Vascular wall shear stress (WSS) has been correlated to the development of atherosclerosis in arteries. As WSS depends on blood flow dynamics, it is sensitive pulsatile effects and local changes geometry. The aim this study therefore investigate if effect motion or a rigid assumption sufficient. Magnetic resonance imaging (MRI) was used acquire subject specific geometry rates human aorta, which were as inputs numerical models. Both models fluid-structure interaction (FSI) considered,...

Abstract The pressure drop across a stenotic vessel is an important parameter in medicine, providing commonly used and intuitive metric for evaluating the severity of stenosis. However, non-invasive estimation under pathological conditions has remained difficult. This study demonstrates novel method to quantify irreversible stenosis using 4D Flow MRI by calculating total turbulence production flow. Simulation acquisitions showed that energy lost can be accurately quantified with within range...

Purpose To assess how 4D flow MRI‐based pressure and energy loss estimates correspond to net transstenotic gradients (TPG ) their dependence on spatial resolution. Methods Numerical velocity data of stenotic were obtained from computational fluid dynamics (CFD) simulations in geometries with varying stenosis degrees, poststenotic diameters rates. MRI measurements simulated at different resolutions. The simplified extended Bernoulli equations, Pressure‐Poisson equation (PPE), integration...

Cardiac hemodynamics can be computed from medical imaging data, and results could potentially aid in cardiac diagnosis treatment optimization. However, simulations are often based on simplified geometries, ignoring features such as papillary muscles trabeculae due to their complex shape, limitations image acquisitions, challenges computational modeling. This severely hampers the use of fluid dynamics clinical practice. The overall aim this study was develop a novel numerical framework that...

Blood flow simulations are making their way into the clinic, and much attention is given to estimation of fractional reserve in coronary arteries. Intracardiac blood also show promising results, here field expected depend on pulmonary venous (PV) rates. In absence vivo measurements, distribution from individual PVs often unknown typically assumed. Here, we performed intracardiac based time-resolved computed tomography three patients, investigated effect PV rate left atrium ventricle. A...

Purpose To investigate four-dimensional (4D) flow CT for the assessment of intracardiac blood patterns as compared with 4D MRI. Materials and Methods This prospective study acquired coronary angiography MRI data between February December 2016 in a cohort 12 participants (age range, 36–74 years; mean age, 57 seven men [age years] five women 52–73 64 years]). Flow simulations based solely on CT-derived cardiac anatomy were assessed together measurements. patterns, rates, stroke volume, kinetic...

Lumped parameter models of the cardiovascular system have potential to assist researchers and clinicians better understand function. The value such increases when they are subject specific. However, most approaches personalize lumped thus far required invasive measurements or fall short being specific due a lack necessary clinical data. Here, we propose an approach parameters in model heart systemic circulation using exclusively non-invasive measurements. personalized is created flow data...

Atrial fibrillation (AF) is associated with an increased risk of stroke, often caused by thrombi that form in the left atrium (LA), and especially atrial appendage (LAA). The underlying mechanism not fully understood but thought to be related stagnant blood flow, which might present despite sinus rhythm. However, measuring flow stasis LAA challenging due its small size low velocities. We aimed compare paroxysmal AF patients controls using computational fluid dynamics (CFD) simulations.The...

Abstract Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal flow, but quantifying these effects, which are dominated by shear stresses highly fluctuating turbulent has not been feasible. This study evaluated novel application turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing and corresponding index (BDI) stenotic flow. The results showed that underestimates maximum principal...

To explore the use of MR-estimated turbulence quantities for assessment turbulent flow effects on vessel wall.Numerical velocity data two patient-derived models was obtained using computational fluid dynamics (CFD) physiological rates. The four-dimensional (4D) Flow MRI measurements were simulated at three different spatial resolutions and used to investigate estimation wall shear stress (tWSS) intravoxel standard deviation (IVSD) kinetic energy (TKE) estimated near wall.Accurate tWSS IVSD...

Purpose To measure the Reynolds stress tensor using 4D flow MRI, and to evaluate its contribution computed pressure maps. Methods A method assess both velocity MRI is presented evaluated. The compared by cross‐sectional integrals of invariants. Pressure maps are Poisson equation—both including neglecting stress. Result Good agreement seen for between computational fluid dynamics, simulated experiment. can significantly influence loss (eg, –0.52% vs –15.34% error; P < 0.001) experimental...

Significant mitral valve regurgitation creates progressive adverse remodeling of the left ventricle (LV). Replacement failing with a prosthesis generally improves patient outcomes but leaves non-physiological intracardiac flow patterns that might contribute to their future risk thrombus formation and embolism. It has been suggested angular orientation implanted modify postoperative distortion intraventricular field. In this study, we investigated effect prosthetic on LV by using heart...

Large eddy simulation was applied for flow of Re=2000 in a stenosed pipe order to undertake thorough investigation the wall shear stress (WSS) turbulent flow. A decomposition WSS into time averaged and fluctuating components is proposed. It concluded that scale resolving technique required completely describe pattern subject specific vessel model, since poststenotic region dominated by large axial circumferential fluctuations. Three regions different characteristics were identified. The...

Purpose Evaluate spiral three‐dimensional (3D) phase contrast MRI for the assessment of turbulence and velocity in stenotic flow. Methods A‐stack‐of‐spirals 3D sequence was evaluated vitro against a conventional Cartesian sequence. Measurements were made flow phantom with 75% stenosis. Both imaging performed using different scan orientations rates. Volume rate, maximum turbulent kinetic energy (TKE) computed both methods. Moreover, estimated TKE compared computational fluid dynamics (CFD)...

To examine methods for visualizing and quantifying flow stasis in abdominal aortic aneurysms (AAA) using 4D Flow MRI. Three were investigated: conventional volumetric residence time (VRT), mean velocity analysis (MVA), particle travel distance (TDA). First, ideal MRI data was generated numerical simulations used as a platform to explore the effects of noise background phase-offset errors, both which are common artifacts. Error-free results compared or offset affected linear regression....

We developed a new comprehensive approach to atrial blood component analysis that includes both conduit flow and residual volume compared the components of fibrillation (AF) patients in sinus rhythm with controls. Conduit reservoir were similar between groups, whereas longer residence time left atrium increased AF group. This could add pathophysiological understanding diseases possibly clinical management.