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.

Jones-matrix mapping of complex degree of mutual anisotropy of birefringent protein networks during the differentiation of myocardium necrotic changes.

The azimuthally stable method of Jones-matrix mapping of histological sections of myocardium tissue biopsy using spatial-frequency selection of the mechanisms of linear and circular birefringence is proposed. Correlation parameter-the complex degree of mutual anisotropy-and its diagnostic application are analytically substantiated. The method of measuring the complex degree of mutual-anisotropy coordinate distributions using spatial filtration of their high- and low-frequency components is developed. The interconnections between such distributions and parameters of linear and circular birefringence of myocardium tissue histological sections are defined. The comparative investigations of coordinate distributions of the complex degree of mutual anisotropy formed by fibrillar networks of myocardium tissues of different necrotic states (dead due to coronary heart disease and acute coronary insufficiency) are performed. The values and ranges of change of the statistical (moments of the first-fourth order) parameters of coordinate distributions of the complex degree of mutual anisotropy are defined. The objective criteria of cause of death differentiation are determined.

Polarization-dependent laser autofluorescence of the polycrystalline networks of blood plasma films in the task of liver pathology differentiation.

Current research presents the results of the investigation of diagnostic efficiency of laser polarization autofluorescence for the set of endogenous fluorophores of blood plasma polycrystalline films in two spectral regions (0.5-0.53 µm and 0.63-0.67 µm) under the excitation of laser radiation with a wavelength of 0.405 µm. A model of generalized optical anisotropy of protein networks of blood plasma polycrystalline films is proposed for the purpose of defining laser autofluorescence processes. Both phase (linear birefringence and optical activity) and amplitude (linear and circular dichroisms) anisotropies have been considered. Interconnections between the optimal condition of probing beam polarization state and the efficiency of induction laser autofluorescence have been found. Statistical analysis of coordinate distributions of laser polarization autofluorescence intensities is suggested by means of determination of the quantitative criteria (statistical moments of the 1st-4th orders). The efficiency of laser polarization autofluorescence of polycrystalline networks in the task of differentiation of nonalcoholic fatty liver disease and chronic hepatitis of human liver has been analyzed.

Fourier polarimetry of human skin in the tasks of differentiation of benign and malignant formations.

The optical model of polycrystalline networks of human tissue has been proposed. The values of statistical parameters (statistical moments of the first to fourth order) characterizing the polarization-inhomogeneous images of skin surface in the Fourier domain have been measured. The diagnostic criteria of pathological processes in human skin and the differentiation of its severity degree have been determined.

Birefringence images of polycrystalline films of human urine in early diagnostics of kidney pathology.

We propose an optical model of the Mueller-matrix description of mechanisms of optical anisotropy of polycrystalline films of urine, namely, optical activity and birefringence. The algorithm of reconstruction of distributions of parameters-optical rotation angles and phase shifts of the indicated anisotropy types-are elaborated upon. The objective criteria of differentiation of urine films taken from healthy donors and albuminuria patients by means of statistical analysis of such distributions are determined. The operational characteristics (sensitivity, specificity, and accuracy) of the Mueller-matrix reconstruction method of the optical anisotropy parameters are defined.

Two wavelength Mueller matrix reconstruction of blood plasma films polycrystalline structure in diagnostics of breast cancer.

The model of a Mueller matrix description of mechanisms of optical anisotropy typical for polycrystalline films of blood plasma--optical activity, birefringence, as well as linear and circular dichroism--is suggested. On this basis, the algorithms of reconstruction of parameters distribution (polarization plane rotations, phase shifts, coefficients of linear and circular dichroism) of the indicated types of anisotropy were found for different spectrally selective ranges. Within the statistical analysis of such distributions, the objective criteria of differentiation of films of blood plasma taken from healthy women and breast cancer patients were determined. From the point of view of probative medicine, the operational characteristics (sensitivity, specificity and accuracy) of the method of Mueller matrix reconstruction of optical anisotropy parameters were found, and its efficiency in diagnostics of breast cancer was demonstrated.