TY - JOUR A1 - Zeilhofer, Hans-Florian A1 - Zachow, Stefan A1 - Fairley, Jeffrey A1 - Sader, Robert A1 - Deuflhard, Peter T1 - Treatment Planning and Simulation in Craniofacial Surgery with Virtual Reality Techiques JF - Journal of Cranio-Maxillofacial Surgery Y1 - 2000 VL - 28 (Suppl. 1) SP - 82 ER - TY - JOUR A1 - Campoli, Gianni A1 - Baka, Nora A1 - Kaptein, Bart A1 - Valstar, Edward A1 - Zachow, Stefan A1 - Weinans, Harrie A1 - Zadpoor, Amir Abbas T1 - Relationship between the shape and density distribution of the femur and its natural frequencies of vibration JF - Journal of Biomechanics N2 - It has been recently suggested that mechanical loads applied at frequencies close to the natural frequencies of bone could enhance bone apposition due to the resonance phenomenon. Other applications of bone modal analysis are also suggested. For the above-mentioned applications, it is important to understand how patient-specific bone shape and density distribution influence the natural frequencies of bones. We used finite element models to study the effects of bone shape and density distribution on the natural frequencies of the femur in free boundary conditions. A statistical shape and appearance model that describes shape and density distribution independently was created, based on a training set of 27 femora. The natural frequencies were then calculated for different shape modes varied around the mean shape while keeping the mean density distribution, for different appearance modes around the mean density distribution while keeping the mean bone shape, and for the 27 training femora. Single shape or appearance modes could cause up to 15% variations in the natural frequencies with certain modes having the greatest impact. For the actual femora, shape and density distribution changed the natural frequencies by up to 38%. First appearance mode that describes the general cortical bone thickness and trabecular bone density had one of the strongest impacts. The first appearance mode could therefore provide a sensitive measure of general bone health and disease progression. Since shape and density could cause large variations in the calculated natural frequencies, patient-specific FE models are needed for accurate estimation of bone natural frequencies. Y1 - 2014 U6 - https://doi.org/10.1016/j.jbiomech.2014.08.008 VL - 47 SP - 3334 EP - 3343 PB - Elsevier ER - TY - JOUR A1 - Hochfeld, Mascha A1 - Lamecker, Hans A1 - Thomale, Ulrich W. A1 - Schulz, Matthias A1 - Zachow, Stefan A1 - Haberl, Hannes T1 - Frame-based cranial reconstruction JF - Journal of Neurosurgery: Pediatrics N2 - The authors report on the first experiences with the prototype of a surgical tool for cranial remodeling. The device enables the surgeon to transfer statistical information, represented in a model, into the disfigured bone. The model is derived from a currently evolving databank of normal head shapes. Ultimately, the databank will provide a set of standard models covering the statistical range of normal head shapes, thus providing the required template for any standard remodeling procedure as well as customized models for intended overcorrection. To date, this technique has been used in the surgical treatment of 14 infants (age range 6-12 months) with craniosynostosis. In all 14 cases, the designated esthetic result, embodied by the selected model, has been achieved, without morbidity or mortality. Frame-based reconstruction provides the required tools to precisely realize the surgical reproduction of the model shape. It enables the establishment of a self-referring system, feeding back postoperative growth patterns, recorded by 3D follow-up, into the model design. Y1 - 2014 U6 - https://doi.org/10.3171/2013.11.PEDS1369 VL - 13 IS - 3 SP - 319 EP - 323 ER - TY - CHAP A1 - Joachimsky, Robert A1 - Ambellan, Felix A1 - Zachow, Stefan T1 - Computerassistierte Auswahl und Platzierung von interpositionalen Spacern zur Behandlung früher Gonarthrose T2 - Proceedings of the Jahrestagung der Deutschen Gesellschaft für Computer- und Roboterassistierte Chirurgie (CURAC) N2 - Degenerative Gelenkerkrankungen, wie die Osteoarthrose, sind ein häufiges Krankheitsbild unter älteren Erwachsenen. Hierbei verringert sich u.a. der Gelenkspalt aufgrund degenerierten Knorpels oder geschädigter Menisci. Ein in den Gelenkspalt eingebrachter interpositionaler Spacer soll die mit der Osteoarthrose einhergehende verringerte Gelenkkontaktfläche erhöhen und so der teilweise oder vollständige Gelenkersatz hinausgezögert oder vermieden werden. In dieser Arbeit präsentieren wir eine Planungssoftware für die Auswahl und Positionierung eines interpositionalen Spacers am Patientenmodell. Auf einer MRT-basierten Bildsegmentierung aufbauend erfolgt eine geometrische Rekonstruktion der 3D-Anatomie des Kniegelenks. Anhand dieser wird der Gelenkspalt bestimmt, sowie ein Spacer ausgewählt und algorithmisch vorpositioniert. Die Positionierung des Spacers ist durch den Benutzer jederzeit interaktiv anpassbar. Für jede Positionierung eines Spacers wird ein Fitness-Wert zur Knieanatomie des jeweiligen Patienten berechnet und den Nutzern Rückmeldung hinsichtlich Passgenauigkeit gegeben. Die Software unterstützt somit als Entscheidungshilfe die behandelnden Ärzte bei der patientenspezifischen Spacerauswahl. KW - Osteoarthrose KW - Kniegelenk KW - Medizinische Planung KW - Visualisierung Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-65321 VL - 16 SP - 106 EP - 111 ER - TY - JOUR A1 - Hoffmann, René A1 - Lemanis, Robert A1 - Falkenberg, Janina A1 - Schneider, Steffen A1 - Wesendonk, Hendrik A1 - Zachow, Stefan T1 - Integrating 2D and 3D shell morphology to disentangle the palaeobiology of ammonoids: A virtual approach JF - Palaeontology N2 - We demonstrate, based on data derived from computed tomography, that integrating 2D and 3D morphological data of ammonoid shells represent an important new approach to disentangle the palaeobiology of ammonoids. Characterization of ammonite morphology has long been constrained to 2D data and only a few studies collect ontogenetic data in 180° steps. We combine this traditional approach with 3D data collected from high-resolution nano-computed tomography. For this approach, ontogenetic morphological data of the hollow shell of a juvenile ammonite Kosmoceras (Jurassic, Callovian) is collected. 2D data is collected in 10° steps and show significant changes in shell morphology. Preserved hollow spines show multiple mineralized membranes never reported before, representing temporal changes of the ammonoid mantle tissue. 3D data show that chamber volumes do not always increase exponentially, as was generally assumed, but may represent a proxy for life events, e.g. stress phases. Furthermore, chamber volume cannot be simply derived from septal spacing in forms comparable to Kosmoceras. Vogel numbers, a 3D parameter for chamber shape, of Kosmoceras are similar to other ammonoids (Arnsbergites, Amauroceras) and modern cephalopods (Nautilus, Spirula). Two methods to virtually document the suture line ontogeny, used to document phylogenetic relationships of larger taxonomic entities, were applied for the first time and seem a promising alternative to hand drawings. The curvature of the chamber surfaces increases during ontogeny due to increasing strength of ornamentation and septal complexity. As increasing curvature may allow for faster handling of cameral liquid, it could compensate for decreasing SA/V ratios through ontogeny. Y1 - 2017 UR - http://dx.doi.org/10.1111/pala.12328 U6 - https://doi.org/10.1111/pala.12328 VL - 61 IS - 1 SP - 89 EP - 104 ER - TY - JOUR A1 - Moldenhauer, Marian A1 - Weiser, Martin A1 - Zachow, Stefan T1 - Adaptive Algorithms for Optimal Hip Implant Positioning JF - PAMM N2 - In an aging society where the number of joint replacements rises, it is important to also increase the longevity of implants. In particular hip implants have a lifetime of at most 15 years. This derives primarily from pain due to implant migration, wear, inflammation, and dislocation, which is affected by the positioning of the implant during the surgery. Current joint replacement practice uses 2D software tools and relies on the experience of surgeons. Especially the 2D tools fail to take the patients’ natural range of motion as well as stress distribution in the 3D joint induced by