CT and MR imaging findings of bowel ischemia from various primary causes

Ischemic bowel disease represents a broad spectrum of diseases with various clinical and radiologic manifestations, which range from localized transie nt ischemia to catastrophic necrosis of the gastrointestinal tract. The pri mary causes of insufficient blood flow to the intestine are diverse and inc lude thromboembolism, nonocclusive causes, bowel obstruction, neoplasms, va sculitis, abdominal inflammatory conditions, trauma, chemotherapy, radiatio n, and corrosive injury. Computed tomography (CT) or magnetic resonance (MR ) imaging can demonstrate the ischemic bowel segment and may be helpful in determining the primary cause. The CT and MR imaging findings include bowel wall thickening with or without the target sign, intramural pneumatosis, m esenteric or portal venous gas, and mesenteric arterial or venous thromboem bolism. Other CT findings include engorgement of mesenteric veins and mesen teric edema, lack of bowel wall enhancement, increased enhancement of the t hickened bowel wall, bowel obstruction, and infarction of other abdominal o rgans. However, regardless of the primary cause, the imaging findings of bo wel ischemia are similar. Furthermore, the bowel changes simulate inflammat ory or neoplastic conditions. Understanding the pathogenesis of various con ditions leading to mesenteric ischemia helps the radiologist recognize isch emic bowel disease and avoid delayed diagnosis, unnecessary surgery, or les s than optimal management.