Hemodynamics in the carotid artery bifurcation: a comparison between numerical simulations and in vitro MRI measurements

The presence of atherosclerotic plaques has been shown to be closely relate d to the vessel geometry. Studies on postmortem human arteries and on the e xperimental animal show positive correlation between the presence of plaque thickness and low shear stress, departure of unidirectional flow and regio ns of flow separation and recirculation. Numerical simulations of arterial blood flow and direct blood flow velocity measurements by magnetic resonance imaging (MRI) are two approaches for th e assessment of arterial blood flow patterns. In order to verify that both approaches give equivalent results magnetic resonance velocity data measure d in a compliant anatomical carotid bifurcation model were compared to the results of numerical simulations performed for a corresponding computationa l vessel model. Cross sectional axial velocity profiles were calculated and measured for th e midsinus and endsinus internal carotid artery. At both locations a skewed velocity profile with slow velocities at the outer vessel wall, medium vel ocities at the side walls and high velocities at the flow divider (inner) w all were observed. Qualitative comparison of the axial velocity patterns re vealed no significant differences between simulations and in vitro measurem ents. Even quantitative differences such as for axial peak flow velocities were less than 10%. Secondary flow patterns revealed some minor differences concerning the form of the vortices but maximum circumferential velocities were In the same range for both methods. (C) 2000 Elsevier Science Ltd. Al l rights reserved.