Molecular Breast Imaging

What is molecular breast imaging?

Molecular breast imaging (MBI) is a nuclear medicine imaging test that looks for breast cancer. A nuclear medicine test uses a small amount of radioactive material to find cancer cells. This radioactive material, known as a tracer, highlights or “lights up” fast-growing cells.

Why would I need molecular breast imaging?

You may need molecular breast imaging if you:

• Are undergoing breast cancer treatment and your provider wants to see how the treatment is working.
• Have dense breast tissue.
• Received an abnormal result on your mammogram or breast ultrasound and your provider needs more detailed images of your breast cells.
• Were diagnosed with breast cancer and your provider needs to check for other areas of cancer.

What’s the difference between molecular breast imaging and a 3D mammogram?

There are some key differences between MBI and 3D mammography (tomosynthesis):

• Images: On a mammogram, cancer cells and dense breast tissue show up as white spots. If you have dense breast tissue, it may be harder to spot some cancers with mammography alone. With molecular breast imaging, many types of cancer cells light up, while other cells, including dense breast tissue, appear darker.
• Technology: A 3D mammogram uses a series of X-rays to take pictures of your breast tissue. MBI uses a radioactive tracer and a gamma camera, which highlight only fast-growing cells.
• Who needs one: Most people assigned female at birth (AFAB) need screening mammograms for breast cancer starting at age 40. Not everyone AFAB needs an MBI scan. Providers may use MBI in addition to a mammogram, but not in place of it.

How does molecular breast imaging work?

Molecular breast imaging shows differences in your breast cells that may indicate cancer. Cancer cells tend to be fast-growing and take up more of the radioactive tracer than normal cells. The camera scans your breast and highlights the areas with more tracer, making potential cancer cells more visible.

How do I prepare for molecular breast imaging?

Most people should avoid foods and non-clear fluids like milk for at least three hours before the test. Drink clear fluids like water or sports drinks to stay hydrated. Not eating helps your breast tissue take up more of the tracer. However, if you have diabetes or another health condition, ask your provider what prep is best for you.

If you have menstrual cycles, try to schedule your MBI appointment between days 7 to 14 of your cycle. Count the first day of your last period as day 1. Although this is the optimal time to have an MBI scan, your provider can perform this test at any point during your cycle, if needed.

How is molecular breast imaging done?

At your MBI appointment, your provider will:

1. Guide you to a private room, where you’ll remove jewelry and clothing from the waist up and put on a hospital gown.
2. Take you to the gamma camera room, where you’ll sit in a chair in front of the imaging equipment.
3. Place an intravenous (IV) line in your arm and inject the radioactive tracer into your IV line.
4. Wait about three to five minutes for the tracer to move into your breast tissue.
5. Start the scan, which may take 20 to 40 minutes. The equipment will lightly compress your breast, but it shouldn’t hurt.

What should I expect after molecular breast imaging?

After your MBI scan, your provider will remove your IV line and you’ll be able to get dressed. Your medical team will advise you on the next steps for your care. You may need a follow-up visit or a referral to another specialist.

What are the risks of molecular breast imaging?

During an MBI scan, you’ll be exposed to a small amount of radiation from the tracer. Repeated exposure to radiation can increase your risk of cancer.

However, the levels of radiation in MBI are considered safe and are similar to those in a mammogram. In most cases, the benefits of finding breast cancer outweigh the risks of radiation exposure.

A small number of people may also experience an allergic reaction to the tracer. Symptoms of an allergic reaction include:

• Hives, itching or rash.
• Nausea or vomiting.
• Trouble breathing or heart rhythm problems (occurring in 0.01% - 0.04% of cases).

What type of results do you get from molecular breast imaging?

A radiologist examines your MBI images to look for cancerous cells. If any spots light up, your provider may take a biopsy (tissue sample) of those areas. A biopsy can confirm whether the cells are cancerous. Your biopsy also helps your provider determine the best treatment for you.

If there are no highlighted areas on your MBI scan, it’s usually considered a “normal” result. Talk with your provider about your breast cancer screening schedule, including when you should get your next mammogram.

How accurate is molecular breast imaging?

Studies show that MBI detected about 90% of cancers in patients with suspected breast cancer. The test detected 82% of smaller cancers (less than 10 millimeters in size). Studies show that these results are similar to the accuracy of breast MRI. Research also suggests that MBI detects two to three times more breast cancers than mammography alone.

When will I know the results of my molecular breast imaging?

Ask your provider when you can expect the results and how they’ll contact you. In most cases, you receive your results within a week of your test.

A note from Cleveland Clinic

Regular mammograms are the best way to screen for breast cancer. But molecular breast imaging may provide additional information when a mammogram alone isn’t enough.

Other breast imaging tests, such as breast ultrasound and breast MRI, can also provide detailed information about abnormal areas in your breast. Each test has pros and cons, so discuss them with your provider. Together, you can use the right screening tests to prevent breast cancer or catch it early, when treatment is more successful.