Spiral CT of the abdomen after distention of small bowel loops with transparent enema in patients with Crohn's disease

Background: To evaluate the capability of a computed tomographic (CT) technique that combines distention of the small bowel loops with a transparent enema with contrast-enhanced spiral CT of the abdomen in patients with Crohn's disease. Methods: We evaluated the abdomen with spiral CT after distention of the small bowel loops with a transparent enema of methylcellulose in 40 patients consecutively referred for radiologic evaluation of Crohn's disease of the small bowel. Fluid was infused through a nasojejunal catheter with a peristaltic pump. Ultrasonography was used to prevent bowel overdistention and detect arrival of methylcellulose to the cecum. Contrast-enhanced spiral CT of the abdomen was then performed, and the degree of contrast enhancement and the thickness of the walls of the involved loops were evaluated. A series of 10 patients with retrograde distention of the last ileal loop from large bowel water enema was used as a control. The results of the CT were compared with those of conventional radiographic small bowel studies. Results: The normal small bowel wall was 1.9–2.5 mm thick (mean = 2.1 mm); density values of the normal enhanced wall varied between 25 and 60 HU (mean = 32 HU) and presented a homogeneous structure. Bowel segments involved by the disease were 4–12.5 mm thick (mean = 9.2 mm), had density values of 75–150 HU (mean = 105 HU), and showed a multilayered appearance. Compared with conventional radiography, CT detected longer lesions or additional segments involved by the disease process in 14 cases, 11 additional fistulas, two abscesses, and mesenteric changes in 21 cases. Conclusions: The small bowel CT enema technique provides good results in the study of patients with Crohn's disease and can be used to evaluate patients with advanced lesions. Received: 24 June 1998/Revision accepted: 27 January 1999