Correct! The diagnosis is moyamoya disease (MMD). MMD is an idiopathic disorder of progressive narrowing of the terminal ICAs, often involving the proximal M1 and A1 segments as well. This condition is associated with both ischemic and hemorrhagic infarcts. This is associated with proliferation of lenticulostriate collateral vessels giving a 'puff of smoke' appearance. Other transdural or pial collaterals can also occur.

In distinction, moyamoya syndrome (MMS) demonstrates a similar radiographic appearance but is due to an underlying cause. Such causes include atherosclerosis, vasculitis, and a variety of other conditions and syndromes.