Motivation: For velocity-selective arterial spin labeling (VSASL), a scaling factor (SIB) was recommended to correct the saturation recovery of arterial blood right before labeling. However, the SIB value needs to consider the inflow effect. Goal(s): To account for the inflow of fresh, unsaturated spins due to the limited coverage of the transmit body coil into VSASL-based CBF quantification. Approach: The SIB was measured using none-selective and slab-selective saturation with varied saturation times, respectively. Results: Slab-selective saturation with a 2.0s delay yielded optimal tSNR efficiency and SIB=0.90 provided more accurate CBF estimation than a simple saturation recovery model. Impact: To account for inflow effects, VSASL-based CBF quantification should use a slab-selective saturation with a 2.0s delay for optimal tSNR efficiency, and apply a scaling factor of 0.90 for more accurate CBF estimation than relying on the saturation recovery model.
Xu et al. (Tue,) studied this question.