To investigate abnormal hemodynamics in pulsatile tinnitus patients in vivo, we use 4DMR. We also use computational fluid dynamics (CFD) to overcome 4DMR’s limited spatial and temporal resolution. To ensure the simulation actually reflects in vivo blood flow, we systematically adjust the simulation boundary conditions to match the CFD and 4DMR data. This requires downsampling CFD data to 4DMR resolution and a quantitative voxel-wise comparison. Our results suggest 4DMR underestimates velocities in vivo due to its resolution. This effect is confirmed by phantom 4DMR data taken at multiple resolutions.