The study of oxygenation dynamics during experimental tumor growth using frequency-domain diffuse optical spectroscopy

Abstract

Abstract The objective of this work was to study the dynamics and mechanisms of oxygenation changes of an experimental rat tumor Plyss lymphosarcoma in the process of its growth using diffuse optical spectroscopy (DOS). DOS in trans-illumination configuration utilizing high-frequency (140 MHz) modulation of light intensity is used to assess absorption and scattering coefficients averaged over tumor tissue at several wavelengths 684, 794, and 850 nm. Those values were used to assess concentrations of tissue oxyhemoglobin and deoxyhemoglobin and oxygen saturation. During the observation period (from the 5th to the 15th day after transplantation) the tumor volume increased up to 25 times. In the process of tumor growth, a gradual increase in the content of deoxyhemoglobin, a decrease of oxyhemoglobin level, and a decrease of blood oxygen saturation without changes in the level of total tissue hemoglobin concentration were observed. Thus, the main mechanisms of oxygen saturation decrease in the process of tumor growth are associated with two effects: the increase of oxygen consumption rate (demonstrated by the increase of deoxyhemoglobin) and the decrease of oxygen supply (demonstrated by the decrease of oxyhemoglobin).