Improving the accuracy of cerebral blood flow measurement by phase contrast MRI

Cerebral blood flow (CBF) is a critical hemodynamic marker for natural aging and pathological conditions. It can be assessed non-invasively by the phase-contrast (PC) magnetic resonance imaging (MRI) technique. Although the technical principle of PC MRI is straightforward, related experimental settings, e.g., spatial resolution, partial volume effect, slice positioning angle, and signal-to-noise ratio (SNR), require deliberate considerations to ensure measurement accuracy. In this study, we performed simulations to systematically investigate the dependence of measurement accuracy of PC MRI on the spatial resolution, extent of partial volume effect, slice imperfection angle, and SNR. It has been found that at least 6 voxels along the vessel diameter are required to ensure accurate CBF measurements. Partial volume effect acts to underestimate CBF measurements. The tolerance against slice imperfection angle is ≤15 degree for the commonly seen artery in mice under isoflurane anesthesia. A normalized SNR of 25.47 dB is required to ensure the accuracy of CBF measurement. Our study will promote the utilization of CBF as a pathophysiological marker for future studies by delineating the factors affecting measurement accuracy in PC MRI.