Magnetic resonance elastography (MRE) is a new way to image the body. It works by combining MRI imaging with sound waves to create a visual map (elastogram) showing the stiffness of body tissues.
MRE is used to detect hardening of the liver caused by many kinds of chronic liver disease. MRE also has the potential to become a noninvasive way to diagnose diseases in other parts of the body.
MRE was invented at Mayo Clinic. The test is available there and at various other centers. 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.
Research shows that MRE is a very effective tool for diagnosing advanced liver fibrosis. 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).
The presence of metal in your body may be a safety hazard or affect a part of the MRE image. Before receiving an 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
- 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. The effects of magnetic fields on fetuses aren't well-understood. Your doctor may recommend choosing an alternative exam or postponing the test.
How you prepare
Before an MRE exam, eat normally and continue to take your usual medications, unless otherwise instructed.
You will be asked to change into a gown and to remove:
- Hearing aids
- Underwire bras
What you can expect
An MRE examination is usually 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 small pad is placed on the surface of your body. The pad emits low-frequency vibrations that pass through your liver. A computer measures the speed at which the vibrations pass through the liver. Vibrations travel faster through stiff tissue.
After the MRE procedure, a computer program creates a color-coded map showing the stiffness of your liver tissue.
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.
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