Prognostic value of Electrical Impedance Spectroscopy (EIS) when used as an adjunct to Colposcopy – a longitudinal study

Abstract

ObjectiveColposcopy can be used with Electrical Impedance Spectroscopy (EIS) as an adjunct, to assess the presence of High Grade Cervical Intra-epithelial Neoplasia (CIN2+). This analysis of longitudinal data has used the results from women with a negative colposcopy, in order to see if the initial (index) EIS results were able to predict the women who subsequently developed CIN2+. A further objective was to investigate what tissue structural changes might be reflected in the electrical impedance spectra.Methods847 patients were referred with low grade cytologly. EIS measurements were made around the transformation zone of the cervix during colposcopy. Every EIS spectrum was matched to a template representing CIN2+ and the result was positive if the match exceeded a probability index threshold. The colposcopic impression was also recorded. All the women who developed biopsy proven CIN2+ within three years of the index colposcopy were identified.ResultsThe median follow-up was 30.5 months. Where both CI and EIS were initially positive, there was an increased prevalence (8.13%) of CIN2+ developing as opposed to 3.45% in the remaining patients (p=0.0159). In addition, if three or more EIS spectra were positive there was a higher prevalence (9.62% as opposed to 3.56% p=0.0132) of CIN2+ at three years. The index spectra recorded from the women who developed CIN2+ showed EIS changes consistent with increases in the extracellular volume and in cell size inhomogeneity.ConclusionEIS does offer prognostic information on the risk of CIN2+ developing over the three-year period following the EIS measurements. The changes in EIS spectra are consistent with an increase in cell size diversity as pre-malignancy develops. These changes may be a consequence of increased genetic diversity as neoplasia develops.

Cervical cancer prognosis and diagnosis using electrical impedance spectroscopy

“…This is very reasonable as these are the features or properties associated with an evolving cervical neoplasia. Equation ( 8 ) actually verifies the speculation postulated in [ 10 ] that the increased risk of developing HG-CIN is associated with the increased diversity of cellular structures or inhomogeneity. Comparing models ( 7 ) and ( 8 ), we can see that once the neoplasia becomes more severe and/or has transferred into HG CIN, the extracellular volume that determines becomes another important property to differentiate between normal and cancerous tissues.…”

“…The research on the evaluation of prognostic value of EIS carried out in this paper is the continuation of the study presented in [ 10 ]. All the women in the study had a negative outcome at their initial colposcopy and were then followed up for three years.…”

“…In the previous study reported in [ 10 ], two single features derived directly from mean spectra of individual women, i.e. the impedance at 152Hz and the slope of the EIS spectra between frequencies 1.22 and 2.44kHz (used as a proxy for were respectively used to build a classifier for separating the two groups.…”

“…A commonly used interpretation [ 10 ] of the four Cole model parameters for tissue structure is that the inverse of extracellular volume determines the inverse of the total volume determines , cell sizes determine which is the centre of the dispersion, and α is determined by the inhomogeneity of the cells within the dispersion. The conductivity of the intracellular and extracellular spaces will also affect both , If the classification model for HG CIN detection can be constructed with the features derived from the four Cole parameter estimates, the above interpretation will provide us with valuable information to understand how the tissue structure changes due to disease might be reflected in the observed EIS spectrum.…”

Tissue Characterization Using an Electrical Bioimpedance Spectroscopy-Based Multi-Electrode Probe to Screen for Cervical Intraepithelial Neoplasia

“…Subsequently, many studies have evaluated whether CIN can be diagnosed based on the electrical properties of cervical tissues [ 9 , 10 , 11 , 12 ]. In addition, clinical studies using four electrodes with colposcopy have been performed to measure the bioimpedance spectra of suspected local regions of the cervix [ 13 , 14 , 15 , 16 ]. However, these methods were performed as auxiliary tools to improve the sensitivity and specificity in the suspected focal region as CIN, in addition to conventional cervical cancer screening tests.…”