06 ER - TY - JOUR A1 - Heppt, Werner A1 - Hildebrandt, Thomas A1 - Steinmann, Alexander A1 - Zachow, Stefan T1 - Aesthetic and Function in Rhinoplasty JF - Springer Journal Y1 - 2007 VL - 264 (Suppl 1), RL 126 SP - 307 ER - TY - CHAP A1 - Zachow, Stefan A1 - Zilske, Michael A1 - Hege, Hans-Christian T1 - 3D Reconstruction of Individual Anatomy from Medical Image Data: Segmentation and Geometry Processing T2 - 25. ANSYS Conference & CADFEM Users’ Meeting Y1 - 2007 CY - Dresden ER - TY - JOUR A1 - Gessat, Michael A1 - Zachow, Stefan A1 - Burgert, Oliver A1 - Lemke, Heinz T1 - Geometric Meshes in Medical Applications - Steps towards a specification of Geometric Models in DICOM JF - Int. J. of Computer Assisted Radiology and Surgery (CARS) Y1 - 2007 U6 - https://doi.org/10.1007/s11548-007-0112-6 SP - 440 EP - 442 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Zachow, Stefan A1 - Steinmann, Alexander A1 - Heppt, Werner T1 - Innovation in der Funktionell-Ästhetischen Nasenchirurgie: Rhino-CFD JF - Face, Int. Mag. of Orofacial Esthetics Y1 - 2007 SP - 20 EP - 23 PB - Oemus Journale Leipzig ER - TY - JOUR A1 - Zachow, Stefan A1 - Steinmann, Alexander A1 - Hildebrandt, Thomas A1 - Heppt, Werner T1 - Understanding nasal airflow via CFD simulation and visualization JF - Proc. Computer Aided Surgery around the Head Y1 - 2007 SP - 173 EP - 176 ER - TY - JOUR A1 - Lamecker, Hans A1 - Kamer, Lukas A1 - Wittmers, Antonia A1 - Zachow, Stefan A1 - Kaup, Thomas A1 - Schramm, Alexander A1 - Noser, Hansrudi A1 - Hammer, Beat T1 - A method for the three-dimensional statistical shape analysis of the bony orbit JF - Proc. Computer Aided Surgery around the Head Y1 - 2007 SP - 94 EP - 97 ER - TY - CHAP A1 - Zachow, Stefan A1 - Lamecker, Hans A1 - Elsholtz, Barbara A1 - Stiller, Michael T1 - Reconstruction of mandibular dysplasia using a statistical 3D shape model T2 - Proc. Computer Assisted Radiology and Surgery (CARS) Y1 - 2005 U6 - https://doi.org/10.1016/j.ics.2005.03.339 SP - 1238 EP - 1243 CY - Berlin, Germany ER - TY - CHAP A1 - Nkenke, Emeka A1 - Häusler, Gerd A1 - Neukam, Friedrich A1 - Zachow, Stefan T1 - Streak artifact correction of CT data by optical 3D imaging in the simulation of orthognathic surgery T2 - Computer Assisted Radiology and Surgery (CARS) Y1 - 2005 U6 - https://doi.org/doi:10.1016/j.ics.2005.03.278 CY - Berlin Germany ER - TY - CHAP A1 - Nkenke, Emeka A1 - Zachow, Stefan A1 - Häusler, Gerd T1 - Fusion von optischen 3D- und CT-Daten des Gebisses zur Metallartefaktkorrektur vor computerassistierter Planung MKG-chirurgischer Eingriffe T2 - Symposium der Arbeitsgemeinschaf für Kieferchirurgie Y1 - 2005 CY - Bad Homburg v.d.H ER - TY - JOUR A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Haberl, Hannes A1 - Stiller, Michael T1 - Medical applications for statistical shape models JF - Computer Aided Surgery around the Head, Fortschritt-Berichte VDI - Biotechnik/Medizintechnik Y1 - 2005 VL - 17 (258) SP - 61 ER - TY - JOUR A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Wittmers, Antonia A1 - Weber, Britta A1 - Hege, Hans-Christian A1 - Elsholtz, Barbara A1 - Stiller, Michael T1 - Automatic segmentation of mandibles in low-dose CT-data JF - Int. J. Computer Assisted Radiology and Surgery Y1 - 2006 VL - 1(1) SP - 393 EP - 395 ER - TY - JOUR A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Zöckler, Maja T1 - Surgical treatment of craniosynostosis based on a statistical 3D-shape model JF - Int. J. Computer Assisted Radiology and Surgery Y1 - 2006 U6 - https://doi.org/10.1007/s11548-006-0024-x VL - 1(1) SP - 253 EP - 254 ER - TY - JOUR A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Computer assisted planning in cranio-maxillofacial surgery JF - Journal of Computing and Information Technology Y1 - 2006 VL - 14(1) SP - 53 EP - 64 ER - TY - JOUR A1 - Zachow, Stefan A1 - Lamecker, Hans A1 - Elsholtz, Barbara A1 - Stiller, Michael T1 - Is the course of the mandibular nerve deducible from the