Hemodynamic analysis of carotid artery after endarterectomy: a preliminary and quantitative imaging study based on computational fluid dynamics and magnetic resonance angiography.

Background: The carotid blood flow following carotid endarterectomy (CEA) is not fully understood. Computational fluid dynamics (CFD) is a promising method to study blood flow. This study is to investigate local hemodynamic characteristics after CEA via the use of unenhanced magnetic resonance angiography (MRA) and CFD.

Methods: Eight carotid arteries with atherosclerosis and sixteen normal carotid arteries were included in this study. Time-of-flight (TOF) and phase contrast (PC) MRA were applied for the measurement of three-dimensional artery geometries and velocity profile under CFD simulation. The hemodynamic parameters of the proximal internal carotid artery (ICA) including velocity, ICA/common carotid artery (CCA) velocity ratio, mean, maximum, minimum and gradient of wall shear stress (WSSmean , WSSmax , WSSmin and WSSG) were calculated before and after CEA. Morphologic characteristics of the carotid including bifurcation angle, tortuosity and planarity were also analyzed.

Results: Compared with pre-CEA, there was a significant reduction in post-CEA velocity, WSSmax , WSSmean , and WSSG, by 87.24%±13.38%, 86.86%±14.97%, 57.32%±56.71% and 69.74%±37.03% respectively, whereas WSSmin was almost unchanged. ICA/ CCA velocity ratios increased significantly after CEA. We also found that the post-CEA flow conditions were positively remodelled to approximate the conditions in normal arteries. The correlation between PC-MRA and CFD was excellent for the measurement of maximum velocity at the external carotid artery (r=0.846).

Conclusions: Our preliminary results indicated that major flow dynamics were restored shortly following CEA, and CFD based on MRA measurements could be useful for quantitative evaluation of hemodynamic outcomes after CEA.