Refractive Properties of Blood Serum of Rats with Experimental Liver Cancer
Currently, optical methods are widely used in medicine. They are easy to use and minimally invasive. However, their application and improvement require the most accurate information on the optical properties of tissues and their components. The refractive index (RI) is one of the major parameters, which characterizes how light interacts with biological tissue. In addition, the RI could be different for healthy and pathological tissues, which makes it possible to use RI as a biological marker.[1, 2].
We studied the refractometric properties of rat serum in the development of liver cancer in the visible, NIR and THz ranges. Studies were performed on laboratory animals for three groups: control, 14 days and 28 days after transplantation of the tumor into the area of the scapulae. The refractive index in the visible and NIR regions was measured using multi-wavelength Abbe refractometer DR-M2/1550 (Atago, Japan). Measurements for the THz region were performed on the terahertz (THz) time-domain spectrometer.
The decrease in the RI in the visible region during the development of oncologic disease in animals is due to a decrease in protein concentration, since the concentration of protein in the blood is linearly related to the refractive index. The high correlation between the data in the THz and visible regions, for example, makes it possible to reconstruct the dispersion dependence in the THz region from known values of the refractive index in the visible region and from the absorption coefficient in the THz region using the Kramers–Kronig relations.
The studies were funded by RFBR project № 17-00-00275 (17-00-00270, 17-00-00272).
 V.V. Tuchin, “Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnosis”, 3rd Ed., Bellingham, SPIE Press, 2015.
M.M. Nazarov, O.P. Cherkasova and A.P. Shkurinov, “Study of the dielectric function of aqueous solutions of glucose and albumin by THz time-domain spectroscopy”, Quantum Electronics, vol. 46(6), pp. 488-495, 2016.
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Ekaterina N. LAZAREVA
1 Saratov State University, Saratov, Russia 2Tomsk State University, Tomsk, Russia
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