In vivo monitoring of oxygen state and hemoglobin concentration in course of tumor model development by optical diffuse spectroscopy A. Orlovaa,b, M. Kirillina*, A. Volovetskyb, N. Shilyaginab, E. Sergeevaa, G. Golubiatnikova, and I. Turchina a Institute of Applied Physics RAS, Nizhny Novgorod, Russia, bN.I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia SFM 2016, Saratov, Russia, 27-30 September, 2016

Motivation Tumor oxygen status is important for choice of treatment strategy Evolution of tumor blood saturation and hemoglobin content allow to conclude on tumor progression and response to treatment Significant difference in absorption spectra of oxy- and deoxyhemoglobin in visible and NIR ranges indicates high efficiency of optical spectroscopy in monitoring blood oxygenation Optical diffuse spectroscopy monitoring of oxygen status and hemoglobin content in tumor and in normal tissue in course of tumor development

Scattering coefficient Absorption coefficient Optical Diffuse Reflectometry Main tissue chromophores ODR measurements Diffusion approximation Lipids, water deoxyhemoglobin (HHb), oxyhemoglobin (HbO2) Scattering coefficient Absorption coefficient Tissue structure Tissue content Blood saturation (StO2) StO2=[HbO2]/[HHb+HbO2] ODR principle source detector measurement volume Tissue blood content tHb Tissue oxygen consumption Blood outflow rate НHb Tissue oxygen delivery HbO2 Torricelli A., et al, Optics Express, 2003, V 11 De Blasi et all, 1993; Lu et all, 2004 Phan T.G., Bullen A., Immunol Cell Biol. 2010. 88(4). 438-44 3

Dynamics of tumor growth * Mice Balb/c-nude (n = 6) SKBR-3 tumor model Asterisk (*) indicates statistically significant differences with the initial level at the beginning of monitoring period (p < 0.05).

Reconstructed absorption spectra Normalized reflectance spectra tumor muscle Reconstructed spectra of absorption coefficient tumor muscle

Dynamics of blood oxygen saturation level Asterisk (*) indicates statistically significant differences with the initial level (p < 0.05). Hash (#) indicates statistically significant differences between the tumor and muscle (p < 0.05).

Oxygen saturation (StO2) versus pO2 values Measurements from 12th, 16th, 19th, and 22th days of tumor growth r is the Pearson's correlation coefficient

Dynamics of hemoglobin concentration μ * # tHb HbO2 μ HHb Asterisk (*) indicates statistically significant differences with the initial level (p < 0.05). Hash (#) indicates statistically significant differences between the tumor and muscle (p < 0.05).

Values of tHb, StO2, HbO2, HHb versus tumor volume for entire monitoring period b) p-value = 0.11 StO2 μ c) p-value < 0.01 HbO2 μ a) p-value < 0.01 tHb μ d) p-value < 0.01 HHb p-value is the significance level from х2-test.

Conclusion Using DOS technique differences in the level of oxygenation and hemoglobin concentration between experimental tumor and normal tissue were revealed. Rapid decrease of tumor oxygenation level preceded the acceleration of its growth during which oxygen state has remained low. Increase of tumor volume was accompanied by the gradual elevation of total hemoglobin concentration (increase of blood content). The main contribution to blood content increase was made by deoxyhemoglobin (increase of tissue oxygen consumption and decreased blood outflow rate). The proposed approach is useful for diagnosis of tumors as well as for study of changes in tumor models blood flow parameters when monitoring tumor response to therapy.

Acknowledgements Anna Maslennikova Maksim Prudnikov Russian Foundation for Basic Research (projects 15-02-04270) Targeted Federal Program of the Ministry of Education and Science of the Russian Federation, Grant No. 14.578.21.0030 (RFMEFI57814X0030). Anna Maslennikova Maksim Prudnikov Kristina Kuznetsova Vladimir Plekhanov Ilya Fiks

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