Should a CT angiogram be obtained in addition to a non-contrast head CT in the evaluation of acute stroke?

If there is ready access to intra-arterial thrombolysis, either in-house or via rapid transfer, a CT angiogram (CTA) should be considered. If a middle cerebral artery occlusion or basilar artery occlusion is noted on CTA and the patient can't be treated with intravenous TPA because of a contraindication, including being outside the time window of 4.5 hours, then intra-arterial thrombolysis is a reasonable option up to about 6 hours after stroke onset.

Source

Oliveira-Filho, J. MD PhD. "Fibrinolytic therapy for acute ischemic stroke" Up to Date. 15 Oct 2008.