Fig. 18

Three-dimensional reconstruction of MRI angiography (time-of-flight technique) of a 46-year-old Down syndrome patient, illustrating occlusion of the left internal carotid artery (ICA) and stenosis of the supraclinoid segment of the right ICA, as well as subocclusion of the right anterior cerebral artery (ACA). The left ACA and middle cerebral artery are not depicted. There are also multiple thin anomalous collateral vessels around the basal cisterns; these findings are compatible with moyamoya syndrome, which is known to have a high incidence in this population