different daily motions into account. Optimizing the hip joint implant position for all possible parametrized motions under the constraint of a contact problem is prohibitively expensive as there are too many motions and every position change demands a recalculation of the contact problem. For the reduction of the computational effort, we use adaptive refinement on the parameter domain coupled with the interpolation method of Kriging. A coarse initial grid is to be locally refined using goal-oriented error estimation, reducing locally high variances. This approach will be combined with multi-grid optimization such that numerical errors are reduced. Y1 - 2017 U6 - https://doi.org/10.1002/pamm.201710071 VL - 17 IS - 1 SP - 203 EP - 204 ER - TY - CHAP A1 - Ambellan, Felix A1 - Tack, Alexander A1 - Wilson, Dave A1 - Anglin, Carolyn A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Evaluating two methods for Geometry Reconstruction from Sparse Surgical Navigation Data T2 - Proceedings of the Jahrestagung der Deutschen Gesellschaft für Computer- und Roboterassistierte Chirurgie (CURAC) N2 - In this study we investigate methods for fitting a Statistical Shape Model (SSM) to intraoperatively acquired point cloud data from a surgical navigation system. We validate the fitted models against the pre-operatively acquired Magnetic Resonance Imaging (MRI) data from the same patients. We consider a cohort of 10 patients who underwent navigated total knee arthroplasty. As part of the surgical protocol the patients’ distal femurs were partially digitized. All patients had an MRI scan two months pre-operatively. The MRI data were manually segmented and the reconstructed bone surfaces used as ground truth against which the fit was compared. Two methods were used to fit the SSM to the data, based on (1) Iterative Closest Points (ICP) and (2) Gaussian Mixture Models (GMM). For both approaches, the difference between model fit and ground truth surface averaged less than 1.7 mm and excellent correspondence with the distal femoral morphology can be demonstrated. KW - Total Knee Arthoplasty KW - Sparse Geometry Reconstruction KW - Statistical Shape Models Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-65339 VL - 16 SP - 24 EP - 30 ER - TY - JOUR A1 - von Tycowicz, Christoph A1 - Ambellan, Felix A1 - Mukhopadhyay, Anirban A1 - Zachow, Stefan T1 - An Efficient Riemannian Statistical Shape Model using Differential Coordinates JF - Medical Image Analysis N2 - We propose a novel Riemannian framework for statistical analysis of shapes that is able to account for the nonlinearity in shape variation. By adopting a physical perspective, we introduce a differential representation that puts the local geometric variability into focus. We model these differential coordinates as elements of a Lie group thereby endowing our shape space with a non-Euclidean structure. A key advantage of our framework is that statistics in a manifold shape space becomes numerically tractable improving performance by several orders of magnitude over state-of-the-art. We show that our Riemannian model is well suited for the identification of intra-population variability as well as inter-population differences. In particular, we demonstrate the superiority of the proposed model in experiments on specificity and generalization ability. We further derive a statistical shape descriptor that outperforms the standard Euclidean approach in terms of shape-based classification of morphological disorders. Y1 - 2018 U6 - https://doi.org/10.1016/j.media.2017.09.004 VL - 43 IS - 1 SP - 1 EP - 9 ER - TY - JOUR A1 - Zinser, Max A1 - Zachow, Stefan A1 - Sailer, Hermann T1 - Bimaxillary "rotation advancement" procedures in patients with obstructive sleep apnea: A 3-dimensional airway analysis of morphological changes JF - International Journal of Oral & Maxillofacial Surgery Y1 - 2013 U6 - https://doi.org/10.1016/j.ijom.2012.08.002 VL - 42 IS - 5 SP - 569 EP - 578 ER - TY - GEN A1 - Deuflhard, Peter A1 - Zachow, Stefan T1 - Mathematische Therapie- und Operationsplanung Y1 - 2012 SP - 89 EP - 90 PB - Berliner Wirtschaftsgespräche e.V. CY - Berlin ER - TY - GEN A1 - Bindernagel, Matthias A1 - Kainmüller, Dagmar A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Analysis of inter-individual anatomical shape variations of joint structures T2 - Proc. Int. Society of Computer Assisted Orthopaedic Surgery (CAOS) Y1 - 2012 IS - 210 ER - TY - CHAP A1 - Nguyen, The Duy A1 - Lamecker, Hans A1 - Kainmüller, Dagmar A1 - Zachow, Stefan ED - Ayache, Nicholas ED - Delingette, Hervé ED - Golland, Polina ED - Mori, Kensaku T1 - Automatic Detection and Classification of Teeth in CT Data T2 - Proc. Medical Image Computing and Computer Assisted Intervention (MICCAI) Y1 - 2012 VL - 7510 SP - 609 EP - 616 ER - TY - JOUR A1 - Nguyen, The Duy A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Automatic bone and tooth detection for CT-based dental implant planning JF - Int. J. Computer Assisted Radiology and Surgery Y1 - 2012 VL - 7, Supplement 1 IS - 1 SP - 293 EP - 294 PB - Springer ER - TY - CHAP A1 - Lamecker, Hans A1 - Zöckler, Maja A1 - Haberl, Hannes A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - Statistical shape modeling for craniosynostosis planning T2 - 2nd International Conference Advanced Digital Technology in Head and Neck Reconstruction 2005, Abstract Volume Y1 - 2005 SP - 64 CY - Banff, Alberta ER - TY - JOUR A1 - Westermark, Anders A1 - Zachow, Stefan A1 - Eppley, Barry T1 - 3D osteotomy planning in maxillofacial surgery, including 3D soft tissue prediction JF - Journal of Craniofacial Surgery Y1 - 2005 VL - 16(1) SP - 100 EP - 104 ER - TY - JOUR A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Maxillofacial surgery planning with 3D soft tissue prediction - modeling, planning, simulation JF - 2. Int. Conf. on Advanced Digital Technology in Head and Neck Reconstruction, Abstract 33 Y1 - 2005 SP - 64 CY - Banff, Alberta, CA ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian ED - Galloway, Robert T1 - Realistic prediction of individual facial emotion expressions for craniofacial surgery simulations T2 - Proc. SPIE medical Imaging 2003 Y1 - 2003 U6 - https://doi.org/10.1117/12.479584 VL - 5029 SP - 520 EP - 527 CY - San Diego, CA, USA ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian T1 - On constitutive modeling of soft tissue for the long-term prediction of cranio-maxillofacial surgery outcome T2 - International Congress Series, CARS2003, Computer Assisted Radiology and Surgery, Proceedings of the 17th International Congress and Exhibition Y1 - 2003 U6 - https://doi.org/10.1016/S0531-5131(03)00500-4 VL - 1256 SP - 343 EP - 348 ER - TY - CHAP A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Sader, Robert A1 - Zeilhofer, Hans-Florian T1 - Draw & Cut: Intuitive 3D Osteotomy Planning on Polygonal Bone Models T2 - Computer Assisted Radiology and Surgery (CARS) Y1 - 2003 U6 - https://doi.org/10.1016/S0531-5131(03)00272-3 SP - 362 EP - 369 CY - London, UK ER - TY - CHAP A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Computergestützte Operationsplanung in der Gesichtschirurgie T2 - Proc. VDE Kongress 2004 - Innovationen für Menschen, Band 2, Fachtagungsberichte DGBMT - GMM - GMA Y1 - 2004 SP - 53 EP - 58 ER - TY - CHAP A1 - Zachow, Stefan A1 - Hierl, Thomas A1 - Erdmann, Bodo T1 - A quantitative evaluation of 3D soft tissue prediction in maxillofacial surgery planning T2 - Proc. 3. Jahrestagung der Deutschen Gesellschaft für Computer- und Roboter-assistierte Chirurgie e.V. Y1 - 2004 CY - München ER - TY - JOUR A1 - Hierl, Thomas A1 - Zachow, Stefan A1 - Wollny, Gert A1 - Berti, Guntram A1 - Schmidt, Jens-Georg A1 - Fingberg, Jochen T1 - Computer-based simulation in distraction osteogenesis JF - Proc. of 3rd Int. Oxford Distraction Symposium of the Craniofacial Skeleton Y1 - 2004 SP - 33 EP - 34 ER - TY - JOUR A1 - Hierl, Thomas A1 - Zachow, Stefan A1 - Wollny, Gert A1 - Berti, Guntram A1 - Schmidt, Jens-Georg A1 - Fingberg, Jochen T1 - Concepts of computer-based simulation in orthognathic surgery JF - Journal of Cranio-Maxillofacial Surgery 32 Suppl. 