What is a breast MRI (magnetic resonance imaging)?
A breast MRI is a type of imaging test that uses magnets, radio waves and computer software to create detailed images of the breast. It’s a diagnostic test for several reasons, from implant leakage to breast cancer screening.
Unlike a mammogram, a breast MRI does not use radiation. Instead, the combination of a magnetic field and a pulse of radiofrequency waves cause atoms in your body to send out signals that are detected by a computer and converted into images. You may also have a special dye, called contrast, to enhance the images. If you need a breast MRI, your care team will guide you through each step so you know what to expect.
Why is an MRI of the breast performed?
You may have a breast MRI to get more detailed images as a follow-up to another imaging test or if you have risk factors. One of the most common reasons for breast MRIs is screening people at high risk for breast cancer or those who have been recently diagnosed with breast cancer.
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Screening for breast cancer
If you’ve been told you’re at high risk for breast cancer, your doctor may order a breast MRI and mammogram to help with yearly screening. Because it’s a different imaging test, it may show early signs of cancer not seen on a mammogram. Sometimes, people with dense breast tissue have a breast MRI to help with breast screening. Regular breast screenings can help give you peace of mind about your breast health, especially if you are at high risk.
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Diagnosing of breast cancer
A breast MRI can give your team more information if you have breast cancer symptoms or a suspicious spot on another imaging test. Regarding imaging tests to diagnose breast cancer, MRIs are typically used after a breast ultrasound or mammogram.
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Determining extent of breast cancer
Your doctor may order an MRI of the breast after you are diagnosed with breast cancer. The test gives your care team more details about your cancer to help create a care plan. This could include deciding whether a lumpectomy or a mastectomy would be the right choice for your care.
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Monitoring response to breast cancer treatment
When you have breast cancer treatment, like chemotherapy, a breast MRI can also help monitor how well your treatment works. Taking MRI images helps your care team see if your tumor is getting smaller, and this guides your following treatment options, such as surgery.
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Other uses of breast MRI
Other breast conditions could also need an MRI to provide your doctor with detailed images of your breast. For example, if you have silicone breast implants and your doctor suspects a leak, an MRI of the breast is one way to diagnose the problem.
What are the risks of a breast MRI?
Breast MRIs are safe, noninvasive imaging tests that give your care team valuable information about your breast health. However, like any test or procedure, there are some risks to having a breast MRI, including false positive results. That’s why a breast MRI isn’t recommended in every case.
A breast MRI can be especially helpful for high-risk breast cancer screening or evaluating breast cancer after a diagnosis. The important benefit of getting the information your team needs to guide your care often outweighs the risks of having an MRI. If you have questions about these risks, talk to your doctor to decide the right choice for you.
A few risks of having an MRI of the breast include:
- Reaction to contrast dye
When you have a breast MRI with contrast, there’s a risk of an allergic reaction, or the contrast may affect those with kidney conditions. Let your team know if you’ve ever had a reaction or sensitivity to contrast or if you have a kidney disorder. - Claustrophobia
Traditional MRI machines are shaped like long tubes; this enclosed space makes some people feel claustrophobic. If you have claustrophobia, talk with your doctor about medications to help you relax. - Metal in the body
Because an MRI of the breast uses strong magnets, you may be unable to have the test if you have specific medical devices containing metal. Talk with your care team if you have a pacemaker, cochlear implants, other electronic devices, or implants like plates, screws, clips or mesh. - False positive results
There is a slight chance that your breast MRI could find a suspicious area that turns out harmless when examined further. This false positive result could cause concern or lead to more testing.
Preparing for a breast MRI
Your doctor will give you specific details on how to get ready for your breast MRI. Some people feel anxious about the enclosed space during an MRI scan. However, newer machines, medications and other relaxation techniques can help you feel more comfortable during your procedure. Talk with your doctor ahead of time about your options.
If you have a menstrual cycle and need an MRI of the breast that isn’t urgent, timing your test with your cycle is helpful. Ask your scheduler about the best time to schedule your breast MRI, typically during the first half of your normal menstrual cycle.
How to prepare for a breast MRI
A breast MRI doesn’t require a lot of preparation ahead of time, but you can do a few things. You’ll generally be able to eat and drink as usual on the day of your procedure. You’ll wear a gown during your test, but take off all jewelry and leave it at home.
Before your MRI, let your care team know if you have:
- Any other medical conditions, including if you might be pregnant or are nursing
- A condition that makes it hard for you to lie down for an extended time or keep your arms above your head
- Any medical devices or implanted metal in your body
- The possibility of traces of metal in your body from a bullet wound or working with metal
- An allergy or a previous reaction to the contrast dye used during an MRI
- Body piercings, permanent eyeliner or tattoos
- A need for medications for claustrophobia
What to expect during a breast MRI
When you arrive on the day of your breast MRI, your care team will talk with you about what to expect and give you a gown to change into. You may also get earplugs to help minimize noise during your exam. Typically, you’ll be at the imaging center for 30 minutes to an hour and a half.
