A 71-year-old woman sustained a watershed infarction 12 years ago and has since remained stroke free on clopidogrel. Recent fluid-attenuated inversion recovery MRI confirmed old frontal infarcts (Figure 1A). Conventional CT angiography showed irregular narrowing of the left internal carotid artery (ICA) C3 segment (Figure 1B). Photon-counting CT revealed an ipsilateral hypoplastic carotid canal (Figure 1C) and apparently continuous, contrast-enhanced dots in this segment (Figure 1D).
