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5Optical coherence elastography for quantitative visualization of
diffusion processes in biotissues
V.Y. Zaitsev1*, A.A. Sovetsky1, E.M. Kasianenko1,2, A.L. Matveyev1, A.A. Zykov1,
Y.M. Alexandrovskaya3
1-A.V Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod,
Russia
2- National Research Center Kurchatov Institute, Moscow, Russia 4Scientific 3- Terra Quantum GmbH, Munich, Germany
In this report we present an emerging application of Optical Coherence Tomography (OCT) based on mapping of strains induced by diffusion of osmotically active solutions into the depth of various biotissues as well as artificial tissue-like materials such a polyacrilamide gels. In recent years, processing of sequences of phase-sensitive OCT scans demonstrated high efficiency for imaging of mechanically produced strains in tissues for realization of Compression Optical Coherence Elastography (C-OCE) [1]. However, a similar principle can be applied for imaging strains of diverse origins (e.g. thermally-induced ones, drying-induced strains, etc.)
A new direction is OCE application for studying diffusion of various solutions which are often osmotically active, so that their penetration in tissues is accompanied by the development of osmotic strains [2,3]. OCE makes it possible to quantitatively monitor in real time the development of osmotically induced slow deformations (on time intervals from seconds to tens of minutes). Such observation may give new information about penetration in tissues of various drugs or osmotically-active solutions often used as optical clearing agents, such as solutions of glycerol. It was found that for many solutions, their diffusion in the tissue bulk is accompanied by the development of peculiar sign-alternating spatial patterns of strain. Depth positions of the visualized positive and negative strain extrema clearly demonstrate proportionality to the square root of the elapsed time, which is typical of diffusion processes. Monitoring of the extremum's position makes it possible to estimate the diffusion coefficient. It was demonstrated that the analysis of dynamics of osmotically-induced deformations can be used to diagnose difference in the cross-linking degree of polyacrylamide gels [3], whereas observations of magnitude and rate of osmotic strains caused by penetration of glycerol in cartilage samples was found to be dependent on the degree of degradation of proteoglycans in cartilage [4]. Application of a similar technique was demonstrated for observing tissue deformations caused by the development of crosslinks under the action of crosslinkers.
The reported results further extent the area of OCE applications beyond the most widely discussed [1] diagnostics of tissue types/states based on differences in their elastic properties.
The study was supported by the Russian Science Foundation grant No. 22-12-00295.
[1] V.Y. Zaitsev, A.L. Matveyev, L.A. Matveev, A.A. Sovetsky, M.S. Hepburn, A. Mowla, B.F. Kennedy, Strain and elasticity imaging in compression optical coherence elastography: The two-decade perspective and recent advances, Journal of Biophotonics, 14(2), e202000257 (2021).
[2] Y. Alexandrovskaya, O. Baum, A. Sovetsky, A. Matveyev, L. Matveev, E. Sobol, V. Zaitsev, Optical Coherence Elastography as a Tool for Studying Deformations in Biomaterials: Spatially-Resolved Osmotic Strain Dynamics in Cartilaginous Samples, Materials, V. 15, 904. (2022).
[3] Y.M. Alexandrovskaya, E.M. Kasianenko, A.A. Sovetsky, A.L. Matveyev, V.Y. Zaitsev, Spatio-Temporal Dynamics of Diffusion-Associated Deformations of Biological Tissues and Polyacrylamide Gels Observed with Optical Coherence Elastography, Materials, V. 16, 2036 (2023).
[4] Y.M. Alexandrovskaya, E.M. Kasianenko, A.A. Sovetsky, A.L. Matveyev, D.A. Atyakshin, O.I. Patsap, M.A. Ignatiuk, A.V. Volodkin, V.Y. Zaitsev, Optical coherence elastography with osmotically induced strains: Preliminary demonstration for express detection of cartilage degradation, Journal of Biophotonics, 1-15 (2024).
