BI-RADS Category 3 Comparison: Probably Benign Category after Recall from Screening before and after Implementation of Digital Breast Tomosynthesis

Abstract

Purpose To evaluate Breast Imaging Reporting and Data System (BI-RADS) category 3 assessment at diagnostic examination after recall from screening in a large urban population after implementation of digital breast tomosynthesis (DBT) by focusing both on overall use and use stratified by recalled finding type and outcome at 2 years. Materials and Methods This was an intuitional review board-approved and HIPAA-compliant retrospective review of 10 728 digital mammography (DM) examinations from September 1, 2010, to August 30, 2011, and 15 571 screening DBT examinations from October 1, 2011, to February 28, 2013. The recall populations for DM and DBT were 1112 of 10 728 (10.4% of women screened) and 1366 of 15 571 (8.8% of women screened), respectively. Recall examinations were classified according to finding type: calcifications, asymmetry or focal asymmetry, mass, and architectural distortion. Differences between groups were compared by using the χ² test. Results Although there was no significant change in the utilization rate of BI-RADS category 3 in those patients screened with DM compared with DBT (168 of 10 728, 1.6% for DM vs 206 of 15 571, 1.3% for DBT; P = .102), there was a mean overall reduction of 2.4 women per 1000 (95% confidence interval [CI]: -0.5, 5.4) recommended for short-term follow-up. Lesion types given a BI-RADS category 3 assessment after diagnostic work-up did not change. The distribution of recalled finding types significantly changed with DBT, with increased recall examinations for architectural distortion and mass (P < .001) and decreased recall examinations for asymmetries (P ≤ .001). There was no change in recall examinations for calcifications (P = .977). Conclusion Screening with DBT did not significantly change the utilization rate of BI-RADS category 3 classification; however, the overall number of patients recommended for short-interval follow-up decreased by a mean of 2.4 women per 1000 (95% CI: -0.5, 5.4). ^© RSNA, 2017 Online supplemental material is available for this article.

Figure 1:

DM images show cancer depicted at 6-month follow-up. A 54-year-old woman was recalled from baseline screening examination for calcifications. She was given a BI-RADS category 3 assessment after additional work-up. A, craniocaudal and, B, mediolateral magnification views at first diagnostic study demonstrate punctate calcifications (arrow). At 6 months, calcifications were stable but a new mass (arrowhead) was noted on, C, craniocaudal and, D, mediolateral magnification views. Biopsy was recommended. Corresponding, E, radial and, F, antiradial orthogonal US images from 6-month diagnostic examination demonstrate a 5 × 5 × 5-mm round hypoechoic mass with indistinct margins. Both calcifications and mass were excised (invasive ductal cancer and ductal carcinoma in situ [ T1N0M0]).

Figure 2:

DBT images depict cancer at 12-month follow-up. A 74-year-old woman was recalled from a screening mammogram for calcifications. She was given a BI-RADS category 3 assessment after additional work-up. A, craniocaudal and, B, mediolateral magnification views at first diagnostic study demonstrate punctate calcifications. At 6-month follow-up (not shown), calcifications were thought to be stable. At 1 year, a mass was noted and biopsy was recommended. In retrospect, the mass (arrow) was likely present on the original screen, C, DM craniocaudal view, but only visible on, D, corresponding DBT craniocaudal view. E, Mass increased in size at 1-year follow-up when it was first detected. Corresponding, F, radial and, G, antiradial orthogonal US images from 1-year diagnostic examination demonstrate a 19 × 12 × 15 mm irregular hypoechoic mass with angular and indistinct margins that represented invasive ductal cancer, 2.5 cm at surgery ( T2N0M0).