Objective To evaluate the value of perfusion imaging mismatch and low perfusion ratio(HIR)based on CT perfusion imaging in predicting acute intracranial large vessel occlusion(LVO)associated with intracranial atherosclerotic stenosis(ICAS).Methods A total of 82 pa-tients with acute intracranial LVO who underwent emergency thrombectomy in our hospital from February 2019 to December 2020 were enrolled in this study.According to the etiology,they were divided into ICAS-related LVO group(ICAS-LVO,65 cases)and cardiogenic embolism group(17 cases).ROC curve was plotted to analyze the predictive value of CT perfusion imaging parame-ters.Results Compared with the cardiogenic embolism group,the ICAS-LVO group had signifi-cantly larger male ratio,higher BMI and TG level,more severe progression of disease,longer time from onset to surgery,larger proportion of ischemic penumbra and higher mismatch ratio,and ob-viously less ratio of atrial fibrillation,lower BNP and HDL levels,smaller infarct volume,and lower HIR(P＜0.05,P＜0.01).ROC curve analysis showed that HIR and mismatch ratio had good predictive value for the etiology of ICAS-LVO.The optimal cut-off value of HIR was 0.26,with an AUC value of 0.74,a specificity of 0.88,and a sensitivity of 0.54.The optimal cutoff for the mismatch ratio was 3.84,with an AUC value of 0.84,a specificity of 0.75,and a sensitivity of 0.90.Generalized linear model revealed that HIR and cerebral blood volume index had no signifi-cant difference in prognostic performance(P=0.175).Conclusion HIR and mismatch ratio are helpful to identify the pathogenesis earlier and formulate surgical strategies more accurately,thereby reducing iatrogenic injury to a greater extent,increasing the effective reperfusion rate,re-ducing the disability and mortality,and improving the prognosis of clinical outcomes.