Identifying Anisotropic Structures of Non-Stained Melanoma Tissue From Images of Its Mueller Matrix Elements.

The Mueller matrix has the capability of providing the complete polarisation information about the response of a medium to the incident polarised light. In this work, we report that the anisotropic structures of non-stained melanoma slices can be identified directly through the Mueller elements. It is observed that the elements M12, M22 and M24 show a high degree of similarity with the three polarisation parameters (the x-y linear diattenuation, the x-y linear depolarization and the ±45° linear birefringence), with PSNR values of 33.4 dB, 35.7 dB and 40.0 dB, respectively. From images of M12, M22 and M24, the cell nuclei and intercellular stroma in the melanoma dermis can be identified with higher contrast. The values of these elements are specific: for the cell nuclei, M22 ranges from -0.75 to -0.27 and M12 ranges from -0.12 to -0.04; for the extracellular matrix, M22, M12 and M24 fall within -0.16 and -0.07, 0.06 and 0.16 and 0.09 and 0.57, respectively. Finally, a theoretical analysis is presented to explain the observations. The results obtained in this is helpful for clinic applications of Mueller matrix images where a method of interpreting measured Mueller matrices rapidly and accurately is essential.