Evaluation of electrical impedance spectroscopy for cervical intraepithelial lesions detection

Abstract

Objective: To evaluate the diagnostic accuracy of electrical impedance spectroscopy (EIS) in detection of pre-invasive cervical lesions. Design: Cross-sectional study of diagnostic validity carried out with 265 women between 15 and 55 years with abnormal pap smear report, referred to colposcopy, who were evaluated between January 2008 and June 2010 in the Cervical Pathology and Colposcopy Network in the Departments of Caldas and Risaralda (Colombia). Measurements of electrical impedance spectroscopy of the cervix were made, new pap smear samples were taken, colposcopic examination and colposcopically directed biopsies were performed. Results: The evaluated parameters were resistivity of the extracellular space (R), resistivity of the intracellular space (S), cell membrane capacitance (Cm) and characteristic frequency (Fc). The results obtained for R parameter were: in squamous normal tissue 21.27 +/- 16.48 (Ωm); in high-grade lesions 4.28 +/- 2.28 (Ω-m); and in low-grade lesions 10.1 +/- 4.59 (Ω-m), showing a decrease of R in neoplastic tissue compared to normal tissue. The sensitivity of the EIS was 0.88 for high grade lesions and 0.71 for low grade lesions. The area under the ROC curves for high grade lesions /normal epithelium was 0.96, for low grade lesions/ normal epithelium was 0.76 and for high grade/low grade was 0.90. Conclusions: This study established that EIS is a useful technique for detection and characterization of cervical intraepithelial lesions, with diagnostic precision greater than 75%, with sensitivity and specificity over 69%, with an acceptable positive predictive value and a negative predictive value close to 90%.