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International Journal for Numerical Methods in Biomedical Engineering

Sandro Queirós, João L Vilaça, Pedro Morais, Jaime C Fonseca, Jan D'hooge, Daniel Barbosa
In daily clinical cardiology practice, left ventricle (LV) global and regional function assessment is crucial for disease diagnosis, therapy selection and patient follow-up. Currently, this is still a time-consuming task, spending valuable human resources. In this work, a novel fast methodology for automatic LV tracking is proposed based on localized anatomically constrained affine optical flow. This novel method can be combined to previously proposed segmentation frameworks or manually delineated surfaces at an initial frame to obtain fully delineated datasets and, thus, assess both global and regional myocardial function...
February 16, 2017: International Journal for Numerical Methods in Biomedical Engineering
Dilaver Singh, Duane S Cronin
The paucity of experimental data for validating computational models of different statures underscores the need for appropriate scaling methods so that models can be verified and validated using experimental data. Scaling was investigated using 50(th) percentile male (M50) and 5(th) percentile female (F05) cervical spine motion segment (C4-C5) finite element models subject to tension, flexion and extension loading. Two approaches were undertaken: geometric scaling of the models to investigate size effects (volumetric scaling) and scaling of the force-displacement or moment-angle model results (data scaling)...
February 15, 2017: International Journal for Numerical Methods in Biomedical Engineering
Ramiro M Irastorza, Macarena Trujillo, Enrique Berjano
All the numerical models developed for radiofrequency (RF) ablation so far have ignored the possible effect of the cooling phase (just after RF power is switched off) on the dimensions of the coagulation zone. Our objective was thus to quantify the differences in the minor radius of the coagulation zone computed by including and ignoring the cooling phase. We built models of RF tumor ablation with two needle-like electrodes: a dry electrode (5 mm long and 17G in diameter) with a constant temperature protocol (70 °C) and a cooled electrode (30 mm long and 17G in diameter) with a protocol of impedance control...
February 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
Rocco Michele Lancellotti, Christian Vergara, Lorenzo Valdettaro, Sanjeeb Bose, Alfio Quarteroni
In this paper, we consider Large Eddy Simulations (LES) for human stenotic carotids in presence of atheromasic plaque, a pathological condition where transitional effects to turbulence may occur, with relevant clinical implications such as plaque rupture. We provide a reference numerical solution obtained at high resolution without any subgrid scale model, to be used to assess the accuracy of LES simulations. In the context we are considering, i.e. hemodynamics, we cannot refer to a statistically homogeneous, isotropic and stationary turbulent regime, hence the classical Kolmogorov theory cannot be used...
January 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
Robert J Cooper, Marlène Mengoni, Dawn Groves, Sophie Williams, Marcus J K Bankes, Philip Robinson, Alison C Jones
Abnormal bony morphology is a factor implicated in hip joint soft tissue damage and an increased lifetime risk of osteoarthritis. Standard two-dimensional radiographic measurements for diagnosis of hip deformities, such as cam deformities on the femoral neck, do not capture the full joint geometry and are not indicative of symptomatic damage. In this study, a three-dimensional geometric parameterisation system was developed to capture key variations in the femur and acetabulum of subjects with clinically diagnosed cam deformity...
January 23, 2017: International Journal for Numerical Methods in Biomedical Engineering
Luigi E Perotti, Aditya V Ponnaluri, Shankarjee Krishnamoorthi, Daniel Balzani, Daniel B Ennis, William S Klug
Quantitative measurement of the material properties (e.g., stiffness) of biological tissues is poised to become a powerful diagnostic tool. There are currently several methods in the literature to estimating material stiffness and we extend this work by formulating a framework that leads to uniquely identified material properties. We design an approach to work with full field displacement data - i.e., we assume the displacement field due to the applied forces is known both on the boundaries and also within the interior of the body of interest - and seek stiffness parameters that lead to balanced internal and external forces in a model...
