Abstract: Objective To assess the diagnostic value of determining infarct core and penumbra using CT perfusion source images (CTP-SI) mismatch model in hemispheric stroke less than 9 hours.Methods "one-stop shop" CT examination including non-contrast enhanced CT (NCCT), CTP, CT angiography (CTA) were performed in 24 patients with symptoms of stroke less than 9 hours.The Alberta Stroke Program Early CT Score (ASPECTS) were analyzed on arterial phase CTP-SI and venous phase CTP SI using Wilcoxon rank-sum test, then compared with the follow up imaging ASPECTS using multiple linear regression.Results The median (min-max) scores of ASPECTS on arterial phase CTP-SI, venous phase CTP-SI and follow-up imaging were 9.0 ( 2.0-10.0 ), 9.3 ( 6.5-10.0 ) and 9.0 ( 7.0-10.0 ),respectively. ASPECTS measured on arterial phase CTP-SI significantly differed from the ASPECTS on venous phase CTP-SI ( Z =-2.812, P = 0.005 ).Moreover, the linear regression analysis showed significant correlation between the ASPECTS on venous phase CTP-SI and follow up imaging ASPECTS ( Beta =0.715,P = 0.003 ).Conclusion CTP-SI mismatch model provides a method of choice in predicting penumbra and infarct core in hemispheric stroke.