Figure 7b. Abdominal radiographs show bowel loops that exhibit the linear pattern of intramural gas. (a) There is a band of radiolucency or black band (black arrow) and a band of soft-tissue opacity or white band (white arrow) along the margin of the involved loop. The black band represents the intramural gas in the serosal layer of the bowel wall, and the white band represents the submucosa and mucosa, which is contrasted on one side by the intramural gas and on the other side by the gas in the lumen. (b) There is extensive intramural gas (arrows) involving almost all of the intestine as well as the stomach in the left upper quadrant. In this patient, the intramural gas is seen as multiple curvilinear black bands, but there are no white bands because the lumen is filled with fluid and there is no gas in the lumen to contrast with the inner aspect of the mucosa.