January 18, 2017: International Journal for Numerical Methods in Biomedical Engineering
Eiji Nakamachi, Tomohiro Noma, Kaito Nakahara, Yoshihiro Tomita, Yusuke Morita
The articular cartilage of a knee joint has a variety of functions including dispersing stress and absorbing shock in the tissue, and lubricating the surface region of cartilage. The metabolic activity of chondrocytes under the cyclic mechanical stimulations regenerates the morphology and function of tissues. Hence, the stress evaluation of the chondrocyte is vital subject to assess the regeneration cycle in the normal walking condition, and predict the injury occurrence in the accidents. Further, the threshold determination of stress for the chondrocytes activation is valuable for development of regenerative bio-reactor of articular cartilage...
January 5, 2017: International Journal for Numerical Methods in Biomedical Engineering
Kun Gou, Thomas J Pence
Angioedema is a tissue swelling pathology due to rapid change in soft tissue fluid content. Its occurrence in the trachea is predominantly localized to the soft mucous tissue that forms the innermost tracheal layer. The biomechanical consequences, such as airway constriction, are dependent upon the ensuing mechanical interactions between all of the various tissues that comprise the tracheal tube. We model the stress interactions by treating the trachea organ as a three-tissue system consisting of swellable mucous in conjunction with nonswelling cartilage and nonswelling trachealis musculature...
January 4, 2017: International Journal for Numerical Methods in Biomedical Engineering
Gabriel Balaban, Henrik Finsberg, Hans Henrik Odland, Marie Rognes, Stian Ross, Joakim Sundnes, Samuel Wall
Computational models of cardiac mechanics, personalized to a patient, offer access to mechanical information above and beyond direct medical imaging. Additionally, such models can be used to optimize and plan therapies in-silico, thereby reducing risks and improving patient outcome. Model personalization has traditionally been achieved by data assimilation, which is the tuning or optimization of model parameters to match patient observations. Current data assimilation procedures for cardiac mechanics are limited in their ability to efficiently handle high dimensional parameters...
December 31, 2016: International Journal for Numerical Methods in Biomedical Engineering
Evgin Goceri, Behiye Goksel, James B Elder, Vinay K Puduvalli, Jose J Otero, Metin N Gurcan
Traditional diagnostic neuropathology relies on subjective interpretation of visual data obtained from a brightfield microscopy. This approach causes high variability, unsatisfactory reproducibility and inability for multiplexing even among experts. These problems may affect patient outcomes and confound clinical decision-making. Also, standard histological processing of pathological specimens leads to auto-fluorescence and other artifacts, a reason why fluorescent microscopy is not routinely implemented in diagnostic pathology...
December 26, 2016: International Journal for Numerical Methods in Biomedical Engineering
Antoine Brault, Laurent Dumas, Didier Lucor
This work aims at quantifying the effect of inherent uncertainties from cardiac output on the sensitivity of a human compliant arterial network response based on stochastic simulations of a reduced-order pulse wave propagation model. A simple pulsatile output form is utilized to reproduce the most relevant cardiac features with a minimum number of parameters associated with left ventricle dynamics. Another source of significant uncertainty is the spatial heterogeneity of the aortic compliance which plays a key role in the propagation and damping of pulse waves generated at each cardiac cycle...
December 10, 2016: International Journal for Numerical Methods in Biomedical Engineering
Hao Gao, Nan Qi, Liuyang Feng, Xingshuang Ma, Mark Danton, Colin Berry, Xiaoyu Luo
Dysfunction of mitral valve causes morbidity and premature mortality and remains a leading medical problem worldwide. Computational modelling aims to understand the biomechanics of human mitral valve and could lead to the development of new treatment, prevention and diagnosis of mitral valve diseases. Compared with the aortic valve, the mitral valve has been much less studied owing to its highly complex structure and strong interaction with the blood flow and the ventricles. However, the interest in mitral valve modelling is growing, and the sophistication level is increasing with the advanced development of computational technology and imaging tools...
December 9, 2016: International Journal for Numerical Methods in Biomedical Engineering
P Mascheroni, R Penta
We investigate the impact of microvascular geometry on the transport of drugs in solid tumors, focusing on the diffusion and consumption phenomena. We embrace recent advances in the asymptotic homogenization literature starting from a double Darcy, double advection-diffusion-reaction system of partial differential equations that is obtained exploiting the sharp length separation between the intercapillary distance and the average tumor size. The geometric information on the microvascular network is encoded into effective hydraulic conductivities and diffusivities, which are numerically computed by solving periodic cell problems on appropriate microscale representative cells...