1 Y1 - 2004 SP - 81 EP - 82 ER - TY - JOUR A1 - Haberl, Hannes A1 - Hell, Bertold A1 - Zöckler, Maja A1 - Zachow, Stefan A1 - Lamecker, Hans A1 - Sarrafzadeh, Asita A1 - Riecke, B. A1 - Langsch, Wolfgang A1 - Deuflhard, Peter A1 - Bier, Jürgen A1 - Brock, Mario T1 - Technical aspects and results of surgery for craniosynostosis JF - Zentralblatt für Neurochirurgie Y1 - 2004 VL - 65 IS - 2 SP - 65 EP - 74 ER - TY - JOUR A1 - Nkenke, Emeka A1 - Zachow, Stefan A1 - Benz, Michaela A1 - Maier, Tobias A1 - Veit, Klaus A1 - Kramer, Manuel A1 - Benz, St. A1 - Häusler, Gerd A1 - Neukam, Friedrich A1 - Lell, Michael T1 - Fusion of computed tomography data and optical 3D images of the dentition for streak artefact correction in the simulation of orthognathic surgery JF - Journal of Dento-Maxillofacial Radiology Y1 - 2004 U6 - https://doi.org/10.1259/dmfr/27071199 VL - 33 SP - 226 EP - 232 ER - TY - CHAP A1 - Zachow, Stefan A1 - Hierl, Thomas A1 - Erdmann, Bodo T1 - On the Predictability of tissue changes after osteotomy planning in maxillofacial surgery T2 - Computer Assisted Radiology and Surgery (CARS) Y1 - 2004 U6 - https://doi.org/10.1016/j.ics.2004.03.043 SP - 648 EP - 653 CY - Chicago, USA ER - TY - CHAP A1 - Zachow, Stefan A1 - Hierl, Thomas A1 - Erdmann, Bodo T1 - Über die Genauigkeit einer 3D Weichgewebeprädiktion in der MKG-Cirurgie T2 - Workshop ’Bildverarbeitung für die Medizin’ (BVM) Y1 - 2004 SP - 75 EP - 79 CY - Berlin, Germany ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian ED - K. Mun, Seong T1 - Adaptive Nonlinear Elastic FEM for Realistic Prediction of Soft Tissue in Craniofacial Surgery Simulations T2 - Proc. SPIE Medical Imaging 2002 Y1 - 2002 U6 - https://doi.org/10.1117/12.466906 VL - 4681 SP - 1 EP - 8 CY - San Diego, USA ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian ED - Mun, Seong T1 - Shape-based Modeling Approach for the Estimation of Individual Facial Mimics in Craniofacial Surgery Planning T2 - Proc. SPIE Medical Imaging 2002: Visualization, Image-Guided Procedures, and Display Y1 - 2002 VL - 4681 SP - 242 EP - 248 CY - San Diego, USA target ER - TY - CHAP A1 - Hege, Hans-Christian A1 - Schirmacher, Hartmut A1 - Westerhoff, Malte A1 - Lamecker, Hans A1 - Prohaska, Steffen A1 - Zachow, Stefan T1 - From Image Data to Three-Dimensional Models - Case Studies on the Impact of 3D Patient Models T2 - Proceedings of the Japan Korea Computer Graphics Conference 2002 Y1 - 2002 PB - Kanazawa University CY - Kanazawa City, Ishikawa, Japan ER - TY - CHAP A1 - Hierl, Thomas A1 - Wollny, Gert A1 - Zachow, Stefan A1 - Klöppel, Rainer T1 - Visualisierung von Knochen und Weichteilveränderungen in der Distraktionsosteogenese des Mittelgesichtes T2 - Proc. 10. Jahrestagung der Deutschen Gesellschaft für Schädelbasischirurgie Y1 - 2002 SP - 111 EP - 116 CY - Heidelberg ER - TY - CHAP A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Towards Patient Specific, Anatomy Based Simulation of Facial Mimics for Surgical Nerve Rehabilitation T2 - Computer Assisted Radiology and Surgery (CARS) Y1 - 2002 SP - 3 EP - 6 PB - Springer Verlag ER - TY - JOUR A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian T1 - Anatomy- and physics-based facial animation for craniofacial surgery simulations JF - Med Biol Eng Comput. Y1 - 2004 U6 - https://doi.org/10.1007/BF02344627 VL - 42(2) SP - 167 EP - 170 ER - TY - CHAP A1 - Zachow, Stefan A1 - Erdmann, Bodo A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Advances in 3D osteotomy planning with 3D soft tissue prediction T2 - Proc. 2nd International Symposium on Computer Aided Surgery around the Head, Abstract Y1 - 2004 SP - 31 CY - Bern ER - TY - CHAP A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Finite-Element Simulation of Soft Tissue Deformation T2 - Computer Assisted Radiology and Surgey (CARS) Y1 - 2000 SP - 23 EP - 28 PB - Elsevier Science B.V. ER - TY - JOUR A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Trepczynski, Adam A1 - Sader, Robert A1 - Zeilhofer, Hans-Florian T1 - 3D Osteotomy Planning in Cranio-Maxillofacial Surgery: Experiences and Results of Surgery Planning and Volumetric Finite-Element Soft Tissue Prediction in Three Clinical Cases JF - Computer Assisted Radiology and Surgery (CARS) Y1 - 2002 SP - 983 EP - 987 PB - Springer Verlag ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Towards a Realistic Simulation of Individual Facial Mimics T2 - Vision Modeling and Visualization 2001 (VMV) Y1 - 2001 SP - 129 EP - 134 CY - Stuttgart, Germany ER - TY - CHAP A1 - Stalling, Detlev A1 - Seebaß, Martin A1 - Zachow, Stefan T1 - Mehrschichtige Oberflächenmodelle zur computergestützten Planung in der Chirurgie T2 - Bildverarbeitung für die Medizin 1999 - Algorithmen, Anwendungen Y1 - 1999 SP - 203 EP - 207 PB - Springer-Verlag, Berlin ER - TY - CHAP A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Zeilhofer, Hans-Florian A1 - Sader, Robert T1 - Improved 3D Osteotomy Planning in Cranio-Maxillofacial Surgery T2 - Proc. Medical Image Computing and Computer-Assisted Intervention (MICCAI 2001) Y1 - 2001 U6 - https://doi.org/10.1007/3-540-45468-3_57 SP - 473 EP - 481 CY - Utrecht, The Netherlands ER - TY - CHAP A1 - Zachow, Stefan A1 - Gladilin, Evgeny A1 - Zeilhofer, Hans-Florian A1 - Sader, Robert T1 - 3D Osteotomieplanung in der MKG-Chirurgie unter Berücksichtigung der räumlichen Weichgewebeanordnung T2 - Rechner- und sensorgestützte Chirurgie, GI Proc. zur SFB 414 Tagung Y1 - 2001 SP - 217 EP - 226 CY - Heidelberg ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian T1 - A Biomechanical Model for Soft Tissue Simulation in Craniofacial Surgery T2 - Medical Imaging and Augmented Reality (MIAR) Y1 - 2001 U6 - https://doi.org/10.1109/MIAR.2001.930276 SP - 137 EP - 141 CY - Hong Kong, China ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian T1 - Virtual Fibers: A Robust Approach for Muscle Simulation T2 - IX Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON) Y1 - 2001 SP - 961 EP - 964 CY - Pula, Croatia ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian T1 - Validierung eines linear elastischen Modells für die Weichgewebesimulation in der Mund-Kiefer-Gesichtschirurgie T2 - Bildverarbeitung für die Medizin (BVM) Y1 - 2001 SP - 57 EP - 61 CY - Lübeck, Germany ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Deuflhard, Peter A1 - Hege, Hans-Christian ED - Mun, Seong T1 - Validation of a Linear Elastic Model for Soft Tissue Simulation in Craniofacial Surgery T2 - Proc. SPIE Medical Imaging 2001 Y1 - 2001 U6 - https://doi.org/10.1117/12.428061 VL - 4319 SP - 27 EP - 35 CY - San Diego, USA ER - TY - CHAP A1 - Gladilin, Evgeny A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - FE-based heuristic approach for the estimation of person-specific facial mimics T2 - Proceedings of Euro-Par 2001: 5-th International Symposium on Computer Methods Y1 - 2001 CY - Rome, Italy ER - TY - CHAP A1 - Zachow, Stefan A1 - Lueth, Tim A1 - Stalling, Detlev A1 - Hein, Andreas A1 - Klein, Martin A1 - Menneking, Horst T1 - Optimized Arrangement of Osseointegrated Implants: A Surgical Planning System for the Fixation of Facial Protheses T2 - Computer Assisted Radiology and Surgery (CARS’99) Y1 - 1999 SP - 942 EP - 946 PB - Elsevier Science B.V. ER - TY - CHAP A1 - Hein, Andreas A1 - Lueth, Tim A1 - Zachow, Stefan A1 - Stien, Malte T1 - A 2D Planning Sytem for Robot-Assisted Interventions T2 - Computer Assisted Radiology and Surgery Y1 - 1999 SP - 1049 PB - Elsevier Science B.V. ER - TY - JOUR A1 - Ehlke, Moritz A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Hege, Hans-Christian A1 - Zachow, Stefan T1 - Fast Generation of Virtual X-ray Images for Reconstruction of 3D Anatomy JF - IEEE Transactions on Visualization and Computer Graphics Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-35928 VL - 19 IS - 12 SP - 2673 EP - 2682 ER - TY - THES A1 - Zachow, Stefan T1 - Design and Implementation of a planning system for episthetic surgery T2 - Entwurf und Implementierung eines chirurgischen Planungssystems für Einsatz in der Epithetik Y1 - 1999 ER - TY - THES A1 - Zachow, Stefan T1 - Computer assisted osteotomy planning in cranio-maxillofacial surgery under consideration of facial soft tissue changes T2 - Computergestützte Osteotomieplanung in der Mund-Kiefer-Gesichtschirurgie unter Berücksichtigung der räumlichen Weichgewebeanordnung Y1 - 2005 UR - www.dr.hut-verlag.de/titelMedizininformatik.html ER - TY - CHAP A1 - Hoffmann, René A1 - Zachow, Stefan T1 - Non-invasive approach to shed new light on the buoyancy business of chambered cephalopods (Mollusca) T2 - Proc. of the