Neuroimaging is of paramount importance in the evaluation and management of
cerebral vasospasm. Arteriographic demonstration of concentric arterial co
nstriction between 4 and 12 days after subarachnoid hemorrhage is the defin
ition of vasospasm. Assessment of angiographic vasospasm is subjective. Vas
ospasm must be differentiated from hypoplasia, atherosclerosis and other no
n specific ar arteriographic conditions. The development of vasospasm is di
rectly correlated with the presence of thick blood clots in the basal subar
achnoid cisterns which can be detected by an early computed tomography scan
. MR imaging and evaluation of cerebral blood flow are useful in the early
identification of cerebral ischemia.