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10STUDY OF SKIN DEHYDRATION INTHE COURSEOF GRAFTED TUMOR DEVELOPMENT USINGSPECTRAL REFRACTOMETRY, NIR AND THZ SPECTROSCOPY
POLINA DYACHENKO (TIMOSHINA)1,2, EKATERINA LAZAREVA1'2, MAXIM NAZAROV3, ALLA BUCHARSKAYA4, VALERY TUCHIN1,2,5 AND ALEXANDER SHKURINOV6
1Saratov State University, Russia 2National Research Tomsk State University, Russia 3NRC «Kurchatov Institute», Russia 4Saratov State Medical University, Russia 5Institute of Precision Mechanics and Control, Russian Academy of Sciences, Saratov, Russia 6Lomonosov Moscow State University, Russia
timoshina2906@mail. ru
Abstract
Currently, different optical methods are widely used for diagnostics and therapy of some diseases. An increase of image contrast induced by tissue dehydration and optical clearing in the area of pathology is extremely important for the monitoring of precancerous conditions, early stages of cancer and other diseases [1]. The combination of studies in the optical and terahertz ranges opens up new possibilities for more reliable diagnosis of a number of diseases.
In this work, experimental studies of the spectral characteristics of the skin of laboratory animals with an inoculated tumor when probed by an optical clearing agent (100% glycerol solution). The reflection spectra were recorded in the spectral range 900-2000 nm using a USB4000-Vis-NIR spectrometer (Ocean Optics, USA) and a QR400-7-Vis / NIR fiber probe (Ocean Optics, USA). The tumor was inoculated by subcutaneous injection of 0.5 ml of a 25% tumor cell suspension in the Hanks solution of PC1 alveolar liver cancer strain into the scapula area. Laboratory rats were divided into two groups: pathological group No. 1 with a tumor inoculated 14 days after vaccination of a tumor and pathological group No. 2 with a vaccinated tumor after 28 days after inoculation of a tumor. NIR Spectroscopy measurements were taken from the skin area directly above the tumor formation and nearby (control area) without neoplasm. For the optical clearing study, a 99.3% glycerol solution was poured into a special cuvette in an amount of 1 ml, which openly touched the skin to ensure complete contact of the OCA with the skin surface for 30 min. After removal of the solution, reflection spectra were recorded from the studied area of the skin. Next, studies of the solution collected after 30 min of exposure to the skin were carried out using refractometry in the visible/NIR and THz spectroscopy. The refractive index of modified glycerol solutions was measured using an Abbe DR-M2 / 1550 multiwave refractometer (Atago, Japan). To select the wavelengths, interference filters were used for 480, 486, 546, 589, 644, 656, 680, 800, 930, 1100, 1300, and 1550 nm.
In both groups, an increase in the concentration of water in the skin of animals under the influence of OCA was recorded. This may happened due to strong glycerol affinity to water molecules which migrated from the in-depth skin layers and subcutaneous tissues to the site, where glycerol is. It was also noted that there are differences in the effect of the optical clearing agent on the concentration of water in the skin of control sites and over the tumor (Fig.1). This indicates a change in the optical properties of the skin under the development of pathology. The development of a malignant neoplasm caused a delayed diffusion of the agent into the skin, which is confirmed by the small effect of the agent on the concentration of water over the tumor neoplasm, in contrast to the skin of a healthy rat. The results obtained by the three methods correlate with each other.
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group 1(14 days) group 2 (28 days) group 1(14 days) group 2 (28 days) group 1(14 days) group 2 (28 days)
(a) (b) (c)
Figure 1: (a) Data on changes in the concentration of water in the skin for both groups by NIR Spectroscopy;(b) data for the ratio of the transmittance amplitude of the sample relative to the transmittance amplitude of a pure glycerol solution in the THz region; (c) water content in glycerol solution according to the results of measurements of the refractive index in the visible/NIR regions. The presented study were made possible with was supported by grants RFBR 17-00-00270 (PD, EL, MN, AS), 17-0000272 (VT).
References
[1] V.V. Tuchin' Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnostics, 3rd ed., SPIE Press, Bellingham, Washington , p. 988, 2015