shape of the mandible? JF - Int. J. of Computer Assisted Radiology and Surgery Y1 - 2006 SP - 415 EP - 417 PB - Springer ER - TY - JOUR A1 - Zachow, Stefan A1 - Steinmann, Alexander A1 - Hildebrandt, Thomas A1 - Weber, Rainer A1 - Heppt, Werner T1 - CFD simulation of nasal airflow: Towards treatment planning for functional rhinosurgery JF - Int. J. of Computer Assisted Radiology and Surgery Y1 - 2006 SP - 165 EP - 167 PB - Springer ER - TY - CHAP A1 - Ehlke, Moritz A1 - Frenzel, Thomas A1 - Ramm, Heiko A1 - Shandiz, Mohsen Akbari A1 - Anglin, Carolyn A1 - Zachow, Stefan T1 - Towards Robust Measurement Of Pelvic Parameters From AP Radiographs Using Articulated 3D Models T2 - Computer Assisted Radiology and Surgery (CARS) N2 - Patient-specific parameters such as the orientation of the acetabulum or pelvic tilt are useful for custom planning for total hip arthroplasty (THA) and for evaluating the outcome of surgical interventions. The gold standard in obtaining pelvic parameters is from three-dimensional (3D) computed tomography (CT) imaging. However, this adds time and cost, exposes the patient to a substantial radiation dose, and does not allow for imaging under load (e.g. while the patient is standing). If pelvic parameters could be reliably derived from the standard anteroposterior (AP) radiograph, preoperative planning would be more widespread, and research analyses could be applied to retrospective data, after a postoperative issue is discovered. The goal of this work is to enable robust measurement of two surgical parameters of interest: the tilt of the anterior pelvic plane (APP) and the orientation of the natural acetabulum. We present a computer-aided reconstruction method to determine the APP and natural acetabular orientation from a single, preoperative X-ray. It can easily be extended to obtain other important preoperative and postoperative parameters solely based on a single AP radiograph. KW - Articulated Models, Statistical Shape And Intensity Models, 2D/3D Anatomy Reconstruction, Pelvic Parameters Measurement, Total Hip Arthroplasty Y1 - 2015 ER - TY - GEN A1 - Ehlke, Moritz A1 - Frenzel, Thomas A1 - Ramm, Heiko A1 - Shandiz, Mohsen Akbari A1 - Anglin, Carolyn A1 - Zachow, Stefan T1 - Towards Robust Measurement of Pelvic Parameters from AP Radiographs using Articulated 3D Models N2 - Patient-specific parameters such as the orientation of the acetabulum or pelvic tilt are useful for custom planning for total hip arthroplasty (THA) and for evaluating the outcome of surgical interventions. The gold standard in obtaining pelvic parameters is from three-dimensional (3D) computed tomography (CT) imaging. However, this adds time and cost, exposes the patient to a substantial radiation dose, and does not allow for imaging under load (e.g. while the patient is standing). If pelvic parameters could be reliably derived from the standard anteroposterior (AP) radiograph, preoperative planning would be more widespread, and research analyses could be applied to retrospective data, after a postoperative issue is discovered. The goal of this work is to enable robust measurement of two surgical parameters of interest: the tilt of the anterior pelvic plane (APP) and the orientation of the natural acetabulum. We present a computer-aided reconstruction method to determine the APP and natural acetabular orientation from a single, preoperative X-ray. It can easily be extended to obtain other important preoperative and postoperative parameters solely based on a single AP radiograph. T3 - ZIB-Report - 15-11 KW - Articulated Models, Statistical Shape And Intensity Models, 2D/3D Anatomy Reconstruction, Pelvic Parameters Measurement, Total Hip Arthroplasty Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-53707 SN - 1438-0064 ER - TY - JOUR A1 - Lemanis, Robert A1 - Zachow, Stefan A1 - Fusseis, Florian A1 - Hoffmann, René T1 - A new approach using high-resolution computed tomography to test the buoyant properties of