Publications
SPP 2311: Robust coupling of continuum-biomechanical in silico models to establish active biological system models for later use in clinical applications – Co-design of modeling, numerics and usability
List
2022
Spitz, Lena; Allgaier, Mareen; Mpotsaris, Anastasios; Behme, Daniel; Preim, Bernhard; Saalfeld, Sylvia
Segmentation of Circle of Willis from 7T TOF-MRI data and immersive exploration using VR Artikel
In: Current Directions in Biomedical Engineering, Bd. 8, Ausg. 1, S. 129-132, 2022.
@article{https://doi.org/10.1515/cdbme-2022-0033,
title = {Segmentation of Circle of Willis from 7T TOF-MRI data and immersive exploration using VR},
author = {Lena Spitz and Mareen Allgaier and Anastasios Mpotsaris and Daniel Behme and Bernhard Preim and Sylvia Saalfeld},
editor = {De Gruyter},
url = {https://www.degruyter.com/document/doi/10.1515/cdbme-2022-0033/html},
doi = {https://doi.org/10.1515/cdbme-2022-0033},
year = {2022},
date = {2022-07-30},
urldate = {2022-07-30},
journal = {Current Directions in Biomedical Engineering},
volume = {8},
issue = {1},
pages = {129-132},
abstract = {7T TOF MRI scans provide high resolution images of intracranial vasculature. When segmented, the Circle of Willis is detailed and thus opens up new possibilities, in research but also in education. We propose a segmentation pipeline for the Circle ofWillis, and introduce a prototype that enables exploration of not just the entire Circle of Willis, but also of its centerline, in an immersive VR enviroment. In our prototype, the model can be freely rotated, placed and scaled. A qualitative evaluation was performed with two experienced neuroradiologists, who rated the prototype and its potential positively.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
7T TOF MRI scans provide high resolution images of intracranial vasculature. When segmented, the Circle of Willis is detailed and thus opens up new possibilities, in research but also in education. We propose a segmentation pipeline for the Circle ofWillis, and introduce a prototype that enables exploration of not just the entire Circle of Willis, but also of its centerline, in an immersive VR enviroment. In our prototype, the model can be freely rotated, placed and scaled. A qualitative evaluation was performed with two experienced neuroradiologists, who rated the prototype and its potential positively.
Goubergrits, Leonid; Vellguth, Katharina; Obermeier, Lukas; Schlief, Adriano; Tautz, Lennart; Bruening, Jan; Lamecker, Hans; Szengel, Angelika; Nemchyna, Olena; Knosalla, Christoph; Kuehne, Titus; Solowjowa, Natalia
In: Front. Cardiovasc. Med., 05 July 2022, Bd. Sec. Cardiovascular Imaging, Ausg. Volume 9 - 2022, S. 901902, 2022.
@article{10.3389/fcvm.2022.901902,
title = {CT-Based Analysis of Left Ventricular Hemodynamics Using Statistical Shape Modeling and Computational Fluid Dynamics},
author = {Leonid Goubergrits and Katharina Vellguth and Lukas Obermeier and Adriano Schlief and Lennart Tautz and Jan Bruening and Hans Lamecker and Angelika Szengel and Olena Nemchyna and Christoph Knosalla and Titus Kuehne and Natalia Solowjowa},
editor = {Frontiers Cardiovascular Medicine},
url = {https://www.frontiersin.org/articles/10.3389/fcvm.2022.901902/full},
doi = {10.3389/fcvm.2022.901902“},
year = {2022},
date = {2022-07-05},
urldate = {2022-07-05},
journal = {Front. Cardiovasc. Med., 05 July 2022},
volume = {Sec. Cardiovascular Imaging},
issue = {Volume 9 - 2022},
pages = {901902},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ganse, Bergita; Orth, Marcel; Roland, Michael; Diebels, Stefan; Motzki, Paul; Seelecke, Stefan; Kirsch, Susanne-Marie; Welsch, Felix; Andres, Annchristin; Wickert, Kerstin; Braun, Benedikt J; Pohlemann, Tim
Concepts and clinical aspects of active implants for the treatment of bone fractures Artikel
In: Acta Biomaterialia, Bd. 146, S. 1–9, 2022, ISSN: 1742-7061.
@article{Ganse2022,
title = {Concepts and clinical aspects of active implants for the treatment of bone fractures},
author = {Bergita Ganse and Marcel Orth and Michael Roland and Stefan Diebels and Paul Motzki and Stefan Seelecke and Susanne-Marie Kirsch and Felix Welsch and Annchristin Andres and Kerstin Wickert and Benedikt J Braun and Tim Pohlemann},
doi = {10.1016/j.actbio.2022.05.001},
issn = {1742-7061},
year = {2022},
date = {2022-07-00},
urldate = {2022-07-00},
journal = {Acta Biomaterialia},
volume = {146},
pages = {1--9},
publisher = {Elsevier BV},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stahl, Janneck; Saalfeld, Sylvia; Alaraj, Ali; Beuing, Oliver; Kaneko, Naoki; Behme, Daniel; Berg, Philipp
Multimodal patient-specific modeling of intracranial arteriovenous malformation hemodynamics including feeding artery and draining vein exploration Proceedings Article
In: S. 691-694, In 7th International Conference on Computational and Mathematical Biomedical Engineering (CMBE) Milano, Italy, 2022.
@inproceedings{nokeyw,
title = {Multimodal patient-specific modeling of intracranial arteriovenous malformation hemodynamics including feeding artery and draining vein exploration},
author = {Janneck Stahl and Sylvia Saalfeld and Ali Alaraj and Oliver Beuing and Naoki Kaneko and Daniel Behme and Philipp Berg},
url = {https://www.lss.ovgu.de/lss/en/Publications.html},
year = {2022},
date = {2022-06-30},
urldate = {2022-06-30},
pages = {691-694},
address = {Milano, Italy},
organization = {In 7th International Conference on Computational and Mathematical Biomedical Engineering (CMBE)},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Cansız, Barış; Kaliske, Michael
In: Journal of Computational and Applied Mathematics, Bd. Vol. 407, 2022.
@article{nokeyx,
title = {A comparative study of fully implicit staggered and monolithic solution methods. Part II: Coupled excitation-contraction equations of cardiac electromechanics},
author = {Barış Cansız and Michael Kaliske},
editor = {Journal Computational and Applied Mathematics},
doi = {https://doi.org/10.1016/j.cam.2021.114021},
year = {2022},
date = {2022-06-30},
urldate = {2022-06-30},
journal = {Journal of Computational and Applied Mathematics},
volume = {Vol. 407},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nogatz, Tessa; Redenbach, Claudia; Schladitz, Katja
3D optical flow for large CT data of materials microstructures Artikel
In: Strain, Bd. 58, Nr. 3, 2022, ISSN: 1475-1305.
@article{Nogatz2022,
title = {3D optical flow for large CT data of materials microstructures},
author = {Tessa Nogatz and Claudia Redenbach and Katja Schladitz},
doi = {10.1111/str.12412},
issn = {1475-1305},
year = {2022},
date = {2022-06-00},
urldate = {2022-06-00},
journal = {Strain},
volume = {58},
number = {3},
publisher = {Wiley},
abstract = {<jats:title>Abstract</jats:title><jats:p>We compute three‐dimensional displacement vector fields to estimate the deformation of microstructural data sets in mechanical tests. For this, we extend the well‐known optical flow by Brox et al. to three dimensions, with special focus on the discretization of nonlinear terms. We evaluate our method first by synthetically deforming foams and comparing against this ground truth and second with data sets of samples that underwent real mechanical tests. Our results are compared to those from state‐of‐the‐art algorithms in materials science and medical image registration. By a thorough evaluation, we show that our proposed method is able to resolve the displacement best among all chosen comparison methods.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title><jats:p>We compute three‐dimensional displacement vector fields to estimate the deformation of microstructural data sets in mechanical tests. For this, we extend the well‐known optical flow by Brox et al. to three dimensions, with special focus on the discretization of nonlinear terms. We evaluate our method first by synthetically deforming foams and comparing against this ground truth and second with data sets of samples that underwent real mechanical tests. Our results are compared to those from state‐of‐the‐art algorithms in materials science and medical image registration. By a thorough evaluation, we show that our proposed method is able to resolve the displacement best among all chosen comparison methods.</jats:p>
Fritz, Marvin; Köppl, Tobias; Oden, John Tinsley; Wagner, Andreas; Wohlmuth, Barbara; Wu, Chengyue
A 1D–0D–3D coupled model for simulating blood flow and transport processes in breast tissue Artikel
In: International Journal for Numerical Methods in Biomedical Engineering, Bd. 38, Ausg. 7, S. e3612, 2022.
