What are the best diagnostic imaging tests for IBD?

While ileocolonoscopy and biopsy are considered ‘first-line’ procedures in the diagnosis of inflammatory bowel disease (IBD), segments of the small bowel beyond the reach of endoscopy may be affected. In such instances, cross-sectional imaging is fundamental to the diagnostic process. The following imaging modalities are extremely useful in IBD diagnosis:1

• Ultrasonography (US) is a well-tolerated, radiation-free diagnostic imaging modality that can aid in identifying penetrating complications. Compared with other modalities, however, it can offer only limited coverage of the gastrointestinal tract.

• Computed tomography (CT) is a highly accurate and less time-consuming procedure than magnetic resonance imaging (MRI). However, the associated radiation exposure, especially to patients undergoing frequent examinations, may limit its use.

• MRI enterography/enteroclysis has similar diagnostic accuracy and indications as CT with the major advantage of not imparting ionising radiation. It is also superior to conventional radiology in detecting extramural abnormalities (e.g. deep-seated fistulas). Accessibility to MRI can be an issue.

• Nuclear medicine (NM) techniques can be used to explore the entire length of the small bowel. Patient exposure to radiation and accessibility to this modality may be a barrier to its use.

• Small bowel follow-through (SBFT) is highly accurate in the detection of mucosal abnormalities, but less useful in detecting extramural complications and is contraindicated in high grade obstruction and perforations.

Research has found no significant difference between US, CT, MRI and NM techniques in terms of diagnostic accuracy. A recent study found SBFT, CT and MRI to be equally accurate in the identification of active inflammation in the small intestine. The ‘best’ imaging modality for IBD diagnosis may therefore depend on the patient, physician and clinic. Factors such as the physician’s expertise, IBD subtype, patient condition and cost may ultimately determine the most appropriate imaging test for the situation.1

1. Panes J et al. Imaging techniques for assessment of inflammatory bowel disease: joint ECCO and ESGAR evidence-based consensus guidelines. J Crohns Colitis 2013; 7: 556–585.

AU-REM0196. Date prepared: April 2014.