Moyamoya
Coronal contrast enhanced T1 shows increased number and size of the lenticulostriate arteries "puff of smoke" that represent collateral circulation as a consequence to the tapering of the great intracerebral vessels. This is a case of Moyamoya. Note reduced caliber of the left MCA shown on the ToF MRA images. Also note on the lateral MIP from the ToF MRA a defect in the basilar artery flow with multiple collateral vessels.