@article{fritz20221d,
title = {A 1D–0D–3D coupled model for simulating blood flow and transport processes in breast tissue},
author = {Marvin Fritz and Tobias Köppl and John Tinsley Oden and Andreas Wagner and Barbara Wohlmuth and Chengyue Wu},
editor = {Wiley Online Library},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/cnm.3612},
doi = {https://doi.org/10.1002/cnm.3612},
year = {2022},
date = {2022-05-06},
urldate = {2022-05-06},
journal = {International Journal for Numerical Methods in Biomedical Engineering},
volume = {38},
issue = {7},
pages = {e3612},
abstract = {In this work, we present mixed dimensional models for simulating blood flow and transport processes in breast tissue and the vascular tree supplying it. These processes are considered, to start from the aortic inlet to the capillaries and tissue of the breast. Large variations in biophysical properties and flow conditions exist in this system necessitating the use of different flow models for different geometries and flow regimes. In total, we consider four different model types. First, a system of 1D nonlinear hyperbolic partial differential equations (PDEs) is considered to simulate blood flow in larger arteries with highly elastic vessel walls. Second, we assign 1D linearized hyperbolic PDEs to model the smaller arteries with stiffer vessel walls. The third model type consists of ODE systems (0D models). It is used to model the arterioles and peripheral circulation. Finally, homogenized 3D porous media models are considered to simulate flow and transport in capillaries and tissue within the breast volume. Sink terms are used to account for the influence of the venous and lymphatic systems. Combining the four model types, we obtain two different 1D–0D–3D coupled models for simulating blood flow and transport processes: The first model results in a fully coupled 1D–0D–3D model covering the complete path from the aorta to the breast combining a generic arterial network with a patient specific breast network and geometry. The second model is a reduced one based on the separation of the generic and patient specific parts. The information from a calibrated fully coupled model is used as inflow condition for the patient specific sub-model allowing a significant computational cost reduction. Several numerical experiments are conducted to calibrate the generic model parameters and to demonstrate realistic flow simulations compared to existing data on blood flow in the human breast and vascular system. Moreover, we use two different breast vasculature and tissue data sets to illustrate the robustness of our reduced sub-model approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work, we present mixed dimensional models for simulating blood flow and transport processes in breast tissue and the vascular tree supplying it. These processes are considered, to start from the aortic inlet to the capillaries and tissue of the breast. Large variations in biophysical properties and flow conditions exist in this system necessitating the use of different flow models for different geometries and flow regimes. In total, we consider four different model types. First, a system of 1D nonlinear hyperbolic partial differential equations (PDEs) is considered to simulate blood flow in larger arteries with highly elastic vessel walls. Second, we assign 1D linearized hyperbolic PDEs to model the smaller arteries with stiffer vessel walls. The third model type consists of ODE systems (0D models). It is used to model the arterioles and peripheral circulation. Finally, homogenized 3D porous media models are considered to simulate flow and transport in capillaries and tissue within the breast volume. Sink terms are used to account for the influence of the venous and lymphatic systems. Combining the four model types, we obtain two different 1D–0D–3D coupled models for simulating blood flow and transport processes: The first model results in a fully coupled 1D–0D–3D model covering the complete path from the aorta to the breast combining a generic arterial network with a patient specific breast network and geometry. The second model is a reduced one based on the separation of the generic and patient specific parts. The information from a calibrated fully coupled model is used as inflow condition for the patient specific sub-model allowing a significant computational cost reduction. Several numerical experiments are conducted to calibrate the generic model parameters and to demonstrate realistic flow simulations compared to existing data on blood flow in the human breast and vascular system. Moreover, we use two different breast vasculature and tissue data sets to illustrate the robustness of our reduced sub-model approach.
Klotz, Thomas; Gizzi, Leonardo; Röhrle, Oliver
Investigating the spatial resolution of EMG and MMG based on a systemic multi-scale model Artikel
In: Biomechanics and Modeling in Mechanobiology, Bd. 21, S. 983-997, 2022, (cite arxiv:2108.05046Comment: Preprint, Submitted to Biomechanics and Modeling in Mechanobiology).
@article{klotz2021investigating,
title = {Investigating the spatial resolution of EMG and MMG based on a systemic multi-scale model},
author = {Thomas Klotz and Leonardo Gizzi and Oliver Röhrle},
editor = {Springer},
url = {https://link.springer.com/article/10.1007/s10237-022-01572-7
https://rdcu.be/dpxtQ},
doi = {https://doi.org/10.48550/arXiv.2108.05046},
year = {2022},
date = {2022-04-20},
urldate = {2022-01-01},
journal = {Biomechanics and Modeling in Mechanobiology},
volume = {21},
pages = {983-997},
abstract = {While electromyography (EMG) and magnetomyography (MMG) are both methods to measure the electrical activity of skeletal muscles, no systematic comparison between both signals exists. Within this work, we propose a systemic in silico model for EMG and MMG and test the hypothesis that MMG surpasses EMG in terms of spatial selectivity. The results show that MMG provides a slightly better spatial selectivity than EMG when recorded directly on the muscle surface. However, there is a remarkable difference in spatial selectivity for non-invasive surface measurements. The spatial selectivity of the MMG
components aligned with the muscle fibres and normal to the body surface outperforms the spatial selectivity of surface EMG. Particularly, for the MMG's normal-to-the-surface component the influence of subcutaneous fat is minimal. Further, for the first time, we analyse the contribution of different structural components, i.e., muscle fibres from different motor units and the extracellular space, to the measurable biomagnetic field. Notably, the simulations show that the normal-to-the-surface MMG component, the contribution from volume currents in the extracellular space and in surrounding inactive
tissues is negligible. Further, our model predicts a surprisingly high contribution of the passive muscle fibres to the observable magnetic field.},
note = {cite arxiv:2108.05046Comment: Preprint, Submitted to Biomechanics and Modeling in Mechanobiology},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
While electromyography (EMG) and magnetomyography (MMG) are both methods to measure the electrical activity of skeletal muscles, no systematic comparison between both signals exists. Within this work, we propose a systemic in silico model for EMG and MMG and test the hypothesis that MMG surpasses EMG in terms of spatial selectivity. The results show that MMG provides a slightly better spatial selectivity than EMG when recorded directly on the muscle surface. However, there is a remarkable difference in spatial selectivity for non-invasive surface measurements. The spatial selectivity of the MMG
components aligned with the muscle fibres and normal to the body surface outperforms the spatial selectivity of surface EMG. Particularly, for the MMG's normal-to-the-surface component the influence of subcutaneous fat is minimal. Further, for the first time, we analyse the contribution of different structural components, i.e., muscle fibres from different motor units and the extracellular space, to the measurable biomagnetic field. Notably, the simulations show that the normal-to-the-surface MMG component, the contribution from volume currents in the extracellular space and in surrounding inactive
tissues is negligible. Further, our model predicts a surprisingly high contribution of the passive muscle fibres to the observable magnetic field.
components aligned with the muscle fibres and normal to the body surface outperforms the spatial selectivity of surface EMG. Particularly, for the MMG's normal-to-the-surface component the influence of subcutaneous fat is minimal. Further, for the first time, we analyse the contribution of different structural components, i.e., muscle fibres from different motor units and the extracellular space, to the measurable biomagnetic field. Notably, the simulations show that the normal-to-the-surface MMG component, the contribution from volume currents in the extracellular space and in surrounding inactive
tissues is negligible. Further, our model predicts a surprisingly high contribution of the passive muscle fibres to the observable magnetic field.