Intl. Assoc. for Mathematical Geosciences, Salzburg Y1 - 2011 U6 - https://doi.org/10.5242/iamg.2011.0163 SP - 1 EP - 11 ER - TY - JOUR A1 - Rybak, Jürgen A1 - Kuß, Anja A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Lienhard, Matthias A1 - Singer, Jochen A1 - Neubert, Kerstin A1 - Menzel, Randolf T1 - The Digital Bee Brain: Integrating and Managing Neurons in a Common 3D Reference System JF - Front. Syst. Neurosci. Y1 - 2010 U6 - https://doi.org/10.3389/fnsys.2010.00030 VL - 4 IS - 30 ER - TY - JOUR A1 - Galloway, Francis A1 - Kahnt, Max A1 - Ramm, Heiko A1 - Worsley, Peter A1 - Zachow, Stefan A1 - Nair, Prasanth A1 - Taylor, Mark T1 - A large scale finite element study of a cementless osseointegrated tibial tray JF - Journal of Biomechanics Y1 - 2013 U6 - https://doi.org//10.1016/j.jbiomech.2013.04.021 VL - 46 IS - 11 SP - 1900 EP - 1906 ER - TY - JOUR A1 - Zachow, Stefan A1 - Lamecker, Hans A1 - Zöckler, Maja A1 - Haberl, Ernst T1 - Computergestützte Planung zur chirurgischen Korrektur von frühkindlichen Schädelfehlbildungen (Craniosynostosen) JF - Face 02/09, Int. Mag. of Orofacial Esthetics, Oemus Journale Leipzig Y1 - 2009 SP - 48 EP - 53 ER - TY - JOUR A1 - Zahn, Robert A1 - Grotjohann, Sarah A1 - Ramm, Heiko A1 - Zachow, Stefan A1 - Pumberger, Matthias A1 - Putzier, Michael A1 - Perka, Carsten A1 - Tohtz, Stephan T1 - Influence of pelvic tilt on functional acetabular orientation JF - Technology and Health Care Y1 - 2016 U6 - https://doi.org/10.3233/THC-161281 VL - 25 IS - 3 SP - 557 EP - 565 PB - IOS Press ER - TY - JOUR A1 - Lemanis, Robert A1 - Korn, Dieter A1 - Zachow, Stefan A1 - Rybacki, Erik A1 - Hoffmann, René T1 - The Evolution and Development of Cephalopod Chambers and Their Shape JF - PLOS ONE N2 - The Ammonoidea is a group of extinct cephalopods ideal to study evolution through deep time. The evolution of the planispiral shell and complexly folded septa in ammonoids has been thought to have increased the functional surface area of the chambers permitting enhanced metabolic functions such as: chamber emptying, rate of mineralization and increased growth rates throughout ontogeny. Using nano-computed tomography and synchrotron radiation based micro-computed tomography, we present the first study of ontogenetic changes in surface area to volume ratios in the phragmocone chambers of several phylogenetically distant ammonoids and extant cephalopods. Contrary to the initial hypothesis, ammonoids do not possess a persistently high relative chamber surface area. Instead, the functional surface area of the chambers is higher in earliest ontogeny when compared to Spirula spirula. The higher the functional surface area the quicker the potential emptying rate of the chamber; quicker chamber emptying rates would theoretically permit faster growth. This is supported by the persistently higher siphuncular surface area to chamber volume ratio we collected for the ammonite Amauroceras sp. compared to either S. spirula or nautilids. We demonstrate that the curvature of the surface of the chamber increases with greater septal complexity increasing the potential refilling rates. We further show a unique relationship between ammonoid chamber shape and size that does not exist in S. spirula or nautilids. This view of chamber function also has implications for the evolution of the internal shell of coleoids, relating this event to the decoupling of soft-body growth and shell growth. Y1 - 2016 U6 - https://doi.org/10.1371/journal.pone.0151404 VL - 11 IS - 3 ER - TY - JOUR A1 - Dunlop, Jason A1 - Apanaskevich, Dmitry A1 - Lehmann, Jens A1 - Hoffmann, Rene A1 - Fusseis, Florian A1 - Ehlke, Moritz A1 - Zachow, Stefan A1 - Xiao, Xianghui T1 - Microtomography of the Baltic amber tick Ixodes succineus reveals affinities with the modern Asian disease vector Ixodes ovatus JF - BMC Evolutionary Biology N2 - Background: Fossil ticks are extremely rare, whereby Ixodes succineus Weidner, 1964 from Eocene (ca. 44-49 Ma) Baltic amber is one of the oldest examples of a living hard tick genus (Ixodida: Ixodidae). Previous work suggested it was most closely related to the modern and widespread European sheep tick Ixodes ricinus (Linneaus, 1758). Results: Restudy using phase contrast synchrotron x-ray tomography yielded images of exceptional quality. These confirm the fossil's referral to Ixodes Latreille, 1795, but the characters resolved here suggest instead affinities with the Asian subgenus Partipalpiger Hoogstraal et al., 1973 and its single living (and medically significant) species Ixodes ovatus Neumann, 1899. We redescribe the amber fossil here as Ixodes (Partipalpiger) succineus. Conclusions: Our data suggest that Ixodes ricinus is unlikely to be directly derived from Weidner's amber species, but instead reveals that the Partipalpiger lineage was originally more widely distributed across the northern hemisphere. The closeness of Ixodes (P.) succineus to a living vector of a wide range of pathogens offers the potential to correlate its spatial and temporal position (northern Europe, nearly 50 million years ago) with the estimated origination dates of various tick-borne diseases. Y1 - 2016 U6 - https://doi.org/10.1186/s12862-016-0777-y VL - 16 IS - 1 ER - TY - JOUR A1 - Bernard, Florian A1 - Salamanca, Luis A1 - Thunberg, Johan A1 - Tack, Alexander A1 - Jentsch, Dennis A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hertel, Frank A1 - Goncalves, Jorge A1 - Gemmar, Peter T1 - Shape-aware Surface Reconstruction from Sparse Data JF - arXiv N2 - The reconstruction of an object's shape or surface from a set of 3D points is a common topic in materials and life sciences, computationally handled in computer graphics. Such points usually stem from optical or tactile 3D coordinate measuring equipment. Surface reconstruction also appears in medical image analysis, e.g. in anatomy reconstruction from tomographic measurements or the alignment of intra-operative navigation and preoperative planning data. In contrast to mere 3D point clouds, medical imaging yields contextual information on the 3D point data that can be used to adopt prior information on the shape that is to be reconstructed from the measurements. In this work we propose to use a statistical shape model (SSM) as a prior for surface reconstruction. The prior knowledge is represented by a point distribution model (PDM) that is associated with a surface mesh. Using the shape distribution that is modelled by the PDM, we reformulate the problem of surface reconstruction from a probabilistic perspective based on a Gaussian Mixture Model (GMM). In order to do so, the given measurements are interpreted as samples of the GMM. By using mixture components with anisotropic covariances that are oriented according to the surface normals at the PDM points, a surface-based tting is accomplished. By estimating the parameters of the GMM in a maximum a posteriori manner, the reconstruction of the surface from the given measurements is achieved. Extensive experiments suggest that our proposed approach leads to superior surface reconstructions compared to Iterative Closest Point (ICP) methods. Y1 - 2016 SP - 1602.08425v1 ER - TY - JOUR A1 - Lemanis, Robert A1 - Zachow, Stefan A1 - Hoffmann, René T1 - Comparative cephalopod shell strength and the role of septum morphology on stress distribution JF - PeerJ N2 - The evolution of complexly folded septa in ammonoids has long been a controversial topic. Explanations of the function of these folded septa can be divided into physiological and mechanical hypotheses with the mechanical functions tending to find widespread support. The complexity of the cephalopod shell has made it difficult to directly test the mechanical properties of these structures without oversimplification of the septal morphology or extraction of a small sub-domain. However, the power of modern finite element analysis now permits direct testing of mechanical hypothesis on complete, empirical models of the shells taken from computed tomographic data. Here we compare, for the first time using empirical models, the capability of the shells of extant Nautilus pompilius, Spirula spirula, and the extinct ammonite Cadoceras sp. to withstand hydrostatic pressure and point loads. Results show hydrostatic pressure imparts highest stress on the final septum with the rest of the shell showing minimal