Semi-automatic assessment of the terminal ileum and colon in Crohn disease patients using MRI ( the VIGOR + + project )

Objectives: To develop and validate a predictive MRI activity score for ileocolonic CD activity based on both subjective and semi-automatic MRI features. Materials and Methods: An MRI activity score (the "VIGOR" score) was developed from 27 validated MR enterography datasets including subjective radiologist observation of mural T2 signal and semi-automatic measurements of bowel wall thickness, excess volume and dynamic contrast enhancement (initial slope of increase; ISI). A second, subjective score was developed based on only radiologist observations. For validation, two observers applied both scores and three existing scores to a prospective dataset of 106 patients (59 female, median age 33) with known CD, using the endoscopic Crohn's Disease Endoscopic Index of Severity (CDEIS) as a reference standard. Results: The VIGOR score (17.1*ISI + 0.2*excess volume + 2.3*mural T2), and other activity scores all had comparable correlation to CDEIS (Ob1/2, r=0.58/0.59, 0.34–0.40/0.43–0.51, respectively). The VIGOR score, however, improved interobserver agreement compared to the other activity scores (ICC=0.81 vs. 0.44–0.59). Diagnostic accuracy of 80%–81% was seen for the VIGOR score, similar to the other scores. Conclusions: The VIGOR score achieves comparable accuracy to conventional MRI activity scores, but with significantly improved reproducibility, favouring its use for disease monitoring and therapy evaluation.