Imaging vasospasm.

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.