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 (Re), intracellular fluid resistance (Ri), and cell membrane capacitance (Cm) in tissues, all of which were compared among the various diseases. It was found that Re and Ri were significantly higher in breast cancers than in benign tumors and normal breast tissues and that Cm was significantly lower in breast cancers than in other tissues. On the other hand, Re and Ri were significantly higher, and Cm was significantly lower, in normal lung tissues than in pulmonary masses. Re and Ri were significantly higher, and Cm was significantly lower, in malignant tumors than in organized pneumonias. The results showed that these parameters (Re, Ri, and Cm) exhibit significant differences among various tissues and tumors, suggesting possible applications in tumor diagnosis.

A new impedance analytical system was developed, and measurements were performed over a frequency range of 0–200 kHz by the three-electrode method. The three electrodes consist of a coaxial needle electrode inserted into the tumor and a large reference electrode on the upper abdominal wall. The electrical bio-impedance was measured in 54 patients with breast tumors. The biological tissue can be regarded electrically as an equivalent consisting of extracellular resistance (Re), intracellular resistance (Ri), and electrical capacitance of the cell membrane (Cm). These three parameters were calculated from the measured values of electrical bio-impedance by the curve-fitting technique using a computer program. It was found that Re and Ri of breast cancers were significantly higher than those of benign tumors (p < 0.01), and that Cm of breast cancers was significantly lower than that of benign tumors (p < 0.01). Measurement of the electrical bio-impedance of breast tumors may have value in the differential diagnosis of breast lesions.