From the Guidelines
MRI enterography correlates moderately well with fecal calprotectin as a biomarker for inflammatory bowel disease activity. Both are valuable tools for assessing intestinal inflammation, though the correlation is not perfect. Fecal calprotectin is a protein released by neutrophils during intestinal inflammation and serves as a non-invasive marker, while MRI enterography provides detailed cross-sectional imaging of the bowel wall and surrounding tissues.
Key Points
- Studies have shown that higher fecal calprotectin levels generally correspond with more severe findings on MRI enterography, particularly for active inflammation, bowel wall thickening, and contrast enhancement 1.
- However, the correlation can vary depending on disease location, with better correlation in ileal Crohn's disease compared to colonic involvement.
- Some discrepancies may occur because fecal calprotectin reflects the overall inflammatory burden throughout the intestine, while MRI may detect structural changes that persist even when active inflammation has subsided.
- In clinical practice, these tools are often used complementarily rather than interchangeably, with fecal calprotectin serving as a screening and monitoring tool, while MRI enterography provides detailed anatomical assessment for disease complications and treatment planning 1.
Clinical Implications
- A recent meta-analysis found that a calprotectin cut-off of 50 μg/g had the best sensitivity to detect endoscopically active disease, with specificity performing best at levels >100 μg/g 1.
- MRI enterography has high diagnostic performance for the detection of Crohn disease–related active bowel inflammation in pediatric patients, with sensitivity values ranging from 66% to 95% and specificity values ranging from 64% to 97% on a bowel segmental basis 1.
- The use of MRI enterography can alter the management of patients with ileal or ileocolonic Crohn's disease, with one study showing that it influenced a change in treatment in 55.3% of patients 1.
From the Research
Correlation between MRI Enterography and Fecal Calprotectin
- The correlation between MRI enterography and fecal calprotectin has been studied in several research papers 2, 3, 4.
- A study published in 2015 found that fecal calprotectin correlates well with the degree of MRI inflammatory activity and with surgical pathology damage in ileal Crohn's disease 2.
- Another study published in 2010 found a trend of positive correlation between MRI scores of activity and calprotectin levels, as well as between MRI scores of thickening of intestinal involvement and calprotectin levels 3.
- A 2019 study found that fecal calprotectin correlates well with MRI enterography assessment of ileal Crohn's disease, with an optimal cut-off of 145 μg/g for severe inflammation on MRI 4.
Diagnostic Accuracy of Fecal Calprotectin
- Fecal calprotectin has been found to have a significant diagnostic accuracy for the detection of small-bowel Crohn's disease 5.
- A meta-analysis published in 2016 found that fecal calprotectin has a significant diagnostic odds ratio for the prediction of active small-bowel disease on capsule endoscopy 5.
- The diagnostic accuracy of fecal calprotectin has been found to be higher for cut-offs of 50 μg/g and 100 μg/g, with a negative predictive value of 91.8% for a cut-off of 50 μg/g 5.
Clinical Implications
- Fecal calprotectin can be used as a surrogate marker of disease control to select patients for MRI enterography assessment and therapeutic adjustment 2.
- MRI enterography parameters, such as length of ileal disease and increased bowel wall thickness, have been found to be associated with long-term biologic- and surgery-free remission 4.
- Fecal calprotectin can be used to monitor disease activity and response to therapy in patients with inflammatory bowel disease 6.