MR enterography

Last revised by Daniel J Bell on 10 Apr 2024

MR enterography (MRE), also known as MRI small bowel study, is a non-invasive technique for the diagnosis of small bowel disorders.

Note: This article is intended to outline some general principles of protocol design. The specifics will vary depending on MRI hardware and software, radiologist's and referrer's preference, institutional protocols, patient factors (e.g. allergy), and time constraints. 

MR enterography, in an analogous way to CT enterography, is most commonly used to evaluate patients with Crohn disease where it is used for assessment of the primary disease and any complications. Other indications include celiac disease, postoperative adhesions, radiation enteritis, scleroderma, small bowel malignancies, and polyposis syndromes.

  • no ionizing radiation

  • excellent soft tissue contrast resolution

  • images can be acquired in customized planes

  • longer scanning time 

  • more susceptible to motion and breathing artefacts

  • MRI incompatible implants or devices may preclude the scan

  • abstinence from all food and drink for 4-6 hours prior to the study

  • oral administration of 1-1.5 L of 2.5% mannitol solution at regular intervals over a period of approximately 40 minutes prior to the study

    • hyperosmolar mannitol draws fluid into the bowel

    • provides biphasic improved MRI soft tissue contrast:

      • low signal intensity on T1-weighted images

      • high signal intensity on T2-weighted images

  • comprehensive MR examination of the small bowel usually requires axial and coronal T1 and T2 weighted images

  • high-resolution ultra-fast sequences such as true fast imaging with steady-state precession (true FISP)

  • HASTE sequence or other T2 with fat suppression

  • fat-suppressed three-dimensional (3D) T1-weighted breath-hold gradient-echo images of the abdomen and pelvis before and after intravenous gadolinium-based contrast material administration

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