Obermeier, Lukas; Vellguth, Katharina; Schlief, Adriano; Tautz, Lennart; Bruening, Jan; Knosalla, Christoph; Kuehne, Titus; Solowjowa, Natalia; Goubergrits, Leonid
In: Frontiers in Cardiovascular Medicine, Ausg. 9/2022, 2022, ISSN: 2297-055X.
@article{Obermeier2022,
title = {CT-Based Simulation of Left Ventricular Hemodynamics: A Pilot Study in Mitral Regurgitation and Left Ventricle Aneurysm Patients},
author = {Lukas Obermeier and Katharina Vellguth and Adriano Schlief and Lennart Tautz and Jan Bruening and Christoph Knosalla and Titus Kuehne and Natalia Solowjowa and Leonid Goubergrits},
doi = {10.3389/fcvm.2022.828556},
issn = {2297-055X},
year = {2022},
date = {2022-03-22},
urldate = {2022-03-22},
journal = {Frontiers in Cardiovascular Medicine},
issue = {9/2022},
abstract = {Background: Cardiac CT (CCT) is well suited for a detailed analysis of heart structures due to its high spatial resolution, but in contrast to MRI and echocardiography, CCT does not allow an assessment of intracardiac flow. Computational fluid dynamics (CFD) can complement this shortcoming. It enables the computation of hemodynamics at a high spatio-temporal resolution based on medical images. The aim of this proposed study is to establish a CCT-based CFD methodology for the analysis of left ventricle (LV) hemodynamics and to assess the usability of the computational framework for clinical practice.
Materials and methods: The methodology is demonstrated by means of four cases selected from a cohort of 125 multiphase CCT examinations of heart failure patients. These cases represent subcohorts of patients with and without LV aneurysm and with severe and no mitral regurgitation (MR). All selected LVs are dilated and characterized by a reduced ejection fraction (EF). End-diastolic and end-systolic image data was used to reconstruct LV geometries with 2D valves as well as the ventricular movement. The intraventricular hemodynamics were computed with a prescribed-motion CFD approach and evaluated in terms of large-scale flow patterns, energetic behavior, and intraventricular washout.
Results: In the MR patients, a disrupted E-wave jet, a fragmentary diastolic vortex formation and an increased specific energy dissipation in systole are observed. In all cases, regions with an impaired washout are visible. The results furthermore indicate that considering several cycles might provide a more detailed view of the washout process. The pre-processing times and computational expenses are in reach of clinical feasibility.
Conclusion: The proposed CCT-based CFD method allows to compute patient-specific intraventricular hemodynamics and thus complements the informative value of CCT. The method can be applied to any CCT data of common quality and represents a fair balance between model accuracy and overall expenses. With further model enhancements, the computational framework has the potential to be embedded in clinical routine workflows, to support clinical decision making and treatment planning.
Keywords: cardiac computed tomography; computational fluid dynamics; fluid-structure interaction; image-based modeling; intraventricular hemodynamics; left ventricle aneurysm; mitral regurgitation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background: Cardiac CT (CCT) is well suited for a detailed analysis of heart structures due to its high spatial resolution, but in contrast to MRI and echocardiography, CCT does not allow an assessment of intracardiac flow. Computational fluid dynamics (CFD) can complement this shortcoming. It enables the computation of hemodynamics at a high spatio-temporal resolution based on medical images. The aim of this proposed study is to establish a CCT-based CFD methodology for the analysis of left ventricle (LV) hemodynamics and to assess the usability of the computational framework for clinical practice.
Materials and methods: The methodology is demonstrated by means of four cases selected from a cohort of 125 multiphase CCT examinations of heart failure patients. These cases represent subcohorts of patients with and without LV aneurysm and with severe and no mitral regurgitation (MR). All selected LVs are dilated and characterized by a reduced ejection fraction (EF). End-diastolic and end-systolic image data was used to reconstruct LV geometries with 2D valves as well as the ventricular movement. The intraventricular hemodynamics were computed with a prescribed-motion CFD approach and evaluated in terms of large-scale flow patterns, energetic behavior, and intraventricular washout.
Results: In the MR patients, a disrupted E-wave jet, a fragmentary diastolic vortex formation and an increased specific energy dissipation in systole are observed. In all cases, regions with an impaired washout are visible. The results furthermore indicate that considering several cycles might provide a more detailed view of the washout process. The pre-processing times and computational expenses are in reach of clinical feasibility.
Conclusion: The proposed CCT-based CFD method allows to compute patient-specific intraventricular hemodynamics and thus complements the informative value of CCT. The method can be applied to any CCT data of common quality and represents a fair balance between model accuracy and overall expenses. With further model enhancements, the computational framework has the potential to be embedded in clinical routine workflows, to support clinical decision making and treatment planning.
Keywords: cardiac computed tomography; computational fluid dynamics; fluid-structure interaction; image-based modeling; intraventricular hemodynamics; left ventricle aneurysm; mitral regurgitation.
Materials and methods: The methodology is demonstrated by means of four cases selected from a cohort of 125 multiphase CCT examinations of heart failure patients. These cases represent subcohorts of patients with and without LV aneurysm and with severe and no mitral regurgitation (MR). All selected LVs are dilated and characterized by a reduced ejection fraction (EF). End-diastolic and end-systolic image data was used to reconstruct LV geometries with 2D valves as well as the ventricular movement. The intraventricular hemodynamics were computed with a prescribed-motion CFD approach and evaluated in terms of large-scale flow patterns, energetic behavior, and intraventricular washout.
Results: In the MR patients, a disrupted E-wave jet, a fragmentary diastolic vortex formation and an increased specific energy dissipation in systole are observed. In all cases, regions with an impaired washout are visible. The results furthermore indicate that considering several cycles might provide a more detailed view of the washout process. The pre-processing times and computational expenses are in reach of clinical feasibility.
Conclusion: The proposed CCT-based CFD method allows to compute patient-specific intraventricular hemodynamics and thus complements the informative value of CCT. The method can be applied to any CCT data of common quality and represents a fair balance between model accuracy and overall expenses. With further model enhancements, the computational framework has the potential to be embedded in clinical routine workflows, to support clinical decision making and treatment planning.
Keywords: cardiac computed tomography; computational fluid dynamics; fluid-structure interaction; image-based modeling; intraventricular hemodynamics; left ventricle aneurysm; mitral regurgitation.
Manjunatha, K.; Behr, M.; Vogt, F.; Reese, S.
Finite Element Modeling of In-Stent Restenosis Buchabschnitt
In: Link, Springer (Hrsg.): S. 305–318, 2022.
