Breast MRI

A breast MRI (magnetic resonance imaging) is a medical imaging test that uses strong magnets and radio waves to create detailed pictures of your breast tissue. Unlike X-rays, it does not use radiation. It is often used for breast cancer screening in high-risk individuals, to evaluate a new cancer diagnosis, or to check breast implants, providing information that other tests might miss.

What is Breast MRI?

Breast MRI (magnetic resonance imaging) is a medical test that uses strong magnets and radio waves to create very detailed pictures of the inside of your breasts. Unlike X-rays or CT scans, it does not use radiation. It helps doctors find changes in breast tissue that might not be visible with other imaging methods, offering a comprehensive view of the breast.

An MRI machine works by creating a powerful magnetic field around your body. This field temporarily aligns the water molecules in your cells. Then, radio waves are pulsed through your body, knocking these aligned molecules out of position. When the radio waves are turned off, the molecules relax back into alignment, releasing energy. A computer detects this released energy and uses it to create highly detailed, cross-sectional images of your breast tissue. These images can show soft tissues, such as glands, fat, and ducts, with great clarity. Often, a special contrast dye called gadolinium is injected into a vein during the MRI. This dye travels through your bloodstream and can highlight areas with increased blood flow, which may indicate abnormal tissue. Breast MRI is often used as a complementary tool to other breast imaging tests, such as mammograms (X-rays of the breast) and ultrasounds (sound wave imaging). It provides different types of information and is particularly good at distinguishing between different types of soft tissue, making it valuable for specific diagnostic and screening purposes.

Why it's ordered

A breast MRI is ordered for several reasons, often when other tests like mammograms or ultrasounds need more clarity or when a person has specific risk factors. It's commonly used for breast cancer screening in individuals with a high risk of the disease, to assess the extent of cancer after a diagnosis, or to check the integrity of breast implants.

One primary reason for ordering a breast MRI is for breast cancer screening in individuals considered to be at high risk. This includes people with a strong family history of breast cancer, known genetic mutations like BRCA1 or BRCA2, or a personal history of certain breast conditions. For these individuals, an MRI can detect cancers that might be missed by mammography, especially in those with dense breast tissue. If breast cancer has already been diagnosed, an MRI can help doctors determine the exact size and location of the tumor, check for additional tumors in the same or opposite breast, and see if the cancer has spread to nearby areas. This information is crucial for planning treatment, such as surgery or radiation therapy. It can also be used to monitor how well chemotherapy is working. Another important use of breast MRI is to evaluate the condition of breast implants. It can effectively detect ruptures or leaks in both silicone and saline implants, even when there are no obvious symptoms. Additionally, an MRI may be ordered to investigate suspicious findings from other imaging tests, to further evaluate a lump or abnormality, or to differentiate between scar tissue and recurrent cancer after treatment.

How to prepare

Preparing for a breast MRI usually involves discussing your medical history and any allergies with your doctor, especially if you have kidney problems or metal implants. You will likely be asked to avoid caffeine before the test and may need to schedule it during a specific time in your menstrual cycle if you are premenopausal. Following these instructions helps ensure clear images.

Before your breast MRI, it's very important to inform your doctor and the MRI technologist about your complete medical history. This includes any allergies, particularly to contrast dyes, and any kidney problems, as the contrast dye used can affect kidney function. You must also disclose all metal implants or objects in your body, such as pacemakers, cochlear implants, artificial joints, surgical clips, or even shrapnel, as the strong magnetic field can interfere with or damage them. You will typically be asked to wear loose, comfortable clothing to your appointment. Before the scan, you will likely change into a hospital gown. It is crucial to remove all metal objects, including jewelry, hairpins, eyeglasses, hearing aids, and any removable dental work, as these can interfere with the MRI images and pose a safety risk. You may also be asked to avoid food or drink for a few hours before the test, and sometimes caffeine is restricted. If you are a premenopausal woman, your doctor might recommend scheduling the MRI during a specific time in your menstrual cycle, usually between days 7 and 14, as hormonal changes can affect breast tissue and image clarity. Always inform your doctor if you are pregnant or breastfeeding, as special precautions or alternative tests may be considered. If you experience claustrophobia (fear of enclosed spaces), discuss this with your doctor beforehand, as sedation might be an option.

What to expect during

During a breast MRI, you will lie face down on a padded table with openings for your breasts. The table then slides into a large, tunnel-shaped scanner. You'll need to stay very still for 30 to 60 minutes while the machine makes loud knocking noises. A contrast dye is often given through an IV in your arm to improve image clarity and highlight specific areas.

When you arrive for your breast MRI, you will be asked to change into a gown and remove all metal objects. The technologist will position you on a padded table, usually lying face down. Your breasts will rest comfortably in special cushioned openings or coils designed to hold them in place and help capture clear images. This positioning is important for the quality of the scan. The table will then slide into the MRI machine, which is a large, tunnel-shaped scanner. During the scan, the machine will make loud knocking, buzzing, and clicking noises as the magnets and radio waves operate. You will be given earplugs or headphones to help reduce the noise. It is very important to remain as still as possible throughout the entire procedure, which typically lasts between 30 and 60 minutes, to avoid blurring the images. In most breast MRIs, a contrast dye called gadolinium is injected into a vein in your arm or hand through an intravenous (IV) line. This dye helps to make certain tissues and blood vessels show up more clearly on the images, which can be particularly useful for identifying abnormal areas. The technologist will be in an adjacent room but can communicate with you through an intercom and will be able to see you at all times. You will also have a call button to alert them if you need assistance.

