Breast magnetic resonance imaging (MRI) is a test used to detect breast cancer and other disorders and diseases of the breast.
A breast MRI takes multiple images of your breast to be combined using a computer to create detailed images.
A breast MRI is usually done after a positive cancer biopsy result, as your doctor needs additional information about the extent of the disease. For some women, breast MRI may be used, along with a mammogram, as a screening tool for breast cancer. This group includes women with a higher risk of breast cancer, a family history of breast cancer, or a hereditary genetic mutation for breast cancer.
The purpose of breast MRI
A breast MRI is used to evaluate breast cancer and to screen for breast cancer in women with a higher risk of developing the disease.
Your doctor may recommend a breast MRI in the following cases:
- If you have been diagnosed with breast cancer and your doctor wants to determine the extent of the cancer
- If you have a high risk of developing breast cancer, which is defined as a lifetime risk of 20% or more, as calculated by risk calculation tools, including family history and other risk factors
- If the mammogram showed hard-to-assess abnormalities
- If you have a suspected leak of a breast implant
- You had radiation therapy to your chest area before age 30
If you are not sure if you are at high risk, ask your doctor to help you determine your risk estimate for breast cancer. Consulting with a breast health specialist can help you better understand the risk of your condition and the appropriate screening options for it.
A breast MRI can be used with a mammogram or other imaging tests, but not as a substitute for a mammogram. Although breast MRI is a sensitive test, some types of breast cancer detected by a mammogram can still be missed.
How to prepare for a breast MRI
To prepare for a breast MRI, you will need to take the following steps:
- Schedule an MRI for the beginning of your menstrual cycle. If you are premenopausal, your doctor may prefer to schedule your MRI scans at a specific time during your menstrual cycle, roughly from day three to fourteen. The first day of menstrual bleeding is the first day of your period. Let the doctor know where you are in your period so that the optimal timing for your breast MRI can be scheduled.
- Inform your doctor about any allergies or allergic reactions you have. Most MRI procedures use a dye, usually given through a vein in your arm, to facilitate the interpretation of the images. Tell your doctor about any allergies you have to avoid complications with the dye.
- Tell your doctor if you are pregnant. MRI is generally not recommended for pregnant women because of the potential risk of gadolinium contrast to the fetus.
- Tell your doctor if you are breastfeeding. Your doctor may recommend that you stop breastfeeding for two days after the MRI; this will give your body sufficient time to get rid of the contrast dye. You can pump out and discard your milk during this time. Before the procedure, you can withdraw and store milk to feed your baby.
- Avoid wearing metallic accessories during the MRI. An MRI scan can damage metal objects such as jewelry, hairpins, and watches.
- Leave metallic items at home or remove them before the MRI.
- Inform your doctor about implanted medical devices. Tell your doctor before an MRI if you have any implanted medical device, such as a pacemaker, defibrillator, implanted portal drug catheter, or an artificial joint.
What you can expect during a breast MRI
When you arrive for your appointment, a member of our breast care clinic will give you a gown to wear. You will receive instructions on removing clothing and accessories. If you have a fear of small confined spaces, tell your doctor before the MRI. You may be given a mild sedative to help you relax.
Before an MRI, a dye (contrast agent) may be injected through a vein in your arm to make tissue or blood vessels more easily visible on the MRI images.
The MRI machine has a large central opening. During an MRI scan, you lie face down on a cushioned scanning table. Your breasts fit into a specific space in the table, which contains coils that detect magnetic signals from the MRI machine. Then the entire table slides into the opening of the machine.
An MRI machine creates a magnetic field around you and emits radio waves directed at your breasts. You will not feel the magnetic field or radio waves, but you may hear loud noises emerging from inside the machine. Due to the loud noise, you may need to wear earplugs.
The technician will watch you during the test from another room, and you can talk to the technician through a microphone. You will be asked to breathe normally but remain lying down as still as possible.
A breast MRI may take 30 minutes to 1 hour.