Breast-Specific Gamma Imaging Not Affected by Breast Density

Contradictory to mammography, recent findings have revealed breast-specific gamma imaging (BSGI), also known as molecular breast imaging (MBI), is as effective in identifying breast cancer in women with both dense and nondense breasts.

These findings were presented at the 2011 Radiological Society of North America (RSNA) annual meeting, held in Chicago (IL, USA), November 27-December 2, 2011. “Dense breast tissue is extremely common, occurring in 50% of premenopausal and 40% of postmenopausal women, and is a strong risk factor for developing breast cancer,” said Rachel Brem, MD, first author of this study from the George Washington University Medical Center (Washington DC, USA). “However, mammography is far less effective in women with dense breasts, missing 35%-45% of breast cancers in these women.”

Mammography in women with dense breasts is limited and necessitates additional imaging modalities that are not impacted by breast density. “As we increasingly appreciate the importance breast density has on risk for developing breast cancer and the limitations of mammography, it is crucial that we find technologies that allow for the detection of breast cancer, regardless of risk,” said Dr. Brem. “It is exciting that BSGI does exactly that and can be used to detect breast cancer in all women, regardless of density.”

Under new US legislation, mammography clinics in Connecticut and Texas are now required to inform patients about their breast density. While other states may follow suit, clinicians are already using advanced diagnostic imaging tools that are effective in the detection of cancer in both dense and nondense breasts.

Researchers from George Washington University Medical Center conducted a retrospective review of their BSGI database from January 2004 to August 2009. They evaluated 344 women with breast cancer, of whom breast density was available per mammography report. The study results revealed there was no difference in the sensitivity of BSGI/MBI in detecting breast cancer in women with nondense and dense breasts. The overall sensitivity of BSGI/MBI for breast cancer detection was 95.6%; 137 of 142 (96.5%) women with nondense breasts, and 192 of 202 (95.1%) women with dense breasts had positive BSGI/MBI examinations.

“The ability to utilize physiologic imaging to improve breast cancer detection is very exciting in that it is equally effective in women with dense and nondense breasts,” said Dr. Brem. “The sensitivity of BSGI has been reported to be equal to MRI, but BSGI is performed with the patient comfortably seated. BSGI requires a fraction of the physician time for image interpretation, has a lower false-positive rate, and can be performed in women who cannot undergo MRI [magnetic resonance imaging], such as those with implantable devices and renal insufficiency. The integration of BSGI in clinical practice is a robust tool for the improved detection of the smallest cancers: those which are detected early, and are most curable,” said Dr. Brem.

As a follow-up to mammography, BSGI/MBI utilizes the Dilon (Newport News, VA, USA) 6800 gamma camera to help physicians more clearly distinguish benign from malignant tissue. To perform BSGI/MBI, the patient receives a pharmaceutical tracing agent that is absorbed by all the cells in the body. Due to their increased rate of metabolic activity, cancerous cells in the breast absorb a greater amount of the tracing agent than normal healthy cells and typically appear as dark spots on the BSGI/MBI image.

Related Links:
George Washington University Medical Center
Dilon