Breast MRI

What is a breast MRI?

Breast MRI (magnetic resonance imaging) is a type of imaging test that uses a large magnet, radio waves and a computer to produce detailed images of breast tissue. Unlike mammograms, a breast MRI doesn’t use X-rays. Your healthcare provider may use a breast MRI along with a mammogram to screen for breast cancer. They may also use it to biopsy breast tissue to see if cancer is present or how far cancer extends into your breast tissue.

Why would my healthcare provider order a breast MRI?

Your healthcare provider may recommend a breast MRI for several reasons, including:

• As part of breast cancer screening in addition to mammography if you’re at high risk for breast cancer (usually because of a strong family history or genetic mutations like BRCA1 or BRCA2).
• For additional screening if you have dense breasts.
• To evaluate the extent of the cancer in people who have a new breast cancer diagnosis.
• To further evaluate breast abnormalities that are difficult to assess with mammography and breast ultrasound.
• To assess breast implant ruptures or detect breast cancer in people with implants.

Depending on the reason for a breast MRI, the test may require an injection of contrast dye (called gadolinium). For many breast MRIs, a technologist or nurse will place an IV in your arm so they can inject contrast dye during the test. This helps a radiologist see normal and abnormal structures in your breast more clearly. This dye is different from the one used during CT scans (computed tomography scans).

Breast MRI and breast cancer

Providers often recommend this test to provide more detail after diagnosing breast cancer. It can also:

• Measure the extent of the cancer and see if it extends into your nipple, skin or underlying chest wall muscle.
• Look for other cancers or abnormal tissue in your breast. MRI is better at detecting small lesions that mammography may miss.
• Check if you have any large lymph nodes in your armpit, which can be a sign that the cancer has spread (metastasized) to that area.
• Monitor the progress of breast cancer treatment, especially chemotherapy to shrink the tumor before surgery.

Breast MRIs may also help your healthcare provider evaluate lumpectomy sites in the years following breast cancer treatment. This is because scarring and recurrent breast cancer can sometimes look similar on mammography and ultrasound.

How do I prepare for a breast MRI?

Before your breast MRI, it’s important to tell your radiologist or radiology technologist if you:

• Are pregnant or breastfeeding (chest feeding). This is important because you can’t get an MRI with contrast if you’re pregnant. Breastfeeding can affect the way your MRI looks.
• Are unable to lie on your stomach for 30 to 60 minutes.
• Have had an allergic reaction to a contrast dye in the past.
• Have claustrophobia (fear of enclosed spaces). You may be able to take a sedative to help you relax for the exam.

If you have metal-containing objects or implanted medical devices in your body, your healthcare team needs to know about them before your exam. Please tell your provider and MRI technologist if you have any of the following:

• Heart pacemaker/defibrillator.
• Electronic/implanted stimulators or devices, such as a vagus nerve stimulator.
• Cochlear implant or other ear implants.
• Aneurysm clips and coils.
• Stents not located in your heart.
• Filters, such as blood clot filters.
• Metal fragments in your body or eye, such as bullets, metal shrapnel or shavings, etc.

You won’t be able to wear the following devices during your MRI:

• Continuous glucose monitor (CGM).
• Insulin pump.
• Medication patches like birth control or nicotine patches.

Talk to the provider you see for these devices to find out what they recommend you do for the MRI.

What should I expect during a breast MRI?

During a breast MRI, you can expect the following:

1. You’ll change into a medical gown.
2. If you’re getting the MRI for anything other than examining a breast implant, a provider will insert an IV line into a vein in your arm to inject the contrast dye during the exam.
3. You’ll lie face down on a table that has openings for your breasts. The technologist will help you get into the correct position for the test. Let them know if you’re uncomfortable.
4. The technologist will move the table into the magnet of the MRI machine. They’ll perform the imaging test with a computer while watching you through a window in a different room. You’ll be able to talk to the technologist via an intercom if needed.
5. While the machine is taking images, it’s important to remain as still as possible to ensure the images aren’t blurry. The MRI machine will make a loud banging noise throughout the entire exam. This means the machine is working properly. The technologist will give you earplugs to help you through the exam.
6. If your MRI test requires a contrast dye, the technologist will inject it after the first series of scans. They’ll take more images during or after the injection.
7. Once the test is done, the technologist may ask you to wait while the radiologist checks the images in case they need more.
8. Once they’ve taken enough pictures, the technologist will remove your IV line and place a bandage over the site. The test is now over.

What should I expect after my breast MRI?

You can resume your usual activities after a breast MRI. But if your exam was an MRI breast biopsy, follow the at-home instructions your provider gives you. If you took a sedative for your exam, you’ll need someone else to drive you home.

How long does a breast MRI take?

Although many facilities plan for 40 to 60 minutes for a breast MRI, the scan itself lasts about 20 minutes. The extra time is for screening questionnaires, IV placement and proper positioning for the exam.

What are the risks of a breast MRI?

There’s very little risk to getting a breast MRI if you and your technologist follow the safety guidelines. The possible risks are:

• Allergy to contrast dye: There’s a chance you might have an allergic reaction to the contrast dye, but this is rare. Reactions are usually mild, and your healthcare team will quickly treat it if it happens.
• False positives: An MRI is extremely sensitive, so false positives are possible. This means it may identify tissue as irregular when it’s not. In any case, if a radiologist sees something in your breast tissue that doesn’t look normal, they’ll order additional tests to determine exactly what the finding is.

What type of results do you get from a breast MRI?

Depending on whether you got a breast MRI for screening purposes, diagnostic purposes or to evaluate known cancer, your MRI report may look different. In any case, the healthcare provider who ordered the breast MRI will discuss your results with you.

All radiologists use the same standardized system to describe screening and diagnostic breast imaging results. This system is called the Breast Imaging Reporting and Data System (BI-RADS). It categorizes results on a scale of 0 through 6.

When should I know the results of my breast MRI?

The results of your MRI will be available in your electronic medical records account (if you have one) and should be available to the healthcare provider who ordered the test within one to two business days. Your provider will discuss the results with you.

What is the difference between a breast MRI and a mammogram?

Healthcare providers use mammograms and breast MRIs to help detect breast cancer and other breast abnormalities.

Mammograms are usually the first option for screening and diagnosis of breast cancer, particularly as mammograms are the only imaging test able to reliably identify microcalcifications — an early sign of some breast cancers.

There are also differences in how the two imaging tests work.

Is a breast MRI better than a mammogram?

One isn’t better than the other. Rather, they have different purposes. Mammograms are the gold standard for breast cancer screening. MRIs may be helpful in addition to mammograms for people with a high risk of breast cancer or who receive a breast cancer diagnosis. Your healthcare provider can discuss which test they recommend based on your situation.