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International Journal for Numerical Methods in Biomedical Engineering

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https://www.readbyqxmd.com/read/28337862/bayesian-sensitivity-analysis-of-a-1d-vascular-model-with-gaussian-process-emulators
#1
A Melis, R H Clayton, A Marzo
One-dimensional models of the cardiovascular system can capture the physics of pulse waves, but involve many parameters. Since these may vary among individuals, patient-specific models are difficult to construct. Sensitivity analysis can be used to rank model parameters by their effect on outputs, and to quantify how uncertainty in parameters influences output uncertainty. This type of analysis is often conducted with a Monte Carlo method, where large numbers of model runs are used to assess input-output relations...
March 24, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28329435/face-shield-design-against-blast-induced-head-injuries
#2
Long Bin Tan, Kwong Ming Tse, Yuan Hong Tan, Mohamad Ali Bin Sapingi, Vincent Beng Chye Tan, Heow Pueh Lee
Blast-induced traumatic brain injury (TBI) has been on the rise in recent years due to the increasing use of improvised explosive devices (IEDs) in conflict zones. Our study investigates the response of a helmeted human head subjected to a blast of 1 atm peak overpressure, for cases with and without a standard polycarbonate (PC) face shield and for face shields comprising of composite PC and aerogel materials and with lateral edge extension. The novel introduction of aerogel into the laminate face shield is explored and its wave-structure interaction mechanics and performance in blast mitigation is analysed...
March 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28294580/effect-of-cerebrospinal-fluid-modelling-on-spherically-convergent-shear-waves-during-blunt-head-trauma
#3
Amit Madhukar, Ying Chen, Martin Ostoja-Starzewski
The MRI-based computational model, previously validated by tagged MRI and HARP imaging analysis technique on in vivo human brain deformation, is employed to study transient wave dynamics during blunt head trauma. Three different constitutive models are used for the cerebrospinal fluid (CSF): incompressible solid elastic, viscoelastic and fluid-like elastic using an equation of state model. Three impact cases are simulated which indicate that the blunt impacts give rise not only to a fast pressure wave but also to a slow, and potentially much more damaging, shear (distortional) wave that converges spherically towards the brain center...
March 14, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28294574/phase-field-boundary-conditions-for-the-voxel-finite-cell-method-surface-free-stress-analysis-of-ct-based-bone-structures
#4
L H Nguyen, S K F Stoter, T Baum, J S Kirschke, M Ruess, Z Yosibash, D Schillinger
The voxel finite cell method employs unfitted finite element meshes and voxel quadrature rules to seamlessly transfer CT data into patient-specific bone discretizations. The method, however, still requires the explicit parametrization of boundary surfaces to impose traction and displacement boundary conditions, which constitutes a potential roadblock to automation. We explore a phase-field based formulation for imposing traction and displacement constraints in a diffuse sense. Its essential component is a diffuse geometry model generated from metastable phase-field solutions of the Allen-Cahn problem that assumes the imaging data as initial condition...
March 11, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28268244/calculation-of-cancellous-bone-elastic-properties-with-the-polarization-based-fft-iterative-scheme
#5
Lucas Colabella, Ariel Alejandro Ibarra Pino, Josefina Ballarre, Piotr Kowalczyk, Adrián Pablo Cisilino
The FFT based method, originally introduced by Moulinec and Suquet in 1994 has gained popularity for computing homogenized properties of composites. In this work, the method is used for the computational homogenization of the elastic properties of cancellous bone. To the authors' knowledge, this is the first study where the FFT scheme is applied to bone mechanics. The performance of the method is analyzed for artificial and natural bone samples of two species: bovine femoral heads and implanted femurs of Hokkaido rats...
March 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28264145/human-body-modeling-method-to-simulate-the-biodynamic-characteristics-of-spine-in-vivo-with-different-sitting-postures
#6
Rui Chun Dong, Li Xin Guo
The aim of this study is to model the computational model of seated whole human body including skeleton, muscle, viscera, ligament, intervertebral disc and skin to predict effect of the factors (sitting postures, muscle and skin, buttocks, viscera, arms, gravity, and boundary conditions) on the biodynamic characteristics of spine. Two finite element (FE) models of seated whole body and a large number of FE models of different ligamentous motion segments were developed and validated. Static, modal and transient dynamic analyses were performed...
March 6, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28257608/research-and-primary-evaluation-of-an-automatic-fusion-method-for-multi-source-tooth-crown-data
#7
Ning Dai, Dawei Li, Xu Yang, Cheng Cheng, Yuchun Sun
BACKGROUND: With the development of 3D scanning technologies in dentistry, high accuracy optical scanning data from the crown and cone beam computed tomography (CBCT) data from the root can be acquired easily. In many dental fields, especially in digital orthodontics, it is useful to fuse the data from the crown and the root. However, the manual fusion method is complex and difficult. A novel automatic fusion method for two-source data from the crown and the root was researched and its accuracy was evaluated in this study...
