Diagnostic Evaluation of Recalled Noncalcified Lesions Using Ultrasound Alone Versus Ultrasound Plus Additional Mammographic Views: A Prospective Study

BACKGROUND. The diagnostic performance of digital breast tomosynthesis (DBT) has been shown to be equal to that of diagnostic mammography. However, the value of additional mammographic views in diagnostic evaluations remains unclear. OBJECTIVE. The purpose of this study was to compare the performance of diagnostic breast ultrasound (US) alone with that of combined US and diagnostic mammography for specific noncalcified recalled abnormalities detected on screening DBT. METHODS. This was a prospective study with a single-arm management strategy. Women recalled for noncalcified lesions on screening DBT underwent initial diagnostic US as part of the study protocol. Additional diagnostic mammography was performed at the discretion of the radiologist. Imaging assessment decisions determined by BI-RADS assessments and management recommendations, biopsy outcomes, and follow-up were recorded using case report forms completed on the day of the diagnostic evaluation and stored in the electronic medical record. RESULTS. From July 10, 2017, to June 6, 2019, a total of 430 recalled noncalcified lesions in 399 women (mean age, 60 ± 12 [SD] years) were included. US alone was performed for 71.2% (306/430) of lesions, whereas US with diagnostic mammography was performed for 28.8% (124/430). Of the recalled lesions, 93.7% (178/190) of masses, 60.0% (51/85) of focal asymmetries, 46.1% (53/115) of asymmetries, 69.2% (9/13) of developing asymmetries, and 55.6% (15/27) of architectural distortions were evaluated with US alone. Of 93 lesions that underwent needle biopsy, 40.9% (38/93) were cancers, all of which were invasive. Thirty-five of 38 (92.1%) cancers were evaluated by US alone, whereas three (7.9%) were evaluated with US and diagnostic mammography. At a median follow- up of 25 months, six cancers were identified (three with US alone and three with US plus diagnostic mammography) in patients with initially benign workup. US alone had two false-negative cancers (one architectural distortion identified at follow-up and one mass biopsied stereotactically at initial detection). CONCLUSION. US alone is effective in the diagnostic evaluation of noncalcified masses recalled on screening tomosynthesis. For asymmetries, diagnostic mammography may be best without the need for additional US, whereas architectural distortions still warrant diagnostic mammography and US. CLINICAL IMPACT. Radiologists should consider performing US first for DBT-recalled noncalcified masses. Omitting diagnostic mammography when US is negative has a low false-negative rate.