MR enterography best identifies fibrotic vs inflammatory strictures in Crohn's disease

By Marilynn Larkin

NEW YORK (Reuters Health) - 23/4/2019

"The lifetime risk for stricture development in patients with Crohn's disease is about 50%," Dr. Dominik Bettenworth of the University of Munster in Germany and Dr. Florian Rieder of Cleveland Clinic in Ohio, told Reuters Health in a joint email. "These strictures consist of variable amounts of inflammatory or fibrotic components and differentiation of the main components is key to define the appropriate treatment approach - i.e., medical versus endoscopic/surgery."

"Due to the transmural nature of Crohn's disease, a full thickness evaluation of the bowel wall is required in case of bowel strictures, which may be achieved best by cross-sectional imaging - ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI)," they said.

To investigate further, Drs. Bettenworth, Rieder and colleagues in the Stenosis Therapy and Anti-Fibrotic Research (STAR) Consortium conducted a systematic literature review, assessing strategies used to detect stricturing in Crohn's disease and to characterize strictures in terms of inflammation and fibrosis. They reported the details of each of the included study findings online April 3 in Gut.

Overall, Drs. Bettenworth and Rieder said, "We found heterogeneous definitions for stricture diagnosis across published studies. However, accuracy rates for stricture detection were high."

"In contrast," they noted, "the precision of cross-sectional imaging techniques that are currently available in clinical practice to differentiate inflammation from fibrosis is not sufficient, making this an unmet need."

Summarizing the findings, they said, "conventional US, CT and MRI are highly accurate to diagnose small bowel Crohn's disease-associated strictures, while MR-enterography is the preferred technique to diagnose strictures and differentiate fibrotic from inflammatory components."

"Conventional US, CT/CTE and MRI/MRE are available in hospitals globally," they added. "In contrast, to date, experimental imaging techniques with promise to separate inflammation from fibrosis are only accessible in specialty centers."

"Clinicians should be aware that the field is moving rapidly," they stressed, "and the STAR consortium, with its partners, is striving to support the testing of anti-fibrotics in patients with stricturing Crohn's disease as soon as possible."

Next steps for the consortium, which recently received more than US$4 million from The Leona M. and Harry B. Helmsley Charitable Trust, is the development of indices for cross-sectional imaging and patient-reported outcome tools that will enable the clinical testing of new anti-fibrotic therapies for Crohn's disease patients, according to Drs. Bettenworth and Rieder.

Dr. Ryan Ungaro, an assistant professor at the Susan and Leonard Feinstein IBD Center at Mount Sinai in New York City, commented by email, "This is an important area of clinical uncertainty. The best definition of stricturing disease in Crohn's is controversial and leads to uncertainty in both clinical practice and research. This review provides a comprehensive overview of the the current understanding and definitions of Crohn's strictures."

"A key element highlighted by this review is the current heterogeneity of stricture definition, which calls for future research to better subset strictures based on composition and clinical outcomes," he said. "In current clinical practice, MRE is often the preferred diagnostic modality, given its performance as well as advantage of limiting radiation exposure to Crohn's patients, who often undergo repeated cross-sectional imaging studies over time."

"Next steps to improve clinical care for Crohn's patients will need to evaluate if different stricture types respond to specific treatment strategies - i.e., anti-inflammatory versus anti-fibrotic versus surgical," Dr. Ungaro concluded.

Dr. Bachir Taouli, Director of Body MRI and of Director of Cancer Imaging Program, also at Mount Sinai, added in an email to Reuters Health, "Recent reports of muscle hypertrophy at histopathology in Crohn's disease strictures should have been more discussed in the paper. This may add to the complexity of imaging characterization and should be assessed in future studies."


Gut 2019.

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