The screening mammogram is a critical early detection tool for breast cancer. But for women with dense breast tissue and those with a higher-than-average lifetime risk of developing breast cancer, molecular breast imaging (MBI) may offer a more accurate reading.
Sentara RMH Medical Center has been offering MBI, also known as scintimammography, for more than a decade. Last year, however, the hospital updated its equipment to enable MBI to be performed using a lower dose of radiation. The upgrade also includes a new device that allows doctors to biopsy suspicious tissue seen only on MBI.
“While we have been doing molecular breast imaging at Sentara RMH for years, it recently has become more widely used and accepted in the broader medical community,” says Emily Ritchie, MD, Sentara RMH radiologist and women’s imaging specialist. “MBI is just now coming to the forefront of breast imaging, but Sentara RMH has long recognized the benefits of this technology.”
Sensitive, Accurate Breast Screening for Higher-Risk Patients
MBI is a nuclear medicine study that uses a radioactive tracer fluid to identify suspicious molecular activity in breast tissue. Once injected into the patient’s arm, the radiotracer fluid will tend to concentrate in tissues that demonstrate increased metabolic activity, compared with normal tissue. A special camera is used to detect “hotspots” where the radiotracer has concentrated, indicating potential tumors.
While the MBI system looks similar to a conventional mammogram machine, the screening process is a bit different. Instead of standing for the procedure, the patient sits, facing the MBI machine. One at a time, each breast is placed on a small platform and compressed slightly—although not as tightly as during a mammogram—while images are taken.
MBI is useful for detecting cancers when screening mammograms and breast ultrasound scans render negative or inconclusive results. Sentara RMH breast surgeon Heidi Rafferty, MD, recalls a recent patient who made an appointment after finding a lump on her right breast. She underwent a mammogram and a breast ultrasound, both of which revealed no tumors. However, the 46-year-old patient had a family history of breast cancer. as well as dense breast tissue, which can mask tumors on mammography images. Taking those factors into consideration, she had a moderately increased risk for breast cancer.
Just to be on the safe side, Dr. Rafferty ordered an MBI study, which revealed a suspicious area on the left breast, on the opposite side from where the patient found the lump. An ultrasound-guided biopsy showed that the spot was cancerous. Fortunately, the lump in the right breast turned out to be benign.
“The mass that this patient could feel in her right breast was not a cancer, but it’s still a good thing she came to see me,” Dr. Rafferty says. “Though her mammogram and ultrasound did not come back positive for cancer, further study was warranted because we did feel a lump, and she did have an elevated risk of breast cancer. We were able to offer the MBI study, which led to her diagnosis and treatment for breast cancer.”
Patients Who Can Benefit from MBI
According to Dr. Ritchie, several groups of patients may benefit from MBI, including the following:
• Patients with increased risk for breast cancer.Patients who are known carriers of genetic mutations such as BRCA1 and BRCA2, or those with a strong family history of breast or ovarian cancer, must be followed very closely. While they may need more sensitive screenings than conventional mammography, an annual breast magnetic resonance imaging (MRI) study may be too costly (MBI is estimated to cost about one-third less than MRI and is often more readily approved by health insurance companies). Patients with dense breast tissue also have an increased risk for breast cancer and may benefit from MBI in combination with a mammogram.
• Patients who need further evaluation after inconclusive diagnostic workup.For patients who have abnormal mammogram results and inconclusive follow-up ultrasound results, MBI may be useful for further evaluating suspicious areas.
“If I do an MBI study and it comes out negative, that makes me feel confident that we can just keep a close watch on this patient, and that there’s probably nothing to be concerned about,” adds Dr. Ritchie. “But if the MBI results show areas of concern, we need to biopsy it and develop a treatment plan.”
• Patients who can’t have a breast MRI.For patients who can’t comfortably lie down for the breast MRI, have renal (kidney) insufficiency, are allergic to the contrast material used during MRI or are claustrophobic, MBI offers an effective alternative.
A Safe, Cost-Effective Solution
“For the vast majority of women, we will find any breast cancer on a mammogram before they would ever need MBI,” Dr. Ritchie notes. “But for women with dense breast tissue, mammograms are less effective. On the other hand, while breast MRI is an extremely accurate test, it’s also much more expensive. Molecular breast imaging offers another advanced, cost-effective option for women with dense breast tissue.”
MBI also is safe, making use of a very low dose of radiation. In fact, a single MBI study can be administered using less than the acceptable national standard of background radiation.
“Every day, we receive radiation that comes from the sun and the Earth,” Dr. Ritchie says. “Undergoing molecular breast imaging exposes a patient to less radiation than we get from just walking around. So MBI is safe, inexpensive and more accommodating for people who can’t have an MRI.”
Adds Dr. Rafferty: “MBI has expanded the options we can offer to our patients to help detect breast cancer as early as possible and ensure the best possible outcomes.”