@incollection{Manjunatha2022,
title = {Finite Element Modeling of In-Stent Restenosis},
author = {K. Manjunatha and M. Behr and F. Vogt and S. Reese},
editor = {Springer Link},
url = {https://link.springer.com/chapter/10.1007/978-3-030-87312-7_30},
doi = {10.1007/978-3-030-87312-7_30},
year = {2022},
date = {2022-03-13},
urldate = {2022-03-13},
pages = {305–318},
abstract = {From the perspective of coronary heart disease, the development of stents has come significantly far in reducing the associated mortality rate, drug-eluting stents being the epitome of innovative and effective solutions. Within this work, the intricate process of in-stent restenosis is modelled considering one of the significant growth factors and its effect on constituents of the arterial wall. A multiphysical modelling approach is adopted in this regard. Experimental investigations from the literature have been used to hypothesize the governing equations and the corresponding parameters. A staggered solution strategy is utilised to capture the transport phenomena as well as the growth and remodeling that follows stent implantation. The model herein developed serves as a tool to predict in-stent restenosis depending on the endothelial injury sustained and the protuberance of stents into the lumen of the arteries.},
keywords = {},
pubstate = {published},
tppubtype = {incollection}
}
From the perspective of coronary heart disease, the development of stents has come significantly far in reducing the associated mortality rate, drug-eluting stents being the epitome of innovative and effective solutions. Within this work, the intricate process of in-stent restenosis is modelled considering one of the significant growth factors and its effect on constituents of the arterial wall. A multiphysical modelling approach is adopted in this regard. Experimental investigations from the literature have been used to hypothesize the governing equations and the corresponding parameters. A staggered solution strategy is utilised to capture the transport phenomena as well as the growth and remodeling that follows stent implantation. The model herein developed serves as a tool to predict in-stent restenosis depending on the endothelial injury sustained and the protuberance of stents into the lumen of the arteries.
Aldakheel, F.; Hudobivnik, B.; Soleimani, M.; Wessels, H.; Weissenfels, C.; Marino, M.
Current Trends and Open Problems in Computational Mechanics Buch
Springer, 2022.
@book{Aldakheel2022,
title = {Current Trends and Open Problems in Computational Mechanics},
author = {F. Aldakheel and B. Hudobivnik and M. Soleimani and H. Wessels and C. Weissenfels and M. Marino},
editor = {Springer-Verlag},
url = {https://link.springer.com/book/10.1007/978-3-030-87312-7},
doi = {https://doi.org/10.1007/978-3-030-87312-7},
year = {2022},
date = {2022-03-12},
publisher = {Springer},
abstract = {This Festschrift is dedicated to Professor Dr.-Ing. habil. Peter Wriggers on the occasion of his 70th birthday. Thanks to his high dedication to research, over the years Peter Wriggers has built an international network with renowned experts in the field of computational mechanics. This is proven by the large number of contributions from friends and collaborators as well as former PhD students from all over the world. The diversity of Peter Wriggers network is mirrored by the range of topics that are covered by this book. To name only a few, these include contact mechanics, finite & virtual element technologies, micromechanics, multiscale approaches, fracture mechanics, isogeometric analysis, stochastic methods, meshfree and particle methods. Applications of numerical simulation to specific problems, e.g. Biomechanics and Additive Manufacturing is also covered. The volume intends to present an overview of the state of the art and current trends in computational mechanics for academia and industry.},
keywords = {},
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tppubtype = {book}
}
This Festschrift is dedicated to Professor Dr.-Ing. habil. Peter Wriggers on the occasion of his 70th birthday. Thanks to his high dedication to research, over the years Peter Wriggers has built an international network with renowned experts in the field of computational mechanics. This is proven by the large number of contributions from friends and collaborators as well as former PhD students from all over the world. The diversity of Peter Wriggers network is mirrored by the range of topics that are covered by this book. To name only a few, these include contact mechanics, finite & virtual element technologies, micromechanics, multiscale approaches, fracture mechanics, isogeometric analysis, stochastic methods, meshfree and particle methods. Applications of numerical simulation to specific problems, e.g. Biomechanics and Additive Manufacturing is also covered. The volume intends to present an overview of the state of the art and current trends in computational mechanics for academia and industry.
Ricken, Tim; Schröder, Jörg; Bluhm, Joachim; Bartel, Florian
In: International Journal of Solids and Structures, 2022, 2022.
@article{Ricken2022,
title = {Theoretical formulation and computational aspects of a two-scale homogenization scheme combining the TPM and FE² method for poro-elastic fuid-saturated porous media},
author = {Tim Ricken and Jörg Schröder and Joachim Bluhm and Florian Bartel},
editor = {Elsevier},
url = {https://www.sciencedirect.com/science/article/pii/S0020768321004674?via%3Dihub},
doi = {https://doi.org/10.1016/j.ijsolstr.2021.111412},
year = {2022},
date = {2022-02-28},
journal = {International Journal of Solids and Structures, 2022},
abstract = {The focus of this investigation lies on the development of a two-scale homogenization scheme for poro-elastic fluid-saturated porous media. For this purpose, the general concepts of the Theory of Porous Media (TPM) are combined with the FE method. After an introduction of the basics of TPM, the weak forms for the macroscopic and the microscopic scale will be formulated and the averaged macroscopic tangent moduli considering the microscale will be derived. Additionally, the formulation of lower level boundary conditions, which refer to the quantities that will be transmitted from the macro- to the microscale, in strict compliance with the Hill–Mandel homogeneity condition, is derived. Finally, a numerical example will be presented, pointing out the gained features of the methodology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The focus of this investigation lies on the development of a two-scale homogenization scheme for poro-elastic fluid-saturated porous media. For this purpose, the general concepts of the Theory of Porous Media (TPM) are combined with the FE method. After an introduction of the basics of TPM, the weak forms for the macroscopic and the microscopic scale will be formulated and the averaged macroscopic tangent moduli considering the microscale will be derived. Additionally, the formulation of lower level boundary conditions, which refer to the quantities that will be transmitted from the macro- to the microscale, in strict compliance with the Hill–Mandel homogeneity condition, is derived. Finally, a numerical example will be presented, pointing out the gained features of the methodology.
Schmid, Laura; Klotz, Thomas; Yavuz, Utku; Maltenfort, Mitchell; Roehrle, Oliver
In: Physiome, 2022.
@article{Schmid2022,
title = {Spindle Model Responsive to Mixed Fusimotor Inputs: an updated version of the Maltenfort and Burke (2003) model},
author = {Laura Schmid and Thomas Klotz and Utku Yavuz and Mitchell Maltenfort and Oliver Roehrle},
doi = {10.36903/physiome.19070171.v2},
year = {2022},
date = {2022-01-27},
urldate = {2022-01-27},
journal = {Physiome},
abstract = {The muscle spindle model presented in Maltenfort and Burke (2003) calculates muscle spindle primary afferent feedback depending on the muscle fibre stretch and fusimotor drive. The aim of this paper is to provide an updated version of the model, which is now capable of replicating the originally published data. This is achieved by modifying the equations describing the modulation of the muscle spindle output in response to dynamic fusimotor drive. EDITOR'S NOTE V2: Showing manuscript and model files.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The muscle spindle model presented in Maltenfort and Burke (2003) calculates muscle spindle primary afferent feedback depending on the muscle fibre stretch and fusimotor drive. The aim of this paper is to provide an updated version of the model, which is now capable of replicating the originally published data. This is achieved by modifying the equations describing the modulation of the muscle spindle output in response to dynamic fusimotor drive. EDITOR'S NOTE V2: Showing manuscript and model files.
Saalfeld, Sylvia; Stahl, Janneck; Korte, Jana; Marsh, Laurel M. Miller; Preim, Bernhard; Beuing, Oliver; Cherednychenko, Yurii; Behme, Daniel; Berg, Philipp
In: Frontiers, Bd. Volume 12 - 2021, 2022.
