Background Strictures are a serious complication of Ileal Crohn’s disease (CD). Current assessment tools poorly differentiate fibrotic from inflammatory lesions and do not predict response. The magnetic resonance index of activity (MaRIA) is a validated means to assess activity. Its ability to characterise fibrosis remains unclear. Recent evidence suggests relative contrast enhancement (REC) of >24% on delayed MRI sequences may accurately detect fibrosis.

Aim Compare MaRIA, RCE and biochemical activity in patients with Ileal CD.

Method Prospective study of patients undergoing MRE for known CD. MRE was performed as standard with additional coronal T1 sequences 7 min post gadolinium administration. Two independent blinded Radiologists calculated RCE and MaRIA’s at 70 s and 7 min. Demographics and CRP were recorded.

Results 26/29 MRE’s performed had ileal CD, median age=41 years, male=10 (38%). RCE >24% and high T2 signal intensity (SI); 6/26 (23%) and 11/26 (42.3%). REC >24% occurred in only 1/10 with a visible stenosis. Average MaRIA’s: 2/26 (7.7%)<7 mild; 3/26 (11.5%) 7-11 moderate; 21/26 (80.7%)>11 severe. MaRIA’s did not change significantly between 70 s and 7 min. As expected T2 SI increased with MaRIA’s>11, 26 v 13 (p<0.001, 95% CI 7.73 to 17.27). RCE did not correlate with MaRIA group, ? 0.09. Consistent with MRE findings, CRP was higher in patients with MaRAI >11 (13.3 vs 5.2) and lower in patients with RCE >24% (3.9 vs 14), p<0.04 95% CI 0.37 to 15.71 and p<0.01 95% CI 2.5 to 19.05 respectively.

Conclusions RCE may be a useful adjunct to current MRE and help detect fibrosis in small bowel lesions and warrants further investigation.