@article{Manjunatha2022b,

title = {A Multiphysics Modeling Approach for In-Stent Restenosis: Theoretical Aspects and Finite Element Implementation},

author = {K. Manjunatha and M. Behr and F. Vogt and S. Reese},

editor = {Elsevier},

url = {https://www.sciencedirect.com/science/article/pii/S0010482522008745},

doi = {10.1016/j.compbiomed.2022.106166},

year  = {2022},

date = {2022-11-15},

urldate = {2022-11-15},

journal = {Computers in Biology and Medicine},

volume = {150},

abstract = {Development of in silico models that capture progression of diseases in soft biological tissues are intrinsic in the validation of the hypothesized cellular and molecular mechanisms involved in the respective pathologies. In addition, they also aid in patient-specific adaptation of interventional procedures. In this regard, a fully-coupled high-fidelity Lagrangian finite element framework is proposed within this work which replicates the pathology of in-stent restenosis observed post stent implantation in a coronary artery. Advection–reaction–diffusion equations are set up to track the concentrations of the platelet-derived growth factor, the transforming growth factor-, the extracellular matrix, and the density of the smooth muscle cells. A continuum mechanical description of volumetric growth involved in the restenotic process, coupled to the evolution of the previously defined vessel wall constituents, is presented. Further, the finite element implementation of the model is discussed, and the behavior of the computational model is investigated via suitable numerical examples. Qualitative validation of the computational model is presented by emulating a stented artery. Patient-specific data are intended to be integrated into the model to predict the risk of in-stent restenosis, and thereby assist in the tuning of stent implantation parameters to mitigate the risk.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Keles2022,

title = {Botulinum Toxin Intervention in Cerebral Palsy-Induced Spasticity Management: Projected and Contradictory Effects on Skeletal Muscles},

author = {Cemre Su Kaya Keles and Filiz Ates},

editor = {Toxins},

url = {https://www.mdpi.com/2072-6651/14/11/772},

doi = {https://doi.org/10.3390/toxins14110772},

year  = {2022},

date = {2022-11-08},

urldate = {2022-11-08},

journal = {Toxins},

volume = {14},

issue = {11},

pages = {772},

abstract = {Spasticity, following the neurological disorder of cerebral palsy (CP), describes a pathological condition, the central feature of which is involuntary and prolonged muscle contraction. The persistent resistance of spastic muscles to stretching is often followed by structural and mechanical changes in musculature. This leads to functional limitations at the respective joint. Focal injection of botulinum toxin type-A (BTX-A) is effectively used to manage spasticity and improve the quality of life of the patients. By blocking acetylcholine release at the neuromuscular junction and causing temporary muscle paralysis, BTX-A aims to reduce spasticity and hereby improve joint function. However, recent studies have indicated some contradictory effects such as increased muscle stiffness or a narrower range of active force production. The potential of these toxin- and atrophy-related alterations in worsening the condition of spastic muscles that are already subjected to changes should be further investigated and quantified. By focusing on the effects of BTX-A on muscle biomechanics and overall function in children with CP, this review deals with which of these goals have been achieved and to what extent, and what can await us in the future.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{10.1136/bmjopen-2022-063051,

title = {Geometric uncertainty in intracranial aneurysm rupture status discrimination: a two-site retrospective study},

author = {Florian Hellmeier and Jan Bruening and Philipp Berg and Sylvia Saalfeld and Andreas Spuler and Erol I. Sandalcioglu and Oliver Beuing and Naomi Larsen and Jens Schaller and Leonid Goubergrits},

editor = {BMJ Open},

url = {https://pubmed.ncbi.nlm.nih.gov/36351732/},

doi = {10.1136/bmjopen-2022-063051},

year  = {2022},

date = {2022-11-08},

urldate = {2022-11-08},

journal = {BMJ Open},

volume = {12},

issue = {11},

abstract = {Assessing the risk associated with unruptured intracranial aneurysms (IAs) is essential in clinical decision making. Several geometric risk parameters have been proposed for this purpose. However, performance of these parameters has been inconsistent. This study evaluates the performance and robustness of geometric risk parameters on two datasets and compare it to the uncertainty inherent in assessing these parameters and quantifies interparameter correlations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Grzegorzewski2022,

