Evaluation of Electrical Impedance Tomography for the Localization of Lung Nodules

Abstract

The objective of this study was to investigate whether tomography can be used to localize lung cancer modules to guide biopsies conducted through a bronchoscope. The dielectric properties of cancerous lung tissue are different from normal lung tissue. Hence, impedance across the electrodes in lung cancer biopsy tools will vary. Simulation in Ansys Q3D of a 3D structure of a lung biopsy tool containing array of electrodes was performed and it was found that the impedance for the normal lung case was higher than the cancer lung case at both 1 KHz and 1 MHz frequencies and at different electrode positions. To support the simulation results, the use of gelatin phantoms for simulating dielectric properties of lung tissues were experimentally investigated. Gelatin phantoms were composed of pure gelatin, sodium chloride and water. Among all the compositions, sample numbers 5 and 8 closely matched the dielectric properties of normal and cancer lung tissue. A prototype probe containing four pairs of electrodes was used in these samples to calculate the total impedance. Consistently, variations of electrical impedance at different electrode positions and frequencies were observed.