Which imaging modality is best for suspected stroke?

Abstract

Patients exhibiting stroke symptoms should have brain imaging immediately within 3 hours of symptom onset (strength of recommendation [SOR]: A, based on systematic review). In the first 3 hours after a suspected cerebrovascular accident (CVA), noncontrast head computerized tomography (CT) is the gold standard for diagnosis of acute hemorrhagic stroke (SOR: C, based on expert panel consensus). However, the sensitivity for hemorrhage declines steeply 8 to 10 days after the event. Eligibility guidelines for acute thrombolytic therapy are currently based on use of CT to rule out acute hemorrhagic stroke. Magnetic resonance imaging (MRI) may be equally accurate in diagnosing an acute hemorrhagic stroke if completed within 90 minutes of presentation for patients whose symptoms began fewer than 6 hours earlier (SOR: B, based on a single high-quality cohort study). MRI is more sensitive than CT for ischemic stroke in the first 24 hours of symptoms (SOR: B, based on systematic review of low-quality studies with consistent findings) and is more sensitive than CT in the diagnosis of hemorrhagic or ischemic stroke greater than 1 week after symptom onset (SOR: B, based on 1 high-quality prospective cohort study).