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International Journal for Numerical Methods in Biomedical Engineering

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https://www.readbyqxmd.com/read/29331052/flow-pattern-analysis-in-type-b-aortic-dissection-patients-after-stent-grafting-repair-comparison-between-complete-and-incomplete-false-lumen-thrombosis
#1
Wan Naimah Wan Ab Naim, Poo Balan Ganesan, Zhonghua Sun, Jing Lei, Shirley Jansen, Shahrul Amry Hashim, Teik Kok Ho, Einly Lim
Endovascular stent graft repair has become a common treatment for complicated Stanford Type B aortic dissection in order to restore true lumen flow and induce false lumen thrombosis. Using computational fluid dynamics, this study reports the differences in flow patterns and wall shear stress distribution in complicated Stanford Type B aortic dissection patients after endovascular stent graft repair. Five patients were included in this study: two having more than 80% false lumen thrombosis (Group 1), while three others had less than 80% false lumen thrombosis (Group 2) within one year following endovascular repair...
January 13, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29316347/effect-of-heated-air-blanket-on-the-dispersion-of-squames-in-an-operating-room
#2
X He, S Karra, P Pakseresht, S V Apte, S Elghobashi
High-fidelity, predictive fluid flow simulations of the interactions between the rising thermal plumes from forced air warming blower and the ultraclean ventilation air in an operating (OR) are conducted to explore whether this complex flow can impact the dispersion of squames to the surgical site. A large-eddy simulation (LES), accurately capturing the spatio-temporal evolution of the flow in three-dimensions together with the trajectories of squames, is performed for a realistic OR consisting of an operating table (OT), side tables, surgical lamps, medical staff, and a patient...
January 9, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29316340/an-adaptive-hybridizable-discontinuous-galerkin-approach-for-cardiac-electrophysiology
#3
J M Hoermann, C Bertoglio, M Kronbichler, M R Pfaller, R Chabiniok, W A Wall
Cardiac electrophysiology simulations are numerically challenging due to the propagation of a steep electrochemical wave front and thus require discretizations with small mesh sizes to obtain accurate results. In this work, we present an approach based on the Hybridizable Discontinuous Galerkin method (HDG), which allows an efficient implementation of high-order discretizations into a computational framework. In particular using the advantage of the discontinuous function space, we present an efficient p-adaptive strategy for accurately tracking the wave front...
January 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29314783/controlling-the-error-on-target-motion-through-real-time-mesh-adaptation-applications-to-deep-brain-stimulation
#4
Huu Phuoc Bui, Satyendra Tomar, Hadrien Courtecuisse, Michel Audette, Stéphane Cotin, Stéphane P A Bordas
An error-controlled mesh refinement procedure for needle insertion simulations is presented. As an example, the procedure is applied for simulations of electrode implantation for Deep Brain Stimulation. We take into account the brain shift phenomena occurring when a craniotomy is performed. We observe that the error in the computation of the displacement and stress fields is localised around the needle tip and the needle shaft during needle insertion simulation. By suitably and adaptively refining the mesh in this region, our approach enables to control, and thus to reduce, the error whilst maintaining a coarser mesh in other parts of the domain...
January 5, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29277960/generalized-backpropagation-algorithm-for-training-second-order-neural-networks
#5
Fenglei Fan, Wenxiang Cong, Ge Wang
The artificial neural network is a popular framework in machine learning. To empower individual neurons, we recently suggested that the current type of neurons could be upgraded to 2nd order counterparts, in which the linear operation between inputs to a neuron and the associated weights is replaced with a nonlinear quadratic operation. A single 2nd -order neurons already has a strong nonlinear modeling ability, such as implementing basic fuzzy logic operations. In this paper, we develop a general backpropagation (BP) algorithm to train the network consisting of 2nd -order neurons...
December 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29274303/magnetic-drug-targeting-simulations-in-blood-flows-with-fluid-structure-interaction
#6
S Calandrini, G Capodaglio, E Aulisa
We present fluid-structure interaction (FSI) simulations of magnetic drug targeting (MDT) in blood flows. In this procedure, a drug is attached to ferromagnetic particles in order to externally direct it to a specific target after it is injected inside the body. The goal is to minimize the healthy tissue affected by the treatment and to maximize the number of particles that reach the target location. MDT has been studied both experimentally and theoretically by several authors. In recent years, computational fluid dynamics (CFD) simulations of MDT in blood flows have been carried out to obtain further insight on the combination of parameters that provide the best capture efficiency...
