What Is a Breast MRI?

Breast magnetic resonance imaging (MRI) is a type of imaging used to produce highly detailed views of breast tissue. It uses a combination of magnetic and radio waves to create a computerized picture of the structures of the breast.  

Although a breast MRI can give a very detailed view, it is typically not used as a substitute for a mammogram. It can sometimes be used to screen for breast cancer in high-risk women. Most commonly, breast MRI is used in the diagnosis and staging of breast cancer.

This article discusses the purpose, risks, and contraindications of a breast MRI. It also explains what to expect if your healthcare team recommends this test for you.

Purpose of Test

Magnetic resonance imaging (MRI) is an imaging technique that is done from the outside of the body (noninvasive). It is completed without exposing you to radiation or breast compression. MRI provides far greater detail of soft tissues compared to an X-ray, computed tomography (CT), or ultrasound.

A breast MRI is typically used in women who have already been diagnosed with cancer. It can help measure the size of a tumor and check for tumors in the opposite breast. A breast MRI can also be used for breast cancer screening or to monitor your health after cancer treatment.

Screening

According to the American College of Radiology and the Society of Breast Imaging, annual (yearly) mammograms are recommended for average-risk women starting at age 40.

For women with a high risk of breast cancer, a breast MRI may be used as an additional screening tool. According to the American Cancer Society, high risk is defined as:

• Having the BRCA1 or BRCA2 gene mutation
• Having a first-degree relative (a parent, sibling, or child) with the BRCA1 or BRCA2 mutation
• Having had chest radiation between the ages of 10 and 30
• Having (or having a first-degree relative with) Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, which predispose to cancer
• Having a greater than 20% lifetime risk of breast cancer (using a risk assessment tool like the Gail Model designed by scientists at the National Cancer Institute)

Other health risks for breast cancer may be factored in by your provider, including a previous history of cancer or precancer, a family history of breast or ovarian cancer, or having especially dense breasts (which can make imaging on a mammogram difficult).

A type of MRI called fast breast MRI, also known as abbreviated MRI (AB-MRI), is being researched as a possible cancer screening tool for average-risk women. MRI has been found to have a higher initial cost, but also to be more effective in identifying cancer.

Although there have been suggestions that fast MRI systems will one day replace mammograms, they are not part of current screening guidelines. Until prices come down and false-positive rates improve, that is unlikely to happen, according to researchers from the NYU School of Medicine.

Diagnosis

A breast MRI is a vital tool in the diagnosis and staging of cancer. It is commonly used when a hard-to-assess abnormality is detected on a mammogram. This may be because breast tissue is especially dense (a situation common in younger women, women with a low body mass index, or those taking hormone therapy for menopause).

Breast MRI may be used for other reasons, including:

• Determining the extent of cancer after a new diagnosis
• Staging cancer based on a tumor's size, location, and other factors
• Evaluating tumor size after neoadjuvant chemotherapy (chemotherapy that's intended to shrink a tumor prior to surgery)
• Monitoring lumpectomy sites in the years following breast cancer treatment 
• Examining breast implants for leakage or rupture

A breast MRI is also effective at finding cancer in the opposite breast, which would allow for early treatment of both tumor sites at once.

Risks and Contraindications

A breast MRI is considered a safe procedure with few side effects. 

Some imaging tests use contrast given intravenously (through an IV) to enhance the quality of the image results. For MRI, the heavy metal gadolinium is typically used. Contrast helps show the difference between types of body tissues and gives more detail. 

Gadolinium is not considered toxic and an MRI with contrast does not expose you to radiation. A small percentage of people are allergic to gadolinium. Notify your healthcare provider and the MRI staff if:

• You have kidney disease or kidney problems.
• You are pregnant (or think you might be pregnant).
• You have had MRI with gadolinium contrast before.

