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International Journal for Numerical Methods in Biomedical Engineering

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https://www.readbyqxmd.com/read/29124903/relationship-between-the-left-ventricular-size-and-the-amount-of-trabeculations
#1
Bruno Paun, Bart Bijnens, Constantine Butakoff
Contemporary imaging modalities offer non-invasive quantification of myocardial deformation; however, they make gross assumptions about internal structure of the cardiac walls. Our aim is to study the possible impact of the trabeculations on the stroke volume, strain and capacity of differently sized ventricles. The cardiac left ventricle is represented by an ellipsoid and the trabeculations by a tissue occupying a fixed volume. The ventricular contraction is modelled by scaling the ellipsoid whereupon the measurements of longitudinal strain, end-diastolic, end-systolic and stroke volume are derived and compared...
November 9, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29119728/a-framework-for-designing-patient-specific-bioprosthetic-heart-valves-using-immersogeometric-fluid-structure-interaction-analysis
#2
Fei Xu, Simone Morganti, Rana Zakerzadeh, David Kamensky, Ferdinando Auricchio, Alessandro Reali, Thomas J R Hughes, Michael S Sacks, Ming-Chen Hsu
Numerous studies have suggested that medical image derived computational mechanics models could be developed to reduce mortality and morbidity due to cardiovascular diseases by allowing for patient-specific surgical planning and customized medical device design. In this work, we present a novel framework for designing prosthetic heart valves using a parametric design platform and immersogeometric fluid-structure interaction (FSI) analysis. We parameterize the leaflet geometry using several key design parameters...
November 9, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29116689/evaluation-of-hemodynamic-performance-of-total-cavopulmonary-connection-tcpc-with-porous-inserts
#3
K Dhayananth, Arunn Narasimhan
Infants born with univentricular heart disease undergo Fontan surgery in order to establish separate systemic and pulmonary circulations. This surgery results in better blood circulation across a single ventricle that supplies oxygenated blood to the body and passively returns venous blood to the lungs through the total cavopulmonary connection (TCPC). Reducing the pressure drop across the TCPC during Fontan circulation helps in reducing the work load of univentricular heart and various designs have been proposed for this purpose...
November 8, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29111608/approach-for-gait-analysis-in-persons-with-limb-loss-including-residuum-and-prosthesis-socket-dynamics
#4
A K LaPrè, M Price, R Wedge, B R Umberger, F Sup
Musculoskeletal modeling and marker based motion capture techniques are commonly used to quantify the motions of body segments, and the forces acting on them during human gait. However, when these techniques are applied to analyze the gait of people with lower limb loss, the clinically relevant interaction between the residual limb and prosthesis socket is typically overlooked. It is known that there is considerable motion and loading at the residuum-socket interface, yet traditional gait analysis techniques do not account for these factors due to the inability to place tracking markers on the residual limb inside of the socket...
November 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29083532/predicting-the-role-of-microstructural-and-biomechanical-cues-in-tumor-growth-and-spreading
#5
Raffaella Santagiuliana, Rui Pereira, Bernhard A Schrefler, Paolo Decuzzi
A multitude of mathematical and computational approaches have been proposed for predicting tumor growth. Yet, most models treat malignant masses as fluids neglecting microstructural and biomechanical features of the tumor extracellular matrix (ECM). Here, a continuum porous media model is developed within the thermodynamically constrained averaging theory (TCAT) framework for elucidating the role of these mechanical cues in regulating tumor growth and spreading. The model comprises three fluid phases - tumor cells, host cells, and interstitial fluid - and a solid phase - the ECM - considered as an elasto-visco-plastic medium...
October 30, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29078042/pet-ct-image-fusion-using-random-forest-and-%C3%A3-trous-wavelet-transform
#6
Ayan Seal, Debotosh Bhattacharjee, Mita Nasipuri, Dionisio Rodríguez-Esparragón, Ernestina Menasalvas, Consuelo Gonzalo-Martin
New image fusion rules for multimodal medical images are proposed in this work. Image fusion rules are defined by Random Forest (RF) learning algorithm and a translation-invariant à-trous wavelet transform (AWT). The proposed method is threefold. First, source images are decomposed into approximation and detail coefficients using AWT. Second, RF is used to choose pixels from the approximation and detail coefficients for forming the approximation and detail coefficients of the fused image. Lastly, inverse AWT (iAWT) is applied to reconstruct fused image...
