Radiology of the gastrointestinal tract

Abstract

The widespread introduction of endoscopic techniques has reduced the need for radiological examination of the intestinal tract and has almost completely rendered imaging of the stomach obsolete. There remains, however, a substantial role for radiological imaging in the investigation of the small and large bowel in the diagnosis of abdominal and gastrointestinal disease. The small intestine may be examined by a number of radiological techniques, including plain films, barium contrast studies, ultrasonography, CT, MRI, and nuclear medicine. Barium studies (follow-through or small-bowel enema) can provide good morphological detail of the mucosal surface of the bowel; cross-sectional imaging (usually CT or MRI) is required for disease in the wall of the bowel or outside it. CT is increasingly used as the primary investigation in suspected bowel obstruction. Nuclear medicine studies have a major role in the examination of the small bowel for the presence of inflammatory conditions, and for demonstration of potential bleeding sources. Colonoscopy has revolutionized imaging approaches to the colon because of its proven diagnostic efficacy and the added facility for biopsy of diffuse mucosal pathology and focal mucosal lesions, but is associated with a small risk of perforation. The use of barium enema continues to decline steadily. The advent of multidetector CT that allows three-dimensional reconstruction has led to a large number of new applications, including virtual colonoscopy or colonography, use of which is steadily increasing and is particularly valuable in the setting of unsuccessful or incomplete optical colonoscopy, although it is disadvantaged by inability to perform biopsy.