Overview
Magnetic resonance elastography (MRE) is a test that combines magnetic resonance imaging (MRI) with low-frequency vibrations to create a visual map called an elastogram. This test shows changes in body tissues caused by disease.
MRE is most often used to detect stiffening of the liver caused by fibrosis and inflammation in chronic liver disease. But MRE also is being tested as a noninvasive way to diagnose diseases in other parts of the body.
MRE technology was invented at Mayo Clinic. The test is available there and at over 2,400 other centers around the world. It's often done as part of a conventional MRI exam.
Why it's done
MRE is used to measure the stiffness of liver tissue. This is done to detect scarring of the liver, called fibrosis, in people with known or suspected liver disease. Scarring increases the stiffness of liver tissue.
Often, people with liver fibrosis don't experience any symptoms. But untreated liver fibrosis may progress to cirrhosis, which is advanced fibrosis and scarring. Cirrhosis can be fatal. If diagnosed, liver fibrosis often can be treated to halt progression and sometimes to reverse the condition.
If you have liver fibrosis, MRE can help gauge the severity of your liver disease, guide treatment decisions and determine how well you are responding to treatment.
The traditional test for liver fibrosis uses a needle to extract a sample of liver tissue, called a biopsy. An MRE scan offers several advantages:
- It's noninvasive and generally safer and more comfortable than a biopsy.
- It assesses the entire liver, not just the portion of liver tissue that is biopsied or evaluated with other noninvasive tests.
- It can detect fibrosis at an earlier stage than can other imaging methods.
- It is effective in people who are obese.
- It can help predict the risk of certain liver complications, including fluid accumulation in the belly, known as ascites.
Risks
The presence of metal in the body may be a safety hazard or affect a part of the MRE image. Before receiving an MRI exam such as MRE, tell the technologist if you have any metal or electronic devices in your body, such as:
- Metallic joint prostheses.
- Artificial heart valves.
- An implantable heart defibrillator.
- A pacemaker.
- Metal clips.
- Cochlear implants.
- Bullets, shrapnel or any other type of metal fragment.
Before you schedule an MRE, tell your healthcare team if you think you're pregnant.
How you prepare
Before any MRI exam, follow the provided instructions. If you are scheduled for an MRE exam of your liver, you will most likely be told not to eat food for at least four hours before the exam, although you may drink water during that time. You should continue to take your usual medicines unless otherwise instructed.
You're asked to change into a gown and to remove:
- Dentures.
- Eyeglasses.
- Hairpins.
- Hearing aids.
- Jewelry.
- Underwire bras.
- Watches.
- Wigs.
What you can expect
An MRE exam is often done as part of a conventional MRI exam. A standard MRI liver exam takes about 15 to 45 minutes. The MRE part of the test takes less than five minutes.
In an MRE exam, a special pad is placed against the body, over a gown. It applies low-frequency vibrations that pass through the liver. The MRI system generates images of the waves passing through the liver and processes the information to create cross-sectional images that show the stiffness of tissue.
Results
A specialist trained to interpret MRE scans, called a radiologist, analyzes the images from your scan and reports the findings to your healthcare team. Someone on your care team discusses any important findings and next steps with you.