Utility of Targeted Ultrasound to Predict Malignancy Among Lesions Detected on Contrast-Enhanced Digital Mammography.

BACKGROUND. Targeted ultrasound (US) can be performed to characterize and potentially biopsy areas of enhancement detected on contrast-enhanced mammography (CEM). OBJECTIVE. The purpose of this study was to assess the utility of targeted US in predicting malignancy of lesions with indeterminate or suspicious enhancement on CEM. METHODS. One thousand consecutive CEM examinations with same-day targeted breast US at one institution between October 2013 and May 2018 were retrospectively reviewed. All patients with indeterminate or suspicious enhancement detected on CEM that underwent US evaluation were included. Patients with palpable or symptomatic lesions, those with suspicious findings on low-energy mammograms or images obtained with another modality, and those with less than 1 year of follow-up were excluded. Medical records, imaging, and pathology data were reviewed. Histopathologic analysis was used as the reference standard for biopsied lesions, and follow-up imaging was used for unbiopsied lesions. Associations between pathologic diagnosis, presence of a US correlate, and lesion characteristics were assessed by Fisher exact, chi-square, and Wilcox-on rank sum tests. RESULTS. Among 153 enhancing lesions detected on CEM in 144 patients, 47 (31%) had a US correlate. The frequency of a correlate between CEM and US was significantly higher among enhancing masses (28/43 [65%]) than among lesions exhibiting nonmass enhancement (19/110 [17%]) (p < .001). The likelihood of malignancy was significantly greater among lesions with a US correlate (12/47 [26%]) than among those without a US correlate (11/106 [10%]) (p = .03), and among mass lesions (11/43 [26%]) than among nonmass lesions (12/110 [11%]) (p = .04). The PPV of US-guided biopsy after CEM-directed US was 32%. CONCLUSION. Enhancing CEM-detected lesions that have a US correlate are more likely to be malignant and can be evaluated with US-guided biopsy to obviate additional breast MRI. CLINICAL IMPACT. CEM-directed US of enhancing lesions is useful given that lesions with a US correlate are more likely to be malignant and can be used as targets for US-guided biopsy until a CEM biopsy system becomes commercially available.