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International Journal for Numerical Methods in Biomedical Engineering

Qi Chen, Xianmin Zhang, Benliang Zhu
Understanding the optimal designs in nature is critical in bionics. This paper presents a method for designing the configuration of fusiform muscle with a maximum contractile displacement based on topology optimization methods. A nearly incompressible continuum constitutive model of skeletal muscle is utilized. The contractile displacement from the relaxed state to the contracted state is regarded as the objective function. To handle the numerical difficulties that result from the existence of element density, an energy interpolation equation is employed, and a modification of the constitutive model of skeletal muscle is proposed...
May 9, 2018: International Journal for Numerical Methods in Biomedical Engineering
Liang Liang, Minliang Liu, Caitlin Martin, Wei Sun
Advances in structural finite element analysis (FEA) and medical imaging have made it possible to investigate the in vivo biomechanics of human organs such as blood vessels, for which organ geometries at the zero-pressure level need to be recovered. Although FEA-based inverse methods are available for zero-pressure geometry estimation, these methods typically require iterative computation, which are time-consuming and may be not suitable for time-sensitive clinical applications. In this study, by using machine learning (ML) techniques, we developed a ML-model to estimate the zero-pressure geometry of human thoracic aorta by given two pressurized geometries of the same patient at two different blood pressure levels...
May 9, 2018: International Journal for Numerical Methods in Biomedical Engineering
M Bilasse, S Chatelin, G Altmeyer, A Marouf, J Vappou, I Charpentier
Dynamic elastography is a virtual palpation tool that aims at investigating the mechanical response of biological soft tissues in vivo. The objective of this study is to develop a finite element model (FEM) with low computational cost for reproducing realistically wave propagation for magnetic resonance elastography (MRE) in heterogeneous soft tissues. Based on the first-order shear deformation theory (FSDT) for moderately thick structures, this model is developed and validated through comparison with analytical formulations of wave propagating in heterogeneous, viscoelastic infinite medium...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
Ahmed Tasnub Takaddus, Prashanta Gautam, Abhilash J Chandy
Urine moves from the kidney to the bladder through the ureter. A series of compression waves facilitates this transport. Due to the highly concentrated mineral deposits in urine, stones are formed in the kidney and travel down through the urinary tract. While passing, a larger stone can get stuck and cause severe damage to ureter wall. Also, stones in the ureter obstructing the urine flow can cause pain and backflow of urine which in turn might require surgical intervention. The current study develops a 2D axisymmetric numerical model in order to gain an understanding of the ureter obstruction and its effects on the flow, which are critical in assessing the different treatment options...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
Alejandra Pérez-Andrés, Estefania Peña
We present a computational framework that integrates experimental techniques and FE modeling to calibrate material fracture parameters of the vena cava and the interaction properties between a retrievable filter (Günther Tulip) and the vena cava wall. The fitted parameters were then used to analyze the interaction of the IVC filter with the vena cava during the deployment process. An idealized cava Finite Element model was then developed including residual stresses and physiological pressure conditions. Filter deployment was simulated and a comprehensive study of tissue-filter interaction was performed by cohesive surface modeling...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
Peng Bao, Jiliu Zhou, Yi Zhang
Classical total variation (TV) based iterative reconstruction algorithms is effective for the reconstruction of piecewise smooth image, but it causes over-smoothing effect for textured regions in the reconstructed image. To address this problem, this work presents a novel computed tomography (CT) reconstruction method for the few-view problem called the group-sparsity regularization-based simultaneous algebraic reconstruction technique (GSR-SART). Group-based sparse representation, which utilizes the concept of a group as the basic unit of sparse representation instead of a patch, is introduced as the image domain prior regularization term to eliminate the over-smoothing effect...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
Guadalupe García Isla, Andy Luis Olivares, Etelvino Silva, Marta Nuñez-García, Constantine Butakoff, Damian Sanchez-Quintana, Hernán Morales, Xavier Freixa, Jérôme Noailly, Tom de Potter, Oscar Camara
The left atrial appendage (LAA) is a complex and heterogeneous protruding structure of the left atrium (LA). In atrial fibrillation (AF) patients, it is the location where 90% of the thrombi are formed. However, the role of the LAA in thrombus formation is not fully known yet. The main goal of this work is to perform a sensitivity analysis to identify the most relevant LA and LAA morphological parameters in atrial blood flow dynamics. Simulations were run on synthetic ellipsoidal left atria models where different parameters were individually studied: pulmonary veins (PV) and mitral valve (MV) dimensions; LAA shape; and LA volume...
