TY - JOUR A1 - Akbari Shandiz, Mohsen A1 - Boulos, Paul A1 - Sævarsson, Stefan A1 - Ramm, Heiko A1 - Fu, Chun Kit A1 - Miller, Stephen A1 - Zachow, Stefan A1 - Anglin, Carolyn T1 - Changes in Knee Shape and Geometry Resulting from Total Knee Arthroplasty JF - Journal of Engineering in Medicine N2 - Changes in knee shape and geometry resulting from total knee arthroplasty can affect patients in numerous important ways: pain, function, stability, range of motion, and kinematics. Quantitative data concerning these changes have not been previously available, to our knowledge, yet are essential to understand individual experiences of total knee arthroplasty and thereby improve outcomes for all patients. The limiting factor has been the challenge of accurately measuring these changes. Our study objective was to develop a conceptual framework and analysis method to investigate changes in knee shape and geometry, and prospectively apply it to a sample total knee arthroplasty population. Using clinically available computed tomography and radiography imaging systems, the three-dimensional knee shape and geometry of nine patients (eight varus and one valgus) were compared before and after total knee arthroplasty. All patients had largely good outcomes after their total knee arthroplasty. Knee shape changed both visually and numerically. On average, the distal condyles were slightly higher medially and lower laterally (range: +4.5 mm to −4.4 mm), the posterior condyles extended farther out medially but not laterally (range: +1.8 to −6.4 mm), patellofemoral distance increased throughout flexion by 1.8–3.5 mm, and patellar thickness alone increased by 2.9 mm (range: 0.7–5.2 mm). External femoral rotation differed preop and postop. Joint line distance, taking cartilage into account, changed by +0.7 to −1.5 mm on average throughout flexion. Important differences in shape and geometry were seen between pre-total knee arthroplasty and post-total knee arthroplasty knees. While this is qualitatively known, this is the first study to report it quantitatively, an important precursor to identifying the reasons for the poor outcome of some patients. Using the developed protocol and visualization techniques to compare patients with good versus poor clinical outcomes could lead to changes in implant design, implant selection, component positioning, and surgical technique. Recommendations based on this sample population are provided. Intraoperative and postoperative feedback could ultimately improve patient satisfaction. Y1 - 2018 UR - http://journals.sagepub.com/eprint/ZVgNrNESA9EjIcaFWSjb/full U6 - https://doi.org/10.1177/0954411917743274 VL - 232 IS - 1 SP - 67 EP - 79 ER - TY - JOUR A1 - Saevarsson, Stefan A1 - Sharma, Gulshan A1 - Amiri, Shahram A1 - Montgomery, Sigrun A1 - Ramm, Heiko A1 - Lichti, Derek A1 - Lieck, Robert A1 - Zachow, Stefan A1 - Anglin, Carolyn T1 - Radiological method for measuring patellofemoral tracking and tibiofemoral kinematics before and after total knee replacement JF - Bone and Joint Research Y1 - 2012 UR - http://www.bjr.boneandjoint.org.uk/content/1/10/263.short U6 - https://doi.org/10.1302/2046-3758.110.2000117 VL - 1 IS - 10 SP - 263 EP - 271 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Goubergrits, Leonid A1 - Heppt, Werner A1 - Bessler, Stefan A1 - Zachow, Stefan T1 - Evaluation of the Intranasal Flow Field through Computational Fluid Dynamics (CFD) JF - Journal of Facial and Plastic Surgery Y1 - 2013 UR - https://www.thieme-connect.de/DOI/DOI?10.1055/s-0033-1341591 U6 - https://doi.org/10.1055/s-0033-1341591 VL - 29 IS - 2 SP - 93 EP - 98 PB - Thieme ER - TY - JOUR A1 - Saevarsson, Stefan A1 - Sharma, Gulshan A1 - Ramm, Heiko A1 - Lieck, Robert A1 - Hutchison, Carol A1 - Werle, Jason A1 - Montgomery, Sigrun A1 - Romeo, Carolina A1 - Zachow, Stefan A1 - Anglin, Carolyn T1 - Kinematic Differences Between Gender Specific And Traditional Knee Implants JF - The Journal of Arthroplasty Y1 - 2013 U6 - https://doi.org/10.1016/j.arth.2013.01.021 VL - 28 IS - 9 SP - 1543 EP - 1550 ER - TY - GEN A1 - Sharma, Gulshan A1 - Ho, Karen A1 - Saevarsson, Stefan A1 - Ramm, Heiko A1 - Lieck, Robert A1 - Zachow, Stefan A1 - Anglin, Carolyn T1 - Knee Pose and Geometry Pre- and Post-Total Knee Arthroplasty Using Computed Tomography T2 - 58th Annual Meeting of the Orthopaedic Research Society (ORS) Y1 - 2012 CY - San Francisco, CA ER - TY - GEN A1 - Sharma, Gulshan A1 - Saevarsson, Stefan A1 - Amiri, Shahram A1 - Montgomery, Sigrun A1 - Ramm, Heiko A1 - Lichti, Derek A1 - Zachow, Stefan A1 - Anglin, Carolyn T1 - Sequential-Biplane Radiography for Measuring Pre and Post Total Knee Arthroplasty Kinematics T2 - 58th Annual Meeting of the Orthopaedic Research Society (ORS) Y1 - 2012 CY - San Francisco, CA ER - TY - CHAP A1 - Stefan, Saevarsson A1 - Gulshan, Sharma A1 - Sigrun, Montgomery A1 - Karen, Ho A1 - Ramm, Heiko A1 - Lieck, Robert A1 - Zachow, Stefan A1 - Hutchison, Carol A1 - Jason, Werle A1 - Carolyn, Anglin T1 - Kinematic Comparison Between Gender Specific and Traditional Femoral Implants T2 - 67th Canadian Orthopaedic Association (COA) Annual Meeting Y1 - 2012 ER - TY - JOUR A1 - Ho, Karen A1 - Saevarsson, Stefan A1 - Ramm, Heiko A1 - Lieck, Robert A1 - Zachow, Stefan A1 - Sharma, Gulshan A1 - Rex, Erica A1 - Amiri, Shahram A1 - Wu, Barnabas A1 - Leumann, Andre A1 - Anglin, Carolyn T1 - Computed tomography analysis of knee pose and geometry before and after total knee arthroplasty JF - Journal of biomechanics Y1 - 2012 UR - http://www.ncbi.nlm.nih.gov/pubmed/22796002 U6 - https://doi.org/10.1016/j.jbiomech.2012.06.004 VL - 45 IS - 13 SP - 2215 EP - 21 ER - TY - JOUR A1 - Xie, Kunpeng A1 - Gruber, Lennart Johannes A1 - Crampen, Martin A1 - Li, Yao A1 - Ferreira, André A1 - Tappeiner, Elias A1 - Gillot, Maxime A1 - Schepers, Jan A1 - Xu, Jiangchang A1 - Pankert, Tobias A1 - Beyer, Michel A1 - Shahamiri, Negar A1 - ten Brink, Reinier A1 - Dot, Gauthier A1 - Weschke, Charlotte A1 - van Nistelrooij, Niels A1 - Verhelst, Pieter-Jan A1 - Guo, Yan A1 - Xu, Zhibin A1 - Bienzeisler, Jonas A1 - Rashad, Ashkan A1 - Flügge, Tabea A1 - Cotton, Ross A1 - Vinayahalingam, Shankeeth A1 - Ilesan, Robert A1 - Raith, Stefan A1 - Madsen, Dennis A1 - Seibold, Constantin A1 - Xi, Tong A1 - Bergé, Stefaan A1 - Nebelung, Sven A1 - Kodym, Oldřich A1 - Sundqvist, Osku A1 - Thieringer, Florian A1 - Lamecker, Hans A1 - Coppens, Antoine A1 - Potrusil, Thomas A1 - Kraeima, Joep A1 - Witjes, Max A1 - Wu, Guomin A1 - Chen, Xiaojun A1 - Lambrechts, Adriaan A1 - Cevidanes, Lucia H Soares A1 - Zachow, Stefan A1 - Hermans, Alexander A1 - Truhn, Daniel A1 - Alves, Victor A1 - Egger, Jan A1 - Röhrig, Rainer A1 - Hölzle, Frank A1 - Puladi, Behrus T1 - Beyond Benchmarks: Towards Robust Artificial Intelligence Bone Segmentation in Socio-Technical Systems JF - Expert Systems With Applications N2 - Despite the advances in automated medical image segmentation, AI models still underperform in various clinical settings, challenging real-world integration. In this multicenter evaluation, we analyzed 20 state-of-the-art mandibular segmentation models across 19,218 segmentations of 1,000 clinically resampled CT/CBCT scans. We show that segmentation accuracy varies by up to 25% depending on socio-technical factors such as voxel size, bone orientation, and patient conditions such as osteosynthesis or pathology. Higher sharpness, isotropic smaller voxels, and neutral orientation significantly improved results, while metallic osteosynthesis and anatomical complexity led to significant degradation. Our findings challenge the common view of AI models as “plug-and-play” tools and suggest evidence-based optimization recommendations for both clinicians and developers. This will in turn boost the integration of AI segmentation tools in routine healthcare. Y1 - 2025 UR - https://www.medrxiv.org/content/10.1101/2025.06.11.25329022v1 U6 - https://doi.org/10.1016/j.eswa.2025.130031 VL - 299 IS - Part D ER - TY - GEN A1 - Deuflhard, Peter A1 - Dössel, Olaf A1 - Louis, Alfred A1 - Zachow, Stefan T1 - Mehr Mathematik wagen in der Medizin N2 - Der Artikel gibt einen Einblick in das reiche Feld der Zusammenarbeit zwischen Mathematik und Medizin. Beispielhaft werden drei Erfolgsmodelle dargestellt: Medizinische Bildgebung, mathematische Modellierung und Biosignalverarbeitung