Brain in stroke, CT scan. Coloured computed tomography (CT) scan of an axial section through the brain of a 62-year-old person affected by hemiplegia (paralysis) of the right side of the body following a stroke (cerebral vascular accident, cva). Here, a large hypodense area (dark, upper right) can be seen affecting the sylvian and ventricular regions. Strokes occur when the blood supply to an area of the brain is restricted, or cut off completely, resulting in cell death of the affected tissue.