Magnetic resonance imaging, also called MRI, uses magnets and radio waves to create 3D, cross-sectional images of areas in the body.

Doctors use MRI for a variety of reasons. In general, MRIs may be used to better understand the size of a cancer before starting surgery or therapy, or to learn more about lumps or cancer you can feel but a mammogram does not see. If you have a known breast cancer, an MRI could help find out if you:

  • have other tumors in the same breast
  • have cancer in the opposite breast
  • need further surgery after a lumpectomy with positive margins, meaning the pathologist sees tumor cells at the edge of a sample of your tissue taken during the surgery

MRI can also help monitor how a breast cancer responds to therapy after starting treatment for early-stage or metastatic breast cancer.

This test is also used

  • to check for breast changes in healthy women at high risk for developing breast cancer because of a known BRCA mutation, a strong family history of breast cancer, a history of radiation to the chest between ages 10 and 30 and some other health situations
  • if your doctor suspects a recurrence but a mammogram, ultrasound, and clinical exam don’t provide enough information, and you cannot get a biopsy
  • if your doctor finds something with a mammogram, ultrasound, or clinical exam but they need more information
  • if you have a breast implant and your doctor believes it has ruptured, the implant makes it difficult to perform a mammogram, or you have a suspicious finding that needs further study

In young women and others with dense breast tissue, MRI can find some cancers that can’t be seen with mammography.

MRI is not for everyone. It is much more expensive than mammography and ultrasound. Though it often shows more detailed pictures than other breast imaging tests, MRI can highlight areas of the breast that are not cancer and cause false positive test results and unneeded biopsies. Also, MRI can miss some cancers, so it is often recommended with mammogram and ultrasound.

Outside of large cities, it may be difficult to find MRI centers with machines built especially for taking pictures of the breast. MRI machines are very expensive to buy, use and maintain, so small hospitals may not be able to support the cost.

Getting the test

Before the test, a technician will inject a liquid called contrast solution that travels through your blood to areas that may have an abnormality. Areas with high blood flow, such as tumors, will attract the solution.

You may change into a hospital gown and will be asked to remove metal jewelry, glasses or other objects. Let the radiologist know if you have metal in your body, such as a pacemaker. It’s possible the MRI machine could cause the pacemaker to move, become very hot or even malfunction.

During the MRI test, you will lie on your stomach on a soft table with padded openings for your breasts. The table will be slid inside the MRI machine, which usually looks like a tube with openings at both ends. If you are afraid of narrow or enclosed spaces, find out if an open MRI machine is available, or ask your doctor to give you a mild sedative.

While you are in the machine, you will hear noises that sound like thumping or tapping. Some people find that wearing ear plugs helps block out the noise. The technologist doing your study should provide ear plugs for you if you ask for them.

You should not feel any pain during the test, but you may be uncomfortable from lying on the table. The test should last about 30 to 45 minutes, and you will need to lie very still.


Reviewed and updated: October 7, 2019

Reviewed by: Brian S. Englander, MD


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