Acute diverticulitis. This 55 year old man presented with left iliac fossa pain. Contrast-enhanced CT shows multiple gas-filled outpouchings from the sigmoid colon, indicating diverticular disease. There is stranding of the fat around the sigmoid colon (arrow), which indicates an inflammatory process i.e. acute diverticulitis. An additional role of CT in this setting is the evaluation of potential complications of diverticulitis e.g. perforation, abscess and fistula formation.