chambered cephalopod shells JF - Paleobiology N2 - The chambered shell of modern cephalopods functions as a buoyancy apparatus, allowing the animal to enter the water column without expending a large amount of energy to overcome its own weight. Indeed, the chambered shell is largely considered a key adaptation that allowed the earliest cephalopods to leave the ocean floor and enter the water column. It has been argued by some, however, that the iconic chambered shell of Paleozoic and Mesozoic ammonoids did not provide a sufficiently buoyant force to compensate for the weight of the entire animal, thus restricting ammonoids to a largely benthic lifestyle reminiscent of some octopods. Here we develop a technique using high-resolution computed tomography to quantify the buoyant properties of chambered shells without reducing the shell to ideal spirals or eliminating inherent biological variability by using mathematical models that characterize past work in this area. This technique has been tested on Nautilus pompilius and is now extended to the extant deep-sea squid Spirula spirula and the Jurassic ammonite Cadoceras sp. hatchling. Cadoceras is found to have possessed near-neutral to positive buoyancy if hatched when the shell possessed between three and five chambers. However, we show that the animal could also overcome degrees of negative buoyancy through swimming, similar to the paralarvae of modern squids. These calculations challenge past inferences of benthic life habits based solely on calculations of negative buoyancy. The calculated buoyancy of Cadoceras supports the possibility of planktonic dispersal of ammonite hatchlings. This information is essential to understanding ammonoid ecology as well as biotic interactions and has implications for the interpretation of geochemical data gained from the isotopic analysis of the shell. Y1 - 2015 U6 - https://doi.org/10.1017/pab.2014.17 VL - 41 IS - 2 SP - 313 EP - 329 PB - Cambridge University Press CY - Cambridge ER - TY - CHAP A1 - Tack, Alexander A1 - Zachow, Stefan T1 - Accurate Automated Volumetry of Cartilage of the Knee using Convolutional Neural Networks: Data from the Osteoarthritis Initiative T2 - IEEE 16th International Symposium on Biomedical Imaging (ISBI 2019) N2 - Volumetry of cartilage of the knee is needed for knee osteoarthritis (KOA) assessment. It is typically performed manually in a tedious and subjective process. We developed a method for an automated, segmentation-based quantification of cartilage volume by employing 3D Convolutional Neural Networks (CNNs). CNNs were trained in a supervised manner using magnetic resonance imaging data and cartilage volumetry readings performed by clinical experts for 1378 subjects provided by the Osteoarthritis Initiative. It was shown that 3D CNNs are able to achieve volume measures comparable to the magnitude of variation between expert readings and the real in vivo situation. In the future, accurate automated cartilage volumetry might support both, diagnosis of KOA as well as longitudinal analysis of KOA progression. Y1 - 2019 U6 - https://doi.org/10.1109/ISBI.2019.8759201 SP - 40 EP - 43 ER - TY - CHAP A1 - Neumann, Mario A1 - Hellwich, Olaf A1 - Zachow, Stefan T1 - Localization and Classification of Teeth in Cone Beam CT using Convolutional Neural Networks T2 - Proc. of the 18th annual conference on Computer- and Robot-assisted Surgery (CURAC) N2 - In dentistry, software-based medical image analysis and visualization provide efficient and accurate diagnostic and therapy planning capabilities. We present an approach for the automatic recognition of tooth types and positions in digital volume tomography (DVT). By using deep learning techniques in combination with dimensionality reduction through non-planar reformatting of the jaw anatomy, DVT data can be efficiently processed and teeth reliably recognized and classified, even in the presence of imaging artefacts, missing or dislocated teeth. We evaluated