Taylor SA, et al. - Researchers performed a multicentre trial focusing on comparative accuracy of magnetic resonance enterography (MRE) and ultrasound for assessing disease extent and activity of newly diagnosed and relapsed Crohn's disease (METRIC). For detecting small bowel disease presence, both MRE and ultrasound have high sensitivity and are identified as valid first-line investigations, and viable alternatives to ileocolonoscopy. However, when available, MRE is generally the preferred radiological investigation in a national health service setting as its sensitivity and specificity exceed ultrasound significantly.

Methods

• Patients from eight UK hospitals were recruited.
• For this study, patients 16 years or older, with newly diagnosed Crohn's disease or with established disease and suspected relapse were eligible.
• MRE and ultrasound were performed on consecutive patients in addition to standard investigations.
• An additional investigation (if not already available) was performed in case of discrepancy between MRE and ultrasound for the presence of small bowel disease.
• Difference in per-patient sensitivity for small bowel disease extent (correct identification and segmental localisation) against a construct reference standard (panel diagnosis) was assessed as the primary outcome.

Results

• The trial was completed by 284 patients (133 in the newly diagnosed group, 151 in the relapse group).
• Small bowel Crohn's disease was identified in 233 (82%) patients using the reference standard.
• MRE displayed significantly greater sensitivity for small bowel disease extent (80% [95% CI 72–86]) and presence (97% [91–99]) than ultrasound (70% [62–78] for disease extent, 92% [84–96] for disease presence); a 10% (95% CI 1–18; p=0·027) difference for extent, and 5% (1–9; p=0·025) difference for presence.
• MRE displayed significantly greater specificity for small bowel disease extent (95% [85–98]) than that of ultrasound (81% [64–91]); a difference of 14% (1–27; p=0·039).
• With MRE and ultrasound, the specificity for small bowel disease presence was 96% (95% CI 86–99) and 84% (65–94), respectively (difference 12% [0–25]; p=0·054).
• No serious adverse events were observed.