March 3, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28249103/a-hybrid-computational-model-to-explore-the-topological-characteristics-of-epithelial-tissues
#8
Ismael González-Valverde, José Manuel García Aznar
Epithelial tissues show a particular topology where cells resemble a polygon-like shape, but some biological processes can alter this tissue topology. During cell proliferation, mitotic cell dilation deforms the tissue and modifies the tissue topology. Additionally, cells are reorganized in the epithelial layer and these rearrangements also alter the polygon distribution. We present here a computer-based hybrid framework focused on the simulation of epithelial layer dynamics that combines discrete and continuum numerical models...
March 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28226417/an-efficient-multi-stage-algorithm-for-full-calibration-of-the-hemodynamic-model-from-bold-signal-responses
#9
Brian Zambri, Rabia Djellouli, Meriem Laleg-Kirati
We propose a computational strategy that falls into the category of prediction/correction iterative-type approaches, for calibrating the hemodynamic model introduced by Friston et al. (2000). The proposed method is employed to estimate consecutively the values of the biophysiological system parameters and the external stimulus characteristics of the model. Numerical results corresponding to both synthetic and real functional Magnetic Resonance Imaging (fMRI) measurements for a single stimulus as well as for multiple stimuli are reported to highlight the capability of this computational methodology to fully calibrate the considered hemodynamic model...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28226410/patient-specific-computational-modeling-of-cortical-spreading-depression-via-diffusion-tensor-imaging
#10
Julia M Kroos, Isabella Marinelli, Ibai Diez, Jesus M Cortes, Sebastiano Stramaglia, Luca Gerardo-Giorda
Cortical Spreading Depression (CSD), a depolarization wave originating in the visual cortex and traveling towards the frontal lobe, is commonly accepted as a correlate of migraine visual aura. As of today, little is known about the mechanisms that can trigger or stop such phenomenon. However, the complex and highly individual characteristics of the brain cortex suggest that the geometry might have a significant impact in supporting or contrasting the propagation of CSD. Accurate patient-specific computational models are fundamental to cope with the high variability in cortical geometries among individuals, but also with the conduction anisotropy induced in a given cortex by the complex neuronal organisation in the grey matter...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28224760/a-tree-parenchyma-coupled-model-for-lung-ventilation-simulation
#11
N Pozin, S Montesantos, I Katz, M Pichelin, I Vignon-Clementel, C Grandmont
In this article we develop a lung-ventilation model. The parenchyma is described as an elastic homogenized media. It is irrigated by a space-filling dyadic resistive pipe network, which represents the tracheo-bronchial tree. In this model the tree and the parenchyma are strongly coupled. The tree induces an extra viscous term in the system constitutive relation, which leads, in the finite element framework, to a full matrix. We consider an efficient algorithm that takes advantage of the tree structure to enable a fast matrix-vector product computation...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28208231/fast-left-ventricle-tracking-using-localized-anatomical-affine-optical-flow
#12
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
https://www.readbyqxmd.com/read/28205412/an-investigation-of-dimensional-scaling-using-cervical-spine-motion-segment-finite-element-models
#13
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
https://www.readbyqxmd.com/read/28146314/how-coagulation-zone-size-is-underestimated-in-computer-modeling-of-rf-ablation-by-ignoring-the-cooling-phase-just-after-rf-power-is-switched-off
#14
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
https://www.readbyqxmd.com/read/28124821/large-eddy-simulations-for-blood-dynamics-in-realistic-stenotic-carotids
#15
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
https://www.readbyqxmd.com/read/28112875/three-dimensional-assessment-of-impingement-risk-in-geometrically-parameterised-hips-compared-with-clinical-measures
#16
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
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
#17
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
https://www.readbyqxmd.com/read/28058781/multi-photon-microscope-measurement-based-biphasic-multi-scale-analyses-of-knee-joint-articular-cartilage-and-chondrocyte-by-using-visco-anisotropic-hyperelastic-finite-element-method-and-smoothed-particle-hydrodynamics-method
#18
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
https://www.readbyqxmd.com/read/28052555/computational-modeling-of-tracheal-angioedema-due-to-swelling-of-the-submucous-tissue-layer
#19
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
https://www.readbyqxmd.com/read/28039961/high-resolution-data-assimilation-of-cardiac-mechanics-applied-to-a-dyssynchronous-ventricle
#20
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
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