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Ultrasound or MRI should be the imaging modality of choice in inflammatory bowel disease, researchers have proposed. "Ultrasound or MRI should be the imaging modality of choice in inflammatory bowel disease (IBD), researchers have proposed [1].

While colonoscopy and barium examination both allow depiction of the mucosal surface, both are time-consuming. In addition, colonoscopy is invasive and carries a risk of perforation in severe ulcerative colitis.

Other options include CT, which is widely used in the US today, as well as ultrasonography, MRI, and scintigraphy. However, reported sensitivities and specificities of these modalities vary.

US researchers conducted a meta-analysis of 33 prospective studies assessing these techniques which used histopathology, ileocolonoscopy, and/or intraoperative findings as the reference standard.

The estimated per-patient sensitivity of ultrasound was 89.7 per cent; that of MRI, 93 per cent; scintigraphy, 87.8 per cent and CT, 84.3 per cent. There were no significant differences between these values.

Per-patient specificity estimates ranged from 84.5 per cent for scintigraphy to 95.6 per cent for US, and the study group reported that this was the only significant difference between any of the imaging modalities.

The authors said: "Because of the relapsing nature of IBD and the young age at which it usually develops, frequent re-evaluation of disease is necessary in many patients. Therefore, it might be preferable to use a technique that does not involve ionizing radiation."

They added: "Although CT is widely used to evaluate IBD, the findings of our meta-analysis, as well as the relatively large radiation dose and the intravenous iodine-based contrast medium needed for CT, favour the use of ultrasound or MRI."

But Dr Mark Baker, of the radiology division of the Cleveland Clinic in Ohio, US, disagreed. He cautioned: "Like any meta-analysis, the conclusions are only as good as the data.

"Right now, at the Cleveland Clinic, CT or MR enterography are the only modalities that are used by the clinicians. Not only is the disease detected, but complications such as strictures and fistulae are identified. So, the public has spoken, the vote is in, we don't do any other kind of study for Crohn's."


[1] Inflammatory bowel disease diagnosed with US, MR, scintigraphy, and CT: Meta-analysis of prospective studies
Radiology 2008;247:64-79"