December 23, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29272565/a-compartment-quasi3d-multiscale-approach-for-drug-absorption-transport-and-retention-in-the-human-lungs
#7
Ravishekar Ravi Kannan, Narender Singh, Andrzej Przekwas
The majority of current models used for modeling the pulmonary drug absorption, transport, and retention are 0D compartmental models where the airways are generally split into the airways and alveolar sections. Such block models deliver low fidelity solutions and the spatial lung drug concentrations cannot be obtained. Other approaches utilize high fidelity CFD models with limited capabilities due to their exorbitant computational cost. Recently, we presented a novel, fast-running and robust Quasi-3D (Q3D) model for modeling the pulmonary airflow...
December 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29266819/machine-learning-based-diagnosis-of-melanoma-using-macro-images
#8
D Gautam, M Ahmed, Y K Meena, A U Haq
Cancer bears a poisoning threat to human society. Melanoma, the skin cancer originates from skin layers and penetrates deep into subcutaneous layers. There exists an extensive research in melanoma diagnosis using dermatoscopic images captured through dermatoscope. While designing a diagnostic model for general handheld imaging systems is an emerging trend. This article proposes a computer aided decision support system for macro images captured by a general purpose camera. The general imaging conditions are adversely affected by the non-uniform illumination which further effect the extraction of relevant information...
December 20, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29265715/multi-level-hp-finite-cell-method-for-embedded-interface-problems-with-application-in-biomechanics
#9
Mohamed Elhaddad, Nils Zander, Tino Bog, László Kudela, Stefan Kollmannsberger, Jan S Kirschke, Thomas Baum, Martin Ruess, Ernst Rank
This work presents a numerical discretization technique for solving three-dimensional material interface problems involving complex geometry without conforming mesh generation. The finite cell method (FCM), which is a high-order fictitious domain approach, is used for the numerical approximation of the solution without a boundary-conforming mesh. Weak discontinuities at material interfaces are resolved by using separate FCM meshes for each material sub-domain, and weakly enforcing the interface conditions between the different meshes...
December 19, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29245182/an-efficient-parallel-simulation-of-unsteady-blood-flows-in-patient-specific-pulmonary-artery
#10
Fande Kong, Vitaly Kheyfets, Ender Finol, Xiao-Chuan Cai
Simulation of blood flows in the pulmonary artery provides some insight into certain diseases by examining the relationship between some continuum metrics, e.g. the wall shear stress acting on the vascular endothelium, which responds to flow-induced mechanical forces by releasing vasodilators/constrictors. In [?kheyfets2015patient], V. Kheyfets studies numerically a patient-specific pulmonary circulation to show that decreasing wall shear stress is correlated with increasing pulmonary vascular impedance. In this paper, we develop a scalable parallel algorithm based on domain decomposition methods to investigate an unsteady model with patient specific pulsatile waveforms as the inlet boundary condition...
December 15, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29218827/computational-study-of-estimating-3d-trabecular-bone-microstructure-for-the-volume-of-interest-from-ct-scan-data
#11
Jung Jin Kim, Jimin Nam, In Gwun Jang
Inspired by the self-optimizing capabilities of bone, a new concept of bone microstructure reconstruction has been recently introduced using 2D synthetic skeletal images. As a preliminary clinical study, this paper proposes a topology optimization-based method that can estimate 3D trabecular bone microstructure for the volume of interest (VOI) from 3D computed tomography (CT) scan data with enhanced computational efficiency and phenomenological accuracy. For this purpose, a localized finite element (FE) model is constructed by segmenting a target bone from CT scan data and determining the physiological local loads for the VOI...
December 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29197163/model-for-pressure-drop-and-flow-deflection-in-the-numerical-simulation-of-stents-in-aneurysms
#12
S Li, J Latt, B Chopard
The numerical simulation of flow diverters like stents contributes to the development and improvement of endovascular stenting procedures, leading ultimately to an improved treatment of intracranial aneurysms. Due to the scale difference between the struts of flow diverters and the full artery, it is common to avoid fully resolved simulations at the level of the stent porosity. Instead, the effect of stents on the flow is represented by a heuristic continuum model. However, the commonly used porous media models describe the properties of flow diverters only partially, because they do not explicitly account for the deflection of the flow direction by the stent...
December 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29181891/fluid-structure-interaction-of-a-pulsatile-flow-with-an-aortic-valve-model-a-combined-experimental-and-numerical-study
#13
J Sigüenza, D Pott, S Mendez, S J Sonntag, T A S Kaufmann, U Steinseifer, F Nicoud
The complex fluid-structure interaction problem associated with the flow of blood through a heart valve with flexible leaflets is investigated both experimentally and numerically. In the experimental test rig, a pulse duplicator generates a pulsatile flow through a biomimetic rigid aortic root where a model of aortic valve with polymer flexible leaflets is implanted. High-speed recordings of the leaflets motion and Particle Image Velocimetry measurements were performed together to investigate the valve kinematics and the dynamics of the flow...
