Wall shear stress distribution at the carotid bifurcation: influence of eversion carotid endarterectomy

Objectives

To test the feasibility of four-dimensional (4D) flow MRI to quantify the systolic wall shear stress (WSS_systole) and oscillatory shear index (OSI) in high-grade internal carotid artery (ICA) stenosis before and after endarterectomy (CEA).

Methods

Twenty patients with ≥60 % ICA stenosis were prospectively and consequently included. Four-dimensional flow MRI was used to measure individual time-resolved 3D blood flow velocities. Segmental WSS_systole and OSI were derived at eight wall segments in analysis planes positioned along the ICA, common (CCA) and external carotid artery (ECA).

Results

Regional WSS_systole of all patients decreased after CEA (P?<?0.05). Changes were most prominent at the ICA bulb but remained unchanged in the CCA and ECA. OSI was significantly lower after CEA in the lateral vessel walls (P?<?0.05). For analysis planes at the stenosis in- and outlet, a reduction of mean WSS_systole by 32 % and 52 % (P?<?0.001) and OSI distal to the stenosis (40 %, P?=?0.01) was found after CEA.

Conclusions

Our findings show the potential of in vivo 4D flow MRI to quantify haemodynamic changes in wall shear stress even in patients with complex flow conditions.

Key Points

? The 4D flow MRI allows in vivo measurement of individual 3D blood flow. ? Regional wall shear stress can be derived from such 3D flow data. ? Even complex flow in high-grade internal carotid artery stenosis can be analysed. ? This technique could be valuable for future studies of carotid atherosclerosis.