Frequency-Difference Electrical Impedance Imaging of Breast Specimens

Imaging abnormality in pathological breast specimens can greatly help pathologists select sites for conducting pathological examination through a microscope. In this study, the frequency-difference electrical impedance tomography (fdEIT) technique was proposed for localizing the abnormality in eight breast specimens. Three 16-electrode probes were developed for this purpose which worked with a high-signal-to-noise ratio (SNR) multifrequency electrical impedance tomography (EIT) system. The frequencies of 10 and 50 kHz were selected. The conductivity of the carcinoma masses was found 2.7-3.8 times higher than that of adipose tissues and 2%-21% higher than that of fibroglandular tissues. The conductivity difference of the masses over the selected frequencies was 2.5-3.5 times higher than that of the surrounding tissues. The probes could sense to a depth of similar to 12 mm from the specimen surface. Five of seven specimens (71.4%) were achieved to visualize the masses. Extremely and heterogeneously dense specimens provided better mass distinction in the images than the scattered dense specimens. A mass with a diameter over 20 mm and near the measuring surface was preferable for detection. However, the mass distinction in the images also depends on the conductivity of the mass itself. Mass could be hard and soft, and the soft masses could have different conductivity. The high conductive mass tended to have a better mass distinction in the images.