IMAGING CERVICAL SPECIMENS FOR PRE-CANCER SCREENING WITH MULTI-FREQUENCY ELECTRICAL IMPEDANCE TOMOGRAPHY TECHNIQUE

Abstract

Screening for precancerous cervical cells can reduce the risk of death. However, most screening methods require laboratory investigation involving equipment, time, and expertise of pathologists. Electrical Impedance Tomography (EIT) is a method that possibly be used to localize cervical intraepithelial neoplasia (CIN), as the conductivity of the abnormality is typically higher than normal tissue. This study investigated this possibility and investigated a configuration of Multi-frequency EIT (mfEIT) Two electrode probes were developed. The experimental results showed that the system SNRs were more than 88 dB. The frequency of 50kHz and that of 10kHz are recommended for mfEIT reconstruction. The conductivity of formalin was approximately 0.586 S/m at 50 kHz excitation. The conductivity of the cervical specimens was 0.377 S/m in cases of abnormal tissue and 0.283 S/m in normal tissue, at 50 kHz excitation. Furthermore, the conductivity of the soft tissue was approximately 0.406 S/m at 50 kHz excitation, close to abnormal tissue. Image reconstruction results on three specimens found that the abnormality can be located. In the images, the region where the conductivity changes over different frequency indicated the location of abnormality or the region of the transformation zone or the endocervical region. Further experiments also found that the reconstruction images obtained with the single frequency EIT method where the measurement at the stroma region was used as the reference. This is because the back of the cervical specimen has the similar electrical characteristic as the soft and abnormal Therefore, the probe can detect abnormality using both single and multiple frequency basis, as the large conductivity change represents the normal region and the small conductivity change represents the abnormal region.

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