compression. S. spirula shows the lowest stress under hydrostatic pressure while N. pompilius shows the highest stress. Cadoceras sp. shows the development of high stress along the attachment of the septal saddles with the shell wall. Stress due to point loads decreases when the point force is directed along the suture as opposed to the unsupported chamber wall. Cadoceras sp. shows the greatest decrease in stress between the point loads compared to all other models. Greater amplitude of septal flutes corresponds with greater stress due to hydrostatic pressure; however, greater amplitude decreases the stress magnitude of point loads directed along the suture. In our models, sutural complexity does not predict greater resistance to hydrostatic pressure but it does seem to increase resistance to point loads, such as would be from predators. This result permits discussion of palaeoecological reconstructions on the basis of septal morphology. We further suggest that the ratio used to characterize septal morphology in the septal strength index and in calculations of tensile strength of nacre are likely insufficient. A better understanding of the material properties of cephalopod nacre may allow the estimation of maximum depth limits of shelled cephalopods through finite element analysis. Y1 - 2016 U6 - https://doi.org/10.7717/peerj.2434 VL - 4 SP - e2434 ER - TY - JOUR A1 - Brüning, Jan A1 - Goubergrits, Leonid A1 - Heppt, Werner A1 - Zachow, Stefan A1 - Hildebrandt, Thomas T1 - Numerical Analysis of Nasal Breathing - A Pilot Study JF - Facial Plastic Surgery N2 - Background: Currently, there is no fully sufficient way to differentiate between symptomatic and normal nasal breathing. Using the nose’s total resistance is disputed as a valid means to objectify nasal airflow, and the need for a more comprehensive diagnostic method is increasing. This work’s aim was to test a novel approach considering intranasal wall shear stress as well as static pressure maps obtained by computational fluid dynamics (CFD). Methods: X-ray computed tomography (CT) scan data of six symptom-free subjects and seven symptomatic patients were used. Patient-specific geometries of the nasal cavity were segmented from these data sets. Inspiratory and expiratory steady airflow simulations were performed using CFD. Calculated static pressures and wall shear stresses (WSS) were mapped onto a common template of the nasal septum, allowing for comparison of these parameters between the two patient groups. Results: Significant differences in wall shear stress distributions during the inspiratory phase could be identified between the two groups, whereas no differences were found for the expiratory phase. It is assumed that one essential feature of normal nasal breathing probably consists in distinctively different intranasal flow fields for inspiration and expiration. This is in accordance with previous investigations. Conclusion: The proposed method seems to be a promising tool for developing a new kind of patient-specific assessment of nasal breathing. However, more studies and a greater case number of data with an expanded focus, would be ideal. Y1 - 2017 U6 - https://doi.org/doi:10.1055/s-0037-1603789 VL - 33 IS - 4 SP - 388 EP - 395 ER - TY - GEN A1 - Weiser, Martin A1 - Erdmann, Bodo A1 - Schenkl, Sebastian A1 - Muggenthaler, Holger A1 - Hubig, Michael A1 - Mall, Gita A1 - Zachow, Stefan T1 - Uncertainty in Temperature-Based Determination of Time of Death N2 - Temperature-based estimation of time of death (ToD) can be per- formed either with the help of simple phenomenological models of corpse cooling or with detailed mechanistic (thermodynamic) heat transfer mod- els. The latter are much more complex, but allow a higher accuracy of ToD estimation as in principle all relevant cooling mechanisms can be taken into account. The potentially higher accuracy depends on the accuracy of tissue and environmental parameters as well as on the geometric resolution. We in- vestigate the impact of parameter variations and geometry representation on the estimated ToD based on a highly detailed 3D corpse model, that has been segmented and geometrically reconstructed from a computed to- mography (CT) data set, differentiating various organs and tissue types. From that we identify the most crucial parameters to measure or estimate, and obtain a local uncertainty quantifcation for the ToD. T3 - ZIB-Report - 17-18 KW - forensic medicine KW - determination of time of death KW - heat transfer equation KW - sensitivity i.r.t. thermal parameters KW - sensitivity i.r.t. geometric resolution Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-63818 SN - 1438-0064 ER - TY - CHAP A1 - Baum, Daniel A1 - Mahlow, Kristin A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Müller, Johannes A1 - Hege, Hans-Christian T1 - The Potential of Surface-based Geometric Morphometrics for Evolutionary Studies: An Example using Dwarf Snakes (Eirenis) T2 - Abstract in DigitalSpecimen 2014 N2 - Geometric morphometrics plays an important role in evolutionary studies. The state-of-the-art in this field are landmark-based methods. Since the landmarks usually need to be placed manually, only a limited number of landmarks are generally used to represent the shape of an anatomical structure. As a result, shape characteristics that cannot be properly represented by small sets of landmarks are disregarded. In this study, we present a method that is free of this limitation. The method takes into account the whole shape of an anatomical structure, which is represented as a surface, hence the term ‘surface-based morphometrics’. Correspondence between two surfaces is established by defining a partitioning of the surfaces into homologous surface patches. The first step for the generation of a surface partitioning is to place landmarks on the surface. Subsequently, the landmarks are connected by curves lying on the surface. The curves, called ‘surface paths’, might either follow specific anatomical features or they can be geodesics, that is, shortest paths on the surface. One important requirement, however, is that the resulting surface path networks are topologically equivalent across all surfaces. Once the surface path networks have been defined, the surfaces are decomposed into patches according to the path networks. This approach has several advantages. One of them is that we can discretize the surface by as many points as desired. Thus, even fine shape details can be resolved if this is of interest for the study. Since a point discretization is used, another advantage is that well-established analysis methods for landmark-based morphometrics can be utilized. Finally, the shapes can be easily morphed into one another, thereby greatly supporting the understanding of shape changes across all considered specimens. To show the potential of the described method for evolutionary studies of biological specimens, we applied the method to the para-basisphenoid complex of the snake genus Eirenis. By using this anatomical structure as example, we present all the steps that are necessary for surface-based morphometrics, including the segmentation of the para-basisphenoid complex from micro-CT data sets. We also show some first results using statistical analysis as well as classification methods based on the presented technique. Y1 - 2014 ER - TY - GEN A1 - Ambellan, Felix A1 - Tack, Alexander A1 - Wilson, Dave A1 - Anglin, Carolyn A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Evaluating two methods for Geometry Reconstruction from Sparse Surgical Navigation Data N2 - In this study we investigate methods for fitting a Statistical Shape Model (SSM) to intraoperatively acquired point cloud data from a surgical navigation system. We validate the fitted models against the pre-operatively acquired Magnetic Resonance Imaging (MRI) data from the same patients. We consider a cohort of 10 patients who underwent navigated total knee arthroplasty. As part of the surgical protocol the patients’ distal femurs were partially digitized. All patients had an MRI scan two months pre-operatively. The MRI data were manually segmented and the reconstructed bone surfaces used as ground truth against which the fit was compared. Two methods were used to fit the SSM to the data, based on (1) Iterative Closest Points (ICP) and (2) Gaussian Mixture Models (GMM). For