Fig. 22
From: Gastrointestinal perforation: clinical and MDCT clues for identification of aetiology
75-year-old patient with obstructive sigmoid carcinoma. a Axial and (b) sagittal non-enhanced images show concentric narrowing of the sigmoid lumen (between arrows), prestenotic colonic dilatation (d), massive pneumoperitoneum (p) and free fluid (f)