The axial CT head slice shows a dense MCA sign on the left indicating the presence of an acute thrombus in the proximal middle cerebral artery.

This is a neurological emergency and if the stroke onset is within 6 hours, endovascular thrombectomy should be undertaken as per stroke foundation Australia guidelines.

The dense artery sign is due to fresh thrombus occluding the vessel. As thrombus can rapidly disperse, this sign is not always present. If seen within proximal MCA, it correlates with a large infarct.

Reference: Grainger & Allison’s Diagnostic Radiology.