A.V. Maslennikova, A.G. Orlova, G.Yu. Golubiatnikov, V.A. Kamensky, V.I. Plekhanov, A.A. Babaev, L.B. Snopova, I.P. Ivanova, T.I. Prianikova, N.M. Shakhova, I.V. Turchin

Tumor hypoxia is considered to be a key factor of tumor progression and resistance to radiotherapy. Understanding of importance of this physiological parameter for prognosis of treatment outcome stimulated the development of noninvasive techniques for assessing tumor oxygen status. Information about location of zones with different oxygenation is essential for adjustment of optimal spatial distribution of radiation dose. At present work with the purpose of determination of spatial distribution of hypoxic and oxygenated tumor regions the method of diffuse optical spectroscopy (DOS) was used. This method allows estimation of concentrations of oxygenated and deoxygenated hemoglobin, and, consequently, calculation of blood oxygen saturation level. For determination of spatial distribution of this chromophores, laser scanning in several wavelengths was used. As a method of verification we utilized immunohistochemical analysis with exogenous hypoxia marker - pimonidazole. Experiments were performed using Pliss-s lymph sarcoma model. It has been demonstrated that DOS method allows recognizing of the heterogeneity of tissue chromophores content. DOT images of the central part of Pliss-s lymph sarcoma demonstrated decreased concentration of oxygenated hemoglobin, the increased concentration of deoxygenated hemoglobin and substantial decrease of oxygen saturation as compared with the external part. As it has been shown by immunohistochemical analysis, the central zone of the tumor, in contrast to the periphery, is hypoxic. Thus, immunohistochemical investigation confirmed the DOS results. This method can be promising tool for estimation of the efficacy of radiomodifiers, chemotherapeutic agents and anti-angiogenesis pharmaceuticals.