Fluid-induced wall shear stress in anthropomorphic brain aneurysm models: MR phase-contrast study at 3 T

Purpose: To study spatial and temporal distribution of wall shear stress (WSS) of intracranial aneurysm models using magnetic resonance phase contrast (MR-PC) imaging, and to compare results to those obtained in our previous study using laser Doppler velocimetry (LDV). Materials and Methods: High-resolution MR-PC imaging was performed on aneurysm models created from 3D in vivo data of a basilar artery (BA) tip and a middle cerebral artery (MCA) aneurysm. WSS was measured by calculating the rate of shearing strain using image postprocessing techniques. WSS was characterized using several parameters, including average WSS and oscillatory shear index (OSI). Results: Both aneurysms showed the highest WSS at an ostium. A bleb region in the BA tip and a dome region in the MCA aneurysm were consistently exposed to high WSS within a small local area with high spatial variation and little temporal change in comparison to other aneurysmal regions. High correlation was noted for the spatial distribution at the peak systole between the MR-PC and the LDV studies, with the correlation coefficient value of 77% to 81%. Conclusion: MR-PC imaging showed good agreement with the reference LDV study, confirming its potential to study hemodynamics of physiologically realistic in vitro intracranial aneurysm models. Characteristic patterns of WSS, such as high spatial variation and absence of temporal variation, combined with locally increased high WSS as determined by MR-PC imaging, may elucidate the effect of WSS on aneurysmal development and rupture.