Performance of 2D Synthetic Mammography Versus Digital Mammography in the Detection of Microcalcifications at Screening

OBJECTIVE. The purpose of this study is to compare the performance of 2D synthetic mammography (SM) to that of full-field digital mammography (FFDM) in the detection of microcalcifications and to evaluate radiologists' preference between the two imaging modalities for assessing calcifications. MATERIALS AND METHODS. A fully crossed, mode-balanced, paired-case (n = 160), retrospective, multireader (n = 3) performance study was implemented to compare screening mammograms acquired with digital breast tomosynthesis and both FFDM and SM between 2015 and 2017. The study cohort included 70 patients with mammograms recalled for microcalcifications (35 with malignant findings and 35 with benign findings) and was supplemented with 90 patients with mammograms with negative findings. In separate sessions, readers interpreted SM or FFDM images by recording a BI-RADS assessment and the probability of malignancy. In a final session that included 70 mammograms with microcalcifications, readers recorded their subjective assessment of microcalcification conspicuity and diagnostic confidence. RESULTS. There was no difference in diagnostic accuracy as assessed by comparing the likelihood of malignancy based on the AUC of plotted ROCs, with AUCs of 91% (95% CI, 83-97%) and 88% (95% CI, 79-95%) observed for SM and FFDM, respectively (p = 0.392), and with noninferiority of SM compared with FFDM (p = 0.011). No significant difference was observed between SM and FFDM in terms of sensitivity (77% vs 73%, respectively; p = 0.366) or negative predictive value (84% vs 82%, respectively; p = 0.598). The specificity and positive predictive value of SM were lower than those of FFDM (91% vs 98%, respectively [p = 0.034], and 87% vs 96%, respectively [p = 0.034]). All readers found calcifications to be more conspicuous on SM (p < 0.0001); however, no significant difference in subjective diagnostic confidence was seen. CONCLUSION. SM is noninferior to FFDM in the detection of microcalcifications. Despite the increased conspicuity of microcalcifications on SM, the subjective diagnostic confidence in the two modalities is comparable.