Dielectric properties of animal tissues in vivo at radio and microwave frequencies: comparison between species.

An improved and modified technique with an open-ended coaxial-line sensor was used for measurement of the dielectric properties of animal tissues in vivo. The permittivity of skeletal muscle, brain cortex, spleen and liver of live cats and rats was measured at frequencies between 0.1 and 10 GHz. The results were compared with various published data on in vivo permittivity of the same and other species. The differences between the properties of the same tissue for various animals are very small. The tissues properties at frequencies above 1 GHz correlate well with the water content. Practically all water in the skeletal muscle is in the free form, while in other tissues both free and bound water are present.