MRI/ MR enterography

Magnetic resonance imaging (MRI) is a technique developed in the 1980’s which uses the differential effect of magnetic fields on different atoms and molecules combined with computational wizardry to create images of the body. It has some advantage over CT (and CTE) because it does not expose the patient to radiation. For some organs and structures it can obtain images which are of similar or better resolution to CT scanning. It usually does involve patients having to lie on a couch within the magnet as illustrated below. As such it is not ideal for patients with claustrophobia. Similarly it is often difficult to undertake this test under anaesthetic because it requires the use of special “non magnetic” equipment. Patients with particular implants, metal fragments within their body and pacemakers need to be screened to make sure that their implants are compatible with the scanner.

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Magnetic resonance enterography (MRE) is a special kind of magnetic resonance imaging test designed to examine the small bowel. It is often used to detect and assess Crohn’s disease, bowel strictures, small bowel abscesses and tumours. Protocols vary depending on the institution performing the test but it often involves patients having to drink contrast to help define the bowel. Intravenous contrast may also be used. Often a contrast agent called gadolinium is used, this is an agent which can be used in patients with iodine allergy (unlike many other contrast agents).