Radiological imaging of acute infectious and non-infectious enterocolitis

Abstract

Computed tomography (CT) is often used as the initial diagnostic test in patients with inflammatory and infectious types of enterocolitis. The differential diagnosis is broad, including infectious, non-infectious and vascular causes, which have substantially different management strategies. Although a definitive diagnosis often relies on endoscopic biopsy results, stool culture results or other clinical features, radiologists often help to guide the diagnosis. This article reviews the CT appearance of different infectious and inflammatory forms of enterocolitis. General and specific intramural and extramural CT findings in the small bowel and colon are discussed. Added focus is placed on distribution patterns and medication side effects that can act as important diagnostic clues. Infectious enterocolitis is due to bowel inflammation caused by bacteria, viruses, or parasites, which show a preferential localization. Pancolitis can be seen with Clostridium difficile with the relatively specific CT finding of the "giraffe coat" sign. Inflammatory enterocolitis can be primary (inflammatory bowel disease, vasculitis) or secondary (radiation therapy, graft versus host disease etc.). Ischemic colitis and enteritis can result from arterial compromise, low flow states that globally reduce perfusion or venous insufficiency. The CT appearance varies depending on the cause, the time of onset and grade of reperfusion. Knowledge of characteristic mural and extramural CT of MRI findings, geographic distributions and therapy effects help to guide the differential diagnostics in inflammatory and infectious types of enterocolitis.