title = {Physiologically based pharmacokinetic (PBPK) modeling of the role of CYP2D6 polymorphism for metabolic phenotyping with dextromethorphan},

author = {Jan Grzegorzewski and Janosch Brandhorst and Matthias König},

editor = {Sec. Pharmacogenetics Frontiers in Pharmacology and Pharmacogenomics},

url = {https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2022.1029073/full},

doi = {https://doi.org/10.3389/fphar.2022.1029073},

year  = {2022},

date = {2022-10-24},

journal = {Frontiers in Pharmacology},

abstract = {The cytochrome P450 2D6 (CYP2D6) is a key xenobiotic-metabolizing enzyme involved in the clearance of many drugs. Genetic polymorphisms in CYP2D6 contribute to the large inter-individual variability in drug metabolism and could affect metabolic phenotyping of CYP2D6 probe substances such as dextromethorphan (DXM). To study this question, we (i) established an extensive pharmacokinetics dataset for DXM; and (ii) developed and validated a physiologically based pharmacokinetic (PBPK) model of DXM and its metabolites dextrorphan (DXO) and dextrorphan O-glucuronide (DXO-Glu) based on the data. Drug-gene interactions (DGI) were introduced by accounting for changes in CYP2D6 enzyme kinetics depending on activity score (AS), which in combination with AS for individual polymorphisms allowed us to model CYP2D6 gene variants. Variability in CYP3A4 and CYP2D6 activity was modeled based on in vitro data from human liver microsomes. Model predictions are in very good agreement with pharmacokinetics data for CYP2D6 polymorphisms, CYP2D6 activity as described by the AS system, and CYP2D6 metabolic phenotypes (UM, EM, IM, PM). The model was applied to investigate the genotype-phenotype association and the role of CYP2D6 polymorphisms for metabolic phenotyping using the urinary cumulative metabolic ratio (UCMR), DXM/(DXO + DXO-Glu). The effect of parameters on UCMR was studied via sensitivity analysis. Model predictions indicate very good robustness against the intervention protocol (i.e. application form, dosing amount, dissolution rate, and sampling time) and good robustness against physiological variation. The model is capable of estimating the UCMR dispersion within and across populations depending on activity scores. Moreover, the distribution of UCMR and the risk of genotype-phenotype mismatch could be estimated for populations with known CYP2D6 genotype frequencies. The model can be applied for individual prediction of UCMR and metabolic phenotype based on CYP2D6 genotype. Both, model and database are freely available for reuse.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Chourdakis2022,

title = {preCICE v2: A sustainable and user-friendly coupling library},

author = {Gerasimos Chourdakis and Kyle Davis and Benjamin Rodenberg and Miriam Schulte and Frédéric Simonis and Benjamin Uekermann and Georg Abrams and Hans-Joachim Bungartz and Lucia Cheung Yau and Ishaan Desai and Konrad Eder and Richard Hertrich and Florian Lindner and Alexander Rusch and Dmytro Sashko and David Schneider and Amin Totounferoush and Dominik Volland and Peter Vollmer and Oguz Ziya Koseomur},

editor = {Open Research Europe},

url = {https://open-research-europe.ec.europa.eu/articles/2-51/v2},

doi = {10.12688/openreseurope.14445.2},

year  = {2022},

date = {2022-09-30},

urldate = {2022-09-30},

journal = {Open Research Europe},

abstract = {preCICE is a free/open-source coupling library. It enables creating partitioned multi-physics simulations by gluing together separate software packages. 

This paper summarizes the development efforts in preCICE of the past five years. During this time span, we have turned the software from a working prototype – sophisticated numerical coupling methods and scalability on ten thousands of compute cores – to a sustainable and user-friendly software project with a steadily-growing community. Today, we know through forum discussions, conferences, workshops, and publications of more than 100 research groups using preCICE. We cover the fundamentals of the software alongside a performance and accuracy analysis of different data mapping methods. Afterwards, we describe ready-to-use integration with widely-used external simulation software packages, tests, and continuous integration from unit to system level, and community building measures, drawing an overview of the current preCICE ecosystem.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bertrand2022,

title = {On robust discretization methods for poroelastic problems: Numerical examples and counter-examples},

author = {Fleurianne Bertrand and Maximilian Brodbeck and Tim Ricken},

editor = {Elsevier},

url = {https://www.sciencedirect.com/science/article/pii/S2666657X22000209?via%3Dihub},

