Impact of perioperative cerebral blood flow evaluation using arterial spin labeling in a patient undergoing carotid artery stenting

•PLD 2500 ms is more suitable than PLD1600 ms for estimating pre-CAS perfusion status.•Arterial spin labeling is useful tool for evaluating post-CAS Hyper Perfusion Phenomenon instead of SPECT.•Δr ASL may be a potential predictor of post-CAS Hyper Perfusion Phenomenon. Hyperperfusion syndrome (HPS) is one of the most serious complications after carotid artery stenting (CAS). Arterial spin labeling (ASL) is a noninvasive method for assessing cerebral perfusion. This study aimed to evaluate the utility of ASL compared to that of SPECT in evaluating changes in intracranial blood flow during the perioperative period of CAS. We retrospectively reviewed prospectively collected data from 49 cases of CAS conducted for symptomatic and asymptomatic carotid artery stenosis. We calculated the relative cerebral blood flow (rCBF) from ASL (post labeling delay [PLD] of 1500 ms and 2500 ms) and SPECT, both pre- and post-CAS. Cerebrovascular reactivity (CVR) was assessed using SPECT with an acetazolamide challenge. We defined the change rate from PLD 1500 ms to 2500 ms before CAS as ΔrASL. Hyperperfusion phenomenon was observed in four cases (8.2 %), with one case (2.0 %) resulting in cerebral hemorrhage and diagnosed as HPS. Positive correlations were noted between ASL and SPECT at both pre- and post-CAS (r = 0.42–0.65, p