May 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
D Truong, C R Bahls, B Nebe, U van Rienen
A numerical model for the adhesion of osteoblasts on titanium micro-pillar structures is suggested and a function representing the concentration level of the adhesion on the pillars is constructed based on experimental observation. With the introduction of this function, the bio-chemo-mechanical model by Deshpande et al. can predict the formation of actin in osteoblasts when they are laid on arrays of titanium micro-pillars of various size attached to silicon substrate. A parameter study suggests that each pillar is associated with a different pattern of adhesion...
May 7, 2018: International Journal for Numerical Methods in Biomedical Engineering
Tobias Köppl, Gabriele Santin, Bernard Haasdonk, Rainer Helmig
In this work, we consider two kinds of model reduction techniques to simulate blood flow through the largest systemic arteries, where a stenosis is located in a peripheral artery i.e. in an artery that is located far away from the heart. For our simulations we place the stenosis in one of the tibial arteries belonging to the right lower leg (right post tibial artery). The model reduction techniques that are used are on the one hand dimensionally reduced models (1-D and 0-D models, the so-called mixed-dimension model) and on the other hand surrogate models produced by kernel methods...
May 6, 2018: International Journal for Numerical Methods in Biomedical Engineering
Katharine Brigham, Samir Gupta, John C Brigham
Infants born prematurely are particularly susceptible to respiratory illness due to underdeveloped lungs, which can often result in fatality. Preterm infants in acute stages of respiratory illness typically require mechanical ventilation assistance, and the efficacy of the type of mechanical ventilation and its delivery has been the subject of a number clinical studies. With recent advances in machine learning approaches, particularly deep learning, it may be possible to estimate future responses to mechanical ventilation in real-time, based on ventilation monitoring up to the point of analysis...
April 17, 2018: International Journal for Numerical Methods in Biomedical Engineering
Fernando Barber, Ignacio García-Fernández, Miguel Lozano, Rafael Sebastian
The reconstruction of the ventricular cardiac conduction system (CCS) from patient-specific data is a challenging problem. High-resolution imaging techniques have allowed only the segmentation of proximal sections of the CCS from images acquired ex-vivo. In this paper we present an algorithm to estimate the location of a set of Purkinje-myocardial junctions from electro-anatomical maps, as those acquired during radio-frequency ablation procedures. The method requires a mesh representing the myocardium with local activation time measurements on a subset of nodes...
April 10, 2018: International Journal for Numerical Methods in Biomedical Engineering
Ángel Ramos-de-Miguel, José M Escobar, David Greiner, Ángel Ramos-Macíŋas
This paper presents a new procedure to design optimal electrodes for cochlear implants. The main objective of this study is to find a set of electrode designs that maximize the focalization and minimize the power consumption simultaneously. To achieve that, a criterion to measure the ability of focalization of an electrode is proposed. It is presented a procedure to determine: (1) The electrical potential induced by an electrode by solving the Laplace equation through the Finite Element Method (FEM); (2) the response of a neuron to an applied field using NEURON, a compartmentalized cell model; (3) the optimization to find the best electrode designs according to power consumption and focalization by two evolutionary multiobjective methods based on the Non-dominated Sorting Genetic Algorithm II (NSGA-II): a straight multiobjective approach and a seeded multiobjective approach...
April 6, 2018: International Journal for Numerical Methods in Biomedical Engineering
S Klinge, S Aygün, R P Gilbert, G A Holzapfel
The present contribution focuses on the application of the multiscale finite element method to the modeling of actin networks which are embedded in the cytosol. These cell components are of particular importance with regard to the cell response to external stimuli. The homogenization strategy chosen uses the Hill-Mandel macro-homogeneity condition for bridging two scales: the macroscopic scale which is related to the cell level, and the microscopic scale related to the representative volume element. For the modeling of filaments, the Holzapfel-Ogden β-model is applied...
April 6, 2018: International Journal for Numerical Methods in Biomedical Engineering
Josep M López, Gerard Fortuny, Dolors Puigjaner, Joan Herrero, Francesc Marimon
Computational fluid dynamics was used to simulate the flow of blood within an inferior vena cava (IVC) geometry model that was reconstructed from computed tomography images obtained from a real patient. The main novelty of the present work is that we simulated the implantation of four different filter models in this realistic IVC geometry. We considered different blood flow rates in the range between Vin =20 and Vin =80cm3 /s and all simulations were performed with both the Newtonian and a non-Newtonian model for the blood viscosity...
