Use of terahertz spectroscopy for in vivo studies of lymphedema development dynamics

A laboratory model of lymphedema development induced by lymphatic vessel resection in rat extremities is presented. In vivo analysis of lymphedema development (monitoring for 4 weeks) employed reflective terahertz spectroscopy with a Dove prism. The incidence angle for an $s$-polarized electromagnetic wave directed to the boundary of the prism and the biological tissue was close to the Brewster's angle. Significant changes in the spectral characteristics of the tissue in the animals' extremities were detected on days 21–28 of lymphedema development. A predictive model for disease diagnostics based on monitoring the changes of the tissue absorbance curve in the 0.4–1.1 THz range was constructed. Principal component analysis and support vector machines were used in the model.