our approach, which is based on 2D Convolutional Neural Networks (CNNs), on 118 manually annotated cases of clinical DVT datasets. Our proposed method correctly classifies teeth with an accuracy of 94% within a limit of 2mm distance to ground truth labels. Y1 - 2019 SN - 978-3-00-063717-9 SP - 182 EP - 188 ER - TY - CHAP A1 - Joachimsky, Robert A1 - Ma, Lihong A1 - Icking, Christian A1 - Zachow, Stefan T1 - A Collision-Aware Articulated Statistical Shape Model of the Human Spine T2 - Proc. of the 18th annual conference on Computer- and Robot-assisted Surgery (CURAC) N2 - Statistical Shape Models (SSMs) are a proven means for model-based 3D anatomy reconstruction from medical image data. In orthopaedics and biomechanics, SSMs are increasingly employed to individualize measurement data or to create individualized anatomical models to which implants can be adapted to or functional tests can be performed on. For modeling and analysis of articulated structures, so called articulated SSMs (aSSMs) have been developed. However, a missing feature of aSSMs is the consideration of collisions in the course of individual fitting and articulation. The aim of our work was to develop aSSMs that handle collisions between components correctly. That way it becomes possible to adjust shape and articulation in view of a physically and geometrically plausible individualization. To be able to apply collision-aware aSSMs in simulation and optimisation, our approach is based on an e� cient collision detection method employing Graphics Processing Units (GPUs). Y1 - 2019 SP - 58 EP - 64 ER - TY - JOUR A1 - Krämer, Martin A1 - Maggioni, Marta A1 - Brisson, Nicholas A1 - Zachow, Stefan A1 - Teichgräber, Ulf A1 - Duda, Georg A1 - Reichenbach, Jürgen T1 - T1 and T2* mapping of the human quadriceps and patellar tendons using ultra-short echo-time (UTE) imaging and bivariate relaxation parameter-based volumetric visualization JF - Magnetic Resonance Imaging N2 - Quantification of magnetic resonance (MR)-based relaxation parameters of tendons and ligaments is challenging due to their very short transverse relaxation times, requiring application of ultra-short echo-time (UTE) imaging sequences. We quantify both T1 and T2⁎ in the quadriceps and patellar tendons of healthy volunteers at a field strength of 3 T and visualize the results based on 3D segmentation by using bivariate histogram analysis. We applied a 3D ultra-short echo-time imaging sequence with either variable repetition times (VTR) or variable flip angles (VFA) for T1 quantification in combination with multi-echo acquisition for extracting T2⁎. The values of both relaxation parameters were subsequently binned for bivariate histogram analysis and corresponding cluster identification, which were subsequently visualized. Based on manually-drawn regions of interest in the tendons on the relaxation parameter maps, T1 and T2⁎ boundaries were selected in the bivariate histogram to segment the quadriceps and patellar tendons and visualize the relaxation times by 3D volumetric rendering. Segmentation of bone marrow, fat, muscle and tendons was successfully performed based on the bivariate histogram analysis. Based on the segmentation results mean T2⁎ relaxation times, over the entire tendon volumes averaged over all subjects, were 1.8 ms ± 0.1 ms and 1.4 ms ± 0.2 ms for the patellar and quadriceps tendons, respectively. The mean T1 value of the patellar tendon, averaged over all subjects, was 527 ms ± 42 ms and 476 ms ± 40 ms for the VFA and VTR acquisitions, respectively. The quadriceps tendon had higher mean T1 values of 662 ms ± 97 ms (VFA method) and 637 ms ± 40 ms (VTR method) compared to the patellar tendon. 