Computed tomography perfusion (CTP) map can sensitively and accurately distinguish between infarct core and ischemic penumbra. However, CTP mapping software might not generate a perfusion map because of head movement; thus, analysing CTP source images (CTP-SI) is necessary in this situation to provide information for stroke diagnosis and therapy. In our work, 'one-stop shop' computed tomography (CT) examination including non-contrast-enhanced CT (NCCT), CTP, CT angiography (CTA) were performed in 24 patients with symptoms of acute stroke less than 9 hours. We divided patients into two groups (with and without delayed perfusion on CTP-SI), and compared the Alberta Stroke Program Early CT Score (ASPECTS) on CTP-SI and CTA-SI with follow-up imaging. Using follow-up imaging ASPECTS as the final infarct size, our results suggests that the ASPECTS of both CTP-SI and CTA-SI effectively predict final infarct core in the group without delayed perfusion, whereas CTP-SI has a potential advantage over CTA-SI in being able to predict final infarct core in the group with delayed perfusion. In conclusion, CTP-SI provides useful complementary information when CTP map software could not generate perfusion maps. [Neurol Res 2009; 31: 1079-1083]