Correlation of permittivity and water content during cerebral edema

Correlation between the permittivity of white matter and cerebral edema was studied. A time domain reflectometer was used to measure the permittivity changes of canine cerebral white matter due to edema produced in vitro by osmosis over a frequency range of 100 MHz to 1 GHz. For all frequencies, a strong correlation was found between the water content and the dielectric constant (R/spl ap/0.86) and loss factor (R/spl ap/0.82). The results suggest that it may be possible to estimate both the tissue water content as well as the composition of the accumulated edematous fluid.