How Is Simplified Magnetic Resonance Index of Activity Useful in Pediatric Crohn Disease?

Researchers assessed the association between simplified magnetic resonance index of activity and IC-measured inflammation levels in children with Crohn disease.

In children newly diagnosed with Crohn disease (CD), the simplified magnetic resonance index of activity (MARIAs) score can accurately reflect disease activity and severity in the terminal ileum (TI), but not in the colon, according to study results published in the Journal of Pediatric Gastroenterology and Nutrition.

Diagnosis of CD usually includes ileocolonoscopy (IC) and magnetic resonance enterography (MRE). The simplified magnetic resonance index of activity (MARIAs) is a score for assessing CD activity and severity in adults. However, a need remains for quantifying disease activity by MRE in children.  

In the current study, researchers sought to determine if MRE assessed with MARIAs could accurately reflect inflammation as determined by IC in children newly diagnosed with CD. Investigators sourced data on pediatric patients with inflammatory bowel diseases (IBD) from Connecticut Children’s from January 2014 to March 2020. A total of 140 children who had been diagnosed with CD and had baseline IC and MRE within 5 weeks of diagnosis were included in the analysis. Study participants had a mean age of 13±2.6 years, 59% were boys, and there was a median 13 days between baseline IC and MRE.

MARIAs was calculated for each intestinal segment, including TI, transverse colon, ascending colon, descending colon, sigmoid colon, and rectum, defined as (1 x thickness>3 mm) plus (1x edema) plus (1x fat stranding) plus (2x ulcers). Researchers determined sensitivity and specificity using receiver operating characteristic curves to compare MARIAs with IC findings.

With IC as the reference standard, investigators found that the MARIAs cutoff of at least 1 identified active inflammation in TI segments with 84% sensitivity, 73% specificity, 85% positive predictive value (PPV), 70% negative predictive value (NPV), and area under the curve (AUC) 0.782 (95% CI, 0.689-0.876). The MARIAs cutoff of at least 2 identified TI segments with severe lesions with 87% sensitivity, 76% specificity, 87% PPV, 76% NPV, and AUC 0.814 (95% CI, 0.712-0.916). Poor sensitivity was observed for all colonic segments.

“This index for quantification of active disease on MRE may possibly be used to monitor the TI over time and help guide treatment decisions but emphasizes the importance of the use of MRE in conjunction with ileocolonoscopy in assessing pediatric patients with CD,” the study authors noted.


Lepus CA, Moote DJ, Bao S, Mosha MH, Hyams JS. Simplified magnetic resonance index of activity is useful for terminal ileal but not colonic disease in pediatric Crohn’s disease. J Pediatr Gastroenterol Nutr. Published online February 10, 2022. doi: 10.1097/MPG.0000000000003412.