Comparison of Breast Density Between Synthesized Versus Standard Digital Mammography

Purpose: To evaluate perceptual difference in breast density classification using synthesized mammography (SM) compared with standard or full-field digital mammography (FFDM) for screening. Materials and Methods: This institutional review board approved, retrospective, multireader study evaluated breast density on 200 patients who underwent baseline screening mammogram during which both SM and FFDM were obtained contemporaneously from June 1, 2016, through November 30, 2016. Qualitative breast density was independently assigned by seven readers initially evaluating FFDM alone. Then, in a separate session, these same readers assigned breast density using synthetic views alone on the same 200 patients. The readers were again blinded to each other's assignment. Qualitative density assessment was based on BI-BADS fifth edition. Interreader agreement was evaluated with K statistic using 95% confidence intervals. Testing for homogeneity in paired proportions was performed using McNemar's test with a level of significance of .05. Results: For patients across the SM and standard 2-D data set, diagnostic testing with McNemar's test with P=0.32 demonstrates that the minimal density transitions across FFDM and SM are not statistically significant density shifts. Taking clinical significance into account, only 8 of 200 (4%) patients had clinically significant transition (dense versus not dense). There was substantial interreader agreement with overall K in FFDM of 0.71 (minimum 0.53, maximum 0.81) and overall SM K average of 0.63 (minimum 0.56, maximum 0.87). Conclusion: Overall subjective breast density assignment by radiologists on SM is similar to density assignment on standard 2-D mammogram.