Quantification of edema in human brain tissue by determination of electromagnetic parameters

In an autopsy, the evaluation of edema is an important task. Especially, the occurrence of edema in the brain can help to verify the cause of death. However, until now there is no standardized procedure in forensic medicine to exactly quantify edema in parenchymatous organs. Thus, the aim of our work is the development of a fast and accurate, but low-cost measurement system that is capable of determining the permittivity of brain tissue that correlates with the tissue's humidity content. Therefore, we investigated the relation between permittivity and humidity content measured with a reference system. Our measuring principle is based on a coaxial measurement of the complex permittivity, leading to short measuring times. With the developed system samples from different brain regions and probates were analyzed and a linear regression with an excellent correlation coefficient between the real part of the permittivity and the humidity content in the tissue was found. Our system was calibrated with a commercial moisture measuring system based on the microwave oven dry method, therefore allowing an objective quantification of edema.