Which MRI sequence is used to detect cytotoxic edema before vasogenic edema?: (A) T1WI, (B) T2WI, (C) SWI, (D) DWI
Answer is D. Vasogenic edema shows HyperIntense T2 and FLAIR signals, which do not show Restricted diffusion.(Cytotoxic cerebral edema, which shows diffusion restriction). The one sequence which is able to identify cytotoxic oedema, and was thus responsible for a revolution in the imaging of acute Ischaemic stroke, is Diffusion Weighted Imaging (DWI).