November 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29181888/preconditioned-augmented-lagrangian-formulation-for-nearly-incompressible-cardiac-mechanics
#14
J O Campos, R W Dos Santos, J Sundnes, B M Rocha
Computational modeling of the heart is a subject of substantial medical and scientific interest, which may contribute to increase the understanding of several phenomena associated with cardiac physiological and pathological states. Modeling the mechanics of the heart have led to considerable insights, but it still represents a complex and a demanding computational problem, especially in a strongly coupled electromechanical setting. Passive cardiac tissue is commonly modeled as hyperelastic, and is characterized by quasi-incompressible, orthotropic and non-linear material behavior...
November 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29178405/acoustophoretic-separation-of-infected-erythrocytes-from-blood-plasma-in-a-microfluidic-platform-using-biofunctionalized-matched-impedance-layers
#15
Tamaghna Gupta, Ritwick Ghosh, Ranjan Ganguly
Acoustophoresis is rapidly gaining prominence in the field of cell manipulation. In recent years, researchers have extensively used this method for separating different types of cells from the bulk fluid. In this paper, we propose a novel acoustophoresis based technique to capture infected or abnormal erythrocytes from blood plasma. A typical acoustic device consisting of a transducer assembly, microfluidic cavity and a reflector is considered. Based on the concept of impedance matching a pair of antibody-coated polystyrene layers is placed in the nodal regions of an acoustic field within the cavity...
November 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29172251/on-computational-fluid-dynamics-models-for-sinonasal-drug-transport-relevance-of-nozzle-subtraction-and-nasal-vestibular-dilation
#16
S Basu, D O Frank-Ito, J S Kimbell
Generating anatomically realistic three-dimensional (3D) models of the human sinonasal cavity for numerical investigations of sprayed drug transport presents a host of methodological ambiguities. For example, subject-specific radiographic images used for 3D reconstructions typically exclude spray bottles. Subtracting a bottle contour from the 3D airspace and dilating the anterior nasal vestibule for nozzle placement augment the complexity of model-building. So, we explored the question: how essential are these steps to adequately simulate nasal airflow and identify the optimal delivery conditions for intranasal sprays? In particular, we focused on particle deposition patterns in the maxillary sinus, a critical target site for chronic rhinosinusitis (CRS)...
November 24, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29171175/computational-predictions-of-damage-propagation-preceding-dissection-of-ascending-thoracic-aortic-aneurysms
#17
S J Mousavi, S Farzaneh, S Avril
Dissections of ascending thoracic aortic aneurysms (ATAA) cause significant morbidity and mortality worldwide. They occur when a tear in the intima-media of the aorta permits the penetration of the blood and the subsequent delamination and separation of the wall in two layers, forming a false channel. In order to predict computationally the risk of tear formation, stress analyses should be performed layer-specifically and they should consider internal or residual stresses which exist in the tissue. In the present paper, we propose a novel layer-specific damage model based on the constrained mixture theory (CMT) which intrinsically takes into account these internal stresses and which can predict appropriately the tear formation...
November 23, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29168345/nonlinear-micro-ct-based-fe-modeling-of-trabecular-bone-sensitivity-of-apparent-response-to-tissue-constitutive-law-and-bone-volume-fraction
#18
F A Sabet, O Jin, S Koric, I Jasiuk
In this study, the sensitivity of the apparent response of trabecular bone to different constitutive models at the tissue-level was investigated using finite element modeling based on micro-computed tomography. Trabecular bone specimens from porcine femurs were loaded under a uniaxial compression experimentally and computationally. The apparent behaviors computed using von Mises, Drucker-Prager, and Cast Iron plasticity models were compared. Secondly, the effect of bone volume fraction was studied by changing the bone volume fraction of a trabecular bone sample and while keeping the same basic architecture...
November 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29160926/electro-mechanical-response-of-a-3d-nerve-bundle-model-to-mechanical-loads-leading-to-axonal-injury
#19
I Cinelli, M Destrade, M Duffy, P McHugh
OBJECTIVE: Traumatic brain injuries and damage are major causes of death and disability. We propose a 3D fully coupled electro-mechanical model of a nerve bundle to investigate the electrophysiological impairments due to trauma at the cellular level. METHODS: The coupling is based on a thermal analogy of the neural electrical activity by using the finite element software Abaqus CAE 6.13-3. The model includes a real-time coupling, modulated threshold for spiking activation and independent alteration of the electrical properties for each 3-layer fibre within a nerve bundle as a function of strain...
November 21, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29124903/relationship-between-the-left-ventricular-size-and-the-amount-of-trabeculations
#20
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
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