Mohr diagram interpretation of anisotropic diffusion indices in MRI

Descriptions of diffusion anisotropy in MR Diffusion Tensor Imaging are often based on scalar indices such as surface-to-volume ratio, volume ratio, fractional anisotropy and rotational anisotropy. Recently, Mohr diagram was introduced to visualize the anisotropic diffusion information, but in a graphical form. Even though both scalar indices and the Mohr diagram are derived from the elements of the diffusion tensor, so far, the relationships between these measures and the key aspects of the Mohr diagram have not been established. This paper demonstrates these relationships both qualitatively and quantitatively for two microscopically heterogeneous biologic tissues, kidney and spinal cord.