Molecular breast imaging (MBI) is a method for detecting breast cancer. The technique is also known as a Miraluma (pronounced mee-ra-LOO-ma) test, sestamibi (pronounced ses-ta-MI-bee), scintimammography, or breast specific gamma imaging.
MBI uses a radioactive tracer that “lights up” any areas of cancer inside the breast. This tracer is injected into the body through a vein in the arm. Breast cancer cells tend to take up the radioactive substance much more than normal cells do. A special camera called a nuclear medicine scanner then scans the breast, looking for any areas where the radioactive substance is concentrated.
MBI is still being tested, but it appears to hold promise for detecting breast cancer in women who are at higher-than-average risk for the disease and have dense breasts. When women have a lot of dense breast tissue, tumors become hard to spot on mammograms. On mammograms, fatty breast tissue looks dark, but dense tissue is light, like tumors, so it can hide any cancerous areas that may be present.
A 2008 Mayo Clinic study of 940 high-risk women with dense breasts found that MBI was better than mammography at finding tumors in the breast. However, one drawback of MBI is that it involves a much greater dose of radiation than mammograms do. A new study plans to compare MBI to MRI (magnetic resonance imaging), which is often the preferred tool for evaluating women who are considered high-risk and have dense breasts. However, MRI is more expensive than MBI and often can return false positive results, leading to unnecessary biopsies.
If you are at average risk for breast cancer and do not have dense breasts, mammography remains the screening tool of choice for you. Many doctors believe that, for most women, mammography is better than MBI at detecting breast tumors when they are small and generally easier to treat.