MRI Measurements of Wall Shear Stress in the Descending Aorta Downstream of an Ascending Aortic Aneurysm

INTRODUCTION Wall shear stress (WSS) may play a vital role in the pathogenesis and pathophysiology of aneurysms. Meng et al. showed that elevated peak longitudinal WSS may initiate aneurysm formation [1], whereas Boussel et al. demonstrated that low peak longitudinal WSS may contribute to aneurysm growth [2]. While measurements of WSS have been investigated within the aneurysmal bodies, the downstream effects of an aneurysm on WSS remain largely unknown. The purpose of this study was to compare measurements of WSS in the descending aorta in healthy volunteers and in patients with ascending aortic aneurysm. The limited spatial resolution of MR flow measurements results in an underestimation of the actual WSS parameters as derived by CFD simulations [3]. However, it is likely to be a surrogate parameter of the actual WSS. Here we used PC VIPR [4], a radially undersampled acquisition with three directional cine velocity encoding, which provides high spatial resolution with isotropic voxel sizes, making this approach well suited for such multidirectional hemodynamic analysis.