Synthetic Mammography: Benefits, Drawbacks, and Pitfalls.

Digital breast tomosynthesis (DBT) allows three-dimensional assessment of breast tissue; however, DBT requires a two-dimensional (2D) image for comparison with prior mammograms and accurate interpretation of calcifications. Traditionally, full-field digital mammography (FFDM) has been performed after the DBT image acquisition. Synthetic mammography (SM), the 2D reconstruction of the tomosynthesis slice dataset, has been designed to replace FFDM. Advantages of SM include decreased image acquisition time and decreased radiation exposure, with maintained or improved screening performance metrics. Because SM algorithms give extra weight to lesion-like characteristics (eg, calcifications and architectural distortions), they may enable increased visibility of these characteristics relative to that at FFDM. Although SM algorithms were designed to improve lesion identification, they have led to varied outcomes in studies reported in the literature. Compared with FFDM, SM has been reported to be associated with a higher false-positive rate for calcifications, decreased conspicuity of asymmetries, lower breast density assessments, and imaging artifacts (eg, metallic artifact, bright-band artifact, blurring of the axilla, and truncation artifact). The authors review the literature on SM, including its implementation, benefits, and artifacts. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Frequency and Outcomes of BI-RADS Category 3 Assessments in Patients With a Personal History of Breast Cancer: Full-Field Digital Mammography Versus Digital Breast Tomosynthesis.

BACKGROUND. Studies establishing the validity of BI-RADS category 3 excluded patients with personal history of breast cancer (PHBC). Use of category 3 in patients with PHBC may be impacted not only by this population's increased breast cancer risk, but also by adoption of digital breast tomosynthesis (DBT) over full-field digital mammography (FFDM). OBJECTIVE. The purpose of this article was to compare the frequency, outcomes, and additional characteristics of BI-RADS category 3 assessments between FFDM and DBT in patients with PHBC. METHODS. This retrospective study included 14,845 mammograms in 10,118 patients (mean age, 63 years) with PHBC who had undergone mastectomy and/or lumpectomy. Of these, 8422 examinations were performed by FFDM from October 2014 to September 2016, and 6423 examinations by FFDM with DBT from February 2017 to December 2018, after interval conversion of the center's mammography units. Information was extracted from the EHR and radiology reports. FFDM and DBT groups were compared in the entire sample and among index category 3 lesions (i.e., earliest category 3 assessment per lesion). RESULTS. The frequency of category 3 assessment was lower for DBT than FFDM (5.6% vs 6.4%; p = .05). DBT, compared with FFDM, showed a lower malignancy rate for category 3 lesions (1.8% vs 5.0%; p = .04), higher malignancy rate for category 4 lesions (32.0% vs 23.2%; p = .03), and no difference in malignancy rate for category 5 lesions (100.0% vs 75.0%; p = .24). Analysis of index category 3 lesions included 438 and 274 lesions for FFDM and DBT, respectively. For category 3 lesions, DBT, compared with FFDM, showed lower PPV3 (13.9% vs 36.1%; p = .02) and a more frequent mammographic finding of mass (33.2% vs 23.1%; p = .003). CONCLUSION. The malignancy rate for category 3 lesions in patients with PHBC was less than the accepted limit (2%) for DBT (1.8%), but not FFDM (5.0%). A lower malignancy rate for category 3 lesions but higher malignancy rate for category 4 lesions for DBT supports more appropriate application of category 3 assessment in patients with PHBC through use of DBT. CLINICAL IMPACT. These insights may help establish whether category 3 assessments in patients with PHBC are within benchmarks for early detection of second cancers and reduction of benign biopsies.