In the acute evaluation of stroke, which imaging study is routinely used to distinguish ischemic from hemorrhagic stroke?

• A. MRI with diffusion.
• B. CT scan.
• C. X-ray skull.
• D. Doppler ultrasound.

Answer: (B)

In the acute stroke scenario, the immediate goal is to determine if there is bleeding in the brain, because treatments differ dramatically between hemorrhagic and ischemic stroke. A non-contrast CT scan of the head is routinely used first because it can be performed very quickly, is widely available in emergency settings, and is highly effective at detecting acute intracranial hemorrhage. If a bleed is found, the focus shifts to managing the hemorrhage; if no bleed is seen, there’s greater confidence to pursue reperfusion therapies for ischemic stroke within the appropriate time window.

MRI with diffusion-weighted imaging is excellent for identifying ischemic tissue and can detect smaller infarcts earlier, but it usually takes longer to perform and isn’t as readily available in every emergency department, which makes it less suitable as the initial screening test in the acute setting. X-ray skull provides limited information for acute stroke and won’t reliably show brain tissue details or hemorrhage. Doppler ultrasound can assess blood flow in large vessels like the carotids but doesn’t visualize the brain parenchyma to differentiate stroke types in the acute phase.

So the non-contrast CT scan stands as the best initial imaging to distinguish ischemic from hemorrhagic stroke in the emergency evaluation.