US and MRI in the evaluation of mammographic BI-RADS 4 and 5 microcalcifications

The aim of this study was to assess diagnostic accuracies of ultrasonography (US) and magnetic resonance imaging (MRI) in lesions that manifest as mammographic BI-RADS 4 and 5 microcalcifications, in the setting of conjoined use of mammography, US, and MRI.

Patients with mammographic BI-RADS 4 or 5 microcalcifications, without additional findings, were included in this prospective study. All patients subsequently underwent breast US and MRI. Histopathologic diagnosis, obtained by US-guided core-needle biopsy or surgical excision, served as a reference standard. Diagnostic accuracies of US and MRI were calculated, and positive predictive value for different MRI BI-RADS imaging features were determined.

The study group consisted of 113 women with 125 areas of suspicious microcalcifications. MRI reached sensitivity, specificity, positive predictive value 3 (PPV3), and negative predictive value (NPV) of 100%, 70.1%, 67.6%, and 100%, respectively. Statistically significant differences in MRI morphologic features and kinetic enhancement curves were observed between malignant and benign microcalcifications. Sensitivity, specificity, PPV3, and NPV for US were: 85.4%, 66.2%, 61.2%, and 87.9%. There was statistically significant difference in presentation of malignant and benign microcalcifications at US.

In the setting of conjoined use of mammography, US, and MRI, MRI can reliably exclude malignancy in suspicious microcalcifications. Thus, negative MRI findings may influence the decision to biopsy the microcalcifications.