Comparison between two-dimensional synthetic mammography reconstructed from digital breast tomosynthesis and full-field digital mammography for the detection of T1 breast cancer.

OBJECTIVE: To evaluate the interpretative performance of two-dimensional (2D) synthetic mammography (SM) reconstructed from digital breast tomosynthesis (DBT) in the detection of T1-stage invasive breast cancers, compared to 2D full-field digital mammography (FFDM). METHODS: This retrospective study enrolled 214 patients. For each patient, FFDM and DBT were performed between January and June 2013, and SM was reconstructed from DBT data. Three radiologists interpreted images and recorded visibility scores and morphologies of cancers. Diagnostic performances of SM and FFDM were compared. Percentages of detected cancers and visibility scores were compared for tumour size, and presence of calcifications for each observer. RESULTS: Observer sensitivity showed no difference for detection with SM and FFDM (P > 0.05). One observer showed a higher specificity (P = 0.02) and higher positive predictive value with SM (95 % CI 0.6-16.4), but the differences in the corresponding values between SM and FFDM for the other observers were not statistically significant. In subgroup analyses according to tumour size and presence of calcifications, percentages of detected cancers and visibility scores were not significantly different. CONCLUSIONS: Diagnostic performances of SM and FFDM are comparable for detecting T1-stage breast cancers. Therefore, our results indicate that SM may eliminate the need for additional FFDM during DBT-based imaging. KEY POINTS: • DBT plus FFDM increases radiation dose compared to FFDM alone. • Detecting T1-stage cancers with only SM is comparable to detection with FFDM. • Two-dimensional SM may replace dose-requiring FFDM in DBT-based imaging.