Magnetic Resonance Enterography (MRE) is a specialized medical imaging procedure designed to capture high-resolution images of the small intestine. MRE uses standard MRI technology, utilizing powerful magnetic fields and radio waves to create detailed cross-sectional pictures of internal anatomy without ionizing radiation. The procedure specifically focuses on the small bowel by employing contrast agents to achieve optimal visualization of the lining, walls, and surrounding structures. MRE is a non-invasive tool that provides physicians with a detailed view of this section of the gastrointestinal tract, which is often challenging to assess using traditional endoscopic methods.
Conditions Diagnosed by MR Enterography
Physicians frequently order MRE to investigate symptoms like chronic abdominal pain, unexplained weight loss, or persistent diarrhea when small bowel pathology is suspected. The test is particularly effective for diagnosing and monitoring inflammatory bowel diseases, such as Crohn’s disease, which commonly affects the small intestine. It allows doctors to evaluate the extent and severity of inflammation in the bowel wall, helping to distinguish between active disease and chronic scarring.
MRE is also valuable for identifying complications associated with inflammatory conditions. This includes locating strictures (areas of abnormal narrowing) or finding fistulas (abnormal connections that form between loops of the bowel or other organs). Beyond inflammatory disease, the procedure can help pinpoint sources of gastrointestinal bleeding that are not accessible by colonoscopy or upper endoscopy. MRE is also used to detect small tumors, polyps, or other lesions within the small bowel wall and surrounding tissues.
Patient Preparation Requirements
MRE requires specific preparation steps designed to distend the small bowel and clear the colon. Patients are instructed to fast from all food and liquid for four to eight hours before the examination. This fasting period is a standard requirement for abdominal imaging studies, ensuring the stomach is empty and improving image quality.
The most distinct part of the preparation involves consuming an oral contrast agent, often a neutral solution like polyethylene glycol or mannitol. This solution fills and distends the small bowel loops, pushing them apart so the radiologist can clearly visualize the entire length of the small intestine. Patients typically drink 1.0 to 1.5 liters of this solution in timed increments over 45 to 90 minutes immediately preceding the scan. This timing ensures the contrast reaches the end of the small bowel when imaging begins.
The MR Enterography Procedure
Once preparation is complete, the patient lies on the table of the MRI scanner, which is a large, tube-shaped machine. Because the MRI machine produces loud thumping and knocking noises during the scan sequences, the technologist provides earplugs or headphones to protect the patient’s hearing. The patient is positioned comfortably, and the table slides into the bore of the scanner.
During the procedure, the technologist administers two types of medication through an intravenous (IV) line placed in the arm. The first is a Gadolinium-based contrast agent, which travels through the bloodstream and enhances the visibility of active inflammation or tumors in the bowel wall and surrounding blood vessels. The second is an antispasmodic medication, such as glucagon, which temporarily slows the natural, involuntary movement of the small bowel. This reduction in motion is performed to minimize blurring on the images, which significantly improves the clarity of the diagnostic pictures. The entire imaging process generally lasts between 30 and 60 minutes, and the patient must remain as still as possible and follow breath-holding instructions for short periods.
Safety Profile and Interpreting the Results
A significant advantage of MRE is its safety profile, especially when compared to imaging techniques that use radiation, such as CT enterography. MRE utilizes strong magnetic fields and radio waves, meaning there is no exposure to ionizing radiation. This is particularly beneficial for younger patients or those with chronic conditions who may require repeated monitoring. Standard MRI safety protocols still apply, meaning the procedure is contraindicated for individuals with certain metal implants, such as pacemakers, cochlear implants, or cerebral aneurysm clips.
Following the scan, a specialized physician called a radiologist analyzes the hundreds of images produced by the MRE. The radiologist looks for signs of inflammation, wall thickening, enhancement patterns, and any structural abnormalities like strictures or fistulas. The radiologist then generates a detailed report summarizing the findings, which is sent directly to the physician who ordered the test. This ordering physician will then discuss the results with the patient, typically within a few days, to determine the next steps for diagnosis and treatment.