TABLE 3.

The imaging scoring systems for assessment of disease activity in Crohn's disease

	Features	Calculation formula	Inflammatory activity grading	Strengths	Limitation	Reference
MRI
MaRIA score	Wall thickness Bowel wall relative contrast enhancement Mural edema Ulcers	1.5 × wall thickness (mm) + 0.02 × relative contrast enhancement + 5 × edema + 10 × ulceration	Score ≥7: active CD Score ≥11: severe activity	Validated against pathology Most investigated score	High time consuming Intravenous contrast injection Incapable of entire small bowel valuation	Rimola et al 28
sMaRIA	Wall thickness Mural edema Ulcers Fat stranding	(1 × thickness >3 mm) + (1 × edema) + (1 × fat stranding) + (2 × ulcers)	Score ≥1: active CD Score ≥2: severe activity	Low time‐consuming Without requirement of contrast material	Incapable of entire small bowel valuation	Roseira et al 29
Clermont score	ADC Wall thickness Ulcers Mural edema	−1.321 × ADC (mm2/s) + 1.646 × wall thickening + 8.306 × ulcers + 5.613 × edema + 5.039	Score ≥8.4: active CD Score ≥12.5: severe activity	Without requirement of contrast material Incorporates apparent diffusion coefficient measurements	Used MaRIA score for validation. Without pathology validation High time‐consuming Incapable of entire small bowel valuation	Buisson et al 30
London score	Bowel wall thickness Mural T2 score	1.79 + 1.34 × mural thickness + 0.94 × mural T2 score	Score ≥4.1: active CD	Low time‐consuming Without requirement of contrast material	Does not evaluate the entire small bowel	Steward et al 31
MEGS	Bowel wall thickness T2WI signal Mesenteric edema T1WI enhancement & enhancement pattern Haustral folds (colon) Length of disease segment Extramural features	Score per segment × multiplication score per segment (jejunum, ileum, terminal ileum, cecum, ascending, transverse, descending, sigmoid and rectum based) + additional score per patient (lymph node + comb sign + abscess + fistula)	MEGS >10: active disease	Incorporates extra‐intestinal damage Additional evaluation of the jejunum and ileum	Without pathology validation Huge evaluated features	Makanyanga et al 32
US
Semiquantitative bowel ultrasound scoring system	Bowel wall thickness US pattern (disrupted stratification) Presence of fistulas or abscesses Presence of stenosis	(2.5 × US pattern) + (1.5 × bowel thickness) + (3 × presence of fistulas/abscesses) + (1.5 × presence of stenosis)	Score >3: Predicted the high risk of surgery	Non‐radiation	Unknown reproducibility	Rigazio et al 33

Abbreviations: ADC, apparent diffusion coefficient; CD, Crohn's disease; MaRIA, magnetic resonance index of activity; MEGS, magnetic resonance enterography global score; MRI, magnetic resonance imaging; sMaRIA, simplified MaRIA; US, ultrasonography.