In-vitro Turbulence Mapping in Prosthetic Heart Valves using Generalized Phase-Contrast MRI

INTRODUCTION Turbulence, characterized by velocity fluctuations, is a sign of suboptimal hemodynamics in prosthetic heart valves [1]. Turbulence causes pressure drops and exposes endothelial cells and blood constituents to abnormal stresses which can lead to blood trauma and promote the pathogenesis of atherosclerosis. Phase-contrast MRI (PC-MRI) has previously been shown to be valuable for the assessment of the mean velocity field around prosthetic heart valves [2]. In addition to mean velocity quantification by conventional velocity mapping, PC-MRI can be used to quantify turbulence intensity via intravoxel velocity standard deviation (IVSD) mapping [3]. In short, this is achieved by exploiting that the presence of multiple spin velocities within a voxel reduces the MR signal magnitude under the influence of a bipolar gradient. The aim of this in-vitro study is to apply PCMRI turbulence measurements to common types of prosthetic heart valves.