Diagnostic potential of targeted electrical impedance scanning in classifying suspicious breast lesions.

Abstract

To evaluate the potential of targeted electrical impedance scanning (EIS) for classifying suspicious breast lesions. EIS was performed in full knowledge of mammographic findings and findings of clinical breast examination. One hundred seventeen patients with a total of 129 breast lesions were examined with EIS before breast biopsy (surgical excision or vacuum core biopsy). Diagnostic indexes of targeted EIS were calculated depending on major lesion characteristics. Capacitance and conductivity of all positive spots (S) and the surrounding normal breast tissue (NBT) were quantified using ROI measurements. The ratio S/NBT was calculated to compare true positive (n = 44) and false positive (n = 18) spots. With respect to histology, of the 129 lesions 71 were malignant and 58 lesions were benign. Overall sensitivity of targeted EIS was 62%, specificity 69%, PPV 71%, and NPV 60%. Sensitivity of EIS varied depending on the tumor size, which was between 48% (> 20 mm) and 71% (11-20 mm). Highest specificity (86%) was observed for large lesions (> 20 mm); however, the NPV was only 35% for lesions of that size. NPV was higher for nonpalpable lesions (74%) and clusters of microcalcifications (85.7%) compared with palpable lesions (39%) and solid lesions (44%). There was no statistical difference of S/NBT ratio neither for conductivity nor capacitance of true and false positive spots. Compared with true positive spots a trend of a higher conductivity ratio at 100 Hz and 200 Hz was seen for false positive spots. EIS showed mediocre overall diagnostic accuracy for classifying suspicious breast lesions. Quantitative analysis of positive EIS findings did not help to differentiate between false and true positive spots.