October 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29076644/image-enhancement-variational-methods-for-enabling-strong-cost-reduction-in-oled-based-point-of-care-immunofluorescent-diagnostic-systems
#7
Damiana Lazzaro, Serena Morigi, Patrizia Melpignano, Elena Piccolomini, Luca Benini
OBJECTIVE: Immunofluorescence diagnostic systems cost is often dominated by high-sensitivity, low-noise CCD-based cameras which are used to acquire the fluorescence images. In this paper we investigate the use of low-cost CMOS sensors in a point-of-care immunofluorescence diagnostic application for the detection and discrimination of four different serotypes of the Dengue virus in a set of human samples. METHODS: A two-phase post-processing software pipeline is proposed which consists in a first image enhancement stage for resolution increasing and segmentation, and a second diagnosis stage for the computation of the output concentrations...
October 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29073332/numerical-methods-for-polyline-to-point-cloud-registration-with-applications-to-patient-specific-stent-reconstruction
#8
Claire Yilin Lin, Alessandro Veneziani, Lars Ruthotto
We present novel numerical methods for Polyline-to-Point-Cloud Registration and their application to patient-specific modeling of deployed coronary artery stents from image data. Patient-specific coronary stent reconstruction is an important challenge in computational hemodynamics and relevant to the design and improvement of the prostheses. It is an invaluable tool in large-scale clinical trials that computationally investigate the effect of new generations of stents on hemodynamics and eventually tissue remodeling...
October 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28990354/influence-of-atrial-contraction-dynamics-on-cardiac-function
#9
Sander Land, Steven A Niederer
In recent years, there has been a move from mono- or biventricular models of the heart, to more complex models that incorporate the electromechanical function in all four chambers. However, the biophysical foundation is still under-developed, with most work in atrial cellular models having focused on electrophysiological properties. Here we present a biophysical model of human atrial contraction at body temperature, and use it to study the effects of atrial contraction on whole organ function, and a study of the effects of remodelling due to atrial fibrillation on atrial and ventricular function...
October 8, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28906592/influence-of-bronchial-diameter-change-on-the-airflow-dynamics-based-on-a-pressure-controlled-ventilation-system
#10
Shuai Ren, Maolin Cai, Yan Shi, Weiqing Xu, Xiaohua Douglas Zhang
Bronchial diameter is a key parameter that affects the respiratory treatment of mechanically ventilated patients. In this paper, to reveal the influence of bronchial diameter on the airflow dynamics of pressure-controlled mechanically ventilated patients, a new respiratory system model is presented which combines multi-generation airways with lungs. Furthermore, experiments and simulation studies to verify the model are performed. Finally, through the simulation study, it can be determined that in airway generations 2 to 7, when the diameter is reduced to half of the original value, the maximum air pressure (maximum air pressure in lungs) decreases by nearly 16%, the maximum flow decreases by nearly 30%, and the total airway pressure loss (sum of each generation pressure drop) is more than 5 times the original value...
September 14, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28898926/hybrid-cell-centred-vertex-model-for-multicellular-systems-with-equilibrium-preserving-remodelling
#11
P Mosaffa, A Rodríguez-Ferran, J J Muñoz
We present a hybrid vertex/cell-centred model for mechanically simulating planar cellular monolayers undergoing cell reorganisation. Cell centres are represented by a triangular nodal network, while the cell boundaries are formed by an associated vertex network. The two networks are coupled through a kinematic constraint which we allow to relax progressively. Special attention is paid to the change of cell-cell connectivity due to cell reorganisation or remodelling events. We handle these situations by using a variable resting length and applying an Equilibrium-Preserving Mapping (EPM) on the new connectivity, which computes a new set of resting lengths that preserve nodal and vertex equilibrium...
September 12, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28898561/haptic-simulation-of-tissue-tearing-during-surgery
#12
C Quesada, I Alfaro, D González, F Chinesta, E Cueto
We present a method for the real-time, interactive simulation of tissue tearing during laparoscopic surgery. The method is designed to work at haptic feedback rates (i.e., around 1kHz). Tissue tearing is simulated under the general framework of continuum damage mechanics. The problem is stated as a general, multidimensional parametric problem, which is solved by means of Proper Generalized Decomposition (PGD) methods. One of the main novelties is the reduction of history-dependent problems, such as damage mechanics, by resorting to an approach in which a reduced-order field of initial damage values is considered as a parameter of the formulation...
