Figure 8a. Effect of varying the window width and level. (a) Supine CT scan (window width, 1500 HU; window level, –200 HU) clearly depicts a thin haustral fold (arrowhead), with loss of differentiation of the fat attenuation of a lipoma (arrow). (b) The same supine CT scan as seen with narrower window settings (width, 400 HU; level, 140 HU) shows better differentiation of the fat attenuation of the lipoma (arrow), but the thin haustral fold (arrowhead) is now displayed incompletely.