During the procedure itself:
- Your technologist will confirm that you’ve removed all jewelry, hair accessories, dental items, hearing aids, eyeglasses or other metal items.
- You will lie face down on the padded MRI table, which includes a hollow space for your breasts.
- The table will slide into the MRI machine.
- You’ll be asked to lie as still as possible while the MRI machine works.
- You may hear thumping or other noises as magnets and radio waves are used, but you won’t feel them.
- You’ll get an injection of contrast dye for additional images as needed.
- Your imaging technologist will monitor your test in the next room and walk you through each step.
What to expect after a breast MRI
If you had any sedative medications or contrast dye during your breast MRI, your care team will monitor you immediately after your test to ensure you don’t have any side effects. You’ll also need someone to drive you home if you had sedatives. You can generally resume your normal activities once you get home after a breast MRI.
Breast MRI scan results
A radiologist will review the images taken during your breast MRI to create a report with your results. Because MRIs of the breast are ordered for various reasons, your radiology report will have different information based on your specific needs. This report will be sent to the doctor who ordered your MRI scan, and your doctor will contact you to explain the results.
Your radiologist will use a standard system to define and explain your results for breast imaging tests, including breast MRIs, mammograms and breast ultrasounds. This system was created by the American College of Radiology and is called BI-RADS, which stands for Breast Imaging Reporting and Data System.
Breast Imaging Reporting and Data System
BI-RADS uses a scale of 0 to 6. Your doctor will help answer your questions about what your BI-RADS category means. The main categories include:
- 0: Incomplete
- 1: Negative
- 2: Benign
- 3: Probably benign
- 4: Suspicious
- 5: Highly suggestive of malignancy
- 6: Known biopsy-proven malignancy
Breast MRI vs. mammogram
A breast MRI and a mammogram are helpful tools to give your care team a closer look at your breast tissue, but they provide images in different ways. A mammogram is a type of X-ray imaging, while an MRI uses magnets and radio waves. For screening, mammograms are usually the first choice for breast imaging, and a breast MRI is used along with a mammogram in those at high risk.
Because these imaging tests use different approaches, one test may show a specific breast condition or change in another way. For example, mammograms are usually better at detecting breast calcifications. The high-resolution images provided by an MRI are often better for detecting breast masses in those with dense breast tissue.
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Breast MRI
- Uses a magnetic field, sound waves and a computer to create images of the breast
- Usually requires an injection of contrast dye through an IV
- Ordered for high-risk screening, as a follow-up test or for known breast conditions
- Typically, it costs more than a mammogram
- Requires up to 30 minutes or longer to take images
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Mammogram
- Uses X-rays to create images of the breast
- Requires the breast tissue to be compressed to get images
- Recommended for routine screening in those with an average risk
- More affordable testing option
- Requires only a few minutes to get images
Breast MRI and breast cancer screening for women at higher risk
A breast MRI usually isn’t needed for those with an average risk of breast cancer. But if you are at a higher risk for breast cancer, then it may be recommended that you have a yearly breast MRI along with your annual mammogram. Generally, high-risk patients start annual screenings with MRIs and mammograms earlier than age 40.
The images a breast MRI provides give your team a different view of your breast tissue. However, breast MRIs are just one piece of your care, and a mammogram may detect something that an MRI doesn’t pick up. That’s why a breast MRI and routine mammogram imaging are essential for a complete look at your breast health.
Talk to your doctor about whether breast screening with a breast MRI is right for you if have:
- An estimated lifetime risk of breast cancer that’s more than 20%
- A known mutation in your BRCA gene, including BRCA1 or BRAC2
- A mother, father, brother, sister or child with a known BRCA gene mutation
- A known inherited genetic mutation such as PTEN, TP53, PALB2 or STK11
- Radiation treatment in the chest area for other cancers like Hodgkin’s lymphoma between ages 10 and 30
- A genetic disorder that increases your risk, including Cowden syndrome and Li-Fraumeni syndrome
Frequently asked questions
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What organs does breast MRI show?
A breast MRI focuses on showing the breast tissue, but your care team will also be able to see the bones, blood vessels and other organs in your chest area. This includes part of your heart and lungs.
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Can breast MRI detect cancer?
Yes. A breast MRI can detect some signs of breast cancer. Studies show that it is most helpful at detecting spots or signs of cancer in those with dense breast tissue or breast implants and those at high risk for breast cancer.
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How long does a breast MRI take?
A breast MRI appointment can take up to 60-90 minutes, including check-in, prep for the scan and any monitoring afterward. The actual images usually take about 20-30 minutes. If you’re having a breast MRI, set aside an hour and a half for the process.
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Does breast MRI show lymph nodes?
Yes. A breast MRI usually shows the axillary lymph nodes in your armpit area, where breast cancer will likely spread first. However, an MRI may not be sensitive enough to provide the details your care team needs so you may need other imaging for your lymph nodes.
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How accurate is MRI in detecting breast cancer?
Reports show the sensitivity of a breast MRI—or its ability to identify breast cancer correctly—is between 77-96%. That makes it one of the most sensitive imaging tests for breast cancer detection.