 Hello everyone. Welcome to another case of the month. Let's take a look at the images of this case. Axial flare images, coronal T2, Axial SWI images, time of flight and geography. Axial flare images show gliotic area in right frontal lobe, multiple hyper-intensities in bilateral deep and subcortical white matter representing chronic ischemic areas, subtle linear hyper-intensities are seen along the sulci bilaterally. Axial T1 images show multiple tiny hyper-intense foci in bilateral ganglothalamic regions. Axial SWI images show multiple horizontal hyper-intensities representing prominent deep medullary veins, MIP and geography images show gross narrowing of supra-cleanoid segments of both internal carotid arteries and M1 segments of both middle cerebral arteries. Multiple prominent collatils are seen. These images show narrowing of A1 segments of both anterior cerebral arteries with A1 segment of left anterior cerebral artery being barely visualized. Mild to moderate narrowing of P1 and P2 segments of right posterior cerebral artery is seen. Time of flight and geography images show prominent dural and leptomeningal collatils as well as prominent collatils in bilateral ganglothalamic regions. These images show prominent bilateral basal collatils. So, to summarize, we have gliotic area in right frontal lobe, multiple hyper-intensities in bilateral deep and sub-cortical white matter representing chronic ischemic areas, subtle linear hyper-intensities along the sulci bilaterally, the so-called IV sign representing prominent pile collatils, multiple punctate hyper-intensities in bilateral ganglothalamic regions and basal cisterns representing collatils. Superclinoid segments of both internal carotid arteries and M1 segments of both middle cerebral arteries are grossly narrowed. A1 segments of both anterior cerebral arteries appear attenuated with left A1 segment being barely visualized. Reformation of distal anterior and middle cerebral arteries is seen with multiple prominent lenticulostride and thalamostride collatils. Mild to moderate stenosis of P1 and P2 segments of right posterior cerebral artery is seen with luminal irregularity. Distal reformation is seen. Angiography images show multiple prominent collateral vessels forming the so-called puff of smoke or Moyamoya appearance. Moyamoya disease is an idiopathic, non-inflammatory, non-arthriosteolarotic, progressive vascular occlusive disease involving the terminal superclinoid internal carotid arteries and circle of villus. Patients present with ischemic strokes, hemorrhage from abnormal vessels or watershed infarcts. Fibrocellular proliferation and thickening of the intima is the main process responsible for vascular stenosis and occlusion. The associated neovascularization may be a compensatory mechanism or part of the disease process itself with the Moyamoya vessels demonstrating various histopathological abnormalities including fibrin deposition, microinherism formation, among other abnormalities. Moyamoya disease affects the bilateral distalicea and circle of villus. Up to 18% of patients with Moyamoya may present with unilateral angiography documented disease. Small abnormal net-like vessels proliferate giving the characteristic puff of smoke or parents on angiography. Although classically described affecting the ICA, over 50% of the patients also have involvement of the posterior cerebral arteries. Imaging features include hemispheric and watershed infarcts, generalized cerebral atrophy, collateral circulation via the abnormal Moyamoya vessels, which are the lentogillostrite, thalamoperforating, leptomeninjil and ural arteries appearing as multiple tortuous flow voids on T1 and T2-wheated sequences. Pial collaterals from the less affected vessels, especially the posterior cerebral artery, forming the so-called IV sign, which is high serpentine, circle flare hyperintensity due to slow flow. Prominent deep medullary veins forming the so-called BRUSS sign on SWI sequences, transdueral branches of the middle meningeal and other ural branches. Other conditions which can give a similar appearance on imaging should be kept in mind. Moyamoya syndrome, also termed as the Moyamoya pattern on phenomenon, is due to numerous conditions that can cause arterial occlusion of the circular villus with resultant collaterals and appearances reminiscent of Moyamoya disease. These conditions include vessel wall abnormalities like atherosclerosis, fibromuscular dysplasia, etc. Fecomatosis including NF1 and tuberous sclerosis, connective tissue disorders like SLE and antifosphorylipid syndrome, blood dyscrasias such as sickle cell anemia, infections including meningitis.