Objective To investigate the value of CT perfusion imaging (CTP) in pressure modulation after ventriculoperitoneal shunt (VP) and determine the relationship between consciousness variation and cerebral perfusion.Methods Thirty cases in a vegetative or minimally conscious state after VP for posttraumatic hydrocephalus were included.There were 26 males and 4 females, aged (56.4 ± 9.2) years.Duration of disease was (88.7 ± 38.0) d.Consciousness evaluation and CT perfusion scan were performed before and two weeks after pressure modulation.Based on the consciousness state, the patients were allocated into consciousness unimproved (n =17) and improved groups (n =13).Relative cerebral blood flow (rCBF) , relative cerebral blood volume (rCBV), relative mean transit time (rMTT) and relative time to peak (rTTP) were evaluated before and after pressure modulation.Results In consciousness improved group rCBF in the alba around anterior horn of lateral ventricle was significantly improved after pressure modulation compared to that before pressure modulation (1.08 ± 0.55 vs.0.75 ± 0.32, P ＜ 0.05), but rCBV, rMTT and rTTP did not differ significantly in the same region (P ＞ 0.05).In consciousness improved group all the measures showed no significant changes in other regions such as encephalomalacia focus, forehead lobe, temporal lobe, basal ganglia and occipital lobe (P ＞ 0.05).However,none was significantly different in consciousness unimproved group (P ＞ 0.05).Conclusions CTP has some reference value on pressure modulation of posttraumatic hydrocephalus patients treated with VP.Consciousness improvement is related to the increased cerebral perfusion in the alba around anterior horn of lateral ventricle.