September 12, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28886617/viscous-effects-in-pelvic-floor-muscles-during-childbirth-a-numerical-study
#13
M C P Vila Pouca, J P S Ferreira, D A Oliveira, M P L Parente, R M Natal Jorge
During vaginal delivery women sustain stretching of their pelvic floor, risking tissue injury and adverse outcomes. Realistic numerical simulations of childbirth can help in the understanding of the pelvic floor mechanics and on the prevention of related disorders. In previous studies, biomechanical finite element simulations of a vaginal delivery have been performed disregarding the viscous effects present on all biological soft tissues. The inclusion of the viscoelastic behaviour is fundamental, since it allows to investigate rate-dependent responses...
September 8, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28884520/relative-pressure-estimation-from-velocity-measurements-in-blood-flows-state-of-the-art-and-new-approaches
#14
Cristóbal Bertoglio, Rodolfo Núñez, Felipe Galarce, David Nordsletten, Axel Osses
The relative pressure difference across stenotic blood vessels serves as an important clinical index for the diagnosis of many cardiovascular diseases. While the clinical gold standard for relative pressure difference measurements is invasive catheterization, Phase-Contrast Magnetic Resonance Imaging has emerged as a promising tool for enabling a non-invasive quantification, by linking highly spatially resolved velocity measurements with relative pressures via the incompressible Navier-Stokes equations. In this work we provide a review and analysis of current methods for relative pressure estimation and propose three additional techniques...
September 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28859253/flow-features-and-device-induced-blood-trauma-in-cf-vads-under-a-pulsatile-blood-flow-condition-a-cfd-comparative-study
#15
Zengsheng Chen, Sofen K Jena, Guruprasad A Giridharan, Steven C Koenig, Mark S Slaughter, Bartley P Griffith, Zhongjun J Wu
In this study, the flow features and device-associated blood trauma in 4 clinical ventricular assist devices (VADs; 2 implantable axial VADs, 1 implantable centrifugal VAD, and 1 extracorporeal VAD) were computationally analyzed under clinically relevant pulsatile flow conditions. The 4 VADs were operated at fixed pump speed at a mean rate of 4.5 L/min. Mean pressure difference, wall shear stress, volume distribution of scalar shear stress (SSS), and shear-induced hemolysis index (HI) were derived from the flow field of each VAD and were compared...
August 31, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28098434/method-for-the-unique-identification-of-hyperelastic-material-properties-using-full-field-measures-application-to-the-passive-myocardium-material-response
#16
Luigi E Perotti, Aditya V S Ponnaluri, Shankarjee Krishnamoorthi, Daniel Balzani, Daniel B Ennis, William S Klug
Quantitative measurement of the material properties (eg, 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-ie, 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...
November 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27943622/uncertainty-quantification-of-inflow-boundary-condition-and-proximal-arterial-stiffness-coupled-effect-on-pulse-wave-propagation-in-a-vascular-network
#17
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 used 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...
October 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27935265/modelling-mitral-valvular-dynamics-current-trend-and-future-directions
#18
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...
October 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27921393/the-role-of-the-microvascular-network-structure-on-diffusion-and-consumption-of-anticancer-drugs
#19
Pietro Mascheroni, Raimondo 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...
October 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27813272/experiment-for-validation-of-fluid-structure-interaction-models-and-algorithms
#20
A Hessenthaler, N R Gaddum, O Holub, R Sinkus, O Röhrle, D Nordsletten
In this paper a fluid-structure interaction (FSI) experiment is presented. The aim of this experiment is to provide a challenging yet easy-to-setup FSI test case that addresses the need for rigorous testing of FSI algorithms and modeling frameworks. Steady-state and periodic steady-state test cases with constant and periodic inflow were established. Focus of the experiment is on biomedical engineering applications with flow being in the laminar regime with Reynolds numbers 1283 and 651. Flow and solid domains were defined using computer-aided design (CAD) tools...
September 2017: International Journal for Numerical Methods in Biomedical Engineering
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