Introduction Crohn's disease management requires knowledge of overall disease burden. A new MRI score of Crohn's disease activity was tested against reference standards of global activity—Harvey Bradshaw index (HBI) and faecal calprotectin.
Methods 34 patients (15 male) median age 33 (range 17–78) with known or suspected Crohn's disease underwent MR enterography (axial/coronal HASTE, TrueFisp and post gadolinium coronal VIBE/THRIVE at 1.5T (n=24) or 3T (n=10)). Same day HBI questionnaire and faecal calprotectin were measured. Two observers qualitatively graded bowel wall thickness, mural T2 signal, mesenteric oedema, T1 enhancement and colonic haustral loss from 0 (normal) to 3 (most abnormal) for the jejunum, proximal ileum, terminal ileum and colon (six segments). Each individual small bowel and colonic segmental score was multiplied according to the length of disease in that segment (0–5 cm×1, 6–15 cm×1.5, and ≥16 cm×2). For each of: lymphadenopathy, comb sign, abscesses and fistulae a score of 5 was added if present. The relationship between MRI score, calprotectin and HBI was evaluated using Kendall's rank correlation.
Results The mean MRI activity score was 15 (range 0–61.5) and was significantly correlated with calprotectin, Kendall's tau b=0.42, p=0.0009, but not with HBI, Kendall's tau b=0.006, p=1.
Conclusion Global Crohn's disease activity measured using a qualitative MRI score is correlated to the faecal calprotectin level. MRI is useful for the global assessment of Crohn's disease activity.
Competing interests None declared.