BSGI Shown to Have Greater Sensitivity, Specificity

CHICAGO - Breast-Specific Gamma Imaging (BSGI) has greater sensitivity and comparable specificity compared to mammography and ultrasound, according to a new study presented Tuesday at RSNA. A second study presented Tuesday showed that, unlike mammography, BSGI is as effective in detecting breast cancer in women with dense and non-dense breasts.

BSGI, also known as Molecular Breast Imaging (MBI), was also shown to be a valuable adjunctive procedure when mammography and ultrasound don’t provide a confident cancer diagnosis, according to the first study, which included four institutions. The researchers included radiologists Jean M. Weigert of Bradley Memorial Hospital in New Britain, Conn.; Margaret L. Bertrand of the Solis Bertrand Breast Center in Greensboro, N.C.; Leora Lanzkowsky of Nevada Imaging in Las Vegas, Nev.; and Lillian H. Stern of Methodist Hospital in Philadelphia. BSGI was conducted with a Dilon 6800 high-resolution gamma camera.

"This study helped show the power of BSGI, especially in patients with indeterminate results on mammography or ultrasound," said Weigert, first author on the study. "Many suspicious areas can show up on an ultrasound. BSGI helps us focus on the areas of true positive and determine where to biopsy."

In the second study, researchers noted that BSGI is not affected by breast density, where mammography in women with dense breasts is limited and necessitates additional imaging. Mammography misses 35 percent to 45 percent of breast cancers in these women, said Rachel Brem, MD, first author of this study from The George Washington University Medical Center, Washington, D.C. "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," she said.

Researchers from The 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. The overall sensitivity of BSGI for breast cancer detection was 95.6 percent; 137 of 142 (96.5 percent) women with non-dense breasts, and 192 of 202 (95.1 percent) women with dense breasts had positive BSGI exams.

"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, 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 Brem.