im Bereich der Dynamik des Herzens sowie mathematische Modellierung und Simulation in der Krebstherapie Hyperthermie und der Mund-Kiefer-Gesichts-Chirurgie. In allen Fällen existiert ein Gleichklang der Interessen von Medizin und Mathematik: Beide Disziplinen wollen die Resultate schnell und zuverlässig. Für die Klinik heißt das, dass notwendige Rechnungen in möglichst kurzer Zeit, und zwar auf dem PC, ablaufen müssen und dass die Resultate so genau und belastbar sein müssen, dass medizinische Entscheidungen darauf aufbauen können. Für die Mathematik folgt daraus, dass höchste Anforderungen an die Effizienz der verwendeten Algorithmen und die darauf aufbauende Software in Numerik und Visualisierung zu stellen sind. Jedes Kapitel endet mit einer Darstellung der Perspektive des jeweiligen Gebietes. Abschließend werden mögliche Handlungsoptionen für Politik und Wirtschaft diskutiert. T3 - ZIB-Report - 08-25 Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-10776 SN - 1438-0064 ER - TY - GEN A1 - Zilske, Michael A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Adaptive Remeshing of Non-Manifold Surfaces N2 - We present a unified approach for consistent remeshing of arbitrary non-manifold triangle meshes with additional user-defined feature lines, which together form a feature skeleton. Our method is based on local operations only and produces meshes of high regularity and triangle quality while preserving the geometry as well as topology of the feature skeleton and the input mesh. T3 - ZIB-Report - 07-01 KW - remeshing KW - non-manifold KW - mesh quality optimization Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-9445 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 - GEN A1 - Ehlke, Moritz A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Hege, Hans-Christian A1 - Zachow, Stefan T1 - Fast Generation of Virtual X-ray Images from Deformable Tetrahedral Meshes N2 - We propose a novel GPU-based approach to render virtual X-ray projections of deformable tetrahedral meshes. These meshes represent the shape and the internal density distribution of a particular anatomical structure and are derived from statistical shape and intensity models (SSIMs). We apply our method to improve the geometric reconstruction of 3D anatomy (e.g.\ pelvic bone) from 2D X-ray images. For that purpose, shape and density of a tetrahedral mesh are varied and virtual X-ray projections are generated within an optimization process until the similarity between the computed virtual X-ray and the respective anatomy depicted in a given clinical X-ray is maximized. The OpenGL implementation presented in this work deforms and projects tetrahedral meshes of high resolution (200.000+ tetrahedra) at interactive rates. It generates virtual X-rays that accurately depict the density distribution of an anatomy of interest. Compared to existing methods that accumulate X-ray attenuation in deformable meshes, our novel approach significantly boosts the deformation/projection performance. The proposed projection algorithm scales better with respect to mesh resolution and complexity of the density distribution, and the combined deformation and projection on the GPU scales better with respect to the number of deformation parameters. The gain in performance allows for a larger number of cycles in the optimization process. Consequently, it reduces the risk of being stuck in a local optimum. We believe that our approach contributes in orthopedic surgery, where 3D anatomy information needs to be extracted from 2D X-rays to support surgeons in better planning joint replacements. T3 - ZIB-Report - 13-38 KW - digitally reconstructed radiographs KW - volume rendering KW - mesh deformation KW - statistical shape and intensity models KW - image registration KW - GPU acceleration Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-41896 SN - 1438-0064 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - GEN A1 - Ehlke, Moritz A1 - Ramm, Heiko A1 - Lamecker, Hans A1 - Zachow, Stefan T1 - Efficient projection and deformation of volumetric intensity models for accurate simulation of X-ray images N2 - We present an efficient GPU-based method