The objective of this study is to determine if the implementation of guidelines utilizing immediate CT Perfusion and CT Angiography in addition to non-contrast CT alters (reduces or increases) the time to decision-making for or against rt-PA in acute ischemic stroke, and by extension, time to therapy in treated patients and time to transfer from the department for all patients. A secondary objective is to determine if using CTP/CTA-inclusive hyperacute stroke guidelines improves safety by decreasing symptomatic intracerebral hemorrhage and mortality in patients who receive rt-PA.

Inclusion Criteria:

• Patients presenting to the emergency Signs and symptoms of acute ischemic stroke: impairment of language, motor function, cognition and/or gaze, vision or neglect.
• Patients with an NIH Stroke Scale score > 4

Exclusion Criteria:

• Age less than 19
• Patient symptomatic for greater than five hours. Intravenous thrombolytic therapy must be instituted within three hours of symptom onset in order to minimize the risk of Intracerebral or symptomatic hemorrhage; other interventions such as intra-arterial thrombolytic therapy and clot retrieval allow for a six-hour window. One hour is an achievable time for arrival to institution of therapy, therefore a five-hour limit on enrollment allows the greatest number of patients the possibility of therapy.
• Inability to verify a clear onset of symptoms. As noted, time elapsed since the patient's last known baseline state is correlated to Intracerebral and symptomatic hemorrhage, and therapy is approved only for patients with a clear time of onset.

Patients presenting to the Emergency Department with acute stroke