Breast MRI Scans
A breast MRI is mainly used for women who have been diagnosed with breast cancer, to help measure the size of the cancer, look for other tumors in the breast, and to check for tumors in the opposite breast. For certain women at high risk for breast cancer, a screening MRI is recommended along with a yearly mammogram. MRI is not recommended as a screening tool by itself because it can miss some cancers that a mammogram would find.
Although MRI can find some cancers not seen on a mammogram, it’s also more likely to find something that turns out not to be cancer (called a false positive). False-positive findings have to be checked out to know that cancer isn’t present. This means more tests and/or biopsies. This is why MRI is not recommended as a screening test for women at average risk of breast cancer, because it would mean unneeded biopsies and other tests for many of these women.
What you need to know about getting a breast MRI
Just as mammograms are done using x-ray machines specially designed for the breasts, breast MRI also requires special equipment. This MRI machine is called an MRI with dedicated breast coils. Not all hospitals and imaging centers have dedicated breast MRI equipment. It’s important to have your screening MRI at a facility with dedicated equipment that can do an MRI-guided breast biopsy. Otherwise, if a biopsy is needed, the MRI will need to be repeated at another facility.
MRI uses strong magnets instead of radiation to make very detailed, cross-sectional pictures of the body. An MRI scan takes pictures from many angles, as if someone were looking at a slice of your body from the front, from the side, or from above your head. MRI creates pictures of soft tissue parts of the body that are sometimes hard to see using other imaging tests.
Tips for getting ready for the test
Check with your insurance company before getting an MRI: Breast MRI costs a lot, and may need to be approved by your insurance company before the scan is done. Most private insurance plans that pay for mammogram screening also pay for MRI as a screening test if a woman can be shown to be at high risk. It might help to go to a center with a high-risk clinic, where the staff has experience getting approval for breast MRIs.
Follow all instructions: You don’t usually need a special diet or preparation before an MRI, but follow any instructions you’re given.
If you have trouble with enclosed spaces: If being in an enclosed space is a problem for you (you have claustrophobia), you might need to take medicine to help you relax while in the scanner. Talking with the technologist or a patient counselor, or getting a tour of the MRI machine before the test can help. You’ll be in the exam room alone, but you can talk to the MR technologist, who can see and hear what’s going on. In some cases, you may be able to have the test done with an open MRI machine that allows more space around your body.
Remove metal objects: Before the test, you will be asked to undress and put on a gown or other clothes without zippers or metal. Be sure to remove any metal objects you can, like hair clips, jewelry, dental work, and body piercings.
If you have metal in your body: Before the scan, the technologist will ask you if you have any metal in your body. Some metallic objects will not cause problems, but others can.
If you have any of these types of medical implants, you should not even enter the MRI scanning area unless told to do so by a radiologist or technologist who knows you have:
- An implanted defibrillator or pacemaker
- Clips used on a brain aneurysm
- A cochlear (ear) implant
- Metal coils inside blood vessels
What’s it like to get a breast MRI?
MRI scans are usually done on an outpatient basis in a hospital or clinic. You’ll lie face down on a narrow, flat table. Your breasts will hang down into an opening in the table so they can be scanned without being compressed. The technologist may use pillows to make you comfortable and help keep you from moving. The table then slides into a long, narrow cylinder.
The test is painless, but you have to lie still inside the narrow cylinder. You may be asked to hold your breath or keep very still during certain parts of the test. The machine may make loud, thumping, clicking, and whirring noises, much like the sound of a washing machine, as the magnet switches on and off. Some facilities give you earplugs or headphones with music to help block noise out during testing.
The most useful MRI exams for breast imaging use a contrast material that’s injected into a vein in the arm before or during the exam. This helps to clearly show breast tissue details. The contrast material used for an MRI exam is called gadolinium. (It’s not the same as the contrast dye used in CT scans.) Let the technologist know if you have any kind of allergies or have had problems with any contrast or dye used in imaging tests in the past.
It’s important to stay very still while the images are being made, which only takes a few minutes at a time. Tell the technologist if you need to move or take a break.
Breast MRI scans can usually take between 45 and 60 minutes. After the test, you may be asked to wait while the pictures are checked to see if more are needed.
Bruening W, Uhl S, Fontanarosa J, Reston J, Treadwell J, Schoelles K. Noninvasive Diagnostic Tests for Breast Abnormalities: Update of a 2006 Review [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2012 Feb. Available from http://www.ncbi.nlm.nih.gov/books/NBK84530/
Last Medical Review: June 1, 2016 Last Revised: August 18, 2016