Molecular Breast Imaging (MBI) is an exciting new imaging technology that has great promise for more accurate (and earlier) breast cancer diagnosis. Studies have shown that early detection and treatment make a tremendous difference in outcomes. While mammography is the standard of care in screening, it is less effective in finding tumors in dense breast tissue. So how does MBI help in cancer detection?

  • When used in conjunction with mammography screening, the likelihood of tumor detection increases significantly with an MBI exam
  • An MBI exam can also rule out cancer more conclusively when a mammogram is indeterminate, which, in turn, can eliminate unnecessary biopsies


Following are some commonly asked questions that women have about an MBI exam. Over the coming months, we will be expanding this section, which is dedicated entirely to the needs and concerns of women. We welcome your feedback.

How do I know if I have dense breast tissue?

Contrary to what you might think, breast density does not correlate to how heavy or firm a woman’s breasts are. At present there is no agreed upon method for measuring breast density, but there is agreement that women with dense breast tissue are more likely to develop cancer (studies estimate between 3 and 6 times more likely). Studies have also shown that mammograms are less effective in identifying cancers in dense breasts, because, in mammograms, cancers can appear white like dense breast tissue. While some states in the U.S. have laws requiring that mammography reports include breast density, there are no recommendations or screening guidelines associated with dense breast assessment. You should discuss your breast cancer risk factors with your doctor. Visit for more information.

Are there any other indicators for having an MBI?

Your doctor may recommend an MBI if your mammogram was indeterminate (the radiologist has a question about whether there is a tumor that the mammogram is not showing clearly). Your doctor may also recommend an MBI exam if you cannot tolerate an MRI. An MBI exam is well tolerated by patients and even more comfortable than a mammogram. An MBI exam does require breast compression, but the compression is a fraction of what a mammogram requires; it is only for keeping the breast stable and has nothing to do with getting a better image.

What does the exam entail?

There is no advance preparation required for the exam. You will receive a low dose injection of a radiotracer intravenously. The tracer accumulates in cancer cells, and is not influenced by breast density. You can sit comfortably in front of the LumaGEM molecular breast imaging system. Your breast is compressed between two special cameras, which take a series of images. Generally, these will be the same views that were taken during your mammogram to make comparison easier. The procedure takes about 40-45 minutes, and the images are available immediately for the radiologist to review.

Are there any allergic reactions to the radiotracer? Is it a harmful amount of radiation? How long does it stay in my system?

There are no reported side effects from the radiotracer. The amount of radiation in the radiotracer is extremely low. You can continue your normal activities as soon as the exam is over. The tracer remains in your body for a short time (about five hours) and is cleared through natural bodily functions.

Is the exam more likely to show that I have cancer? If the exam does show a lesion, what is the next step?

MBI, in combination with a standard screening mammography, provides much higher sensitivity (91% compared to 27% sensitivity with mammography alone). So the likelihood is much higher that an MBI will detect a tumor (possibly at an earlier stage) in dense breast tissue if your mammogram is inconclusive or even negative. If your MBI exam reveals a suspicious lesion, then it is likely that your doctor will suggest a biopsy as a next step. If your MBI exam confirms that you are cancer-free, it may eliminate an unnecessary biopsy.

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