Imaging of small intestine with MR enterography (MRE)

by Dr. Dimos Michailidis

Imaging the small intestine by endoscopic methods is a difficult procedure. In particular, for inflammatory diseases of the small intestine, where intravascular stenoses are often present, the use of more modern endoscopic methods, such as the endoscopic capsule, is contraindicated. Transverse MRE or Computed Tomography Enterography (CTE) is a specialized method for the imaging of small intestine. However, MRE has the benefit over CTE on the fact that it does not involve ionizing radiation.

Clinical findings

MRE is most commonly used to evaluate patients with Crohn’s disease. MRE can also pinpoint ileus, small bowel tumors, unexplained small bowel bleeding and abdominal pain in pregnant women and young people.

Preparation for MRE

The patient should be fasting for 8 hours (usually since the night prior to testing). On the day of the test, the medical center’s staff will provide the patient with an amount of 1.5 – 2 liters of laxative solution to consume orally (approximately 1 glass every 10-15 minutes). The test lasts about 20-25 minutes during which the patient is in a prone position, and they are administered with an intravenous contrast agent and an anticonvulsant drug. Finally, the sufficient dilation of the small intestine is the parameter for the successful conduction of the test.

Crohn’s disease

In cases where a method detects a potential Crohn’s disease, such as after screening and / or a positive biopsy on colonoscopy findings in the large intestine and / or the ileum, MRE may reveal further areas of small intestine where the disease is involved.

MRE can assess the activity of the disease by evaluating various imaging factors, such as the degree of wall thickening, the presence of parietal and perienteric edema (high T2 signal intensity), the degree and stromal distribution of the contrast agent, the presence of restricted diffusion, the presence of mesenteric lymphadenitis, and engorgement of the mesenteric vessels (Comb sign). The evaluation of the disease’s activity is an important clinical information for choosing the most appropriate treatment or responding to an existing one.

Furthermore, the correct classification (active inflammation, fibrostenotic or fistula) of intestinal stenosis results in the appropriate treatment. During MRE the imaging signs that indicate fibrostenosis are the compression of the intestinal tract, the marked prosthetic dilatation, and the absence of the aforementioned imaging markers of active inflammation. The presence of these fibrostenotic elements can lead to surgical treatment of stenoses.

MRE also plays a key role in marking the spread of the disease, in the form of fistulas and / or abscesses, which may also influence the therapeutic approach.

In conclusion, MRE is the specialized test for small intestine imaging and for Crohn’s Disease as it can contribute to the initial diagnosis, staging, and classification of the disease.

* FRCR* FRCP, Medical Radiologist Alpha Evresis Diagnostic Center, Bioiatriki Healthcare Group in Cyprus