Magnetic resonance elastography

Overview

Magnetic resonance elastography (MRE) is a technology that combines MRI imaging with low-frequency vibrations to create a visual map (elastogram) that shows stiffness of body tissues.

Currently, MRE is used to detect stiffening of the liver caused by fibrosis and inflammation in chronic liver disease. But MRE is also being evaluated 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 1,000 other centers around the world. It's usually done as part of a conventional MRI exam.

Why it's done

MRE measures the stiffness of liver tissue in people with known or suspected liver disease. Liver disease can result in scarring of the liver (fibrosis), which increases the stiffness of liver tissue.

Often, people with liver fibrosis don't experience any signs or symptoms. But untreated liver fibrosis may progress to cirrhosis (advanced fibrosis and scarring), which 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 will respond to treatment.

The traditional test for liver fibrosis uses a needle to extract a sample (biopsy) of liver tissue. An MRE scan offers several advantages:

• It's noninvasive and generally safer and more comfortable than biopsy is.
• It assesses the entire liver, not just the portion of liver tissue that is biopsied or imaged by 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 abdomen (ascites).

Risks

The presence of metal in your 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
• Implantable heart defibrillator
• Pacemaker
• Metal clips
• Cochlear implants
• Bullet, shrapnel or any other type of metal fragment

Before you schedule an MRE, tell your doctor if you think you're pregnant.

How you prepare

Before any MRI exam, follow the instructions that you will be provided. If you are scheduled for an MRE exam of your liver, you will most likely be asked not to eat food for four hours prior to the exam, although you may drink water during that time. You should continue to take your usual medications, unless otherwise instructed.

You will be 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 examination is often done as part of a conventional MRI examination. A standard MRI liver examination takes about 15 to 45 minutes. The MRE part of the test takes less than five minutes.

In an MRE examination, a special pad is placed against your body, over your gown. It applies low-frequency vibrations that pass through your 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 doctor specially trained to interpret MRE scans (radiologist) will analyze the images from your scan and report the findings to your doctor. Your doctor will discuss any important findings and next steps with you.