CT in inflammatory bowel disease

CT enterography (CTE) is used to image the small and large bowel to detect and stage inflammatory bowel disease (IBD) and alternative small bowel disorders. The principal benefits of CTE in Crohn's patients are to identify suspected and occult mural inflammation and penetrating complications that will change medical or interventional treatment. CTE is a high spatial resolution CT exam of the abdomen and pelvis, following the administration of a large volume of oral enteric contrast agent, providing visualization of the gut lumen, wall, and peri-enteric tissues. Methods for enteric contrast delivery, intravenous contrast administration, and routine and low-dose image acquisition and reconstruction are discussed and can be tailored to the patient. Imaging findings such as mural hyperenhancement, stratification, and wall thickening that reflect small and large bowel mural inflammation are summarized and illustrated, as are penetrating complications (abscess, fistulas), low- and high-grade bowel obstruction, and other extra-enteric complications of IBD. CTE performance characteristics for detecting mural inflammation, penetrating complications, and obstruction are summarized and favorable. The relationship of IBD patient symptoms to CTE imaging findings is reviewed. Although CTE is considered as a complementary test with ileocolonoscopy in the evaluation of IBD patients, it has specific advantages, limitations, and risks compared with alternative small bowel-imaging strategies such as MR enterography, capsule endoscopy, and small bowel fluoroscopy.