In this example we see the evolution of cytotoxic edema over the course of 3 days. At presentation, if the patient is imaged within ~4 hours of presentation, one should expect to see a relatively normal head CT without much edema. In a completed infarct, after ~ 6-8 hours you will start to appreciate loss of the gray/white matter differentiation as we see at 1 day after presentation. Notice how the distribution of this edema is wedge shaped and in the vascular territory of the middle cerebral artery. At day 3, despite the decompressive craniectomy, the patient's edema is significant and results in mass effect and midline shift. At Day 3, the anterior cerebral artery territory is now affected likely due to subfalcine herniation.