What is Molecular Breast Imaging?
Molecular breast imaging is a test that uses a radioactive tracer and special camera to find breast cancer.
Rather than simply taking a picture of a breast, molecular breast imaging is a type of functional imaging. This means the pictures it creates show differences in the activity of the tissue. Tissue that contains cells that are rapidly growing and dividing, such as cancer cells, appears brighter than less active tissue.
During molecular breast imaging, a small amount of radioactive tracer is injected into a vein in your arm. The tracer attaches to breast cancer cells that can then be detected using a camera that detects the gamma radiation released by the tracer (gamma camera).
Molecular breast imaging is a new technology, so it isn’t yet widely available.
Why is Molecular Breast Imaging performed?
Molecular breast imaging may be used to:
- Screen for breast cancer in women with dense breast tissue. Molecular breast imaging, when combined with a breast X-ray (mammogram), detects more breast cancers in women with dense breast tissue than a mammogram alone. Typically, if you and your doctor decide you will have molecular breast imaging, it is done every other year along with an annual mammogram. Breast tissue is composed of milk glands, milk ducts and supportive tissue (dense breast tissue), and fatty tissue. Women with dense breasts have more dense breast tissue than fatty tissue. Both dense breast tissue and cancers appear white on a mammogram, which may make breast cancer more difficult to detect in a woman with dense breasts. Studies show combining molecular breast imaging and a mammogram results in finding 3 times more breast cancers than a mammogram alone. Molecular breast imaging has Food and Drug Administration clearance, which is an acceptance for lower-risk medical devices, and there is evidence of its benefits in detecting cancers in women with dense breasts.
- Investigate breast abnormalities. Molecular breast imaging may help doctors evaluate a breast lump or an unusual area detected on a mammogram. Your doctor may recommend molecular breast imaging if other imaging tests have been inconclusive. Molecular breast imaging may be used in women for whom an MRI is recommended, but can’t be performed, such as those with allergies to the contrast material.
What should I know before receiving Molecular Breast Imaging?
Molecular breast imaging is a safe procedure. Like every test, it carries certain risks and limitations, such as:
- Exposure to a low level of radiation. During molecular breast imaging, you’re exposed to a minimal dose of radiation that’s considered safe for routine screening. For most women the benefits of the test will outweigh the risks of radiation. When molecular breast imaging is used for breast cancer screening, it’s typically done along with a mammogram, so you’ll be exposed to more radiation than you would receive if you had a mammogram alone.
- Allergic reaction to tracer. Though extremely rare, allergic reactions to the radioactive tracer can occur. Tell your doctor about any allergies you have.
- The test may find something that, after additional tests, turns out to not be cancer. Molecular breast imaging may identify a suspicious area that, after additional tests, turns out to be noncancerous. This is known as a false-positive result and it can cause unneeded anxiety if you undergo additional imaging and testing, such as a biopsy, to assess the suspicious area.
- The test can’t detect all cancers. As with all tests, molecular breast imaging may miss some cancers. Some cancers may be too small to be detected by the gamma camera. Others may be located in areas that are difficult to view using molecular breast imaging, such as those near the chest wall.
How to prepare for Molecular Breast Imaging?
Doctors don’t recommend molecular breast imaging for pregnant women. Before scheduling molecular breast imaging, be sure to tell your doctor if you’re pregnant, or may be pregnant.
If you’re breastfeeding, the radioactive tracer may be present in breast milk for 12 hours or so. You can pump and store some milk before the test. Ask your doctor when it’s safe to resume breastfeeding.
Tell your doctor about any known allergies you have. Since you’ll have to remain still for the test, let them know if you have difficulty remaining still for 10 minutes at a time.
Premenopausal women should schedule the test during the beginning of their menstrual cycle, preferably seven to 14 days after the first day of their period.
You may need to stop eating a few hours before the test. This will allow more of the tracer to travel to your breast tissue and produce clearer images. Drinking liquids like water, plain coffee, or tea won’t affect the test.
Other than that, there’s no special preparation necessary for this test.
What happens during Molecular Breast Imaging?
Molecular breast imaging is an outpatient procedure that takes about 45 minutes to one hour.
You’ll undress from the waist up and put on a gown with an opening in the front.
Your doctor will inject the radioactive tracer into a vein in your arm. You might notice a slight metallic taste for a few minutes. You’ll be ready for imaging in about five minutes.
The breast imaging machine looks a lot like a mammogram machine. One difference is that you’ll remain seated as your breast is compressed. This may be a little uncomfortable, but it doesn’t usually cause pain.
The special gamma cameras will monitor the activity of the tracer in your breast. The breast imaging machine technician will take two images. It will take about 10 minutes to take each image. During this time you must remain still. You’ll have a chance to move around a bit between images when your breast is repositioned.
It’s possible to repeat the process for the other breast if necessary, or in other cases, like if you have very large breasts.
The technician will most likely ask you to wait while they check the images for quality. If the images aren’t clear, you may need to repeat the procedure. Once you get the go-ahead, you can leave and resume normal activity right away.
What happens after Molecular Breast Imaging?
Once the test is complete, you’ll be asked to wait while a technologist checks the quality of the images. If there are problems with the images, you may have to repeat part of the test.
Afterward, you may dress and resume normal activity.
If you have any questions about the Molecular Breast Imaging, please consult with your doctor to better understand your instructions.
Explanation of results
What do my results mean?
The radioactive tracer is more likely to collect in cancerous cells than healthy ones. Areas of the breast that absorb the most tracer will appear highlighted on the images.
It’s important to remember that it’s only possible to confirm cancer with a biopsy. Molecular breast imaging can’t definitively say you have breast cancer.
The radiologist will study the scans and send a report to your doctor. They’ll explain the results to you.
Molecular breast imaging can help your doctor decide if more invasive testing, such as a biopsy, is necessary.
Depending on the laboratory and hospital, the normal range for Molecular Breast Imaging may vary. Please discuss with your doctor any questions you may have about your test results.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Molecular Breast Imaging Test: What to Expect. https://www.healthline.com/health/breast-cancer/molecular-breast-imaging. Accessed October 19, 2018.
Molecular breast imaging. https://www.mayoclinic.org/tests-procedures/molecular-breast-imaging/about/pac-20394710. Accessed October 19, 2018.
Review Date: November 4, 2018 | Last Modified: September 12, 2019