A Development Of Electrode Probes For Imaging Precancerous Lesions With Electrical Impedance Tomography Technique: A Phantom Study

Abstract

Cervical abnormality screening can reduce the risk of getting cancer. Screening methods mostly depend on laboratory investigation which requires equipment, time, and pathologist experience. Electrical bioimpedance has been reported that can be used to identify the presence of cervical intraepithelial neoplasia (CIN) since the conductivity of CIN could be 4-5 times higher than that of normal tissue. In this study, an electrode probe having 8 round electrodes is developed with 1.5 mm-electrode distance. Tissue conductivity can be directly estimated with the probe based on the four-point measurement method, and the image of conductivity distribution can be reconstructed at the same time. The simulation result showed that when tissue thickness was thicker than 4 mm, the commonly-used formula for estimating conductivity is applicable regardless of the electrode shape, but a correction factor was needed with a value up to 1.2 when the thickness was down to 1 mm. The localization performance of the reconstruction images was investigated in a phantom experiment – on a piece of sausage with a burning spot on the surface. Five current excitations were performed from 2 kHz to 125 kHz. The burning surface could be located with a localization error of 0.23 mm with a frequency higher than 2 kHz. However, artifacts were still observable in the images at the boundary region of the electrode array. Thus, increasing the number of electrodes and increasing the probe tip area or decreasing the electrode diameter are still recommended.

Keywords

• electrode probe
• cervical precancerous tissues
• reconstruction
• tissue conductivity