Non-contrast axial CT brain of a 55 years-old female with acute ischemic infarction involving the left middle cerebral artery territory. Patient presented with right hemiplegia that evolved over past 9 hours. Large ill-defined low density area (arrows) involving the left parietal lobe and causing effacement of the adjacent sulci is the characteristic finding of an acute ischemic infarction on non-contrast CT. Note absence of any significant mass effect