to generate virtual X-ray images from tetrahedral meshes which are associated with attenuation values. In addition, a novel approach is proposed that performs the model deformation on the GPU. The tetrahedral grids are derived from volumetric statistical shape and intensity models (SSIMs) and describe anatomical structures. Our research targets at reconstructing 3D anatomical shapes by comparing virtual X-ray images generated using our novel approach with clinical data while varying the shape and density of the SSIM in an optimization process. We assume that a deformed SSIM adequately represents an anatomy of interest when the similarity between the virtual and the clinical X-ray image is maximized. The OpenGL implementation presented here generates accurate (virtual) X-ray images at interactive rates, thus qualifying it for its use in the reconstruction process. T3 - ZIB-Report - 12-40 KW - Digitally Reconstructed Radiograph (DRR), Anatomy Reconstruction, Statistical Shape and Intensity Model (SSIM), GPU acceleration Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-16580 SN - 1438-0064 ER - TY - GEN A1 - Ramm, Heiko A1 - Morillo Victoria, Oscar Salvador A1 - Todt, Ingo A1 - Schirmacher, Hartmut A1 - Ernst, Arneborg A1 - Zachow, Stefan A1 - Lamecker, Hans T1 - Visual Support for Positioning Hearing Implants N2 - We present a software planning tool that provides intuitive visual feedback for finding suitable positions of hearing implants in the human temporal bone. After an automatic reconstruction of the temporal bone anatomy the tool pre-positions the implant and allows the user to adjust its position interactively with simple 2D dragging and rotation operations on the bone's surface. During this procedure, visual elements like warning labels on the implant or color encoded bone density information on the bone geometry provide guidance for the determination of a suitable fit. T3 - ZIB-Report - 13-53 KW - bone anchored hearing implant KW - surgery planning KW - segmentation KW - visualization Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-42495 SN - 1438-0064 ER - TY - GEN A1 - Ambellan, Felix A1 - Lamecker, Hans A1 - von Tycowicz, Christoph A1 - Zachow, Stefan T1 - Statistical Shape Models - Understanding and Mastering Variation in Anatomy N2 - In our chapter we are describing how to reconstruct three-dimensional anatomy from medical image data and how to build Statistical 3D Shape Models out of many such reconstructions yielding a new kind of anatomy that not only allows quantitative analysis of anatomical variation but also a visual exploration and educational visualization. Future digital anatomy atlases will not only show a static (average) anatomy but also its normal or pathological variation in three or even four dimensions, hence, illustrating growth and/or disease progression. Statistical Shape Models (SSMs) are geometric models that describe a collection of semantically similar objects in a very compact way. SSMs represent an average shape of many three-dimensional objects as well as their variation in shape. The creation of SSMs requires a correspondence mapping, which can be achieved e.g. by parameterization with a respective sampling. If a corresponding parameterization over all shapes can be established, variation between individual shape characteristics can be mathematically investigated. We will explain what Statistical Shape Models are and how they are constructed. Extensions of Statistical Shape Models will be motivated for articulated coupled structures. In addition to shape also the appearance of objects will be integrated into the concept. Appearance is a visual feature independent of shape that depends on observers or imaging techniques. Typical appearances are for instance the color and intensity of a visual surface of an object under particular lighting conditions, or measurements of material properties with computed tomography (CT) or magnetic resonance imaging (MRI). A combination of (articulated) statistical shape models with statistical models of appearance lead to articulated Statistical Shape and Appearance Models (a-SSAMs).After giving various examples of SSMs