LAUSR

Arterial spin labeling (ASL) is an established noninvasive MRI technique used for cerebral blood flow measurement, which generally suffers from a low signal‐to‐noise ratio (SNR). The use of ultra‐high fields to enhance sensitivity inevitably results in an increase in TR because of specific absorption rate (SAR) constraints, causing inadequate sampling of hemodynamic response in functional MRI, and adversely affecting concurrent measurement such as blood oxygen level dependent. To address this problem, variable‐rate selective excitation (VERSE) radiofrequency (RF) pulses were used.