First, the anisotropic and isotropic tissues can be distinguished by using the diagonal elements. The porcine liver (red lines) and fat (blue lines) tissues are predominantly isotropic; therefore, their m22 and m33 curves are almost the same (for example, for the fat tissue, P1 of the m22 and m33 are 0.041 and 0.041, P2 are 0.013 and 0.012). The anisotropic bovine skeletal muscle (black lines) and chicken heart (green lines) tissues, however, display differences between the m22 and m33, which become more prominent as the anisotropy increases. Table 3 shows that the differences in P1 of m22 and m33 elements for anisotropic skeletal muscle and heart samples are 0.127 and 0.014, respectively. This is because that the fibers in skeletal muscle sample are well aligned in almost the same direction, while in heart sample the fibers are distributed in different orientations. For isotropic fat and liver tissues, the differences in P1 of m22 and m33 elements are 0 and 0.002. This is because the fat tissue is totally isotropic, while the liver sample has a small portion of birefringent connective tissues. Second, we also notice that the distribution widths of the FDHs (the values of P2) for bovine skeletal muscle, chicken heart, and porcine liver samples are larger than the fat sample, indicating more complicated microstructures for these metabolic exuberant tissues. The FDHs of the m24, m42, m34, and m43 elements for skeletal muscle, heart, and liver tissues show small positive or negative values, which are related to the birefringent structures in these tissues. The signs of the elements can be used to determine the aligned fibers directions.18 At last, the different depolarization power of tissues can also be observed from Fig. 6 and Table 3: the liver tissue sample has the largest P1 values of the diagonal elements, showing the smallest depolarization power, while the smallest P1 values of the diagonal elements indicate the most prominent depolarization property of the fat tissue.10 Although more studies are still needed to reveal the relationships between the derived parameters and tissue morphology, it has been shown that the parameter P2 should be sensitive to the complexity of a sample: a large value of P2 means that the measured polarization data are distributed in a wider range, indicating a complex structural feature of the tissue. The parameter P3 should be sensitive to the heterogeneity of a sample: a large value of P3 means that the measured polarization data are unequally distributed around the expected value. The parameter P4 can also be used to reflect the complexity of a sample: a large P4 shows that most measured polarization data are distributed very close to the mean value, meaning that the microstructural features are similar.