Patient-Specific Modeling of Atherosclerotic Carotid Arteries From Multi-Modality Image Data

2003 ◽  
Author(s):  
Juan R. Cebral ◽  
Christopher Putman ◽  
Richard Pergolizzi ◽  
James E. Burgess
Keyword(s):  
Shear Stress ◽  
Magnetic Resonance ◽  
Wall Shear Stress ◽  
Carotid Arteries ◽  
Stokes Equations ◽  
Duplex Ultrasound ◽  
Flow Patterns ◽  
Patient Specific ◽  
Detailed Knowledge ◽  
Wall Shear

Estimation of the wall shear stress distribution in stenotic carotid arteries is important for assessing risk of stroke. Since there are no reliable experimental methods to determine wall shear stress distributions, realistic patient-specific computational fluid dynamics models are constructed from medical images. Anatomical and physiologic data are obtained from multiple image modalities including 3D rotational angiography, contrast-enhanced magnetic resonance angiography, carotid duplex ultrasound and phase-contrast magnetic resonance. These images are used to construct patient-specific finite element grids and to solve the incompressible Navier-Stokes equations under physiological pulsatile flow conditions. The detailed knowledge of the carotid hemodynamics derived from these models can be used to enhance our understanding of the relationship between flow patterns and symptoms, and ultimately risk of stroke. This methodology can also be used to correllate flow patterns with the outcome of endovascular procedures such as angioplasty and stenting.

Calculation of Unsteady Flows in Curved Pipes

2001 ◽  
Vol 123 (4) ◽  
pp. 869-877 ◽  
Author(s):  
H. A. Dwyer ◽  
A. Y. Cheer ◽  
T. Rutaganira ◽  
N. Shacheraghi
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Mass Flow ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Velocity Profiles ◽  
Frequency Parameter ◽  
Detailed Knowledge ◽  
Curved Pipes ◽  
Wall Shear

Highly unsteady three-dimensional flows in curved pipes with significant variation of flow geometry and flow parameters are studied. Using improvements in computational efficiency, detailed knowledge concerning flow structures is obtained. The numerical solutions of the Navier-Stokes equations have been obtained with a variation of the projection method, and the numerical method was enhanced by new algorithms derived from the physics of the flow. These enhancements include a prediction of the flow unsteady pressure gradient based on fluid acceleration and global pressure field corrections based on mass flow. This new method yields an order of magnitude improvement in the calculation’s efficiency, allowing the study of complex flow problems. Numerical flow simulations for oscillating flow cycles show that the curved pipe flows have a significant inviscid-like nature at high values of the frequency parameter. The shape of the velocity profiles is strongly influenced by the frequency parameter, whereas the influence of variations on the pipe cross-sectional area is shown to be rather weak. For large values of the frequency parameter the flow history strongly influences the low mass flow part of the cycle leading to highly unusual velocity profiles. The wall shear stress is studied for all the flows calculated. Our results show that wall shear stress is sensitive to area constrictions, the frequency parameter, as well as the shape of the entrance profile.

Comparison of Carotid Bifurcation Hemodynamics in Patient-Specific Geometries at Rest and During Exercise

2013 ◽  
Author(s):  
Rodward L. Hewlin ◽  
John P. Kizito
Keyword(s):  
Cardiovascular Disease ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Normal Stress ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
Patient Specific ◽  
Local Risk ◽  
Wall Shear ◽  
Hemodynamic Flow

The ultimate goal of the present study is to determine whether investigations of flow patterns (flow reversal and flow branching) and mechanical factors (wall shear stress and normal stress) have a role in local risk factors and if flow modeling can truly rely on surrogate geometric sites (simplified geometries). Cardiovascular disease is considered to be the leading cause of morbidity and mortality across the world and improved methods of disease management are desperately needed. One of the main forms of cardiovascular disease is atherosclerosis. The presence of atherosclerotic plaques has been shown to be closely related to arterial vessel geometry and hemodynamic flow patterns. Computational fluid dynamic simulations were performed on 3 carotid bifurcation arteries to demonstrate that hemodynamic factors are significant determinants for the development of vascular pathology. Relationships between disturbed flow and various geometric factors from rest-state and exercise were examined. Wall shear stress, normal stress, and vorticity were used to verify the role of age, gender, and geometry on hemodynamic flow patterns.