both approaches, the difference between model fit and ground truth surface averaged less than 1.7 mm and excellent correspondence with the distal femoral morphology can be demonstrated. T3 - ZIB-Report - 17-71 KW - Knee Arthroplasty KW - Sparse Geometry Reconstruction KW - Statistical Shape Models Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-66052 SN - 1438-0064 ER - TY - GEN A1 - Joachimsky, Robert A1 - Ambellan, Felix A1 - Zachow, Stefan T1 - Computerassistierte Auswahl und Platzierung von interpositionalen Spacern zur Behandlung früher Gonarthrose N2 - Degenerative Gelenkerkrankungen, wie die Osteoarthrose, sind ein häufiges Krankheitsbild unter älteren Erwachsenen. Hierbei verringert sich u.a. der Gelenkspalt aufgrund degenerierten Knorpels oder geschädigter Menisci. Ein in den Gelenkspalt eingebrachter interpositionaler Spacer soll die mit der Osteoarthrose einhergehende verringerte Gelenkkontaktfläche erhöhen und so der teilweise oder vollständige Gelenkersatz hinausgezögert oder vermieden werden. In dieser Arbeit präsentieren wir eine Planungssoftware für die Auswahl und Positionierung eines interpositionalen Spacers am Patientenmodell. Auf einer MRT-basierten Bildsegmentierung aufbauend erfolgt eine geometrische Rekonstruktion der 3D-Anatomie des Kniegelenks. Anhand dieser wird der Gelenkspalt bestimmt, sowie ein Spacer ausgewählt und algorithmisch vorpositioniert. Die Positionierung des Spacers ist durch den Benutzer jederzeit interaktiv anpassbar. Für jede Positionierung eines Spacers wird ein Fitness-Wert zur Knieanatomie des jeweiligen Patienten berechnet und den Nutzern Rückmeldung hinsichtlich Passgenauigkeit gegeben. Die Software unterstützt somit als Entscheidungshilfe die behandelnden Ärzte bei der patientenspezifischen Spacerauswahl. T3 - ZIB-Report - 17-72 KW - Osteoarthrose KW - Kniegelenk KW - Medizinische Planung KW - Visualisierung Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-66064 SN - 1438-0064 ER - TY - JOUR A1 - Weiser, Martin A1 - Erdmann, Bodo A1 - Schenkl, Sebastian A1 - Muggenthaler, Holger A1 - Hubig, Michael A1 - Mall, Gita A1 - Zachow, Stefan T1 - Uncertainty in Temperature-Based Determination of Time of Death JF - Heat and Mass Transfer N2 - Temperature-based estimation of time of death (ToD) can be per- formed either with the help of simple phenomenological models of corpse cooling or with detailed mechanistic (thermodynamic) heat transfer mod- els. The latter are much more complex, but allow a higher accuracy of ToD estimation as in principle all relevant cooling mechanisms can be taken into account. The potentially higher accuracy depends on the accuracy of tissue and environmental parameters as well as on the geometric resolution. We in- vestigate the impact of parameter variations and geometry representation on the estimated ToD based on a highly detailed 3D corpse model, that has been segmented and geometrically reconstructed from a computed to- mography (CT) data set, differentiating various organs and tissue types. Y1 - 2018 U6 - https://doi.org/10.1007/s00231-018-2324-4 VL - 54 IS - 9 SP - 2815 EP - 2826 PB - Springer ER - TY - JOUR A1 - Bernard, Florian A1 - Salamanca, Luis A1 - Thunberg, Johan A1 - Tack, Alexander A1 - Jentsch, Dennis A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hertel, Frank A1 - Goncalves, Jorge A1 - Gemmar, Peter T1 - Shape-aware Surface Reconstruction from Sparse 3D Point-Clouds JF - Medical Image Analysis N2 - The reconstruction of an object’s shape or surface from a set of 3D points plays an important role in medical image analysis, e.g. in anatomy reconstruction from tomographic measurements or in the process of aligning intra-operative navigation and preoperative planning data. In such scenarios, one usually has to deal with sparse data, which significantly aggravates the problem of reconstruction. However, medical applications often provide contextual information about the 3D point data that allow to incorporate prior knowledge about the shape that is to be reconstructed. To this end, we propose the use of a statistical shape model (SSM) as a prior for surface reconstruction. The SSM is represented by a point distribution model (PDM), which is associated with a surface mesh. Using the shape distribution that is modelled by the PDM, we formulate the problem of surface reconstruction from a probabilistic perspective based on a Gaussian Mixture Model (GMM). In order to do so, the given points are interpreted as samples of the GMM. By using mixture components with anisotropic covariances that are “oriented” according to the surface normals at the PDM points, a surface-based fitting is accomplished. Estimating the parameters of the GMM in a maximum a posteriori manner yields the reconstruction of the surface from the given data points. We compare our method to the extensively used Iterative Closest Points method on several different anatomical datasets/SSMs (brain, femur, tibia, hip, liver) and demonstrate superior accuracy and robustness on sparse data. Y1 - 2017 UR - http://www.sciencedirect.com/science/article/pii/S1361841517300233 U6 - https://doi.org/10.1016/j.media.2017.02.005 VL - 38 SP - 77 EP - 89 ER - TY - JOUR A1 - Lube, Juliane A1 - Flack, Natasha A1 - Cotofana, Sebastian A1 - Özkurtul, Orkun A1 - Woodley, Stephanie A1 - Zachow, Stefan A1 - Hammer, Niels T1 - Pelvic and lower extremity physiological cross-sectional areas: An MRI study of the living young and comparison to published research literature JF - Surgical and Radiologic Anatomy N2 - Purpose: Morphological data pertaining to the pelvis and lower extremity muscles are increasingly being used in biomechanical modeling to compare healthy and pathological conditions. Very few data sets exist that encompass all of the muscles of the lower limb, allowing for comparisons between regions. The aims of this study were to (a) provide physiological cross-sectional area (PCSA) data for the pelvic, thigh, and leg muscles in young, healthy participants, using magnetic resonance imaging (MRI), and (b) to compare these data with summarized PCSAs obtained from the literature. Materials and Methods: Six young and healthy volunteers participated and were scanned using 3 T MRI. PCSAs were calculated from volumetric segmentations obtained bilaterally of 28 muscles/muscle groups of the pelvis, thigh, and leg. These data were compared to published, summarized PCSA data derived from cadaveric, computed tomography, MRI and ultrasound studies. Results: The PCSA of the pelvis, thigh, and leg muscles tended to be 20–130% larger in males than in females, except for the gemelli which were 34% smaller in males, and semitendinosus and triceps surae which did not differ (<20% different). The dominant and the non-dominant sides showed similar and minutely different PCSA with less than 18% difference between sides. Comparison to other studies revealed wide ranges within, and large differences between, the cadaveric and imaging PCSA data. Comparison of the PCSA of this study and published literature revealed major differences in the iliopsoas, gluteus minimus, tensor fasciae latae, gemelli, obturator internus, biceps femoris, quadriceps femoris, and the deep leg flexor muscles. Conclusions: These volume-derived PCSAs of the pelvic and lower limb muscles alongside the data synthesised from the literature may serve as a basis for comparative and biomechanical studies of the living and healthy young, and enable calculation of muscle forces. Comparison of the literature revealed large variations in PCSA from each of the different investigative modalities, hampering omparability between studies. Sample size, age, post-mortem changes of muscle tone, chemical fixation of cadaveric tissues, and the underlying physics of the imaging techniques may potentially influence PCSA calculations. Y1 - 2017 U6 - https://doi.org/10.1007/s00276-016-1807-6 VL - 39 IS - 8 SP - 849 EP - 857 ER - TY - CHAP A1 - Mukhopadhyay, Anirban A1 - Morillo, Oscar A1 - Zachow, Stefan A1 - Lamecker, Hans T1 - Robust and Accurate Appearance Models Based on Joint Dictionary Learning Data from the Osteoarthritis Initiative T2 - Lecture Notes in Computer Science, Patch-Based Techniques in Medical Imaging. Patch-MI 2016 N2 - Deformable model-based approaches to 3D image segmentation have been shown to be highly successful. Such methodology requires