The validity of the acute stroke assessment using rapid pseudo-continuous arterial spin labeling (ASAP-ASL) method for acute thrombectomy

BACKGROUND: Recent clinical trials demonstrated the efficacy of thrombectomy for ischemic stroke against acute large vessel occlusion (LVO). To overcome the problem with excessive examination time for diagnosis of cerebral perfusion and/or the use of contrast agent to determine penumbra, we adopted a new magnetic resonance imaging technique named Acute Stroke Assessment using rapid Pseudo-continuous arterial spin labeling (ASAP-ASL) method. METHODS: The study included healthy volunteers and clinical patients. The signal to noise ratio (SNR) and acquisition time were compared with various numbers of signal average (NSA) of rapid pseudo-continuous arterial spin labeling (pCASL) using the 10-mm thick slice width and narrow scan range focusing the level of basal ganglia by healthy volunteers. After applying clinically acceptable protocol for ASAP-ASL, we then checked image qualities and an accuracy of the method by comparing with the angiographical imaging obtained from the clinical patients regarding the degree of consistency. RESULTS: NSA were compared between two and fourteen, and 10 NSA was decided to be introduced for clinical use (1 minutes and 17 second) for obtaining clinically acceptable image, which was shorter than the time required for ordinary whole brain pCASL (approximately 5 minutes). In the clinical study, the occlusion site estimated by ASAP-ASL showed high correlation with that of digital subtraction angiography (ic=0.630.79). CONCLUSIONS: ASAP-ASL method requires approximately one minutes to obtain clinically relevant brain perfusion imaging which can successfully identify ischemic region in LVO patients.