Mueller-matrix mapping of optically anisotropic fluorophores of biological tissues in the diagnosis of cancer

We report the results of studying the polarisation manifestations of laser autofluorescence of optically anisotropic structures in biological tissues. A Mueller-matrix model is proposed to describe their complex anisotropy (linear and circular birefringence, linear and circular dichroism). The relationship is established between the mechanisms of optical anisotropy and polarisation manifestations of laser autofluorescence of histological sections of rectal tissue biopsy in different spectral regions. The ranges of changes in the statistical moments of the 1st-to-4th orders, which describe the distribution of the azimuth-invariant elements of Mueller matrices of rectal tissue autofluorescence, are found. Effectiveness of laser autofluorescence polarimetry is determined and the histological sections of biopsy of benign (polyp) and malignant (adenocarcinoma) tumours of the rectal wall are differentiated for the first time.