for human organs, skeletal structures, faces, and bodies, we will shortly describe clinical applications where such models have been successfully employed. Statistical Shape Models are the foundation for the analysis of anatomical cohort data, where characteristic shapes are correlated to demographic or epidemiologic data. SSMs consisting of several thousands of objects offer, in combination with statistical methods ormachine learning techniques, the possibility to identify characteristic clusters, thus being the foundation for advanced diagnostic disease scoring. T3 - ZIB-Report - 19-13 Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-72699 SN - 1438-0064 ER - TY - GEN A1 - Ambellan, Felix A1 - Tack, Alexander A1 - Ehlke, Moritz A1 - Zachow, Stefan T1 - Automated Segmentation of Knee Bone and Cartilage combining Statistical Shape Knowledge and Convolutional Neural Networks: Data from the Osteoarthritis Initiative N2 - We present a method for the automated segmentation of knee bones and cartilage from magnetic resonance imaging (MRI) that combines a priori knowledge of anatomical shape with Convolutional Neural Networks (CNNs).The proposed approach incorporates 3D Statistical Shape Models (SSMs) as well as 2D and 3D CNNs to achieve a robust and accurate segmentation of even highly pathological knee structures.The shape models and neural networks employed are trained using data from the Osteoarthritis Initiative (OAI) and the MICCAI grand challenge "Segmentation of Knee Images 2010" (SKI10), respectively. We evaluate our method on 40 validation and 50 submission datasets from the SKI10 challenge.For the first time, an accuracy equivalent to the inter-observer variability of human readers is achieved in this challenge.Moreover, the quality of the proposed method is thoroughly assessed using various measures for data from the OAI, i.e. 507 manual segmentations of bone and cartilage, and 88 additional manual segmentations of cartilage. Our method yields sub-voxel accuracy for both OAI datasets. We make the 507 manual segmentations as well as our experimental setup publicly available to further aid research in the field of medical image segmentation.In conclusion, combining localized classification via CNNs with statistical anatomical knowledge via SSMs results in a state-of-the-art segmentation method for knee bones and cartilage from MRI data. T3 - ZIB-Report - 19-06 Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-72704 SN - 1438-0064 N1 - Innovation Excellence Award 2020 ER - TY - CHAP A1 - Ambellan, Felix A1 - Lamecker, Hans A1 - von Tycowicz, Christoph A1 - Zachow, Stefan ED - Rea, Paul M. T1 - Statistical Shape Models - Understanding and Mastering Variation in Anatomy T2 - Biomedical Visualisation N2 - In our chapter we are describing how to reconstruct three-dimensional anatomy from medical image data and how to build Statistical 3D Shape Models out of many such reconstructions yielding a new kind of anatomy that not only allows quantitative analysis of anatomical variation but also a visual exploration and educational visualization. Future digital anatomy atlases will not only show a static (average) anatomy but also its normal or pathological variation in three or even four dimensions, hence, illustrating growth and/or disease progression. Statistical Shape Models (SSMs) are geometric models that describe a collection of semantically similar objects in a very compact way. SSMs represent an average shape of many three-dimensional objects as well as their variation in shape. The creation of SSMs requires a correspondence mapping, which can be achieved e.g. by parameterization with a respective sampling. If a corresponding parameterization over all shapes can be established, variation between individual shape characteristics can be mathematically investigated. We will explain what Statistical Shape Models are and how they are constructed. Extensions of Statistical Shape Models will be motivated for articulated coupled structures. In addition to shape also the appearance of objects will be integrated into the concept. Appearance is a visual feature independent of shape that depends on observers