Objective:To explore the application values of arterial transit artifact (ATA) showed by 3D arterial spin labeling (3D-ASL) combined with hyperintense vessel sign (HVS) showed by T2-magnetic resonance fluid attenuation inversion recovery (T2-FLAIR) in evaluating collateral circulation and clinical prognoses in patients with acute ischemic stroke (AIS).Methods:One hundred and one AIS patients admitted to our hospital from September 2017 to November 2019 were included in the study. According to the degrees of vascular stenosis, these patients were divided into middle cerebral artery (MCA) positive group (stenosis degree≥50%, n=60) and MCA negative group (stenosis degree<50%, n=41); according to whether there was ATA, the MCA-positive patients were divided into ATA(+) group ( n=33) and ATA(-) group ( n=27). The cerebral blood flow (CBF) of the ischemic penumbra (IP) and National Institute of Health stroke scale (NIHSS) scores at admission and at discharge in patients from different groups were recorded; the relative CBF (rCBF) and drop degrees of NIHSS scores at discharge were calculated; a comparative analysis of the relations of ATA and HVS with clinical prognoses was performed. Results:There were significant differences in HVS grading, rCBF, NIHSS scores at admission and at discharge and drop degrees of NIHSS scores at discharge between MCA positive group and MCA negative group ( P<0.05). Among the 60 patients from MCA-positive group, 16 were classified as HVS grading 0, 14 as HVS grading I, 17 as HVS grading II, and 13 as HVS grading III; there were statistical differences in rCBF and drop degrees of NIHSS scores at discharge among patients with different HVS grading ( P<0.05); the higher the HVS grading was, the greater the decrease of rCBF and drop degrees of NIHSS scores were. Spearman correlation analysis showed that there was a high positive correlation between HVS grading and rCBF ( r s=0.808, P=0.000), and a moderate positive correlation between HVS grading and drop degrees of NIHSS scores at discharge ( r s=0.737, P=0.000). Patients in the ATA(+) group had significantly greater decrease of rCBF and drop degrees of NIHSS scores, and significantly lower NIHSS scores at discharge as compared with patients from the ATA(-) group ( P<0.05). Spearman correlation analysis showed that ATA had moderate positive correlations with rCBF and drop degrees of NIHSS scores ( r s=0.403, P=0.001; r s=0.550, P=0.000); there was a highly positive correlation between rCBF and drop degrees of NIHSS scores ( r s=0.827, P=0.000). Receiver operating characteristic curve showed that the sensitivities of ATA and HVS to assess cerebral blood perfusion changes were 83.3% and 66.7%, and the specificities were 52.1% and 89.6%, respectively; the combined sensitivity of the two was 83.3% and the specificity was 64.6%. Conclusion:HVS combined with ATA can effectively evaluate the perfusion in IP region and prognoses of AIS patients.