Breast magnetic resonance imaging (MRI) is an imaging test that uses magnetic fields and radio waves to create detailed, computer-generated images of your breast tissue.
Why is a breast MRI needed?
This test has many uses:
Screen for breast cancer in people who are at a high risk for the disease or have a personal history of breast cancer.
Diagnose and evaluate breast tumors. An MRI may identify a small mass within a breast better than a mammogram or ultrasound. This is particularly true for very dense, non-fatty breast tissue.
Learn more about a tumor that a doctor feels in the breast but cannot see on a mammogram or ultrasound.
Determine the size of the tumor after an initial breast cancer diagnosis.
Monitor how well chemotherapy is working to treat the cancer by checking to see if the cancer is shrinking.
Find a rupture of a breast implant.
Limitations of using breast MRI for cancer screening
A breast MRI is a highly effective test. However, an MRI is not a replacement for mammography because it may sometimes fail to find cancer that a mammogram detects. A breast MRI may also lead to a "false-positive" result. This means that the test finds a mass or other change that seems to show cancer but it is not cancer. If this happens, your doctor may recommend a targeted ultrasound. If the area is still not seen with the ultrasound, he or she may recommend an MRI biopsy.
How to prepare for a breast MRI
For best results, if you menstruate, you may want to schedule your exam at certain times of your menstrual cycle. For example, the MRI facility may ask you to schedule the procedure during days 5 through 15 of your menstrual cycle. Be sure to discuss this with your doctor.
When you schedule your MRI, you will get detailed instructions on how to prepare. Talk with your health care team about anything that is unclear. Here are some general suggestions:
Tell your doctor about all the medications you are taking. This includes prescription and over the counter drugs, as well as herbs and supplements. Discuss any drug allergies.
Make sure your doctor knows about other medical conditions you have before the test, including kidney or liver problems.
Tell your doctor if there is any chance you may be pregnant.
If you are breastfeeding, let your health care team know. Breastfeeding can impact the clarity of images during an MRI and an MRI may not be the best option for you. Your doctor may recommend waiting until 4 to 6 months after you finish breastfeeding to get your MRI. If your doctor recommends an MRI while you are breastfeeding, you do not need to stop breastfeeding or discard any milk after receiving any contrast medium.
Tell your doctor and the person performing your breast MRI about any metal implants or metal fragments in your body. These can cause serious complications when exposed to the MRI’s strong magnetic pull. People with pacemakers, for example, cannot have an MRI. And, people who have breast expanders that have valves also cannot have an MRI.
Tell your doctor and the person performing your breast MRI about any tattoos.
Consider asking whether you can bring music with you to the scan. Some facilities allow people to listen to music through headphones during this examination to help them relax.
Tell your doctor and technician if you have ever had a reaction to the dye used in the test.
Be prepared to sign a consent form when you arrive for the test. It states you understand the benefits and risks of the breast MRI and agree to have the test done. Talk with your doctor about any concerns you have about the procedure. Not all doctors will require a consent form.
Before the breast MRI
A breast MRI can be done in a hospital or outpatient clinic. A radiologist or radiology technologist may perform the test. A radiologist is a medical doctor who performs and interprets imaging tests to diagnose disease. A radiology technologist is specially trained and certified to perform MRI scans but not interpret them.
You will need to remove all jewelry or other metal objects before the exam. You also may need to change into a hospital gown.
A nurse or doctor will give you gadolinium through an intravenous (IV) line. They will insert a small needle into a vein in your arm or hand. This needle connects to a tube. At first, saline solution flows through the IV line and then gadolinium dye. The dye travels through your bloodstream and helps create a clearer picture of your breasts.
People having a breast MRI for a ruptured implant do not need the dye. For some people, the dye causes allergic reactions. It may also cause complications in people with kidney or liver problems. So, be sure to tell your doctor about any health conditions you may have before the test.
A breast MRI is not painful. But if you receive an IV, the needle injection can be uncomfortable. The saline solution in the IV may cause a cool feeling at the injection site.
You will need to lie still for most of the scan, which could be tiring. The loud sounds coming from the machine may also make you uncomfortable. You may receive earplugs or earphones to wear during the test. If you are concerned about the loud noises, ask your doctor if you can listen to music during the test.
If you have a fear of being in small spaces, tell the radiologist or another member of your health care team beforehand. A doctor may prescribe a sedative to help you relax. Typically, you can take the sedative in advance or bring it with you to the testing location.
What happens during a breast MRI?
The radiologist will help position you on a padded table specially designed for a breast MRI. You will lie face down on your stomach with your arms at your side and your head on a headrest. The table has openings for your breasts so they can be scanned without being squeezed.
The table will then slide into the MRI machine. This machine looks like a large donut with a narrow, tunnel-like opening. Some centers have MRI machines that are more open. These machines can accommodate larger people and help people who are afraid of small spaces.
You will need to lie very still during the 2 to 6 imaging sequences. You will know that the machine is taking images because you will hear extremely loud tapping and knocking sounds.
You will always be in contact with a technician in a nearby room via an intercom. The technician will give you instructions about when to hold your breath during the test. They will remind you to lie still and check to make sure you are comfortable in the machine. Usually, you can relax slightly between each imaging sequence, but you will need to maintain your same body position as much as possible.
Your breasts may feel warm during the MRI. Or you may feel as if you have to urinate during the procedure. This is normal.
The breast imaging session typically lasts about 30 minutes and the appointment should last no more than 90 minutes. Ask your technician what to expect before you begin. When the procedure is complete, you may have to remain on the table while the radiologist reviews the images to determine whether the images are clear. If not, they need to take additional images.
What happens after a breast MRI?
You can expect to resume your normal activities, including driving, after the breast MRI exam, unless you took a sedative. A radiologist reviews the images from your breast MRI and sends them to your doctor. Make sure to provide the testing center with a list of doctors to whom you want your test results sent. Your doctor will discuss the results with you at a follow-up appointment.
You can also ask for a copy of your test results. This may be provided on a disk, along with a written report, that you can take with you to your doctor visits.
Questions to ask the health care team
Before having a breast MRI, consider asking your health care team the following questions:
Do I need an order (prescription) to schedule the test?
Does my insurance provider need to authorize this test beforehand?
Who will perform the exam?
What will happen during the breast MRI?
How long will the procedure take?
Can a friend or family member sit in the MRI room during my examination?
What are the risks and benefits of having a breast MRI?
Is the imaging facility accredited to perform breast MRIs? (Please note that this link takes you to another, independent website.)
When will I learn the results of this test?
Who will explain the results to me?
What further tests may be necessary, depending on the results?
Magnetic Resonance Imaging (MRI)
RadiologyInfo.org: Magnetic Resonance Imaging (MRI) – Breast