A 62-year-old diabetic man presents with acute right hemiplegia, left gaze deviation and aphasia. Non-contrast CT head performed 90 minutes after onset shows a hyperdense tubular structure in the left sylvian fissure with subtle effacement of the insular cortex. The hyperdense vessel seen on this CT represents:
- A Calcification of the middle cerebral artery wall
- B Contrast reflux from prior angiography
- C Intraluminal thrombus in the proximal M1 segment of the MCA ✓
- D Acute microbleed within the sylvian fissure
Correct answer: C. Intraluminal thrombus in the proximal M1 segment of the MCA
Explanation
The hyperdense middle cerebral artery sign represents fresh intraluminal thrombus in the proximal MCA, usually the M1 segment, and indicates a large vessel occlusion with poor prognosis. It correlates with clot burden and helps select patients for thrombectomy. Calcified atherosclerotic plaque is far less dense, focal and does not have the full tubular appearance of an occluded vessel.
Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.
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