Abstract 235: Integration of Patient-specific Computational Hemodynamics and Vessel Wall Shear Stress Into MRI Diagnosis of Vascular Diseases

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Huidan W Yu ◽  
Xi Chen ◽  
Zhiqiang Wang ◽  
Rou Chen ◽  
Chen Lin ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Carotid Arteries ◽  
Vascular Diseases ◽  
Patient Specific ◽  
Imaging Data ◽  
Mri Imaging ◽  
Measured Velocity ◽  
Tof Mra ◽  
Wall Shear

The research objective is to expand the capability of current MRI imaging technique in assessing the overall risk and predicted outcomes of atherosclerotic diseases through the quantification of individual patient-specific hemodynamics, including flow, pressure, and wall-shear stress. A unique computational modeling technique, named InVascular, is integrated directly into clinical MRI scanners as the extension of the image reconstruction and post-processing pipeline so that velocity, pressure, vorticity, and WSS can be available immediately with other diagnostic images. InVascular is a unified and GPU accelerated computation platform to model and simulate patient-specific hemodynamics and flow-vessel interaction based on MRI imaging data. In this study, we validate the efficiency and accuracy of InVascular through quantitative hemodynamics in vertebral and carotid arteries. A group of five volunteers participated in the scanning of high resolution time-of-flight (TOF) and low resolution electrocardiogram (ECG) gated phase contrast (PC) MR angiogram (MRA) images. For each case, InVascular successively processes the images to get vessel geometry from TOF MRA and velocity slices from PC MRA and solve the fluid dynamics inside the carotid arteries with PC MRA measured velocity at the inlet and outlet (Fig. 1 a-c). The velocity profiles from Invascular and PC MRA are compared at the same location (Fig. 1 d-g ). We conclude that integration of MRAs and InVascular can well captured the velocity fields as MRI measures. InVascular can provide quantitative pressure and WSS (Fig. 1h ) information as well.

scholarly journals Wall shear stress gradient is independently associated with middle cerebral artery aneurysm development: a case-control CFD patient-specific study based on 77 patients

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mikołaj Zimny ◽  
Edyta Kawlewska ◽  
Anna Hebda ◽  
Wojciech Wolański ◽  
Piotr Ładziński ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Case Control ◽  
Independent Effect ◽  
Patient Specific ◽  
Aneurysm Formation ◽  
Wall Shear ◽  
Mca Aneurysm

Abstract Background Previously published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results. Our study analysed the involvement of the combination of high wall shear stress (WSS) and a positive WSS gradient (WSSG) in IA formation. Methods We designed a case-control study with a selection of 38 patients with an unruptured middle cerebral artery (MCA) aneurysm and 39 non-aneurysmal controls to determine the involvement of WSS, oscillatory shear index (OSI), the WSSG and its absolute value (absWSSG) in aneurysm formation based on patient-specific CFD simulations using velocity profiles obtained from transcranial colour-coded sonography. Results Among the analysed parameters, only the WSSG had significantly higher values compared to the controls (11.05 vs − 14.76 [Pa/mm], P = 0.020). The WSS, absWSSG and OSI values were not significantly different between the analysed groups. Logistic regression analysis identified WSS and WSSG as significant co-predictors for MCA aneurysm formation, but only the WSSG turned out to be a significant independent prognosticator (OR: 1.009; 95% CI: 1.001–1.017; P = 0.025). Significantly more patients (23/38) in the case group had haemodynamic regions of high WSS combined with a positive WSSG near the bifurcation apex, while in the control group, high WSS was usually accompanied by a negative WSSG (14/39). From the analysis of the ROC curve for WSSG, the area under the curve (AUC) was 0.654, with the optimal cut-off value −0.37 Pa/mm. The largest AUC was recognised for combined WSS and WSSG (AUC = 0.671). Our data confirmed that aneurysms tend to form near the bifurcation apices in regions of high WSS values accompanied by positive WSSG. Conclusions The development of IAs is determined by an independent effect of haemodynamic factors. High WSS impacts MCA aneurysm formation, while a positive WSSG mainly promotes this process.

