Wall shear stress in an in vitro and in vivo intracranial aneurysm estimated with phase contrast MRI

Objective The objective was to study the performance of an in-house developed wall shear stress (WSS) algorithm using PC-MRI in intracranial aneurysms. Materials & Methods First, the algorithm was applied to a high resolution in vitro PC-MRI measurement under steady and pulsatile fl ow conditions. A CFD simulation was performed with similar infl ow boundary conditions. Second, WSS was estimated in steady PC-MRI data acquired at different resolutions. Third, the algorithm was applied to a pulsatile in vivo measurement and compared with CFD. The direction and magnitude of WSS vectors were computed and compared with Spearman’s correlation coeffi cient. Results Quantitative agreement was moderate for the phantom (Spearman ρ=0.69). The WSS magnitude of PC-MRI was lower than CFD for both the in vitro and in vivo case. However, there was qualitative agreement between PC-MRI and CFD, i.e. WSS vector direction was similar for both modalities. chapter 8 153 Wall shear stress Circular WSS patterns were found both in vitro and in vivo for PC-MRI and CFD. Increasing resolution uncovered complex WSS patterns with higher mean WSS magnitude. Conclusion The algorithm can robustly estimate wall shear stress patterns in aneurysm geometries with similar directions as CFD. PC-MRI based estimation of abnormal WSS patterns may aid in the identifi cation of risk factors for aneurysm disease progression. 154 Wall shear stress in an in vitro and in vivo intracranial aneurysm estimated with phase contrast MRI 8.