A breast magnetic resonance imaging (MRI) scan is a type of imaging test that uses magnets and radio waves to check for abnormalities in the breast.
An MRI gives doctors the ability to see the soft tissues within your body. Your doctor may ask you to undergo a breast MRI scan if they suspect there are abnormalities in your breasts.
A breast MRI is used to examine your breasts when other imaging tests are inadequate or inconclusive, to screen for breast cancer in women with a high risk of developing the disease, and to monitor the progression of breast cancer as well as the efficacy of its treatment.
Your doctor may also order a breast MRI if you have:
- dense breast tissue
- signs of breast cancer
- family history of breast cancer
- leaking or ruptured breast implant
- lump in the breast
- precancerous breast changes
Breast MRIs are meant to be used with mammograms. While breast MRIs can detect many abnormalities, there are some breast cancers that a mammogram can better visualize.
An MRI is considered a safer alternative to scans that use radiation, such as CT scans, for women who are pregnant. While the radiation levels in CT scans are safe for adults, they aren’t safe for developing fetuses.
There is no evidence to suggest that the magnetic fields and radio waves in a breast MRI are in anyway harmful.
While safer than CT scans, breast MRIs do carry a few considerations:
- “false-positive” results: an MRI does not always distinguish between cancerous and noncancerous growths, therefore it can detect masses that may appear cancerous when they are not. You may need a biopsy to confirm the results of your test.
- allergic reaction to contrast dye: MRIs use a dye injected into your bloodstream to make the images easier to see. The dye has been known to cause allergic reactions, as well as serious complications for people with kidney problems.
Before your MRI, your doctor will explain the test and review your complete physical and medical history. During this time, you should tell your doctor about any medication you may be taking or any known allergies. Tell your doctor if you have any implanted medical devices, as these can be affected by the test.
Tell your doctor if you have had prior allergic reactions to contrast dye or if you have been diagnosed with kidney problems. You should also tell your doctor if you are pregnant, think you may be pregnant, or are breastfeeding. Breast MRIs aren’t considered safe for pregnant women, and nursing mothers should not breastfeed their children for about two days after the test.
It’s also important to schedule your MRI at the beginning of your menstrual cycle. The best time for this is between days seven and 14 of your menstrual cycle.
The MRI machine is in a tight, enclosed space, so you should tell your doctor if you are claustrophobic. The doctor may give you a sedative to help you relax. In extreme cases, your doctor may opt for an “open” MRI, where the machine is not as close to your body. Your doctor can best explain your options.
An MRI machine encompasses a flat table that can slide in and out of the machine. The rounded, wheel-like part is where the magnets and radio waves emit from to produce images of your breast.
Before your scan, you will change into a hospital gown and remove all jewelry and body piercings. If you’re using a contrast dye, an IV will be inserted into your arm so that the dye can be injected into your bloodstream.
In the MRI room, you will lay on your stomach on a padded table. There will be depressions in the table where your breasts will rest. The technician will then slide you into the machine.
The technician will give you instructions on when to hold still and when to hold your breath. The technician will be in a separate room, watching monitors that are collecting images, and therefore these instructions will be given over a microphone.
You won’t feel the machine working, but you may hear some loud noises, such as clacks or thuds, and possibly a whirring noise. The technician may give you earplugs.
The test may take up to an hour. Once the images have been recorded, you can change and leave.
A radiologist will review your breast MRI scan, dictate their interpretation findings, and give the findings to your doctor, who will review them upon receipt of results. Your doctor will be in touch to discuss your results or to schedule a follow-up appointment.
MRI images are black and white images. Tumors and other abnormalities may appear as bright white spots. These white spots are where the contrast dye has collected due to the enhanced cell activity.
If your MRI shows that a mass could be cancerous, your doctor will order a biopsy as a follow-up test. This is the surgical removal of a small sample of tissue from the suspected lump. A biopsy will help your doctor learn if the lump is cancerous or not.