Although an MRI is not contraindicated during pregnancy, you need to inform the technologist if you are pregnant. According to 2016 guidelines (reaffirmed in 2019) from the American College of Obstetricians and Gynecologists (ACOG), the use of gadolinium should be limited during pregnancy due to a lack of research on its safety.

Because MRIs use powerful magnets, you need to tell your healthcare provider about any metals you may have in or on your body. While artificial joints, brain shunts, and artificial heart valves are often considered safe, others may be problematic based on the metal type.

Possible contraindications include:

• Heart pacemaker or defibrillator
• Cerebral aneurysm clip (used to prevent the rupture of a blood vessel in the brain)
• Implanted medication pump
• Implanted TENS nerve stimulator
• Cochlear ear implant
• Implanted spinal stabilization rod
• Metal dental work
• Metal eye socket
• Intrauterine device (IUD)
• Inferior vena cava (IVC) filter or stent
• Tissue expander with magnetic port following mastectomy

Typically, you will be asked questions about possible implanted devices and other screening questions to ensure it is safe for you to be near the magnet. Be sure to bring any device cards or information about your medical history.

Before the Test

If a breast MRI is recommended, tell your healthcare provider if you are claustrophobic or if you experience anxiety in closed spaces. Unlike some newer MRI units, which have open sides, breast MRIs are enclosed. If needed, your healthcare provider can prescribe a mild sedative like Valium (diazepam), Xanax (alprazolam), or Ativan (lorazepam) to help you relax.

Some facilities will prefer to schedule the MRI between days 7 and 14 of your cycle. When scheduling the appointment, let the facility know where you are in your cycle so that optimal timing can be scheduled.

Timing

The scanning portion of the MRI will take around 30 to 60 minutes to complete. With the gadolinium infusion and the time it takes to change in and out of your clothes, expect to spend at least two hours at the facility.

Location

MRIs are performed at hospitals or specialized imaging centers and generally require an order from your healthcare provider. You will be in one room for the actual scan, while the MRI technologist will operate the machine and capture images from an adjacent control room. You will be able to communicate with the technologist via a two-way speaker.

What to Wear

Prior to the infusion and MRI scan, you will be asked to change into a hospital gown. While there may be a locked facility to store your belongings, try to leave any valuables at home.

You should also avoid wearing metal of any sort to the test center. While the focus of the scan will be on the breasts, your entire body will go inside the tube. As such, you will need to take care not to bring the following into the MRI room:

• Jewelry
• Watches
• Hearing aids
• Hairpins
• Zippered pants
• Dentures
• Body piercings
• Cell phones
• Credit cards (which can demagnetize)

If at all possible, leave these items at home.

Food and Drink

You can eat and drink as you normally would prior to a breast MRI. You can also take daily medications as usual. If your provider gives you different instructions, please follow them.

Cost and Health Insurance

MRIs tend to be pricey and insurance coverage can vary. A 2018 research study found that the average cost of a breast MRI was $1,197.

If you have insurance, check to ensure that the facility is an in-network provider. Out-of-network providers almost always cost more.

If you are paying out of pocket, shop around for the best price. You can also ask the facility if they offer a monthly payment plan or a discount for upfront payment.

What to Bring

You will need to bring your ID and insurance card with you. If you intend to use a mild sedative, bring someone along who can drive you home after the MRI.

During the Test

For this test, you will be working with an MRI technologist who will perform the scan and provide you with instructions. A nurse may also be present to assist.

Pre-Test

Upon arrival, you will be provided with a consent form and a medical history questionnaire. If you plan to take a mild sedative, discuss your plan with the MRI team. It generally takes between 20 and 40 minutes to feel the sedative effect.

Once the documents have been completed, you will head to a changing room. Most of the time, you will be asked to change into a hospital gown. You will need to take off any and all removable metal objects. The staff will let you know where you can store your personal belongings.

You will then be led to an examining room where the technologist or nurse will review your medical history and allergies, and check your heart rate, temperature, and blood pressure. If you are prone to claustrophobia or have taken a sedative, let the medical staff know at this time.