scholarly journals Genetic correlates of wall shear stress in a patient-specific 3D-printed cerebral aneurysm model

2019 ◽  
Vol 11 (10) ◽  
pp. 999-1003 ◽  
Author(s):  
Michael R Levitt ◽  
Christian Mandrycky ◽  
Ashley Abel ◽  
Cory M Kelly ◽  
Samuel Levy ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Cerebral Aneurysm ◽  
Cell Morphology ◽  
Patient Specific ◽  
Parent Vessel ◽  
3D Printed ◽  
Wall Shear ◽  
Dynamics Simulations

ObjectivesTo study the correlation between wall shear stress and endothelial cell expression in a patient-specific, three-dimensional (3D)-printed model of a cerebral aneurysm.Materials and methodsA 3D-printed model of a cerebral aneurysm was created from a patient’s angiogram. After populating the model with human endothelial cells, it was exposed to media under flow for 24 hours. Endothelial cell morphology was characterized in five regions of the 3D-printed model using confocal microscopy. Endothelial cells were then harvested from distinct regions of the 3D-printed model for mRNA collection and gene analysis via quantitative polymerase chain reaction (qPCR.) Cell morphology and mRNA measurement were correlated with computational fluid dynamics simulations.ResultsThe model was successfully populated with endothelial cells, which survived under flow for 24 hours. Endothelial morphology showed alignment with flow in the proximal and distal parent vessel and aneurysm neck, but disorganization in the aneurysm dome. Genetic analysis of endothelial mRNA expression in the aneurysm dome and distal parent vessel was compared with the proximal parent vessels. ADAMTS-1 and NOS3 were downregulated in the aneurysm dome, while GJA4 was upregulated in the distal parent vessel. Disorganized morphology and decreased ADAMTS-1 and NOS3 expression correlated with areas of substantially lower wall shear stress and wall shear stress gradient in computational fluid dynamics simulations.ConclusionsCreating 3D-printed models of patient-specific cerebral aneurysms populated with human endothelial cells is feasible. Analysis of these cells after exposure to flow demonstrates differences in both cell morphology and genetic expression, which correlate with areas of differential hemodynamic stress.

scholarly journals Effects of a Short-Term Left Ventricular Assist Device on Hemodynamics in a Heart Failure Patient-Specific Aorta Model: A CFD Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Yu Wang ◽  
Junwei Wang ◽  
Jing Peng ◽  
Mingming Huo ◽  
Zhiqiang Yang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pressure Difference ◽  
Left Ventricular ◽  
Patient Specific ◽  
Short Term ◽  
Ventricular Assist ◽  
Left Ventricular Assist ◽  
Wall Shear ◽  
Hemodynamic Performance

Patients with heart failure (HF) or undergoing cardiogenic shock and percutaneous coronary intervention require short-term cardiac support. Short-term cardiac support using a left ventricular assist device (LVAD) alters the pressure and flows of the vasculature by enhancing perfusion and improving the hemodynamic performance for the HF patients. However, due to the position of the inflow and outflow of the LVAD, the local hemodynamics within the aorta is altered with the LVAD support. Specifically, blood velocity, wall shear stress, and pressure difference are altered within the aorta. In this study, computational fluid dynamics (CFD) was used to elucidate the effects of a short-term LVAD for hemodynamic performance in a patient-specific aorta model. The three-dimensional (3D) geometric models of a patient-specific aorta and a short-term LVAD, Impella CP, were created. Velocity, wall shear stress, and pressure difference in the patient-specific aorta model with the Impella CP assistance were calculated and compared with the baseline values of the aorta without Impella CP support. Impella CP support augmented cardiac output, blood velocity, wall shear stress, and pressure difference in the aorta. The proposed CFD study could analyze the quantitative changes in the important hemodynamic parameters while considering the effects of Impella CP, and provide a scientific basis for further predicting and assessing the effects of these hemodynamic signals on the aorta.

scholarly journals An MRI-based method to register patient-specific wall shear stress data to histology

PLoS ONE ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. e0217271 ◽  
Author(s):  
A. M. Moerman ◽  
K. Dilba ◽  
S. Korteland ◽  
D. H. J. Poot ◽  
S. Klein ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Patient Specific ◽  
Wall Shear
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