March 30, 2018: International Journal for Numerical Methods in Biomedical Engineering
José Luis Alonzo-Velázquez, Salvador Botello-Rionda, Rafael Herrera-Guzmán, Mauricio Carrillo-Tripp
Viruses are the most abundant pathogens affecting all forms of life. A major component of a virus is a protein shell, known as the viral capsid, that encapsulates the genomic material. The fundamental functions of the capsid are to protect and transport the viral genome, and recognize the host cell. Descriptions of this macromolecular complex have been proposed at different scales of approximation. Here, we introduce a methodology to generate a structured volumetric mesh of icosahedral viral capsids (CapsidMesh) based on the atomic positions of their constituents...
March 30, 2018: International Journal for Numerical Methods in Biomedical Engineering
María E Santana Artiles, Demetrios T Venetsanos
Femoroplasty is the injection of bone cement into the proximal femur, enhances the bone load capacity and is typically applied to osteoporotic femora. To minimize the required injected volume of bone cement and maximize the load capacity enhancement, an optimization problem must be solved, where the modulus of elasticity of the augmented bone is a key element. This paper, through the numerical investigation of a fall on the greater trochanter of an osteoporotic femur, compares different ways to calculate this modulus and introduces an approach, based on the concept of bone cement porosity, which provides results statistically similar to those obtained with other considerations...
March 30, 2018: International Journal for Numerical Methods in Biomedical Engineering
Mahsa Ghaffari, Ali Alaraj, Xinjian Du, Xiaohong Joe Zhou, Fady T Charbel, Andreas A Linninger
In the last decade, detailed hemodynamic analysis of blood flow in pathological segments close to aneurysm and stenosis has provided physicians with invaluable information about the local flow patterns leading to vascular disease. However, these diseases have both local and global effects on the circulation of the blood within the cerebral tree. The aim of this paper is to demonstrate the importance of extending subject-specific hemodynamic simulations to the large-scale cerebral arterial tree with hundreds of bifurcations and vessels, as well as evaluate hemodynamic risk factors and waveform shape characteristics throughout the cerebral arterial trees...
March 30, 2018: International Journal for Numerical Methods in Biomedical Engineering
A Quaglino, S Pezzuto, P-S Koutsourelakis, A Auricchio, R Krause
We present a fast, patient-specific methodology for uncertainty quantification in electrophysiology, aimed at meeting the time constraints of clinical practitioners. We focus on computing the statistics of the activation map, given the uncertainties associated with the conductivity tensor modeling the fibers orientation in the heart. We employ a fast parallel solution method implemented on a GPU for the eikonal approximation, in order to compute the activation map and to sample the random fiber field with correlation based on geodesic distances...
March 26, 2018: International Journal for Numerical Methods in Biomedical Engineering
Mikel Landajuela, Christian Vergara, Antonello Gerbi, Luca Dedé, Luca Formaggia, Alfio Quarteroni
In this work, we consider the numerical approximation of the electromechanical coupling in the left ventricle with inclusion of the Purkinje network. The mathematical model couples the 3D elastodynamics and bidomain equations for the electrophysiology in the myocardium with the 1D monodomain equation in the Purkinje network. For the numerical solution of the coupled problem, we consider a fixed-point iterative algorithm that enables a partitioned solution of the myocardium and Purkinje network problems. Different levels of myocardium-Purkinje network splitting are considered and analyzed...
March 25, 2018: International Journal for Numerical Methods in Biomedical Engineering
Jorge Aramburu, Raúl Antón, Alejandro Rivas, Juan Carlos Ramos, Gorka S Larraona, Bruno Sangro, José Ignacio Bilbao
Balloon-occluded transarterial chemoembolization (B-TACE) is a valuable treatment option for patients with inoperable malignant tumors in the liver. B-TACE consists of the transcatheter infusion of an anticancer drug mixture and embolic agents. Contrary to conventional TACE, B-TACE is performed via an artery-occluding microballoon catheter, which makes the blood-flow to redistribute due to the intra- and extrahepatic arterial collateral circulation. Several recent studies have stressed the importance of the redistribution of blood-flow in enhancing the treatment outcome...
March 25, 2018: International Journal for Numerical Methods in Biomedical Engineering
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