Apply the segmental MRI metrics for wall thickness, contrast, and focal lesions to visualize disease activity.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Objective assessment of Crohn's disease inflammatory activity via Magnetic Resonance Enterography (MRE)
Monitoring response to biological therapy in small bowel Crohn's where endoscopy is impractical
Quantifying "Radiological Remission" in patients with quiescent clinical symptoms
Clinical Objective
The MARIA index (Magnetic Resonance Index of Activity) is a validated tool for identifying active inflammation and ulceration with high sensitivity and specificity, using standardized radiological features.
Section 2
Formula & Logic
The 4 Radiological Variables (per segment)
01
Wall Thickening (mm).
02
Relative Contrast Enhancement (RCE): Compared to psoas muscle or healthy wall.
03
Presence of Mural Oedema: High T2 signal within the wall.
04
Presence of Ulcers: Macroscopic mucosal defects on contrast MR.
The MARIA score has a high correlation ($r > 0.8$) with the SES-CD (Simplified Endoscopic Score for CD). Its primary advantage is the ability to visualize the entire small bowel wall, including transmural complications like "Creeping Fat" or mesenteric hyperaemia (vasa recta engorgement), which colonososcopy misses.
The 15-Point Cutoff
A MARIA score ≥ 15 is a highly reliable predictor of mucosal ulceration. In some European centers, a MARIA score ≥ 15 is used as a surrogate for "Deep Remission" failure, triggering an immediate switch in biological therapy.
Clinical Pearls
The score must be calculated per segment (Ileum, Right Colon, etc.); the segment with the highest score determines the overall activity grade
Mural oedema is the most weight-sensitive marker for active SIRS-like flares
Diffusion-weighted imaging (DWI) is an emerging addition that may simplify the score in future "Contrast-free" versions
Section 4
Next Steps
Management Pathways
01
MARIA < 7: Target achieved; maintain therapy.
02
MARIA ≥ 15: Deep ulceration present; consider dose escalation of biologicals or adding a thiopurine/methotrexate.
Complementary Motility Tools
SES-CD (Endoscopic Score)
Lémann Index (Bowel Damage)
Faecal Calprotectin Interpretation
Section 5
Evidence Appraisal
The Foundational Score
Magnetic resonance for assessment of disease activity and severity in ileocolonic Crohn's disease.
Rimola J et al. • Gut. 2009;58(8):1113-20. The primary derivation and validation study.
Developed by Dr. Jordi Rimola and the IBD management group at the Hospital Clínic de Barcelona. Their work transformed cross-sectional imaging from a purely "anatomical" tool into a "physiological" tool that could reliably steer Crohn's therapy.
