Summary of magnetic resonance enterography activity scoring index
|
Scoring index | Formula | Strengths | Limitations | Further research questions |
| sMaRIA | *(1 × WT>3 mm) + (1 × wall oedema) + (1 × fat stranding) + (2 × ulcers) | Can be applied to small-bowel and large-bowel segments, can grade by severity, good responsiveness to treatment change, quick to derive, does not require gadolinium. | Reproducibility needs evaluating. | Reproducibility and specificity in multicentre and multireader settings with a range of reference standards. |
| London | †1.79 + 1.34 × mural thickness + 0.94 × mural T2 score | Quick to derive, does not require gadolinium, can assess treatment response. | Only applicable to small-bowel segments, does not allow grading by severity | Specificity in multicentre, multireader settings with a range of reference standards |
| ‘Extended’ London | ‡Mural thickness +mural T2 score +perimural T2 signal +contrast | Quick to derive, can assess treatment response. | Requires gadolinium, only applicable to small-bowel segments, does not allow grading by severity. | Ability to assess responsiveness to treatment; specificity in multicentre, multireader settings with a range of reference standards. |
| MaRIA | §1.5 × WT + 0.02 × RCE + 5 × oedema + 10 × ulcer | Accurate for small and large-bowel segments, allows grading by severity, can assess treatment response, most investigated. | Time consuming to calculate, requires gadolinium. | Practicality in clinical practice. |
| Clermont | −1.321 × ADC (mm2/s) + 1.646 × WT + 8.306 × ulcers + 5.613 × oedema + 5.039 | Accurate for small and large-bowel segments, allows grading by severity, can assess treatment response. | Time consuming to calculate, requires diffusion-weighted sequences. | Practicality in clinical practice. |
*WT=Wall thickness >3 mm scores 1 point, presence of oedema scores 1 point, presence of fat stranding scores 1 point, presence of ulcers scores 2 points. Thus, the score for each segment ranges from 0 (completely normal) to 5 (markedly inflamed).
†Where mural thickness and mural T2 score are classified in four categories according to severity (0=absent, 1=mild, 2=moderate, 3=marked).
‡Where mural thickness, mural T2 score and contrast enhancement are classified in four categories according to severity (0=absent, 1=mild, 2=moderate, 3=marked).
§Where WT is measured in millimeters and RCE in arbitrary units, and evidence of oedema or ulcer is assigned a value of 1 if present and a value of 0 if absent.
ADC, apparent diffusion coefficients ; MaRIA, Magnetic Resonance Index of Activity; RCE, Relative Contrast Enhancement; sMaRIA, simplified MaRIA.