Ek T. Tan1, Luca Marinelli1, Christopher J. Hardy1, Kevin F. King2, Jonathan I. Sperl3, Marion I. Menzel3
1GE Global Research, Niskayuna, NY, United States; 2GE Healthcare, Waukesha, WI, United States; 3GE Global Research, Garching, Germany
Diffusional anisotropy is an important indicator for axonal integrity, but conventional DTI-based fractional anisotropy (FA) is not well-suited to describing anisotropy of multi-directional diffusivities. A multi-directional anisotropy (MDA) metric was proposed, which is analytically and experimentally shown to be equivalent to FA in single-fibers. In double-fibers, the mean MDA was higher than FA, while the variation of MDA was smaller than FA. In addition, fiber counts can be inferred from the diffusion propagator. The availability of both MDA and fiber counting can be useful for multi-parametric analysis of anisotropy in crossing-fiber and gray matter regions.
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