New methods for computational fluid dynamics modeling of carotid artery from magnetic resonance angiography

Abstract

Computational fluid dynamics (CFD) models of the carotid artery are constructed from contrast-enhanced magnetic resonance angiography (MRA) using a deformable model and a surface-merging algorithm. Physiologic flow conditions are obtained from cine phase-contrast MRA at two slice locations below and above the carotid bifurcation. The methodology was tested on image data from a rigid flow-through phantom of a carotid artery with 65% degree stenosis. Predicted flow patterns are in good agreement with MR flow measurements at intermediate slice locations. Our results show that flow in a rigid flow-through phantom of the carotid bifurcation with stenosis can be simulated accurately with CFD. The methodology was then tested on flow and anatomical data from a normal human subject. The sum of the instantaneous flows measured at the internal and external carotids differs from that at the common carotid, indicating that wall compliance must be modeled. Coupled fluid-structure calculations were able to reproduce the significant dampening of the velocity waveform observed between different slices along the common carotid artery. Visualizations of the blood flow in a compliant model of the carotid bifurcation were produced. A comparison between compliant and rigid models shows significant differences in the time-dependent wall shear stress at selected locations. Our results confirm that image-based CFD techniques can be applied to the modeling of hemodynamics in compliant carotid arteries. These capabilities may eventually allow physicians to enhance current image-based diagnosis, and to predict and evaluate the outcome of interventional procedures non- invasively.