Diagnostic accuracy of simple magnetic resonance imaging markers for detection of treatment response compared to complex disease activity scores in patients with active Crohn's disease

BackgroundMagnetic resonance imaging (MRI) scores have been validated for monitoring Crohn's disease (CD) but are not widely used in clinical practice.PurposeTo evaluate treatment response in patients with active CD using simple imaging markers compared to complex multifactorial scores.Material and MethodsThis was a post-hoc analysis of MRI-enterocolonographies performed in a prospective, blinded, multicenter study. Patients with endoscopically active CD completed ileocolonoscopy and MRI with intravenous contrast and diffusion-weighted sequences before and after medical treatment. Response was defined as ≥50% reduction of the Simple Endoscopic Score for Crohn's Disease. Changes in bowel wall thickness (BWT) and apparent diffusion coefficient (ADC) were compared to the magnetic resonance index of activity (MaRIA), simplified MaRIA, and Clermont score.ResultsA total of 42 patients entered the analysis, and endoscopic response was achieved in 19 (45.2%). All activity scores improved in patients with endoscopic response compared to non-responders (<i>P</i> <0.05). The relative reduction of BWT for the most severely affected bowel segment (area under the curve [AUC]=0.76, 95% confidence interval [CI]=0.61-0.91) trended towards a higher diagnostic accuracy compared to the global MaRIA score (AUC=0.63, 95% CI=0.45-0.81; <i>P</i> = 0.1). The per-segment response was more accurately evaluated with BWT compared to the segmental MaRIA score (AUC=0.82 and 0.67, respectively; <i>P</i> = 0.05). A 17% decrease in BWT resulted in an optimal sensitivity and specificity of 78.9% (95% CI=54.4-93.9) and 85.2% (95% CI=66.3-95.8), respectively.ConclusionBWT is not inferior to MaRIA when determining treatment response in CD. This measure is simple to perform and does not require intravenous contrast.