Benefit to Radiation Risk of Breast-specific Gamma Imaging Compared with Mammography in Screening Asymptomatic Women with Dense Breasts

Purpose: To estimate the benefit-to-radiation risk ratios of mammography alone, breast-specific gamma imaging (BSGI) alone, and mammography plus BSGI in women with dense breasts who were asymptomatic and examined in the 2015 study by Rhodes et al. Materials and Methods: This study uses previously published breast cancer detection rates and estimates of radiation dose and radiation risk and is, therefore, exempt from institutional review board approval. By using breast cancer detection rates for mammography alone, BSGI alone, and mammography plus BSGI from the study by Rhodes et al, as well as lifetime estimates of radiation-induced cancer mortality for mammography and BSGI on the basis of the Biologic Effects of Ionizing Radiation VII report, the benefit-to-radiation risk ratios of mammography alone, BSGI alone, and mammography plus BSGI performed annually over 10-year age intervals from ages 40 to 79 years are estimated. Results: The benefit-to-radiation risk ratio is estimated to be 13 for women who are 40-49 years old and are screened with mammography, a figure that approximately doubles for each subsequent 10-year age interval up to 70-79 years old. For low-dose BSGI, annual screening benefitto- radiation risk ratios are estimated to be 5 for women 40-49 years old and to double by age 70-79 years, while mammography plus BSGI has benefit-to-radiation risk ratios similar to those of BSGI alone. There are wide ranges for all of these estimates. Conclusion: While lower dose (300 MBq) BSGI has estimated benefit-to-radiation risk ratios well in excess of 1 for screening of asymptomatic women with dense breasts who are 40 years old and older, it does not match the benefit-to-radiation risk ratio of screening mammography. (C) RSNA, 2016