Stable nonspecific patchy periventricular white matter hypoattenuation. No evidence of subacute or chronic infarction. CTA demonstrates multifocal stenoses of the right vertebral artery with narrower calibre throughout its length. There is little if any opacification of the proximal V4 segment. There is progressive reduced opacification of the V3 segment as it passes through the right C1 transverse foramen and around the posterior aspect of the right C1 lateral mass. There are multiple short segments of stenosis noted throughout the V1 and V2 portions. The left vertebral artery shows short segments of stenosis in the V1 and V2 segments and severe stenosis at the V3-V4 junction adjacent to the atlanto-occipital joint. The basilar artery is patent. The right and left PCAs are patent but of smaller calibre. Stenoses at the bilateral lacerum and cavernous ICA segments noted. Small probable left ophthalmic ICA aneurysm. The bilateral ACAs and MCAs are patent and of relatively preserved calibre.