MRI Enterography (MRE) for Crohn’s: What It Shows + How to Prep
Last Updated Jan 15, 2026
Magnetic resonance enterography (MRE) is a special magnetic resonance imaging (MRI) scan designed to take detailed pictures of the small intestine, an area where Crohn’s disease often hides. For many care teams, an MRE for Crohn’s helps answer practical questions: Where is inflammation happening, how deep does it go, and are there complications that might change the next steps. This overview explains what MRE can show and what MRI enterography prep commonly looks like, so the experience feels less like a mystery.
What MRE shows in Crohn’s, and how results can guide next steps
MRE is a “cross-sectional” test, meaning it can look through the bowel wall and around it, not only at the inner lining. In Crohn’s, that matters because inflammation can be “transmural,” affecting the full thickness of the intestine and nearby tissues. MRE is often used to map the extent of disease and to look for changes that can help a gastroenterology team tell the difference between active inflammation and longer-term narrowing from scar tissue (fibrosis). It can also help identify complications such as fistulas (abnormal tunnels), strictures (narrowed segments), and areas that may suggest an abscess (a pocket of infection). [1]
Common phrases that may show up in an MRE report, and what they often mean in plain language:
Active inflammation: signs the bowel may be irritated and swollen right now.
Stricture (narrowing): a tight area that can slow passage through the bowel; some strictures have more inflammation, others have more scarring.
Fistula or abscess concern: findings outside the bowel that may matter for safety and planning.
MRE vs colonoscopy is often best thought of as “different tools for different questions.” A colonoscopy allows a clinician to look directly at the bowel lining (usually the colon and the end of the small intestine) using a flexible camera and can support biopsy (a small tissue sample). Imaging like MRI looks from the outside in and can be helpful when symptoms suggest small bowel Crohn’s or deeper complications beyond what a scope can easily see. [2]
MRI enterography prep: what happens, what the drink is like, and contrast side effects
Prep instructions vary by facility, but many centers ask for no food or drink for about 4 hours before the scan (sometimes with exceptions for essential medicines, depending on the site). [3] Screening for metal is a big part of safety, since MRI uses a strong magnet, so clothing without metal and leaving jewelry at home can make check-in smoother.
During most MRE exams, several steps are common:
1. Oral contrast drink: a large amount of liquid is usually taken before the scan to help fill and outline the small bowel.
2. IV (intravenous) line: many protocols use IV contrast to make inflammation easier to see.
3. Medicine to slow bowel motion: a medication may be given to reduce intestinal movement, which can blur images.
4. The scan itself: lying still in the scanner, with short breath-holds at times.
People often wonder what the drink and contrast feel like. Some experience mild nausea, cramping, or diarrhea afterward from the oral contrast or medications used during the test. Allergic reactions to contrast dye are possible, and kidney-related risks are considered when IV contrast is planned, especially if kidney function is reduced. [4]
When IV contrast includes gadolinium, a rare condition called nephrogenic systemic fibrosis has been linked mainly to exposure to certain older gadolinium-based agents in people with advanced kidney disease, and this risk has decreased with newer agents and careful screening. [5]