RATIONALE AND OBJECTIVES: Breast arterial calcification (BAC) detected on mammography is frequently not included in final reports. However, previous studies have indicated that BAC may be evidence of general atherosclerotic vascular disease, and it can potentially be a useful marker of coronary artery disease. In addition, there are currently no available techniques for the quantification of calcium mass using mammography. The purpose of this study was to evaluate the reproducibility and inter-reader agreement of a technique for the quantification of BAC using standard digital mammography. MATERIALS AND METHODS: BAC mass was measured in a convenient, consecutive sample of 39 women aged 49 to 82 years attending routine mammographic examinations. BAC mass measurements were performed in standard mediolateral oblique (MLO) and craniocaudal (CC) views. To assess reproducibility, the BAC measurements obtained in MLO and CC views were compared. RESULTS: The measured BAC masses in CC (M(CC)) and MLO (M(MLO)) projections were related by M(CC) = 0.82(M(MLO)) + 0.27 mg (r = 0.97; standard error of estimation [SEE], 3.44 mg). The measured BAC masses in the left (M(L)) and right (M(R)) breasts were related by M(L) = 0.86(M(R)) – 0.06 mg (r = 0.95; SEE, 4.30 mg). The intraclass correlation coefficients for the measurement of calcium mass ranged from 0.94 in the left CC view to 0.99 in the right CC view. CONCLUSION: A densitometry technique for the quantification of BAC mass was evaluated in patients using standard full-field digital mammography. The results demonstrated that this densitometric technique for the quantification of BAC mass is highly reproducible and has excellent inter-reader agreement. This technique may provide a quantitative metric for future studies relating the severity of BAC and cardiovascular risk.