@article{https://doi.org/10.3389/fneur.2021.771694,
title = {Can Endovascular Treatment of Fusiform Intracranial Aneurysms Restore the Healthy Hemodynamic Environment? - A Virtual Pilot Study},
author = {Sylvia Saalfeld and Janneck Stahl and Jana Korte and Laurel M. Miller Marsh and Bernhard Preim and Oliver Beuing and Yurii Cherednychenko and Daniel Behme and Philipp Berg},
url = {https://www.frontiersin.org/articles/10.3389/fneur.2021.771694/full},
doi = {https://doi.org/10.3389/fneur.2021.771694},
year = {2022},
date = {2022-01-24},
urldate = {2022-01-24},
journal = {Frontiers},
volume = {Volume 12 - 2021},
abstract = {Numerous studies assess intracranial aneurysm rupture risk based on morphological and hemodynamic parameter analysis in addition to clinical information such as aneurysm localization, age, and sex. However, intracranial aneurysms mostly occur with a saccular shape located either lateral to the parent artery or at a bifurcation. In contrast, fusiform intracranial aneurysms (FIAs), i.e., aneurysms with a non-saccular, dilated form, occur in approximately 3–13% of all cases and therefore have not yet been as thoroughly studied. To improve the understanding of FIA hemodynamics, this pilot study contains morphological analyses and image-based blood flow simulations in three patient-specific cases. For a precise and realistic comparison to the pre-pathological state, each dilation was manually removed and the time-dependent blood flow simulations were repeated. Additionally, a validated fast virtual stenting approach was applied to evaluate the effect of virtual endovascular flow-diverter deployment focusing on relevant hemodynamic quantities. For two of the three patients, post-interventional information was available and included in the analysis. The results of this numerical pilot study indicate that complex flow structures, i.e., helical flow phenomena and the presence of high oscillating flow features, predominantly occur in FIAs with morphologically differing appearances. Due to the investigation of the individual healthy states, the original flow environment could be restored which serves as a reference for the virtual treatment target. It was shown that the realistic deployment led to a considerable stabilization of the individual hemodynamics in all cases. Furthermore, a quantification of the stent-induced therapy effect became feasible for the treating physician. The results of the morphological and hemodynamic analyses in this pilot study show that virtual stenting can be used in FIAs to quantify the effect of the planned endovascular treatment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Numerous studies assess intracranial aneurysm rupture risk based on morphological and hemodynamic parameter analysis in addition to clinical information such as aneurysm localization, age, and sex. However, intracranial aneurysms mostly occur with a saccular shape located either lateral to the parent artery or at a bifurcation. In contrast, fusiform intracranial aneurysms (FIAs), i.e., aneurysms with a non-saccular, dilated form, occur in approximately 3–13% of all cases and therefore have not yet been as thoroughly studied. To improve the understanding of FIA hemodynamics, this pilot study contains morphological analyses and image-based blood flow simulations in three patient-specific cases. For a precise and realistic comparison to the pre-pathological state, each dilation was manually removed and the time-dependent blood flow simulations were repeated. Additionally, a validated fast virtual stenting approach was applied to evaluate the effect of virtual endovascular flow-diverter deployment focusing on relevant hemodynamic quantities. For two of the three patients, post-interventional information was available and included in the analysis. The results of this numerical pilot study indicate that complex flow structures, i.e., helical flow phenomena and the presence of high oscillating flow features, predominantly occur in FIAs with morphologically differing appearances. Due to the investigation of the individual healthy states, the original flow environment could be restored which serves as a reference for the virtual treatment target. It was shown that the realistic deployment led to a considerable stabilization of the individual hemodynamics in all cases. Furthermore, a quantification of the stent-induced therapy effect became feasible for the treating physician. The results of the morphological and hemodynamic analyses in this pilot study show that virtual stenting can be used in FIAs to quantify the effect of the planned endovascular treatment.
Hessenthaler, Andreas; Falgout, Robert D; Schroder, Jacob B; Vecchi, Adelaide; Nordsletten, David; Röhrle, Oliver
In: Computer Methods in Applied Mechanics and Engineering, Bd. 389, S. 114368, 2022.
@article{hessenthaler2022time,
title = {Time-periodic steady-state solution of fluid-structure interaction and cardiac flow problems through multigrid-reduction-in-time},
author = {Andreas Hessenthaler and Robert D Falgout and Jacob B Schroder and Adelaide Vecchi and David Nordsletten and Oliver Röhrle},
doi = {https://doi.org/10.1016/j.cma.2021.114368},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Computer Methods in Applied Mechanics and Engineering},
volume = {389},
pages = {114368},
publisher = {Elsevier},
keywords = {},
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Arf, Jeremias; Simeon, Bernd
In: etna, Bd. 55, S. 310–340, 2022, ISSN: 1068-9613.
@article{Arf2022,
title = {A space-time isogeometric method for the partial differential-algebraic system of Biot's poroelasticity model},
author = {Jeremias Arf and Bernd Simeon},
doi = {10.1553/etna_vol55s310},
issn = {1068-9613},
year = {2022},
date = {2022-00-00},
urldate = {2022-00-00},
journal = {etna},
volume = {55},
pages = {310--340},
publisher = {Osterreichische Akademie der Wissenschaften, Verlag},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2021
Christ, Uta Dahmen Maximilian Collatz Bruno; König, Matthias; Lambers, Lena; Marz, Manja; Meyer, Daria; Radde, Nicole; Reichenbach, Jürgen R.; Ricken, Tim; Tautenhahn, Hans-Michael
In: Frontiers in Physiology (12), 2021.
@article{Christ2021,
title = {Hepatectomy-induced alterations in hepatic perfusion and function – Towards multi-scale modeling for a better risk assessment in liver surgery},
author = {Uta Dahmen Maximilian Collatz Bruno Christ and Matthias König and Lena Lambers and Manja Marz and Daria Meyer and Nicole Radde and Jürgen R. Reichenbach and Tim Ricken and Hans-Michael Tautenhahn},
editor = {Sec. Computational Physiology Frontiers in Physiology and Medicine},
url = {https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.733868/full},
doi = {https://doi.org/10.3389/fphys.2021.733868},
year = {2021},
date = {2021-11-18},
journal = {Frontiers in Physiology (12)},
abstract = {Liver resection causes marked perfusion alterations in the liver remnant both on the organ scale (vascular anatomy) and on the microscale (sinusoidal blood flow on tissue level). These changes in perfusion affect hepatic functions via direct alterations in blood supply and drainage, followed by indirect changes of biomechanical tissue properties and cellular function. Changes in blood flow impose compression, tension and shear forces on the liver tissue. These forces are perceived by mechanosensors on parenchymal and non-parenchymal cells of the liver and regulate cell-cell and cell-matrix interactions as well as cellular signaling and metabolism. These interactions are key players in tissue growth and remodeling, a prerequisite to restore tissue function after PHx. Their dysregulation is associated with metabolic impairment of the liver eventually leading to liver failure, a serious post-hepatectomy complication with high morbidity and mortality. Though certain links are known, the overall functional change after liver surgery is not understood due to complex feedback loops, non-linearities, spatial heterogeneities and different time-scales of events. Computational modeling is a unique approach to gain a better understanding of complex biomedical systems. This approach allows (i) integration of heterogeneous data and knowledge on multiple scales into a consistent view of how perfusion is related to hepatic function; (ii) testing and generating hypotheses based on predictive models, which must be validated experimentally and clinically. In the long term, computational modeling will (iii) support surgical planning by predicting surgery-induced perfusion perturbations and their functional (metabolic) consequences; and thereby (iv) allow minimizing surgical risks for the individual patient. Here, we review the alterations of hepatic perfusion, biomechanical properties and function associated with hepatectomy. Specifically, we provide an overview over the clinical problem, preoperative diagnostics, functional imaging approaches, experimental approaches in animal models, mechanoperception in the liver and impact on cellular metabolism, omics approaches with a focus on transcriptomics, data integration and uncertainty analysis, and computational modeling on multiple scales. Finally, we provide a perspective on how multi-scale computational models, which couple perfusion changes to hepatic function, could become part of clinical workflows to predict and optimize patient outcome after complex liver surgery.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Liver resection causes marked perfusion alterations in the liver remnant both on the organ scale (vascular anatomy) and on the microscale (sinusoidal blood flow on tissue level). These changes in perfusion affect hepatic functions via direct alterations in blood supply and drainage, followed by indirect changes of biomechanical tissue properties and cellular function. Changes in blood flow impose compression, tension and shear forces on the liver tissue. These forces are perceived by mechanosensors on parenchymal and non-parenchymal cells of the liver and regulate cell-cell and cell-matrix interactions as well as cellular signaling and metabolism. These interactions are key players in tissue growth and remodeling, a prerequisite to restore tissue function after PHx. Their dysregulation is associated with metabolic impairment of the liver eventually leading to liver failure, a serious post-hepatectomy complication with high morbidity and mortality. Though certain links are known, the overall functional change after liver surgery is not understood due to complex feedback loops, non-linearities, spatial heterogeneities and different time-scales of events. Computational modeling is a unique approach to gain a better understanding of complex biomedical systems. This approach allows (i) integration of heterogeneous data and knowledge on multiple scales into a consistent view of how perfusion is related to hepatic function; (ii) testing and generating hypotheses based on predictive models, which must be validated experimentally and clinically. In the long term, computational modeling will (iii) support surgical planning by predicting surgery-induced perfusion perturbations and their functional (metabolic) consequences; and thereby (iv) allow minimizing surgical risks for the individual patient. Here, we review the alterations of hepatic perfusion, biomechanical properties and function associated with hepatectomy. Specifically, we provide an overview over the clinical problem, preoperative diagnostics, functional imaging approaches, experimental approaches in animal models, mechanoperception in the liver and impact on cellular metabolism, omics approaches with a focus on transcriptomics, data integration and uncertainty analysis, and computational modeling on multiple scales. Finally, we provide a perspective on how multi-scale computational models, which couple perfusion changes to hepatic function, could become part of clinical workflows to predict and optimize patient outcome after complex liver surgery.
