Impact of prior mammograms on combined reading of digital mammography and digital breast tomosynthesis

Background: Although digital breast tomosynthesis (DBT) is an emerging technique yielding higher sensitivity and specificity compared to digital mammography (DM) alone, relative contribution of prior mammograms on the interpretation of DBT combined with DM has not been investigated. Purpose: To retrospectively compare the diagnostic performances of DM, DM+DBT, and DM+DBT with prior mammograms. Material and Methods: Three breast radiologists independently reviewed images of 116 patients with 24 cancers in the sequential order of DM, DM+DBT, and DM+DBT with prior mammograms using Breast Imaging Reporting and Data System (BI-RADS) assessment categories. Results: The average areas under the receiver operating characteristic curve (AUC) of DM, DM+DBT, and DM+DBT with prior mammograms were 0.712, 0.777, and 0.816, respectively. Adding prior mammograms did not significantly affect the AUC of DM+DBT (P = 0.108), whereas adding DBT significantly increased the AUC of DM (P = 0.009). Sensitivity for DM, DM+DBT, and DM+DBT with prior mammograms was 58.3%, 69.4%, and 69.4%, and specificities were 84.1%, 85.9%, and 93.8%, respectively. Addition of DBT significantly increased the sensitivity (P = 0.0090) of DM. Prior mammograms significantly improved the specificity of DM+DBT (P + 0.0004), whereas adding prior mammogram did not affect sensitivity of DM+DBT (P = 1.000). Conclusion: DBT significantly increases the overall sensitivity and diagnostic performance of DM. Prior mammograms significantly increase the specificity of DM+DBT but have no significant effect on sensitivity and overall diagnostic performance.