A validation of a flow quantification by MR phase mapping software

Aim: We evaluated a Siemens software of flow quantification (FQ) by MR phase mapping, in the framework of a common practical use. Methods: Experiments with a laminar flow phantom and in vivo pulsatile flow were performed. In particular, FQ in ascending aorta was investigated in healthy volunteers. Results and conclusion: Flow phantom experiments reveal that the FQ slightly underestimates (8% on the average) actual velocities (mean velocities over a vessel area), and also that velocity uncertainties are related to the encoding velocity value, whatever the measured velocity. Furthermore, using well characterized working criteria, we found low intraobserver variability and negligible interobserver variability in ascending aorta FQs. The role played by the choice of reference area in FQ accuracy is emphasized. When recording several cardiac cycles during the same acquisition, it is shown that the FQ software may provide erroneous results. Several comments for FQ software use in the ascending aorta are added.