Understanding your results

After your breast MRI, a radiologist (a doctor specializing in medical imaging) will carefully interpret the detailed pictures and send a report to your referring doctor. Your doctor will then discuss the findings with you, explaining what they mean in the context of your overall health and medical history. It's important to remember that an abnormal finding does not always mean cancer.

Once your breast MRI is complete, the images are sent to a radiologist. This doctor has specialized training in interpreting medical images and will analyze the hundreds of pictures taken during your scan. The radiologist looks for any areas that appear unusual or different from normal breast tissue. They will then prepare a detailed report summarizing their findings and send it to the doctor who ordered your MRI. Your referring doctor will then review the radiologist's report and discuss the results with you. They will explain what the findings mean for your specific situation, taking into account your medical history, any symptoms you have, and the results of other tests you may have had. It's crucial to understand that an abnormal finding on an MRI does not automatically mean you have cancer. Many changes in breast tissue are benign (non-cancerous). If the MRI shows a suspicious area, your doctor may recommend further tests, such as additional imaging, a biopsy (where a small tissue sample is removed for examination), or a follow-up MRI to monitor the area. Conversely, a normal result means no suspicious areas were found. Regardless of the findings, your doctor will guide you through the next steps and ensure you receive appropriate care based on your individual results.

Risks

Breast MRI is generally considered a safe procedure, but there are a few potential risks to be aware of. These include possible reactions to the contrast dye, such as mild nausea or headache, and a very rare risk of a more serious allergic reaction. For individuals with certain metal implants, the strong magnetic field can pose a danger, and claustrophobia can be a concern for some.

One of the main risks associated with breast MRI involves the contrast dye, gadolinium, which is often used. Most people tolerate the dye well, but some may experience mild side effects such such as nausea, headache, dizziness, or a cold sensation at the injection site. More serious allergic reactions, though rare, can occur and may include hives, itching, or difficulty breathing. If you have a history of allergies, it's important to inform your doctor. For individuals with severe kidney disease, there is an extremely rare but serious complication called nephrogenic systemic fibrosis (NSF) linked to gadolinium. This is why your kidney function is usually checked before the test if contrast dye is planned. The strong magnetic field of the MRI machine also poses a risk for people with certain metal implants or devices, such as pacemakers, cochlear implants, certain types of surgical clips, or metal fragments in the body. These items can malfunction, heat up, or move, potentially causing injury. It is vital to disclose all metal in your body to your doctor and the MRI technologist. Another concern for some people is claustrophobia, which is a fear of enclosed spaces, as the MRI machine is a large, tunnel-shaped scanner. If you experience claustrophobia, discussing this with your doctor beforehand may allow for options like mild sedation. Unlike X-rays or CT scans, breast MRI does not use ionizing radiation, so there is no radiation exposure risk. While generally avoided in the first trimester of pregnancy, an MRI may be performed later in pregnancy if medically necessary, after discussion with your doctor.

Frequently asked questions

Is a breast MRI painful?

Generally, a breast MRI is not painful. You might feel a slight pinch when the IV is inserted for the contrast dye. The main discomfort for some people comes from needing to lie still in an enclosed space for an extended period, and the machine can be quite noisy, though earplugs are provided.

Can I have a breast MRI if I have breast implants?

Yes, you can have a breast MRI with implants. In fact, breast MRI is often used specifically to check the integrity of breast implants for ruptures or leaks. It is important to inform your doctor and the technologist about your implants before the scan.

How is a breast MRI different from a mammogram?

A breast MRI uses strong magnets and radio waves to create detailed images of breast tissue and does not involve radiation. A mammogram uses X-rays. MRI is particularly good at imaging soft tissues and is often used for high-risk screening or further evaluation, while mammograms are the standard screening tool for average-risk individuals.

Do I need a referral for a breast MRI?

Yes, a breast MRI typically requires a referral from your doctor. This is because your doctor needs to assess your medical history and specific risk factors to determine if a breast MRI is the appropriate test for your situation.

How long does it take to get breast MRI results?

The time it takes to get breast MRI results can vary, but it usually ranges from a few days to about a week. A radiologist needs time to carefully review all the images and prepare a detailed report, which is then sent to your referring doctor for discussion with you.

Can men get a breast MRI?

Yes, men can get a breast MRI if clinically indicated. Although breast cancer is much less common in men, a breast MRI may be ordered for similar reasons as in women, such as evaluating a suspicious lump, assessing cancer extent, or for high-risk screening in specific circumstances.

Sources

• MedlinePlus — Breast MRI
• Mayo Clinic — Breast MRI
• Cochrane Library — Breast MRI