Abstract: Background and purpose: The use of full-field digital mammography (FFDM) can significantly reduce the mortality rate of breast cancer. However, it is a two-dimensional imaging method, the sensitivity and specificity of diagnosis are significantly reduced in patients with dense breast. This study compared the detectability of FFDM alone versus FFDM plus digital breast tomosynthesis (DBT), and the detectability of scan angle of 40° (HR-mode) DBT versus scan angle of 15° (ST-mode) DBT for the diagnostic evaluation of breast lesion. Methods: The prospective study enrolled 175 women with clinically suspected breast lesion from July 2016 to September 2016 in Fudan University Shanghai Cancer Center. One hundred and seventy-five patients confirmed by biopsy or surgery were included. All the patients underwent full-field digital mammography (FFDM) and DBT examinations, and patients were randomly allocated into DBT-ST group or DBT-HR group. The images of FFDM and FFDM plus DBT were analyzed. According to Breast Imaging Reporting and Data System (BI-RADS, version 2013), the receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency of FFDM and FFDM plus DBT, referring to the pathology as the gold standard. The sensitivities and specificities of DBT-HR and DBT-ST were analyzed according to different breast compositions. Results: A total of 181 lesions were detected in 145 patients, including 50 benign lesions and 131 malignant lesions. The sensitivities of FFDM and FFDM plus DBT were 81.92% and 91.15%, and the specificities were 77.45% and 87.25%, respectively. There was significant difference in the area under curve (AUC) between the two methods (0.88 vs 0.94, Z value was 5.37, P<0.01). There were 86 lesions randomly allocated into DBT-HR group and 95 lesions into DBT-ST group. For DBT-HR group, the consistency rate of finding between FFDM and DBT was 83.14%, and the only DBT detected rate was 3.49%. For DBT-ST group, the consistency rate of finding between FFDM and DBT was 92.63%, and the only DBT detected rate was 0.53%. Compared with the non-dense breast after combining the DBT, the improvement in sensitivity and specificity was more obvious in dense breast, especially the improvement in sensitivity of dense breast in DBT-HR (18.72%) and specificity of dense breast in DBT-ST (14.28%). Conclusion: The diagnostic efficiency of FFDM plus DBT is superior to that of FFDM, and the DBT-HR better than DBT-ST, especially in dense breast.

Key words: Breast cancer, Digital breast tomosynthesis, High-resolution-mode, Standard-mode