doi = {https://doi.org/10.1016/j.exco.2022.100087},

year  = {2022},

date = {2022-09-24},

journal = {Examples and Counterexamples (2)},

abstract = {Finite element approximations of poroelastic materials are nowadays used within multiple applications. Due to wide variation of possible material parameters, robustness of the considered discretization is important. Within this contribution robust of discretization schemes, initially developed for Biot’s theory, will be applied within the Theory of Porous Media. Selected numerical test-cases, special attention will be paid to incompressible and impermeable regimes, are conducted.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Vellguth2022,

title = {Effect of transcatheter edge-to-edge repair device position on diastolic hemodynamic parameters: An echocardiography-based simulation study},

author = {Katharina Vellguth and Fabian Barbieri and Markus Reinthaler and Mario Kasner and Ulf Landmesser and Titus Kuehne and Anja Hennemuth and Lars Walczak and Leonid Goubergrits},

doi = {10.3389/fcvm.2022.915074},

issn = {2297-055X},

year  = {2022},

date = {2022-08-24},

urldate = {2022-08-24},

journal = {Front. Cardiovasc. Med.},

volume = {9},

publisher = {Frontiers Media SA},

abstract = {<jats:sec><jats:title>Background</jats:title><jats:p>Transcatheter edge-to-edge repair (TEER) has developed from innovative technology to an established treatment strategy of mitral regurgitation (MR). The risk of iatrogenic mitral stenosis after TEER is, however, a critical factor in the conflict of interest between maximal reduction of MR and minimal impairment of left ventricular filling. We aim to investigate systematically the impact of device position on the post treatment hemodynamic outcome by involving the patient-specific segmentation of the diseased mitral valve.</jats:p></jats:sec><jats:sec><jats:title>Materials and methods</jats:title><jats:p>Transesophageal echocardiographic image data of ten patients with severe MR (age: 57 ± 8 years, 20% female) were segmented and virtually treated with TEER at three positions by using a position based dynamics approach. Pre- and post-interventional patient geometries were preprocessed for computational fluid dynamics (CFD) and simulated at peak-diastole with patient-specific blood flow boundary conditions. Simulations were performed with boundary conditions mimicking rest and stress. The simulation results were compared with clinical data acquired for a cohort of 21 symptomatic MR patients (age: 79 ± 6 years, 43% female) treated with TEER.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Virtual TEER reduces the mitral valve area (MVA) from 7.5 ± 1.6 to 2.6 ± 0.6 cm<jats:sup>2</jats:sup>. Central device positioning resulted in a 14% smaller MVA than eccentric device positions. Furthermore, residual MVA is better predictable for central than for eccentric device positions (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.81 vs. <jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.49). The MVA reduction led to significantly higher maximal diastolic velocities (pre: 0.9 ± 0.2 m/s, post: 2.0 ± 0.5 m/s) and pressure gradients (pre: 1.5 ± 0.6 mmHg, post: 16.3 ± 9 mmHg) in spite of a mean flow rate reduction by 23% due to reduced MR after the treatment. On average, velocities were 12% and pressure gradients were 25% higher with devices in central compared to lateral or medial positions.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Virtual TEER treatment combined with CFD is a promising tool for predicting individual morphometric and hemodynamic outcomes. Such a tool can potentially be used to support clinical decision making, procedure planning, and risk estimation to prevent post-procedural iatrogenic mitral stenosis.</jats:p></jats:sec>},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Braun2022,

title = {Bewegungsanalyse und muskuloskeletale Simulation in der Pseudarthrosentherapie – Erfahrungen und erste klinische Ergebnisse},

author = {Benedikt J. Braun and Tina Histing and Steven C. Herath and Mika F. R. Rollmann and Marie Reumann and Maximilian M. Menger and Fabian Springer and Annchristin Andres and Stefan Diebels and Michael Roland},

doi = {10.1007/s00113-022-01208-6},

issn = {2731-703X},

year  = {2022},

date = {2022-08-00},

urldate = {2022-08-00},

journal = {Unfallchirurgie},

volume = {125},

number = {8},

pages = {619--627},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@article{https://doi.org/10.1515/cdbme-2022-0032,

title = {Impact of patient-specific inflow boundary conditions on intracranial aneurysm hemodynamics},

