Computed tomography angiography image of a 72‐year‐old man presenting with a left middle cerebral artery territory infarction. Two regions‐of‐interest (ROI) were placed in the perivascular fat surrounding the stenotic (arrow) left internal cerebral artery (ICA) and 2 ROIs were placed in the perivascular fat surrounding the nonstenotic right ICA on the same axial slice. In this case, the 2 left ROIs were −65.3 and −62.8 and the 2 right ROIs were −80.3 and −78.9.