an appearance model that drives the deformation of a geometric model to the image data. Appearance models are usually either created heuristically or through supervised learning. Heuristic methods have been shown to work effectively in many applications but are hard to transfer from one application (imaging modality/anatomical structure) to another. On the contrary, supervised learning approaches can learn patterns from a collection of annotated training data. In this work, we show that the supervised joint dictionary learning technique is capable of overcoming the traditional drawbacks of the heuristic approaches. Our evaluation based on two different applications (liver/CT and knee/MR) reveals that our approach generates appearance models, which can be used effectively and efficiently in a deformable model-based segmentation framework. Y1 - 2016 U6 - https://doi.org/10.1007/978-3-319-47118-1_4 VL - 9993 SP - 25 EP - 33 ER - TY - JOUR A1 - Sahu, Manish A1 - Mukhopadhyay, Anirban A1 - Szengel, Angelika A1 - Zachow, Stefan T1 - Addressing multi-label imbalance problem of Surgical Tool Detection using CNN JF - International Journal of Computer Assisted Radiology and Surgery N2 - Purpose: A fully automated surgical tool detection framework is proposed for endoscopic video streams. State-of-the-art surgical tool detection methods rely on supervised one-vs-all or multi-class classification techniques, completely ignoring the co-occurrence relationship of the tools and the associated class imbalance. Methods: In this paper, we formulate tool detection as a multi-label classification task where tool co-occurrences are treated as separate classes. In addition, imbalance on tool co-occurrences is analyzed and stratification techniques are employed to address the imbalance during Convolutional Neural Network (CNN) training. Moreover, temporal smoothing is introduced as an online post-processing step to enhance run time prediction. Results: Quantitative analysis is performed on the M2CAI16 tool detection dataset to highlight the importance of stratification, temporal smoothing and the overall framework for tool detection. Conclusion: The analysis on tool imbalance, backed by the empirical results indicates the need and superiority of the proposed framework over state-of-the-art techniques. Y1 - 2017 UR - https://link.springer.com/article/10.1007/s11548-017-1565-x U6 - https://doi.org/10.1007/s11548-017-1565-x N1 - Selected for final oral presentation VL - 12 IS - 6 SP - 1013 EP - 1020 PB - Springer ER - TY - JOUR A1 - Schenkl, Sebastian A1 - Muggenthaler, Holger A1 - Hubig, Michael A1 - Erdmann, Bodo A1 - Weiser, Martin A1 - Zachow, Stefan A1 - Heinrich, Andreas A1 - Güttler, Felix Victor A1 - Teichgräber, Ulf A1 - Mall, Gita T1 - Automatic CT-based finite element model generation for temperature-based death time estimation: feasibility study and sensitivity analysis JF - International Journal of Legal Medicine N2 - Temperature based death time estimation is based either on simple phenomenological models of corpse cooling or on detailed physical heat transfer models. The latter are much more complex, but allow a higher accuracy of death time estimation as in principle all relevant cooling mechanisms can be taken into account. Here, a complete work flow for finite element based cooling simulation models is presented. The following steps are demonstrated on CT-phantoms: • CT-scan • Segmentation of the CT images for thermodynamically relevant features of individual geometries • Conversion of the segmentation result into a Finite Element (FE) simulation model • Computation of the model cooling curve • Calculation of the cooling time For the first time in FE-based cooling time estimation the steps from the CT image over segmentation to FE model generation are semi-automatically performed. The cooling time calculation results are compared to cooling measurements performed on the phantoms under controlled conditions. In this context, the method is validated using different CTphantoms. Some of the CT phantoms thermodynamic material parameters had to be experimentally determined via independent experiments. Moreover the impact of geometry and material parameter uncertainties on the estimated cooling time is investigated by a sensitivity analysis. KW - temperature based death time estimation KW - finite element method KW - CT segmentation KW - sensitivity analysis Y1 - 2017 U6 - https://doi.org/doi:10.1007/s00414-016-1523-0 VL - 131 IS - 3 SP - 699 EP - 712 ER - TY - JOUR A1 - Zachow, Stefan T1 - Computational Planning in Facial Surgery JF - Facial Plastic Surgery N2 - This article reflects the research of the last two decades in computational planning for cranio-maxillofacial surgery. Model-guided and computer-assisted surgery planning has tremendously developed due to ever increasing computational capabilities. Simulators for education, planning, and training of surgery are often compared with flight simulators, where maneuvers are also trained to reduce a possible risk of failure. Meanwhile, digital patient models can be derived from medical image data with astonishing accuracy and thus can serve for model surgery to derive a surgical template model that represents the envisaged result. Computerized surgical planning approaches, however, are often still explorative, meaning that a surgeon tries to find a therapeutic concept based on his or her expertise using computational tools that are mimicking real procedures. Future perspectives of an improved computerized planning may be that surgical objectives will be generated algorithmically by employing mathematical modeling, simulation, and optimization techniques. Planning systems thus act as intelligent decision support systems. However, surgeons can still use the existing tools to vary the proposed approach, but they mainly focus on how to transfer objectives into reality. Such a development may result in a paradigm shift for future surgery planning. Y1 - 2015 U6 - https://doi.org/10.1055/s-0035-1564717 VL - 31 IS - 5 SP - 446 EP - 462 ER - TY - GEN A1 - Lamas-Rodríguez, Julián A1 - Ehlke, Moritz A1 - Hoffmann, René A1 - Zachow, Stefan T1 - GPU-accelerated denoising of large tomographic data sets with low SNR BT - Application for non-invasive analysis of paleontological data N2 - Enhancements in tomographic imaging techniques facilitate non-destructive methods for visualizing fossil structures. However, to penetrate dense materials such as sediments or pyrites, image acquisition is typically performed with high beam energy and very sensitive image intensifiers, leading to artifacts and noise in the acquired data. The analysis of delicate fossil structures requires the images to be captured in maximum resolution, resulting in large data sets of several giga bytes (GB) in size. Since the structural information of interest is often almost in the same spatial range as artifacts and noise, image processing and segmentation algorithms have to cope with a very low signal-to-noise ratio (SNR). Within this report we present a study on the performance of a collection of denoising algorithms applied to a very noisy fossil dataset. The study shows that a non-local means (NLM) filter, in case it is properly configured, is able to remove a considerable amount of noise while preserving most of the structural information of interest. Based on the results of this study, we developed a software tool within ZIBAmira that denoises large tomographic datasets using an adaptive, GPU-accelerated NLM filter. With the help of our implementation a user can interactively configure the filter's parameters and thus its effectiveness with respect to the data of interest, while the filtering response is instantly visualized for a preselected region of interest (ROI). Our implementation efficiently denoises even large fossil datasets in a reasonable amount of time. T3 - ZIB-Report - 15-14 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-56339 SN - 1438-0064 ER - TY - JOUR A1 - Zahn, Robert A1 - Grotjohann, Sarah A1 - Ramm, Heiko A1 - Zachow, Stefan A1 - Putzier, Michael A1 - Perka, Carsten A1 - Tohtz, Stephan T1 - Pelvic tilt compensates for increased acetabular anteversion JF - International Orthopaedics N2 - Pelvic tilt determines functional orientation of the acetabulum. In this study, we investigated the interaction of pelvic