Differential Mueller matrix imaging of partially depolarizing optically anisotropic biological tissues.

Since recently, a number of innovative polarization-based optical imaging modalities have been introduced and extensively used in various biomedical applications, with an ultimate aim to attain the practical tool for the optical biopsy and functional characterization of biological tissues. The techniques utilize polarization properties of light and Mueller matrix mapping of microscopic images of histological sections of biological tissues or polycrystalline films of biological fluids. The main drawback of currently developed laser polarimetry approaches and Mueller matrix mapping techniques is poor reproducibility of experimental data. This is due to azimuthal dependence of polarization and ellipticity values of most matrix elements to sample orientation in respect to incidence light polarization. Current study aims to generalize the methods of laser polarimetry for diagnosis of partially depolarizing optically anisotropic biological tissues. A method of differential Mueller matrix mapping for reconstruction of linear and circular birefringence and dichroism parameter distributions of partially depolarizing layers of biological tissues of different morphological structure is introduced and practically implemented. The coordinate distributions of the value of the first-order differential matrix elements of histological sections of brain tissue with spatially structured, optically anisotropic fibrillar network, as well as of parenchymatous tissue of the rectum wall with an "islet" polycrystalline structure are determined. Within the statistical analysis of polarization reproduced distributions of the averaged parameters of phase and amplitude anisotropy, the significant sensitivity of the statistical moments of the third and fourth orders to changes in the polycrystalline structure of partially depolarizing layers of biological tissue is observed. The differentiation of female reproductive sphere connective tissue is realized with excellent accuracy. The differential Mueller matrix mapping method for reconstruction of distributions of linear and circular birefringence and dichroism parameters of partially depolarizing layers of biological tissues of different morphological structures is proposed and substantiated. Differential diagnostics of changes in the phase (good balanced accuracy) and amplitude (excellent balanced accuracy) of the anisotropy of the partially depolarizing layers of the vagina wall tissue with prolapse of the genitals is realized. The maximum diagnostic efficiency of the first-order differential matrix method was demonstrated in comparison with the traditional methods of polarization and Mueller matrix mapping of histological sections of light-scattering biological tissues.

THE COMPARATIVE ANALYSIS OF DIFFERENT TECHNIQUES OF LASER POLARIMETRY FOR DETERMINATION OF TIME OF DEATH IN THE STUDY OF POLYCRYSTALLINE FILMS OF CEREBROSPINAL FLUID.

The estimation of death coming prescription (DCP) is one of the most important issues that confronts a medical examiner during the corpse examination right at the scene of death. The most promising biological object for the DCP estimation is cerebrospinal fluid. Aim - to compare the effectiveness of methods being used: stokes-polarimetry, stokes-colorimetry, autofluorescence polarimetry in order to improve the accuracy of DCP for the long - and short-term time intervals. The object of the study - cerebrospinal fluid from 75 cadavers (study group) and 20 live individuals (control group). Methods used: stokes polarimetry, stokes-colorimetry, autofluorescence polarimetry. When analyzing the image of the biological sample within the statistical analysis using the stokes polarimetry it is possible to obtain some quantitative characteristics about the amount of the statistical moments of the 1st - 4th orders, which can be used to find the relationship between them and the DCP. However, the coordinate and morphological structure of biological samples are ignored when using this approach. A correlation method in this context is more functional and sensitive. Due to this a higher accuracy of DCP is achieved in a short period. The analysis revealed that the spatial-frequency filtration of polarization-inhomogeneous images of polycrystal films of cerebrospinal fluid improves the time monitoring sensitivity of biochemical changes in optically active molecular compounds. Speaking about fluorescence microscopy - it carries the information about the concentration of molecular complexes of proteins, NADH, flavins, porphyrins, etc. As in the postmortem period the changes in the cerebrospinal fluid begin with the changes in the concentration of biochemical compounds, and crystalline changes are secondary, this method is the most effective for diagnosing the death coming prescription in the first 8 hours. The fluorescent methods of laser polarimetric are precise at a short interval of DCP estimation, and the polarization ones allow us to estimate this parameter at the long-term time intervals, though with less accuracy.

[TIME SINCE DEATH ESTIMATION BY USING THE METHOD OF POLYCRYSTALLINE CEREBROSPINAL FLUID FILMS IMAGES MUTUAL POLARIZATION DEGREE LEVELS DISTRIBUTIONS TWO-DIMENSIONAL MAPPING WITH FINE-SCALE SPATIAL FREQUENCY FILTRATION].

Objective - to develop a method of two-dimensional Stokes-polarimetric spatial-frequency mapping of small-scale components of cerebrospinal fluid to improve the accuracy of post-mortem interval estimation. The object of the study was polycrystalline cerebrospinal fluid films taken from 69 corpses (the main study group) and 20 healthy volunteers (comparison group). For each sample, the coordinate distribution of the values of the complex degree of mutual polarization was determined in the optical arrangement of the Stokes polarimeter. The value of the statistical moments of 1 - 4 orders with further statistical processing was calculated. Time dependences of the variation of the value of the most sensitive statistical moments were built to achiev of values stabilization. The interval and the accuracy of the post-mortem interval were estimated by generalizing of the time dependences of the third and fourth order statistical moments of the polarization maps obtained by the two-dimensional mapping of the values distributions of the complex degree of mutual polarization of the small-scale component of polycrystalline networks of cerebrospinal fluid films. An interval of 10 h and the accuracy of post-mortem interval estimation ΔT = ± 12.5 min was established.