A tourniquet will then be placed on your arm and an IV line inserted into either your arm or hand. You will then go to the MRI room for the test.

Throughout the Test

Upon arrival, you will be seated on the MRI table, which glides in and out of a tube-like chamber. A normal saline solution with heparin, an anticoagulant, will be delivered through the intravenous line to prevent clotting. The gadolinium agent will then be administered.

You will then be positioned facedown with your breasts inserted into hollow depressions in the table, which house donut-shaped coils that act as signal receivers for the imaging process. Your arms will be placed above your head and your face will rest in the table's padded face cradle, similar to the hole in a massage table.

The technologist will then use remote controls to slide your body into the MRI tube, communicating with you via the two-way speaker. The unit will make loud thumping and whirring noises as the magnet switches on and off while capturing images. Some facilities may provide you with headphones or earplugs to help block out the noise.

Post-Test

Once the test is complete, you will need to wait until the technologist confirms that all of the images are clear and readable. If required, you may be asked to repeat certain images. Once those are approved and the IV line is removed, you can return to the dressing room to change.

Unless you have taken a sedative, you can leave once you are dressed. Some facilities may ask you to sign out. If you have taken a sedative, do not drive yourself home. If you did not pre-arrange a ride, ask the office staff to help you call a taxi.

After the Test

Generally speaking, there are no after-effects of a breast MRI procedure. You may have pain, redness, or bruising at the IV injection site. On rare occasions, you may experience an allergic reaction to the gadolinium solution. Most cases are mild.

Although anaphylactic reactions to gadolinium are rare (occurring in 0.0004% of cases, according to a 2016 study from Italy), they can be life-threatening unless treated immediately.

If you were given gadolinium and are nursing, some healthcare providers will tell you to wait 24 hours before breastfeeding. However, ACOG says that there is no need to interrupt breastfeeding after a gadolinium infusion. Discuss any plans to breastfeed with your medical team.

Interpreting Results

Once the technologist approves the MRI images, they send them to a radiologist for review and interpretation. A copy of the scans and the radiologist's report will be sent to your healthcare provider, usually within a few days to a week.

A typical radiology report will include a detailed list of scans along with a classification of findings (usually normal, abnormal, or potentially abnormal). The radiologist will also interpret the findings and the likely diagnoses. If the results are inconclusive, the report may include other possible causes to explore (referred to as differential diagnoses).

Follow-Up

An MRI can provide strong evidence of a condition such as cancer but cannot usually provide a definitive diagnosis on its own. A biopsy is the only test that can officially diagnose breast cancer.

If used for cancer staging, pre-surgical assessment, or post-treatment evaluation, an MRI can provide valuable information to help direct medical care.

If a finding is abnormal, potentially abnormal, or inconclusive, your healthcare provider may recommend additional tests to either reach a definitive diagnosis or explore the extent of a cancer.

These may include:

• A repeat breast MRI
• Other imaging tests, such as X-ray, CT, or ultrasound
• Breast biopsy, which might be done with fine-needle aspiration, core needle biopsy, or open (surgical) biopsy
• Positron-emission tomography (PET) to help stage the cancer
• Magnetic resonance angiography (MRA) to assess blood circulation in the breast

A breast MRI may be performed for screening purposes yearly along with a mammogram if you are at increased risk of cancer. Your healthcare team will review the current screening guidelines and make you aware of their recommendations.

Summary

Breast MRI is typically used for diagnosis of a potential breast cancer that was spotted on a mammogram. In certain situations, such as in high-risk women, it may also be a helpful screening tool. There is little preparation you need for the test. It takes about an hour, and you should hear about your results in a few days.

A Word From Verywell

However safe it may be, a breast MRI can cause distress and anxiety. In most cases, it will only be ordered if there is a cause for concern. This shouldn't suggest that having a breast MRI means that you have cancer or will likely get cancer. It is simply one of many tools used when other tests cannot provide enough information.