Adding 3D Breast Tomosynthesis to Digital Mammography: Values and Limitations

INTRODUCTION: The technology of 3D breast Tomosynthesis (BT) promises elimination of effect of overlapping tissue seen on full field digital mammography (DM).This is by its ability to create 1mm slice thickness images of the breast, that are reviewed on a dedicated work station. OBJECTIVES: To assess the value of adding BT to DM, for improving lesion visibility, characterization and BIRADS assessment. METHODS AND MATERIALS: 929 cases were evaluated with DM and BT in a dedicated breast imaging unit with diagnostic and screening services. Both DM and BT were performed in craniocaudal and mediolateral oblique views in different exposures. Evaluation and BIRADS scoring was given to DM followed by BT. A final BIRADS score considering both interpretations and any additional information by ultrasound was later decided. RESULTS: 70.8 % of cases were screening and 29.2 % were diagnostic. According to the final assessment categories; 25.3%, 53.3%, 11.2%, 5.5%, 4.7% of cases were given a BIRADS score of 1, 2, 3, 4, 5 respectively. +PP, -PP and Accuracy of DM alone were 89.71, 97.33, 96.77%. On adding BT results were 87.5, 99.17, 98.06 % respectively. Agreement between BT BIRADS and final BIRADS score was 91.8% (kappa 0.872). Between DM and Final BIRADS was 81.1% (Kappa 0.710). Regarding the cancers detected in very dense breasts (more than 75% glandular tissue) DBT could diagnose 76.4%, while only 5.8% were diagnosed by DM. CONCLUSION: Adding BT to DM improves accuracy by analysis of margins, focal asymmetry, number of lesions, however, it did not show additional information in evaluation of microcalcifications.