Braun, Benedikt J.; Orth, Marcel; Diebels, Stefan; Wickert, Kerstin; Andres, Annchristin; Gawlitza, Joshua; Bücker, Arno; Pohlemann, Tim; Roland, Michael
In: Front. Surg., Bd. 8, 2021, ISSN: 2296-875X.
@article{Braun2021,
title = {Individualized Determination of the Mechanical Fracture Environment After Tibial Exchange Nailing—A Simulation-Based Feasibility Study},
author = {Benedikt J. Braun and Marcel Orth and Stefan Diebels and Kerstin Wickert and Annchristin Andres and Joshua Gawlitza and Arno Bücker and Tim Pohlemann and Michael Roland},
doi = {10.3389/fsurg.2021.749209},
issn = {2296-875X},
year = {2021},
date = {2021-09-29},
urldate = {2021-09-29},
journal = {Front. Surg.},
volume = {8},
publisher = {Frontiers Media SA},
abstract = {<jats:p>Non-union rate after tibial fractures remains high. Apart from largely uncontrollable biologic, injury, and patient-specific factors, the mechanical fracture environment is a key determinant of healing. Our aim was to establish a patient-specific simulation workflow to determine the mechanical fracture environment and allow for an estimation of its healing potential. In a referred patient with failed nail-osteosynthesis after tibial-shaft fracture exchange nailing was performed. Post-operative CT-scans were used to construct a three-dimensional model of the treatment situation in an image processing and computer-aided design system. Resulting forces, computed in a simulation-driven workflow based on patient monitoring and motion capturing were used to simulate the mechanical fracture environment before and after exchange nailing. Implant stresses for the initial and revision situation, as well as interfragmentary movement, resulting hydrostatic, and octahedral shear strain were calculated and compared to the clinical course. The simulation model was able to adequately predict hardware stresses in the initial situation where mechanical implant failure occurred. Furthermore, hydrostatic and octahedral shear strain of the revision situation were calculated to be within published healing boundaries—accordingly the fracture healed uneventfully. Our workflow is able to determine the mechanical environment of a fracture fixation, calculate implant stresses, interfragmentary movement, and the resulting strain. Critical mechanical boundary conditions for fracture healing can be determined in relation to individual loading parameters. Based on this individualized treatment recommendations during the early post-operative phase in lower leg fractures are possible in order to prevent implant failure and non-union development.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p>Non-union rate after tibial fractures remains high. Apart from largely uncontrollable biologic, injury, and patient-specific factors, the mechanical fracture environment is a key determinant of healing. Our aim was to establish a patient-specific simulation workflow to determine the mechanical fracture environment and allow for an estimation of its healing potential. In a referred patient with failed nail-osteosynthesis after tibial-shaft fracture exchange nailing was performed. Post-operative CT-scans were used to construct a three-dimensional model of the treatment situation in an image processing and computer-aided design system. Resulting forces, computed in a simulation-driven workflow based on patient monitoring and motion capturing were used to simulate the mechanical fracture environment before and after exchange nailing. Implant stresses for the initial and revision situation, as well as interfragmentary movement, resulting hydrostatic, and octahedral shear strain were calculated and compared to the clinical course. The simulation model was able to adequately predict hardware stresses in the initial situation where mechanical implant failure occurred. Furthermore, hydrostatic and octahedral shear strain of the revision situation were calculated to be within published healing boundaries—accordingly the fracture healed uneventfully. Our workflow is able to determine the mechanical environment of a fracture fixation, calculate implant stresses, interfragmentary movement, and the resulting strain. Critical mechanical boundary conditions for fracture healing can be determined in relation to individual loading parameters. Based on this individualized treatment recommendations during the early post-operative phase in lower leg fractures are possible in order to prevent implant failure and non-union development.</jats:p>
Seyedpour, Seyed M.; Nabati, Mehdi; Lambers, Lena; Nafisi, Sara; Tautenhahn, Hans-Michael; Sack, Ingolf; Reichenbach, Jürgen R.; Ricken, Tim
Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review Artikel
In: Frontiers in Physiology (12), 2021.
@article{Seyedpour2021,
title = {Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review},
author = {Seyed M. Seyedpour and Mehdi Nabati and Lena Lambers and Sara Nafisi and Hans-Michael Tautenhahn and Ingolf Sack and Jürgen R. Reichenbach and Tim Ricken},
editor = {Sec. Computational Physiology Frontiers in Physiology and Medicine},
url = {https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.733393/full},
doi = {https://doi.org/10.3389/fphys.2021.733393},
year = {2021},
date = {2021-09-22},
urldate = {2021-09-22},
journal = {Frontiers in Physiology (12)},
abstract = {MRI-based biomechanical studies can provide a deep understanding of the mechanisms governing liver function, its mechanical performance but also liver diseases. In addition, comprehensive modeling of the liver can help improve liver disease treatment. Furthermore, such studies demonstrate the beginning of an engineering-level approach to how the liver disease affects material properties and liver function. Aimed at researchers in the field of MRI-based liver simulation, research articles pertinent to MRI-based liver modeling were identified, reviewed, and summarized systematically. Various MRI applications for liver biomechanics are highlighted, and the limitations of different viscoelastic models used in magnetic resonance elastography are addressed. The clinical application of the simulations and the diseases studied are also discussed. Based on the developed questionnaire, the papers' quality was assessed, and of the 46 reviewed papers, 32 papers were determined to be of high-quality. Due to the lack of the suitable material models for different liver diseases studied by magnetic resonance elastography, researchers may consider the effect of liver diseases on constitutive models. In the future, research groups may incorporate various aspects of machine learning (ML) into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
MRI-based biomechanical studies can provide a deep understanding of the mechanisms governing liver function, its mechanical performance but also liver diseases. In addition, comprehensive modeling of the liver can help improve liver disease treatment. Furthermore, such studies demonstrate the beginning of an engineering-level approach to how the liver disease affects material properties and liver function. Aimed at researchers in the field of MRI-based liver simulation, research articles pertinent to MRI-based liver modeling were identified, reviewed, and summarized systematically. Various MRI applications for liver biomechanics are highlighted, and the limitations of different viscoelastic models used in magnetic resonance elastography are addressed. The clinical application of the simulations and the diseases studied are also discussed. Based on the developed questionnaire, the papers' quality was assessed, and of the 46 reviewed papers, 32 papers were determined to be of high-quality. Due to the lack of the suitable material models for different liver diseases studied by magnetic resonance elastography, researchers may consider the effect of liver diseases on constitutive models. In the future, research groups may incorporate various aspects of machine learning (ML) into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification.
