An Electrical Impedance Tomography System for Thyroid Gland with a Tiny Electrode Array

Abstract

Electrical impedance Tomography (EIT) is a non-invasive imaging technique based on measuring of the electrical conductivity and capacitance of abnormal and normal human tissues. The present work aims to develop an EIT imaging system for imaging thyroid gland. Patients with thyroid nodules were eligible for the study. The study was conducted on two groups of participants: control group consists of 20 normal female cases and experimental consists of 20 goiter female patients. The thyroid nodule location, size, and type measured by ultrasound. Thyroid gland conductivity and permittivity were recorded using EIT. The impedance measurement is done through the applying of two probes: one probe to the neck region (scanning probe) and the rest region (reference probe) with electrolytic gel for each probe, then the system software proceeds to reconstruct the image and calculate the electrical impedance of the thyroid gland on a personal computer which acts as an output display and storage for case information. The thyroid scanning probe has 64 electrodes embedded on a small space (30 mm diameter and 50 mm height) inside of the probe. Multifrequency impedance measurements are typically made by applying an electric current to a target mass by using of the scanning probe and measuring the developed voltage. The present EIT system provides real- time visualization of the spatial distribution of the electrical properties of the thyroid tissue. Images obtained from the bioimpedance (BI) were compared to images obtained from the ultrasound imaging, results showed great similarity between the two diagnostic images. Tumor tissue has higher resistance and capacitance value than that of normal thyroid gland.