Abstract： Objective First, to investigate hemedynamic changes in patients with unilateral stenosis or occlusion of ICA using CTP and, second to evaluate its potential value in identifying higher risk patients for TIA or stroke. Methods Twenty - five patients (21 men, 4 women; mean age, 56.72±11.07 years) with unilateral stenosis or occlusion of the ICA underwent 64 - detector CTP. The patients were divided into three stenotic groups according to the NASCET criteria. The rCBV, rCBF, rTS and rTP were derived by the comparison between stenotic and contrlateral hemispheres and the data were analyzed by using the One - way ANOVA and Kruskal - Wallis test. Results (1) All the patients in occlusion group and 4 patients in high - grade group had abnormal perfusion characterized on TS and TP color maps. (2) No statistically significant difference in rCBV and rCBF was found among the three stenotic groups. (3)There were statistical significance in rTS and rTP of temporal lobe and basal ganglia region ( P <0. 05 ). (4)The gray matter and white matter of the anterior washeld regions and the gray matter of posterior washeld region had statistical significance among three stenotic groups ( P < 0. 05 ). However, only the rTS in the white matter of posterior wasbeld region had statistical significance among three stenotic groups (P<0. 05). Conclusion CTP may provide valuable information of the cerebral hemodynamic status in patients with unilateral stenosis or occlusion of the ICA and identifying patients at higher risk for TIA or stroke.