Which imaging modality is most useful for identifying an occlusion in suspected large-vessel stroke?

Which imaging modality is most useful for identifying an occlusion in suspected large-vessel stroke?

• A. MRI without contrast
• B. Duplex ultrasound
• C. CT perfusion
• D. CT angiography

Answer: (D)

When a large-vessel stroke is suspected, the critical need is to quickly confirm the exact arterial blockage so you can decide on urgent reperfusion therapy. CT angiography does this best because it injects contrast and provides rapid arterial-phase images from the neck through the brain, letting you see the lumen of major vessels and pinpoint where the occlusion is (for example, carotid, MCA segments, or basilar artery). It also gives a sense of collateral blood flow, which helps guide prognosis and treatment decisions, especially regarding mechanical thrombectomy. Alternative imaging has limitations for identifying the occlusion itself. MRI without contrast mainly shows tissue injury and is slower to obtain; MR angiography can visualize vessels but takes longer and may delay therapy. Duplex ultrasound assesses extracranial carotid disease but misses many intracranial occlusions and is operator-dependent. CT perfusion reveals perfusion deficits, not the exact occluded vessel, so it’s more about tissue status than directly locating the blockage.

When a large-vessel stroke is suspected, the critical need is to quickly confirm the exact arterial blockage so you can decide on urgent reperfusion therapy. CT angiography does this best because it injects contrast and provides rapid arterial-phase images from the neck through the brain, letting you see the lumen of major vessels and pinpoint where the occlusion is (for example, carotid, MCA segments, or basilar artery). It also gives a sense of collateral blood flow, which helps guide prognosis and treatment decisions, especially regarding mechanical thrombectomy.

Alternative imaging has limitations for identifying the occlusion itself. MRI without contrast mainly shows tissue injury and is slower to obtain; MR angiography can visualize vessels but takes longer and may delay therapy. Duplex ultrasound assesses extracranial carotid disease but misses many intracranial occlusions and is operator-dependent. CT perfusion reveals perfusion deficits, not the exact occluded vessel, so it’s more about tissue status than directly locating the blockage.