Repetitive CT perfusion for detection of cerebral vasospasm-related hypoperfusion in aneurysmal subarachnoid hemorrhage.

BACKGROUND Delayed cerebral infarction after aneurysmal subarachnoid hemorrhage (aSAH) still remains the leading cause of disability in patients that survive the initial ictus. It has been shown that CT perfusion (CTP) imaging can detect hypoperfused brain areas. The aim of this study was to evaluate if a single acute CTP examination at time of neurological deterioration is sufficient or if an additional baseline CTP increases diagnostic accuracy. METHODS Retrospective analysis of acute and baseline (within 24 hours after aneurysm treatment) CTP examinations of patients with neurological deterioration because of vasospasm-related hypoperfusion. Patients without clinical deterioration during the vasospasm period served as controls. The following CTP parameters were analyzed for predefined brain regions: time to drain (TTD), mean transit time, time to peak, cerebral blood flow and volume. RESULTS 33 patients with and 23 without neurological deterioration were included. Baseline CTP examination did not ameliorate diagnostic accuracy of the acute CTP examination in symptomatic patients. The same was true for inter-hemispheric comparison of perfusion parameters of the acute examination. The CTP parameter with the highest diagnostic yield was TTD of the symptomatic brain region (threshold value 4.7 sec, sensitivities 97 %, specificities 96 %). CONCLUSIONS Acute CTP examination in case of suspected vasospasm-induced neurological deterioration after aSAH has the highest diagnostic accuracy to detect misery perfusion. Additional baseline CTP is not needed. The most sensitive parameter to detect critically perfused brain areas is TTD.