Breast cancer staging: Combined digital breast tomosynthesis and automated breast ultrasound versus magnetic resonance imaging

Purpose: To investigate whether combined Digital breast tomosynthesis and Automated breast volume scanner (DBT-ABVS) are comparable to Magnetic resonance imaging (MRI) in staging breast cancer. Methods: We retrospectively included seventy-three patients with histologically proven breast cancer who underwent preoperative DBT, ABVS and 1.5 T MRI in the period July 2015-July 2016. Two radiologists in consensus recorded the number, site and Breast imaging-reporting and data system (BI-RADS) category of breast findings during two independent reading strategies, i.e. DBT-ABVS vs. MRI. Using histology or 1-year follow up as the standard of reference, we calculated the accuracy for cancer of both imaging strategies. Bland-Altman analysis was used to evaluate the agreement between MRI vs. DBT or ABVS in cancer size assessment. Results: Patients showed a total of 160 lesions (108 malignant and 52 benign). Malignant lesions were unifocal, multifocal, multicentric and biltateral in 53, 15, 4 and 1 cases, respectively. Diagnostic accuracy of DBT-ABVS vs. MRI was comparable for all cancers (90.0% [95% C.I. 84.3-94.2] vs. 93.8% [95% C.I. 88.8-97.0], respectively). DBT-ABVS showed lower sensitivity and positive predictive values for additional disease (76.5% [95% C.I. 58.8-89.3] vs. 91.7% [95% C.I. 84.6-96.1], and 78.8% [95% C.I. 61.0-91.0] vs 93.4% [95% C.I. 86.9-97.3], respectively). Compared to MRI, ABVS + DBT missed 6 lesions, including two invasive cancers and one extensive intravascular invasion associated to ductal carcinoma in situ. Bland-Altman analysis showed ABVS to agree with MRI at a higher extent than DBT in assessing cancer size. Conclusions: Though less performing than MRI, DBT-ABVS showed acceptable diagnostic accuracy in staging breast cancer. This strategy might be used if MRI is unavailable or unfeasible.