The negative predictive value of electrical impedance scanning in BI-RADS category IV breast lesions

OBJECTIVES: We sought to prospectively assess the value of electrical impedance scanning (EIS) in discriminating benign from malignant lesions classified as BI-RADS category IV in mammography in comparison with ultrasound (US), with a special focus on negative prediction. MATERIALS AND METHODS: EIS was performed on 128 BI-RADS category IV lesions in 121 women (mean, 51.8 years). The newly developed EIS software 2.67 calculates a BI-RADS-like level of suspicion (LOS) on a 5-grade scale. LOS 1, 2, and 3 were considered negative; LOS 4 and 5 were considered positive. Histopathologic results were obtained in all lesions. RESULTS: Histology proved 37 lesions malignant, 91 benign. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of EIS compared with US were 94.6%, 74.7%, 80.5%, 60.3%, 97.1% versus 90.5%, 33.8%, 47.2%, 29.7%, 92.0%, respectively. In 43 lesions sized < or = 10 mm, EIS demonstrated better sensitivity, specificity, accuracy, PPV, and NPV of 100%, 83.3%, 90.7%, 82.6%, and 100%, respectively. Although NPV was also high, US showed no sufficient results in 39 (30.5%) lesions because of microcalcifications. Receiver operating curve analysis revealed best results for a combined use of US and EIS. CONCLUSIONS: With a NPV of 97.1% of EIS in BI-RADS category IV breast lesions, a negative result in these lesions could be firm indication to manage them as BI-RADS-category III and refer patients for a 6-month short-interval follow-up rather than performing a biopsy. The best adjunctive diagnostic performance can be achieved by a combination of US and EIS. Costs and patient morbidity could be minimized.