Large region of increased TMax/MTT with smaller region of reduced CBV/CBF in the left MCA territory.
The M1 on the right opacifies but no flow is seen distal to this. This is consistent with an occlusion at the level of the bifurcation.
The markedly calcific distal M1 presumably represents heavily calcified plaque and a preexisting stenosis that has now been complicated by thromboembolism.
Calcific plaque present at the carotid bifurcation bilaterally, causing up to 50% stenosis of the proximal right ICA but no high-grade stenosis of the proximal left ICA.
Densely calcified left subclavian artery, probably occluded. The small left vertebral artery probably fills retrogradely. Right vertebral artery is large calibre with no focal stenosis.
No aneurysm or vascular malformation. No evidence of dissection.
Occlusion of the left MCA from bifurcation, likely at the site of pre-existing stenosis from calcific plaque. Perfusion study is consistent with an established infarct core in the left MCA territory, although with a larger surrounding ischaemic penumbra.