A Study of the Electrical Bio-impedance of Tumors

Abstract

A new system of impedance measurement over a frequency range of 0 to 200 kHz was developed by a three-electrode method. In this study, the electrical impedances of various tumors were measured in vivo in 54 patients with breast disease (31 breast cancers, 13 fibroadenomas, and 10 fibrocystic diseases) and 57 patients with pulmonary disease (44 lung cancers, 5 metastatic pulmonary tumors, 4 pulmonary tuberculoses, and 4 organized pneumonias). On the basis of those impedance measurements and the equivalent circuits in vivo, we calculated the extracellular resistance (R_e), intracellular fluid resistance (R_i), and cell membrane capacitance (C_m) in tissues, all of which were compared among the various diseases. It was found that R_e and R_i were significantly higher in breast cancers than in benign tumors and normal breast tissues and that C_m was significantly lower in breast cancers than in other tissues. On the other hand, R_e and R_i were significantly higher, and C_m was significantly lower, in normal lung tissues than in pulmonary masses. R_e and R_i were significantly higher, and C_m was significantly lower, in malignant tumors than in organized pneumonias. The results showed that these parameters (R_e, R_i, and C_m) exhibit significant differences among various tissues and tumors, suggesting possible applications in tumor diagnosis.