Diagnostic imaging in Crohn's disease: comparison of magnetic resonance imaging and conventional imaging methods

Conventional enteroclysis remains the method of choice in the diagnosis of inflammatory small bowel disease. The reported sensitivity rates, however, for the diagnosis of extraintestinal processes, such as fistulae and absces ses, are moderate. Computed tomography (CT) is the method of choice for the diagnosis of extraintestinal complications. The anatomical designation of the affected bowel segment may, however, prove difficult due to axial slice s, and the applied radiation dose is high. The use of magnetic resonance im aging (MRI) in the diagnosis of inflammatory small bowel disease is a relat ively new indication for the method; prerequisites were the development of breathhold sequences and phased array coils. Optimized magnetic resonance t omographic imaging requires a combined method of enteroclysis and MRI, whic h guarantees an optimal tilling and distension of the small bowel. The high filling volume leads to a secondary paralysis of the small bowel and avoid s motion artifacts. In a trial of 84 patients with histological and endosco pic correlation the sensitivity in diagnosing inflammatory bowel disease wa s 85.4% for enteroclysis and 95.2% for MRI, and the specificity was 76.9% f or enteroclysis and 92.6% for MRI. As none of the abscesses was diagnosed w ith enteroclysis, the sensitivity was 0% for enteroclysis, but 77.8% for MR I. The sensitivity in diagnosing fistulae was 17.7% for enteroclysis and 70 .6% for MRI. In summary, MRI can detect the most relevant findings in patie nts with inflammatory small bowel disease with an accuracy superior to that of enteroclysis.