A pilot study from a Korean group performed brain CT perfusion in 45 patients with hydrocephalus related or unrelated to subarachnoid hemorrhage (SAH) and with or without ventriculoperitoneal (VP) shunt, to analyse differences in brain perfusion parameters and maximum contrast enhancement. Patients with hydrocephalus and VP shunt showed perfusion changes in the frontal white matter and in the basal ganglia. Perfusion of the frontal white matter was lower when hydrocephalus was related to SAH, suggesting that SAH slows the recovery of cerebral perfusion.