Seyedpour, Seyed M.; Nabati, Mehdi; Lambers, Lena; Nafisi, Sara; Tautenhahn, Hans-Michael; Sack, Ingolf; Reichenbach, Jürgen R.; Ricken, Tim
Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review Artikel
In: Front. Physiol., Bd. 12, 2021, ISSN: 1664-042X.
@article{Seyedpour2021b,
title = {Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review},
author = {Seyed M. Seyedpour and Mehdi Nabati and Lena Lambers and Sara Nafisi and Hans-Michael Tautenhahn and Ingolf Sack and Jürgen R. Reichenbach and Tim Ricken},
doi = {10.3389/fphys.2021.733393},
issn = {1664-042X},
year = {2021},
date = {2021-09-22},
journal = {Front. Physiol.},
volume = {12},
publisher = {Frontiers Media SA},
abstract = {MRI-based biomechanical studies can provide a deep understanding of the mechanisms governing liver function, its mechanical performance but also liver diseases. In addition, comprehensive modeling of the liver can help improve liver disease treatment. Furthermore, such studies demonstrate the beginning of an engineering-level approach to how the liver disease affects material properties and liver function. Aimed at researchers in the field of MRI-based liver simulation, research articles pertinent to MRI-based liver modeling were identified, reviewed, and summarized systematically. Various MRI applications for liver biomechanics are highlighted, and the limitations of different viscoelastic models used in magnetic resonance elastography are addressed. The clinical application of the simulations and the diseases studied are also discussed. Based on the developed questionnaire, the papers' quality was assessed, and of the 46 reviewed papers, 32 papers were determined to be of high-quality. Due to the lack of the suitable material models for different liver diseases studied by magnetic resonance elastography, researchers may consider the effect of liver diseases on constitutive models. In the future, research groups may incorporate various aspects of machine learning (ML) into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stahl, Janneck; Saalfeld, Sylvia; McGuire, L. Stone; Brunozzi, D.; Alaraj, Ali; Hasan, D.; Berg, Philipp
Multimodal hemodynamic evaluation of vessel wall enhanced cerebral draining veins for the assessment of arteriovenous malformations Proceedings Article
In: S. 1-8, The 18th International Conference on Fluid Flow Technologies Budapest, Hungary, 2021.
@inproceedings{nokeyy,
title = {Multimodal hemodynamic evaluation of vessel wall enhanced cerebral draining veins for the assessment of arteriovenous malformations},
author = {Janneck Stahl and Sylvia Saalfeld and L. Stone McGuire and D. Brunozzi and Ali Alaraj and D. Hasan and Philipp Berg},
url = {https://www.lss.ovgu.de/lss/en/Publications.html},
year = {2021},
date = {2021-02-01},
urldate = {2021-02-01},
pages = {1-8},
address = {Budapest, Hungary},
organization = {The 18th International Conference on Fluid Flow Technologies},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Korte, Jana; Pravdivtseva, M.; Marsh, L.; Gaidzig, F.; Larsen, N.; Janiga, G.; Berg, Philipp
Can black blood MRI predict hemodynamics in intracranial aneurysms? – comparing in-vitro and in-silico flow investigations Proceedings Article
In: S. 1-6, The 18th International Conference on Fluid Flow Technologies Budapest, Hungary, 2021.
@inproceedings{nokeyz,
title = {Can black blood MRI predict hemodynamics in intracranial aneurysms? – comparing in-vitro and in-silico flow investigations},
author = {Jana Korte and M. Pravdivtseva and L. Marsh and F. Gaidzig and N. Larsen and G. Janiga and Philipp Berg},
url = {https://www.lss.ovgu.de/lss/en/Publications.html},
year = {2021},
date = {2021-02-01},
urldate = {2021-02-01},
pages = {1-6},
address = {Budapest, Hungary},
organization = {The 18th International Conference on Fluid Flow Technologies},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Bleiler, Christian; Castañeda, Pedro Ponte; Röhrle, Oliver
In: Journal of the Mechanics and Physics of Solids, Bd. 147, S. 104251, 2021, ISSN: 0022-5096.
@article{Bleiler2021,
title = {Tangent second-order homogenisation estimates for incompressible hyperelastic composites with fibrous microstructures and anisotropic phases},
author = {Christian Bleiler and Pedro Ponte Castañeda and Oliver Röhrle},
url = {https://doi.org/10.1016/j.jmps.2020.104251},
doi = {10.1016/j.jmps.2020.104251},
issn = {0022-5096},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Journal of the Mechanics and Physics of Solids},
volume = {147},
pages = {104251},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Gizzi, Leonardo; Vujaklija, Ivan; Sartori, Massimo; Röhrle, Oliver; Severini, Giacomo
In: Front. Bioengineering and Biotechnology, Sec. Bionics and Biomimetics, Bd. 9, 2021.
@article{gizzi2021editorial,
title = {Editorial: Somatosensory Integration in Human Movement: Perspectives for Neuromechanics, Modelling and Rehabilitation},
author = {Leonardo Gizzi and Ivan Vujaklija and Massimo Sartori and Oliver Röhrle and Giacomo Severini},
url = {https://doi.org/10.3389%2Ffbioe.2021.725603},
doi = {10.3389/fbioe.2021.725603},
year = {2021},
date = {2021-01-01},
urldate = {2021-01-01},
journal = {Front. Bioengineering and Biotechnology, Sec. Bionics and Biomimetics},
volume = {9},
publisher = {Frontiers Media SA},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
Braun, Benedikt J.; Grimm, Bernd; Hanflik, Andrew M.; Marmor, Meir T.; Richter, Peter H.; Sands, Andrew K.; Sivananthan, Sureshan
Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery Artikel
In: EFORT Open Reviews, Bd. 5, Nr. 7, S. 408–420, 2020, ISSN: 2058-5241.
@article{Braun2020,
title = {Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery},
author = {Benedikt J. Braun and Bernd Grimm and Andrew M. Hanflik and Meir T. Marmor and Peter H. Richter and Andrew K. Sands and Sureshan Sivananthan},
doi = {10.1302/2058-5241.5.200021},
issn = {2058-5241},
year = {2020},
date = {2020-07-00},
urldate = {2020-07-00},
journal = {EFORT Open Reviews},
volume = {5},
number = {7},
pages = {408--420},
publisher = {Bioscientifica},
abstract = {<jats:p> There are many digital solutions which assist the orthopaedic trauma surgeon. This already broad field is rapidly expanding, making a complete overview of the existing solutions difficult. The AO Foundation has established a task force to address the need for an overview of digital solutions in the field of orthopaedic trauma surgery. Areas of new technology which will help the surgeon gain a greater understanding of these possible solutions are reviewed. We propose a categorization of the current needs in orthopaedic trauma surgery matched with available or potential digital solutions, and provide a narrative overview of this broad topic, including the needs, solutions and basic rules to ensure adequate use in orthopaedic trauma surgery. We seek to make this field more accessible, allowing for technological solutions to be clearly matched to trauma surgeons’ needs. </jats:p><jats:p> Cite this article: EFORT Open Rev 2020;5:408-420. DOI: 10.1302/2058-5241.5.200021 </jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:p> There are many digital solutions which assist the orthopaedic trauma surgeon. This already broad field is rapidly expanding, making a complete overview of the existing solutions difficult. The AO Foundation has established a task force to address the need for an overview of digital solutions in the field of orthopaedic trauma surgery. Areas of new technology which will help the surgeon gain a greater understanding of these possible solutions are reviewed. We propose a categorization of the current needs in orthopaedic trauma surgery matched with available or potential digital solutions, and provide a narrative overview of this broad topic, including the needs, solutions and basic rules to ensure adequate use in orthopaedic trauma surgery. We seek to make this field more accessible, allowing for technological solutions to be clearly matched to trauma surgeons’ needs. </jats:p><jats:p> Cite this article: EFORT Open Rev 2020;5:408-420. DOI: 10.1302/2058-5241.5.200021 </jats:p>
Haßler, S.; Ranno, A.; Behr, M.