tilt and functional acetabular anteversion (AA) in supine position. Y1 - 2015 U6 - https://doi.org/10.1007/s00264-015-2949-6 VL - 40 IS - 8 SP - 1571 EP - 1575 ER - TY - CHAP A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Statistical Shape Modeling of Musculoskeletal Structures and Its Applications T2 - Computational Radiology for Orthopaedic Interventions N2 - Statistical shape models (SSM) describe the shape variability contained in a given population. They are able to describe large populations of complex shapes with few degrees of freedom. This makes them a useful tool for a variety of tasks that arise in computer-aided madicine. In this chapter we are going to explain the basic methodology of SSMs and present a variety of examples, where SSMs have been successfully applied. Y1 - 2016 SN - 978-3-319-23481-6 U6 - https://doi.org/10.1007/978-3-319-23482-3 VL - 23 SP - 1 EP - 23 PB - Springer ER - TY - JOUR A1 - Zachow, Stefan A1 - Heppt, Werner T1 - The Facial Profile JF - Facial Plastic Surgery N2 - Facial appearance in our societies is often associated with notions of attractiveness, juvenileness, beauty, success, and so forth. Hence, the role of facial plastic surgery is highly interrelated to a patient's desire to feature many of these positively connoted attributes, which of course, are subject of different cultural perceptions or social trends. To judge about somebody's facial appearance, appropriate quantitative measures as well as methods to obtain and compare individual facial features are required. This special issue on facial profile is intended to provide an overview on how facial characteristics are surgically managed in an interdisciplinary way based on experience, instrumentation, and modern technology to obtain an aesthetic facial appearance with harmonious facial proportions. The facial profile will be discussed within the context of facial aesthetics. Latest concepts for capturing facial morphology in high speed and impressive detail are presented for quantitative analysis of even subtle changes, aging effects, or facial expressions. In addition, the perception of facial profiles is evaluated based on eye tracking technology. Y1 - 2015 U6 - https://doi.org/10.1055/s-0035-1566132 VL - 31 IS - 5 SP - 419 EP - 420 ER - TY - CHAP A1 - Ramm, Heiko A1 - Victoria Morillo, Oscar Salvador A1 - Todt, Ingo A1 - Schirmacher, Hartmut A1 - Ernst, Arneborg A1 - Zachow, Stefan A1 - Lamecker, Hans ED - Freysinger, Wolfgang T1 - Visual Support for Positioning Hearing Implants T2 - Proceedings of the 12th annual meeting of the CURAC society Y1 - 2013 SP - 116 EP - 120 ER - TY - JOUR A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Heller, Markus O. A1 - Weber, Britta A1 - Hege, Hans-Christian A1 - Zachow, Stefan T1 - Omnidirectional Displacements for Deformable Surfaces JF - Medical Image Analysis Y1 - 2013 U6 - https://doi.org/10.1016/j.media.2012.11.006 VL - 17 IS - 4 SP - 429 EP - 441 PB - Elsevier ER - TY - JOUR A1 - Lamas-Rodríguez, Julián A1 - Heras, Dora Blanco A1 - Argüello, Francisco A1 - Kainmüller, Dagmar A1 - Zachow, Stefan A1 - Bóo, Montserrat T1 - GPU-accelerated level-set segmentation JF - Journal of Real-Time Image Processing Y1 - 2013 UR - http://dx.doi.org/10.1007/s11554-013-0378-6 U6 - https://doi.org/10.1007/s11554-013-0378-6 SN - 1861-8200 SP - 1 EP - 15 PB - Springer Berlin Heidelberg ER - TY - JOUR A1 - Hoffmann, René A1 - Schultz, Julia A. A1 - Schellhorn, Rico A1 - Rybacki, Erik A1 - Keupp, Helmut A1 - Gerden, S. R. A1 - Lemanis, Robert A1 - Zachow, Stefan T1 - Non-invasive imaging methods applied to neo- and paleontological cephalopod research JF - Biogeosciences N2 - Several non-invasive methods are common practice in natural sciences today. Here we present how they can be applied and contribute to current topics in cephalopod (paleo-) biology. Different methods will be compared in terms of time necessary to acquire the data, amount of data, accuracy/resolution, minimum/maximum size of objects that can be studied, the degree of post-processing needed and availability. The main application of the methods is seen in morphometry and volumetry of cephalopod shells. In particular we present a method for precise buoyancy calculation. Therefore, cephalopod shells were scanned together with different reference bodies, an approach developed in medical sciences. It is necessary to know the volume of the reference bodies, which should have similar absorption properties like the object of interest. Exact volumes can be obtained from surface scanning. Depending on the dimensions of the study object different computed tomography techniques were applied. Y1 - 2014 U6 - https://doi.org/10.5194/bg-11-2721-2014 N1 - To access the corresponding discussion paper go to www.biogeosciences-discuss.net/10/18803/2013/ - Biogeosciences Discuss., 10, 18803-18851, 2013 VL - 11 IS - 10 SP - 2721 EP - 2739 ER - TY - CHAP A1 - von Berg, Jens A1 - Dworzak, Jalda A1 - Klinder, Tobias A1 - Manke, Dirk A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Lorenz, Cristian T1 - Temporal Subtraction of Chest Radiographs Compensating Pose Differences T2 - SPIE Medical Imaging Y1 - 2011 ER - TY - CHAP A1 - Bindernagel, Matthias A1 - Kainmüller, Dagmar A1 - Seim, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - An Articulated Statistical Shape Model of the Human Knee T2 - Bildverarbeitung für die Medizin 2011 Y1 - 2011 U6 - https://doi.org/10.1007/978-3-642-19335-4_14 SP - 59 EP - 63 PB - Springer ER - TY - CHAP A1 - Kahnt, Max A1 - Galloway, Francis A1 - Seim, Heiko A1 - Lamecker, Hans A1 - Taylor, Mark A1 - Zachow, Stefan T1 - Robust and Intuitive Meshing of Bone-Implant Compounds T2 - CURAC Y1 - 2011 SP - 71 EP - 74 CY - Magdeburg ER - TY - GEN A1 - SK, Saevarsson A1 - GB, Sharma A1 - S, Montgomery A1 - KCT, Ho A1 - Ramm, Heiko A1 - Lieck, Robert A1 - Zachow, Stefan A1 - C, Anglin T1 - Kinematic Comparison Between Gender Specific and Traditional Femoral Implants T2 - Proceedings of the 11th Alberta Biomedical Engineering (BME) Conference (Poster) Y1 - 2011 SP - 80 ER - TY - CHAP A1 - Deuflhard, Peter A1 - Dössel, Olaf A1 - Louis, Alfred A1 - Zachow, Stefan T1 - Mehr Mathematik wagen in der Medizin T2 - acatech diskutiert, Produktionsfaktor Mathematik - Wie Mathematik Technik und Wirtschaft bewegt Y1 - 2008 U6 - https://doi.org/10.1007/978-3-540-89435-3 SP - 435 EP - 459 PB - Springer ER - TY - CHAP A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - Coupling Deformable Models for Multi-object Segmentation T2 - Proc. Int. Symp. on Computational Models for Biomedical Simulation (ISBMS) Y1 - 2008 U6 - https://doi.org/10.1007/978-3-540-70521-5_8 SP - 69 EP - 78 ER - TY - CHAP A1 - Kainmüller, Dagmar A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Heller, Markus O. A1 - Hege, Hans-Christian T1 - Multi-Object Segmentation with Coupled Deformable Models T2 - Proc. Medical Image Understanding and Analysis Y1 - 2008 SP - 34 EP - 38 ER - TY - CHAP A1 - Seim, Heiko A1 - Kainmüller, Dagmar A1 - Kuss, Anja A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Menzel, Randolf A1 - Rybak, Juergen T1 - Model-based autosegmentation of the central brain of the honeybee, Apis mellifera, using active statistical shape models T2 - Proc. 1st INCF Congress of Neuroinformatics: Databasing and Modeling the Brain Y1 - 2008 U6 - https://doi.org/10.3389/conf.neuro.11.2008.01.064 ER - TY - CHAP 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 - Towards model-based 3-D reconstruction of the human rib cage from radiographs T2 - Proc. 7. Jahrestagung der Deutschen Gesellschaft für Computer-Roboterassistierte Chirurgie (CURAC) Y1 - 2008 SP - 193 EP - 196 ER - TY - CHAP A1 - Seim, Heiko A1 - Kainmüller, Dagmar A1 - Heller, Markus O. A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Hege, Hans-Christian T1 - Automatic Segmentation of the Pelvic Bones from CT Data Based on a Statistical Shape Model T2 - Eurographics Workshop on Visual Computing for Biomedicine (VCBM) Y1 - 2008 SP - 93 EP - 100 CY - Delft, Netherlands ER - TY - CHAP A1 - Deuflhard, Peter A1 - Dössel, Olaf A1 - Louis, Alfred A1 - Zachow, Stefan T1 - More Mathematics into Medicine! T2 - Production Factor Mathematics Y1 - 2010 UR - http://www.springer.com/mathematics/book/978-3-642-11247-8 SP - 357 EP - 378 PB - Springer ER - 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 -