3D volumetric visualization of the relaxation times revealed that T1 values are not constant over the volume of both tendons, but vary locally. This work provided additional data to build upon the scarce literature available on relaxation times in the quadriceps and patellar tendons. We were able to segment both tendons and to visualize the relaxation parameter distributions over the entire tendon volumes. Y1 - 2019 U6 - https://doi.org/10.1016/j.mri.2019.07.015 VL - 63 IS - 11 SP - 29 EP - 36 ER - TY - CHAP A1 - Ambellan, Felix A1 - Zachow, Stefan A1 - von Tycowicz, Christoph T1 - An as-invariant-as-possible GL+(3)-based Statistical Shape Model T2 - Proc. 7th MICCAI workshop on Mathematical Foundations of Computational Anatomy (MFCA) N2 - We describe a novel nonlinear statistical shape model basedon differential coordinates viewed as elements of GL+(3). We adopt an as-invariant-as possible framework comprising a bi-invariant Lie group mean and a tangent principal component analysis based on a unique GL+(3)-left-invariant, O(3)-right-invariant metric. Contrary to earlier work that equips the coordinates with a specifically constructed group structure, our method employs the inherent geometric structure of the group-valued data and therefore features an improved statistical power in identifying shape differences. We demonstrate this in experiments on two anatomical datasets including comparison to the standard Euclidean as well as recent state-of-the-art nonlinear approaches to statistical shape modeling. Y1 - 2019 U6 - https://doi.org/10.1007/978-3-030-33226-6_23 VL - 11846 SP - 219 EP - 228 PB - Springer ER - TY - GEN A1 - Ambellan, Felix A1 - Zachow, Stefan A1 - von Tycowicz, Christoph T1 - A Surface-Theoretic Approach for Statistical Shape Modeling N2 - We present a novel approach for nonlinear statistical shape modeling that is invariant under Euclidean motion and thus alignment-free. By analyzing metric distortion and curvature of shapes as elements of Lie groups in a consistent Riemannian setting, we construct a framework that reliably handles large deformations. Due to the explicit character of Lie group operations, our non-Euclidean method is very efficient allowing for fast and numerically robust processing. This facilitates Riemannian analysis of large shape populations accessible through longitudinal and multi-site imaging studies providing increased statistical power. We evaluate the performance of our model w.r.t. shape-based classification of pathological malformations of the human knee and show that it outperforms the standard Euclidean as well as a recent nonlinear approach especially in presence of sparse training data. To provide insight into the model's ability of capturing natural biological shape variability, we carry out an analysis of specificity and generalization ability. T3 - ZIB-Report - 19-20 KW - Statistical shape analysis KW - Principal geodesic analysis KW - Lie groups KW - Classification KW - Manifold valued statistics Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-74497 SN - 1438-0064 ER - TY - GEN A1 - Ambellan, Felix A1 - Zachow, Stefan A1 - von Tycowicz, Christoph T1 - An as-invariant-as-possible GL+(3)-based Statistical Shape Model N2 - We describe a novel nonlinear statistical shape model basedon differential coordinates viewed as elements of GL+(3). We adopt an as-invariant-as possible framework comprising a bi-invariant Lie group mean and a tangent principal component analysis based on a unique GL+(3)-left-invariant, O(3)-right-invariant metric. Contrary to earlier work that equips the coordinates with a specifically constructed group structure, our method employs the inherent geometric structure of the group-valued data and therefore features an improved statistical power in identifying shape differences. We demonstrate this in experiments on two anatomical datasets including comparison to the standard Euclidean as well as recent state-of-the-art nonlinear approaches to statistical shape modeling. T3 - ZIB-Report - 19-46 KW - Statistical shape analysis KW - Tangent principal component analysis KW - Lie groups KW - Classification KW - Manifold valued statistics Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-74566 SN - 1438-0064 ER -