MRE or IUS for Crohn’s Disease Imaging?

Magnetic resonance enterography (MRE) and intestinal ultrasound (IUS) have emerged as the primary noninvasive options for diagnosing and monitoring Crohn disease (CD). A recent review article in the Journal of Crohn’s and Colitis addresses how to choose which cross-sectional technique to use in clinical practice.

“The decision … is multifaceted and depends on patient characteristics, the clinical question, scanner and interpretative expertise availability, and patient preference,” wrote corresponding author Stuart A. Taylor, MD, PhD, of University College London, London, England, and coauthors. “In general, all tests have their strengths and limitations, and the question is not binary but rather which test is most suitable for a particular patient at a particular point in their disease course.”

Broadly speaking, diagnostic accuracy is similar with IUS and MRE, according to the article. One study did suggest MRE may be better for staging the location of small bowel CD and, as a result, may be better for defining disease distribution and phenotype at the time of diagnosis. On the other hand, IUS may have better performance in the colon. Both have proven utility for monitoring CD, assessing treatment response, and identifying intra-abdominal complications.

Both also offer a low patient burden. However, findings from the Magnetic Resonance Enterography or Ultrasound in Crohn’s disease (METRIC) trial suggest longer recovery times with MRE and a lower rate of patient willingness to undergo the test again: 91%, compared with 99% for IUS. An Australian study also found patients preferred IUS for CD monitoring.  

Overall, for screening patients with suspected CD, IUS is typically preferred but MRE is also appropriate, according to the review. For diagnosing relapse in patients with known CD, especially those with a complex phenotype, MRE is generally preferred, although IUS can be used as well.

“For regular monitoring, during a course of therapy for example, IUS is very well suited,” the authors continued. “In all instances, if the images from the IUS study are unsatisfactory, for instance due to body habitus or obscuration from bowel gas, MRE should be performed.”

Reference

Kumar S, De Kock I, Blad W, Hare R, Pollok R, Taylor SA. Magnetic resonance enterography and intestinal ultrasound for the assessment and monitoring of Crohn's disease. J Crohns Colitis. 2024;18(9):1450-1463. doi:10.1093/ecco-jcc/jjae042