CT
Findings: Non-contrast CT of the head shows a hyperdense middle cerebral artery on the right side, the insular ribbon sign, hypodensity of the right middle cerebral artery (MCA) territory and loss of gray- white matter differentiation.
Other, non-acute findings include an old, right anterior cerebral artery infarction and extensive arteriosclerosis. No intracerebral haemorrhage. Mild to moderate microangiopathic changes.
Correspondingly, the CT angiography demonstrates a complete occlusion of the terminal segment of the right internal carotid artery (ICA) with complete lack of opacification of the proximal M1 segment of the right MCA. There is collateral reperfusion of the right MCA in the distal M1 segment. Very poor perfusion of the distal MCA branches compared to the contralateral side. Mild to moderate stenosis of the right vertebral artery in segment V4. The other intracerebral vessels appear patent.
Conclusion: Acute, right MCA infarction with complete occlusion of the terminal ICA / proximal M1 segment and poor collateralisation of the periphery. Hyperdense middle cerebral artery sign and insular ribbon sign are visualised on the non-contrast CT.