Velocity-selective arterial spin labelling bolus duration measurements: Implications for consensus recommendations

Velocity-selective ASL (VSASL) measurement of CBF is relatively insensitive to arterial arrival times, unlike other ASL techniques, making it suitable for measuring CBF in patient groups with long arrival times. However, VSASL can underestimate CBF when the trailing edge of the labelled bolus arrives before imaging. Our study finds substantial spatial heterogeneity in bolus duration in Fourier Transform velocity-selective inversion (FT-VSI), with short bolus durations in anterior regions and longer bolus durations in posterior regions. These results build on a recent VSASL consensus paper contributing to recommendations for cerebrovascular reactivity mapping experiments.