or imaging techniques. Typical appearances are for instance the color and intensity of a visual surface of an object under particular lighting conditions, or measurements of material properties with computed tomography (CT) or magnetic resonance imaging (MRI). A combination of (articulated) statistical shape models with statistical models of appearance lead to articulated Statistical Shape and Appearance Models (a-SSAMs).After giving various examples of SSMs for human organs, skeletal structures, faces, and bodies, we will shortly describe clinical applications where such models have been successfully employed. Statistical Shape Models are the foundation for the analysis of anatomical cohort data, where characteristic shapes are correlated to demographic or epidemiologic data. SSMs consisting of several thousands of objects offer, in combination with statistical methods ormachine learning techniques, the possibility to identify characteristic clusters, thus being the foundation for advanced diagnostic disease scoring. Y1 - 2019 SN - 978-3-030-19384-3 SN - 978-3-030-19385-0 U6 - https://doi.org/10.1007/978-3-030-19385-0_5 VL - 3 IS - 1156 SP - 67 EP - 84 PB - Springer Nature Switzerland AG ET - 1 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Bruening, Jan Joris A1 - Schmidt, Nora Laura A1 - Lamecker, Hans A1 - Heppt, Werner A1 - Zachow, Stefan A1 - Goubergrits, Leonid T1 - The Healthy Nasal Cavity - Characteristics of Morphology and Related Airflow Based on a Statistical Shape Model Viewed from a Surgeon’s Perspective JF - Facial Plastic Surgery N2 - Functional surgery on the nasal framework requires referential criteria to objectively assess nasal breathing for indication and follow-up. Thismotivated us to generate amean geometry of the nasal cavity based on a statistical shape model. In this study, the authors could demonstrate that the introduced nasal cavity’s mean geometry features characteristics of the inner shape and airflow, which are commonly observed in symptom-free subjects. Therefore, the mean geometry might serve as a reference-like model when one considers qualitative aspects. However, to facilitate quantitative considerations and statistical inference, further research is necessary. Additionally, the authorswere able to obtain details about the importance of the isthmus nasi and the inferior turbinate for the intranasal airstream. KW - statistical shape model KW - nasal cavity KW - nasal breathing KW - nasal airflow KW - isthmus nasi KW - inferior turbinate Y1 - 2019 U6 - https://doi.org/10.1055/s-0039-1677721 VL - 35 IS - 1 SP - 9 EP - 13 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Bruening, Jan Joris A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Heppt, Werner A1 - Schmidt, Nora A1 - Goubergrits, Leonid T1 - Digital Analysis of Nasal Airflow Facilitating Decision Support in Rhinosurgery JF - Facial Plastic Surgery N2 - Successful functional surgery on the nasal framework requires reliable and comprehensive diagnosis. In this regard, the authors introduce a new methodology: Digital Analysis of Nasal Airflow (diANA). It is based on computational fluid dynamics, a statistical shape model of the healthy nasal cavity and rhinologic expertise. diANA necessitates an anonymized tomographic dataset of the paranasal sinuses including the complete nasal cavity and, when available, clinical information. The principle of diANA is to compare the morphology and the respective airflow of an individual nose with those of a reference. This enablesmorphometric aberrations and consecutive flow field anomalies to localize and quantify within a patient’s nasal cavity. Finally, an elaborated expert opinion with instructive visualizations is provided. Using diANA might support surgeons in decision-making, avoiding unnecessary surgery, gaining more precision, and target-orientation for indicated operations. KW - nasal airflow simulation KW - nasal breathing KW - statistical shape model KW - diANA KW - nasal obstruction KW - rhinorespiratory homeostasis Y1 - 2019 U6 - https://doi.org/10.1055/s-0039-1677720 VL - 35 IS - 1 SP - 1 EP - 8 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 -