This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
[{'content': 'Puff of smoke appearance on cerebral angiography is seen in: \nSelect and explain. \nA. ACA aneurysm, B. Cavernous sinus thrombosis, C. Moyamoya disease, D. Vein of Galen malformation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Moyamoya disease is an idiopathic, non inflammatory, non atherosclerotic progressive vasculo-occlusive disease involving the circle of Willis, typically the supraclinoid internal carotid aeries. Small abnormal net-like vessels proliferate giving the characteristic "puff of smoke" appearance on direct angiography. CTA and MRA is not always able to demonstrate this appearance on account of lower flow and spatial resolution. REF : DAVID SUTTON 7th ed', 'role': 'assistant'}]