In: CMAME, Ausg. 369, 2020.
@article{Haßler2020,
title = {Finite-Element Formulation for Advection–Reaction Equations with Change of Variable and Discontinuity Capturing},
author = {S. Haßler and A. Ranno and M. Behr},
editor = {Elsevier},
url = {https://www.sciencedirect.com/science/article/pii/S004578252030356X},
doi = {10.1016/j.cma.2020.113171},
year = {2020},
date = {2020-06-11},
urldate = {2020-06-11},
journal = {CMAME},
issue = {369},
abstract = {We propose a change of variable approach and discontinuity capturing methods to ensure physical constraints for advection–reaction equations discretized by the finite element method. This change of variable confines the concentration below an upper bound in a very natural way. For the non-negativity constraint, we propose to use a discontinuity capturing method defined on the reference element that is combined with an anisotropic crosswind-dissipation operator. This discontinuity capturing cannot completely eliminate negative values but effectively minimizes their occurrence. The proposed methods are applied to different biophysical models and show a good agreement with experimental results for the FDA benchmark blood pump for a physiological red blood cell pore formation model.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We propose a change of variable approach and discontinuity capturing methods to ensure physical constraints for advection–reaction equations discretized by the finite element method. This change of variable confines the concentration below an upper bound in a very natural way. For the non-negativity constraint, we propose to use a discontinuity capturing method defined on the reference element that is combined with an anisotropic crosswind-dissipation operator. This discontinuity capturing cannot completely eliminate negative values but effectively minimizes their occurrence. The proposed methods are applied to different biophysical models and show a good agreement with experimental results for the FDA benchmark blood pump for a physiological red blood cell pore formation model.
Emamy, Nehzat; Litty, Pascal; Klotz, Thomas; Schulte, Miriam; Röhrle, Oliver
In: IUTAM Symposium on Model Order Reduction of Coupled Systems, Stuttgart, Germany, May 22–25, 2018, S. 177–190, 2020.
@article{Nehyat2020,
title = {POD-DEIM Model Order Reduction for the Monodomain Reaction-Diffusion Sub-Model of the Neuro-Muscular System},
author = {Nehzat Emamy and Pascal Litty and Thomas Klotz and Miriam Schulte and Oliver Röhrle},
doi = {https://doi.org/10.1007/978-3-030-21013-7_13},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {IUTAM Symposium on Model Order Reduction of Coupled Systems, Stuttgart, Germany, May 22–25, 2018},
pages = {177–190},
publisher = {Springer International Publishing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2019
Braun, Benedikt J.; Pohlemann, Tim; Herath, Steven C.; Klein, Moritz; Rollmann, Mika F.; Derr, Ralf; Diebels, Stefan; Roland, Michael
In: Arch Appl Mech, Bd. 89, Nr. 11, S. 2351–2360, 2019, ISSN: 1432-0681.
@article{Braun2019,
title = {An individualized simulation model based on continuous, independent, ground force measurements after intramedullary stabilization of a tibia fracture},
author = {Benedikt J. Braun and Tim Pohlemann and Steven C. Herath and Moritz Klein and Mika F. Rollmann and Ralf Derr and Stefan Diebels and Michael Roland},
doi = {10.1007/s00419-019-01582-5},
issn = {1432-0681},
year = {2019},
date = {2019-11-00},
urldate = {2019-11-00},
journal = {Arch Appl Mech},
volume = {89},
number = {11},
pages = {2351--2360},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Braun, Benedikt J; Osche, David; Rollmann, Mika; Orth, Marcel; Mörsdorf, Philipp; Histing, Tina; Pohlemann, Tim; Herath, Steven C
In: Injury, Bd. 50, Nr. 7, S. 1329–1332, 2019, ISSN: 0020-1383.
@article{Braun2019b,
title = {Increased therapy demand and impending loss of previous residence status after proximal femur fractures can be determined by continuous gait analysis – A clinical feasibility study},
author = {Benedikt J Braun and David Osche and Mika Rollmann and Marcel Orth and Philipp Mörsdorf and Tina Histing and Tim Pohlemann and Steven C Herath},
doi = {10.1016/j.injury.2019.05.007},
issn = {0020-1383},
year = {2019},
date = {2019-07-00},
urldate = {2019-07-00},
journal = {Injury},
volume = {50},
number = {7},
pages = {1329--1332},
publisher = {Elsevier BV},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
0000
[Kein Titel] Abschlussarbeit
0000.
@mastersthesis{nokey_27,
title = {[Kein Titel]},
url = {https://www.nature.com/articles/s41598-023-42141-x},
doi = {https://doi.org/10.1038/s41598-023-42141-x},
abstract = {Physics-informed neural networks (PINNs) leverage data and knowledge about a problem. They provide a nonnumerical pathway to solving partial differential equations by expressing the field solution as an artificial neural network. This approach has been applied successfully to various types of differential equations. A major area of research on PINNs is the application to coupled partial differential equations in particular, and a general breakthrough is still lacking. In coupled equations, the optimization operates in a critical conflict between boundary conditions and the underlying equations, which often requires either many iterations or complex schemes to avoid trivial solutions and to achieve convergence. We provide empirical evidence for the mitigation of bad initial conditioning in PINNs for solving one-dimensional consolidation problems of porous media through the introduction of affine transformations after the classical output layer of artificial neural network architectures, effectively accelerating the training process. These affine physics-informed neural networks (AfPINNs) then produce nontrivial and accurate field solutions even in parameter spaces with diverging orders of magnitude. On average, AfPINNs show the ability to improve the $latex mathscr L_2$ relative error by 64.84% after 25,000 epochs for a one-dimensional consolidation problem based on Biot’s theory, and an average improvement by 58.80% with a transfer approach to the theory of porous media.},
keywords = {},
pubstate = {published},
tppubtype = {mastersthesis}
}
Physics-informed neural networks (PINNs) leverage data and knowledge about a problem. They provide a nonnumerical pathway to solving partial differential equations by expressing the field solution as an artificial neural network. This approach has been applied successfully to various types of differential equations. A major area of research on PINNs is the application to coupled partial differential equations in particular, and a general breakthrough is still lacking. In coupled equations, the optimization operates in a critical conflict between boundary conditions and the underlying equations, which often requires either many iterations or complex schemes to avoid trivial solutions and to achieve convergence. We provide empirical evidence for the mitigation of bad initial conditioning in PINNs for solving one-dimensional consolidation problems of porous media through the introduction of affine transformations after the classical output layer of artificial neural network architectures, effectively accelerating the training process. These affine physics-informed neural networks (AfPINNs) then produce nontrivial and accurate field solutions even in parameter spaces with diverging orders of magnitude. On average, AfPINNs show the ability to improve the $latex mathscr L_2$ relative error by 64.84% after 25,000 epochs for a one-dimensional consolidation problem based on Biot’s theory, and an average improvement by 58.80% with a transfer approach to the theory of porous media.
[Kein Titel] Abschlussarbeit
0000.
@mastersthesis{nokey_28,
title = {[Kein Titel]},
doi = {https://doi.org/10.1038/s41598-023-42141-x},
keywords = {},
pubstate = {published},
tppubtype = {mastersthesis}
}