author = {Janneck Stahl and Anna Bernovskis and Daniel Behme and Sylvia Saalfeld and Philipp Berg},

editor = {De Gruyter},

url = {https://www.degruyter.com/document/doi/10.1515/cdbme-2022-0032/html},

doi = {https://doi.org/10.1515/cdbme-2022-0032},

year  = {2022},

date = {2022-07-30},

urldate = {2022-07-30},

journal = {Current Directions in Biomedical Engineering},

volume = {8},

issue = {1},

pages = {125-128},

abstract = {For hemodynamic simulations of intracranial aneurysms boundary conditions (BC) are required. In most cases, these are not patient-specific and thus do not reflect the real flow conditions in the patient. This study investigates the influence of patient-specific inflow BC on intra-aneurysmal hemodynamics. The focus lies on gender and age variations of the patients. To asses the impact, four different inflow curves representing the velocity profile of the inflow over one cardiac cycle is modeled. These four inflow BC are varied in the simulations of each aneurysm from selected subgroups. From the results of the simulations, the hemodynamic parameters are determined for each inflow BC and the percent differences between inflow BC are determined. The results show that the hemodynamic parameters are not obust to varying inflow BC. It can be seen that age has more influence on the hemodynamic parameters than gender. This study demonstrates the dependence of valid hemodynamic parameters on realistic inflow BC. Thus, if available, patient-specific inflow curves are recommended.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{https://doi.org/10.1515/cdbme-2022-0004,

title = {Centerline and blockstructure for faststructured mesh generation},

author = {Annika Niemann and Gabor Janiga and Bernhard Preim and Daniel Behme and Sylvia Saalfeld},

editor = {De Gruyter},

url = {https://www.degruyter.com/document/doi/10.1515/cdbme-2022-0004/html},

doi = {https://doi.org/10.1515/cdbme-2022-0004},

year  = {2022},

date = {2022-07-30},

urldate = {2022-07-30},

journal = {Current Directions in Biomedical Engineering},

abstract = {In contrast to unstructured meshes, structured meshes yield faster simulation results for bio-medical simulations, but are very time-consuming to create. A preprocessing step in the generation of structured meshes is the manual construction of a block structure approximating the vessel. Here, we present an automatic centreline calculation and blockstructure generation to reduce the user effort and time of structured mesh generation. The center line is detected as points in between opposite faces. Based on the centerline, cross sections are determined and a blockstructure which approximates the vessel is automatically generated. The centreline detection does not require time-consuming user input and meshes with more than 195,000 vertices are processed in less than 160 seconds. The results of the presented automatic centreline detection are compared to a centreline with manual input generated by the widely used vmtk tool. The centerlines are similar, small differences occur at bifurcation and at the aneurysm.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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 = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@article{Grosjean0000,

title = {An in-silico approach to meniscus tissue regeneration: Modeling, numerical simulation, and experimental analysis},

author = {Elise Grosjean and Alex Keilmann and Henry Jäger and Shimi Mohanan and Claudia Redenbach and Bernd Simeon and Christina Surulescu and Luisa de Roy and Andreas Seitz and Graciosa Teixeira and Martin Dauner and Carsten Linti and Günter Schmidt},

url = {https://arxiv.org/abs/2403.05909},

doi = {https://doi.org/10.48550/arXiv.2403.05909},

journal = {Applied Mathematical Modelling},

abstract = {We develop a model the dynamics of human mesenchymal stem cells (hMSCs) and chondrocytes evolving in a nonwoven polyethylene terephtalate (PET) scaffold impregnated with hyaluron and supplied with a differentiation medium. The scaffold and the cells are assumed to be contained in a bioreactor with fluid perfusion. The differentiation of hMSCs into chondrocytes favors the production of extracellular matrix (ECM) and is influenced by fluid stress. The model takes deformations of ECM and PET scaffold into account. The scaffold structure is explicitly included by statistical assessment of the fibre distribution from CT images. The effective macroscopic equations are obtained by appropriate upscaling from dynamics on lower (microscopic and mesoscopic) scales and feature in the motility terms an explicit cell diffusion tensor encoding the assessed anisotropic scaffold structure. Numerical simulations show its influence on the overall cell and tissue dynamics. },

keywords = {},

pubstate = {published},

tppubtype = {article}

}