Magnetic resonance (MR) enterography is a type of non-invasive imaging procedure used to examine the small intestines, often for suspected inflammation, bleeding, obstructions or other bowel issues. Images are taken with a magnetic field rather than ionizing radiation, common with X-rays and CT scans.
What is MR Enterography?
Using magnetic resonance imaging (MRI) technology, MR enterography involves a magnetic field, radio waves and a computer to display images of the tissues. As with other MRI procedures, the patient will pass through a cylindrical-shaped machine with a magnet at the center; a table passes below.
An electrical current passes through wire coils to create the magnetic field. As the coils generate and receive radio waves, the radio waves line up with the body’s hydrogen atoms. The atoms return to their natural places and the energy they give off is received. These signals become the basis for the images that are displayed on the computer. Typically, images will be taken from multiple angles.
As one significant benefit, MRI technology better differentiates between normal and diseased tissue, compared to X-rays, CT scans and ultrasound. Additionally:
- MRI technology can detect abnormalities behind bones that might otherwise have been obscured and eliminates the need for video capsule endoscopy (VCE).
- Compared to iodine-based dyes, the gadolinium contrast dye is less likely to cause an allergic reaction and, in these rare instances, it’s easily controlled by medication.
- It assists with diagnosing inflammatory diseases like Crohn’s and eliminating radiation makes it ideal for diagnosing younger patients.
On the other hand, the procedure has a few risks due to the magnetic field created, particularly if the patient has an implanted medical device.
Who Should Have This Procedure?
Doctors may recommend MR enterography to detect the presence of:
- Inflammatory bowel diseases
- Crohn’s disease
- Vascular abnormalities
- Bowel obstructions
MR enterography is not always the best imaging procedure for patients with certain metal implants or other foreign metal objects in their bodies. Patients with the following types of medical devices have a greater risk of complications and need to provide documentation for the type of implant and MRI compatibility:
- Cochlear implants
- Certain clips used for brain aneurysms
- Certain metal coils used for blood vessels
- Older cardiac defibrillators and pacemakers
Although objects used for orthopedic surgery do not pose these risks, patients who recently received an artificial joint may need a different imaging exam:
- Iron tattoo dyes
- Tooth fillings
Patients must be able to consume the full amount of oral contrast and remain still during the procedure, following the radiologist’s directions for breathing. Based on these parameters, certain other health conditions may affect or be affected by the imaging procedure:
- Larger-bodied patients
- Irregular heartbeat
- Kidney disease
- Pregnancy – MR enterography should be avoided during the first trimester
MR enterography is performed on an outpatient basis and typically takes 30 to 45 minutes. Prior to the procedure, patients must tell their doctors about any existing health problems, medications used, allergies or recent medical procedures. These conditions include:
- Kidney disease
- Allergic reaction to iodine or gadolinium contrast material
In some cases, a doctor may conduct a prior blood test to assess kidney function or recommend a medication to counteract potential allergic reactions or anxiety.
Patients will be asked to not eat or drink for 4 hours prior to their procedure. Patients are advised to arrive in loose, comfortable clothing and leave all metal objects – including jewelry, electronics, watches, credit cards, piercings, eyeglasses and hearing aids – outside the room. Patients will be asked to change completely out of their clothes, into a gown for the procedure.
Patients may need to drink the oral contrast solution mixed with several glasses of water at a steady pace ahead of time, so the contrast fills the small bowel. Some patients may experience diarrhea, cramping or nausea, and are advised to tell their doctor if these symptoms persist.
As the procedure starts, you will lie down on the exam table and devices with the wire coils may be placed around the area being examined. An IV will be started to administer an intravenous contrast dye.
At this point, the table slides under the magnet in the scanner and the procedure starts. In between each pass, patients may relax but should stay in the same position without moving. You will be asked to hold your breath at times. During the intravenous contrast injection, patients may experience minor discomfort or briefly sense a metallic taste in their mouth.
As this occurs, the radiologist and technologist sit in an adjacent room where the computer is located, observing the images. You’ll be asked to stay in place until all images are taken. At this point, the IV is removed and patients, unless sedated, can resume their day-to-day tasks and normal diet.
Following an MR enterography, the radiologist and your doctor will discuss the images. Based on the results, your doctor may request a follow-up visit or may additional testing.
Has your doctor recommended an MR enterography procedure? Contact us to make an appointment today!