Quantitative Methods for Comparisons between Velocity Encoded MR-Measurements and Finite Element Modeling in Phantom Models

Wall Shear Stress is a key factor in the development of atherosclerosis. To assess the WSS in-vivo, velocity encoded MRI is combined with geometry measurements by 3D MR-Angiography (MRA) and with blood flow calculations using the Finite Element Method (FEM). The 3D geometry extracted from the MRA data was converted to a mesh suitable for FEM calculations. Aiming at in-vivo studies the goal of this study was to quantify the differences between FEM calculations and MRI measurements. Two phantoms, a curved tube and a carotid bifurcation model were used. The geometry and the time-dependent flow-rate (measured by MRI) formed input for the FEM calculations. For good data quality, 2D velocity profiles were analyzed further by the Kolmogorov-Smirnov method. For the curved tube calculations and measurements matched well (prob?S approximately above 0.20). The carotid needs further investigation in segmentation and simulation to obtain similar results. It can be concluded that the error-analysis performs reliably.