Magnetic Resonance Index of Activity (MaRIA)

Last revised by Tom Foster on 5 Apr 2022

The Magnetic Resonance Index of Activity (MaRIA) scoring system is used to assess ileocolonic Crohn disease activity on contrast-enhanced MRI enterography. The segmental index represents disease severity in one bowel segment, whilst assessing six defined anatomic regions these can be combined into a global MaRIA index. Due to the complexity of the original system in 2019 a new, simplified system was proposed (MARIAs), which does not require contrast-enhanced sequences. 

The MaRIA score is calculated with the following equation 1:

  • MaRIA = 1.5 x wall thickness + 0.02 x RCE + 5 x edema + 10 x ulceration

The relative contrast enhancement (RCE)  of the bowel wall needs to be first calculated using this formula:

  • RCE = [(WSI postgadolinium – WSI pregadolinium) / (WSI pregadolinium)] x 100 x (SD noise pregadolinium / SD noise postgadolinium)

The wall signal intensity (WSI) of the bowel wall is measured on T1-weighted (e.g. VIBE sequences). Three pre-and postcontrast measurements should be performed, and the regions of interest (ROIs) should be positioned to identical locations pre-and postcontrast. 

SD noise represents the average of three SD of the signal intensity measured outside the body before and after administration of the contrast agent 1,2.

  • the cutoff points of the MaRIA score are:
    • moderate disease: ≥7
    • severe disease: ≥11

Due to the complexity of the original MaRIA score in 2019 a significantly simplified new scoring system was proposed, the MARIAs. It not only uses a more simple formula but also does not require contrast-enhanced imaging. The formula of the MARIAs is: 

  • MARIAs = (1 x thickness >3 mm) + (1 x edema) + (1 x fat stranding) + (2 x ulcers)

It has been shown that MARIAs >1 identifies segments with active Crohn disease with 90% sensitivity and 81% specificity, whilst a score >2 indicates severe lesions with 85% sensitivity and 92% specificity 3

The global index requires calculating the segmental MaRIA, or simplified MARIAs score in the following six segments 1,2:

Afterwards, the individual scores have to be added to get the global MaRIA or MARIAs index. The global MARIAs has a significant advantage over the earlier MaRIA index, as in the simplified MARIAs system normal bowel segments have a score of 0, and thus do not contribute to the global index. This is particularly important for patients who had prior bowel resections, where the MaRIA index can underestimate the severity since the missing segments decrease the overall score 3

  • bowel wall should be measured in millimeters
  • bowel wall edema should be assessed on T2-weighted images by comparing its signal intensity to the psoas muscle
  • global MaRIA index has been shown to have a significant correlation with endoscopic and clinical severity indices, as well as c-reactive protein (CRP) levels 1
  • while the MaRIA index can be used to assess rectal disease activity, other dedicated scoring systems such as the Van Assche index exist for this purpose
  • for noncontrast enterography the Clermont score can be used as an alternative, with similar clinical performance

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