LAUSR

710 A 52‐year‐old male with encephalopathy for 5 days, underwent an MRI brain examination. On MRI [Figure 1], there was the loss of signal void in bilateral internal carotid arteries (ICA); however, with preserved flow void in the intracranial arteries on the T2W images. Suscept ib i l i ty weighted imaging (SWI) showed accentuated susceptibility changes in the intracranial arteries with hyperintense signal in bilateral ICA. We term this sign as a “differential arterial flow signal sign.” The likely cause of hyperintense signal in the ICA in our case is slow/stagnant flow, whereas hypointense signal on T2W/SWI in the intracranial arteries represent the loss of signal due to increased cerebral oxygen extraction and deoxygenated blood representing cerebral autoregulation. The increased susceptibility effect in the intracranial arteries has been reported earlier in a series of brain‐dead patients due to hypoxia.[1]