December 6, 2016: International Journal for Numerical Methods in Biomedical Engineering
Manuel K Rausch, Alexander M Zöllner, Martin Genet, Brian Baillargeon, Wolfgang Bothe, E Kuhl
Functional mitral regurgitation, a backward leakage of the mitral valve, is a result of left ventricular growth and mitral annular dilatation. Its gold standard treatment is mitral annuloplasty, the surgical reduction in mitral annular area through the implantation of annuloplasty rings. Recurrent regurgitation rates may, however, be as high as 30% and more. While the degree of annular downsizing has been linked to improved long-term outcomes, too aggressive downsizing increases the risk of ring dehiscences and significantly impairs repair durability...
February 2017: International Journal for Numerical Methods in Biomedical Engineering
J E Malik, J D Swarts, S N Ghadiali
The inability to open the collapsible Eustachian tube (ET) leads to the development of chronic Otitis Media (OM). Although mucosal inflammation during OM leads to increased mucin gene expression and elevated adhesion forces within the ET lumen, it is not known how changes in mucosal adhesion alter the biomechanical mechanisms of ET function. In this study, we developed a novel multi-scale finite element model of ET function in adults that utilizes adhesion spring elements to simulate changes in mucosal adhesion...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
Jia Zhao, Qi Wang
A three-dimensional (3D) hydrodynamic model for cytokinesis of eukaryotic cells is developed, in which we model dynamics of actomyosins in the cell cortex, in particular, along the cytokinetic ring formed in the cortex and in the neighborhood of the cell's division plane explicitly. Specifically, the active force actuated by the actomyosin's activity along the cytokinetic ring is modeled by a surface force whose strength is proportional to the actomyosin concentration while the cell morphology is tracked by a phase field model...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
M H de Vaal, M W Gee, U A Stock, W A Wall
Because aortic occlusion is arguably one of the most dangerous aortic manipulation maneuvers during cardiac surgery in terms of perioperative ischemic neurological injury, the purpose of this investigation is to assess the structural mechanical impact resulting from the use of existing and newly proposed occluders. Existing (clinically used) occluders considered include different cross-clamps (CCs) and endo-aortic balloon occlusion (EABO). A novel occluder is also introduced, namely, constrained EABO (CEABO), which consists of applying a constrainer externally around the aorta when performing EABO...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
Peter Wise, Neil H Davies, Mazin S Sirry, Jeroen Kortsmit, Laura Dubuis, Chen-Ket Chai, Frank P T Baaijens, Thomas Franz
Biomaterial injectates are promising as a therapy for myocardial infarction to inhibit the adverse ventricular remodeling. The current study explored interrelated effects of injectate volume and infarct size on treatment efficacy. A finite element model of a rat heart was utilized to represent ischemic infarcts of 10%, 20%, and 38% of left ventricular wall volume and polyethylene glycol hydrogel injectates of 25%, 50%, and 75% of the infarct volume. Ejection fraction was 49.7% in the healthy left ventricle and 44...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
Mao Li, Karol Miller, Grand Roman Joldes, Ron Kikinis, Adam Wittek
Patient-specific biomechanical models have been advocated as a tool for predicting deformations of soft body organs/tissue for medical image registration (aligning two sets of images) when differences between the images are large. However, complex and irregular geometry of the body organs makes generation of patient-specific biomechanical models very time-consuming. Meshless discretisation has been proposed to solve this challenge. However, applications so far have been limited to 2D models and computing single organ deformations...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
David Roy, Sophie Lerouge, Karina Inaekyan, Claude Kauffmann, Rosaire Mongrain, Gilles Soulez
Although the endovascular repair of abdominal aortic aneurysms is a less invasive alternative than classic open surgery, complications such as endoleak and kinking still need to be addressed. Numerical simulation of endovascular repair is becoming a valuable tool in stent-graft (SG) optimization, patient selection and surgical planning. The experimental and numerical forces required to produce SG deformations were compared in a range of in vivo conditions in the present study. The deformation modes investigated were: bending as well as axial, transversal and radial compressions...
December 2016: International Journal for Numerical Methods in Biomedical Engineering
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