What imaging is first-line in suspected acute ischemic stroke in the ED?

• A. MRI with contrast
• B. Non-contrast CT to exclude hemorrhage
• C. X-ray skull
• D. PET scan

Answer: (B)

In suspected acute ischemic stroke, the priority is to quickly distinguish ischemia from hemorrhage so that treatment decisions (like thrombolysis) are safe to pursue. Non-contrast head CT is the first-line imaging because it can be performed rapidly, is widely available in emergency settings, and most importantly, it can immediately rule out intracranial hemorrhage. If a hemorrhage is found, thrombolytic therapy is contraindicated, so this step directly guides the next move in management.

MRI with contrast, while more sensitive for early ischemic changes, takes longer to perform, may be less accessible on an emergent basis, and isn’t needed as the initial test. X-ray skull provides little information about acute ischemia, and PET scans aren’t used in the acute ED stroke setting due to availability and practicality.

So the initial imaging choice is non-contrast CT to exclude hemorrhage and quickly inform urgent treatment decisions. After that, additional imaging like CT angiography or CT perfusion can be used to assess vessel occlusion and tissue at risk.