With the help of double
diffusion encoding experiments with two weighting periods applied
successively microscopic tissue parameter can be gained. Rotationally
invariant measures of the microscopic diffusion anisotropy such as
the MA index may yield additional information complementary to DTI.
Recent studies showed that MA can be determined in the living human
brain, and normal values and their variation in groups of young and
old healthy volunteers have been reported. In this study, the
age-correlation of the diffusion anisotropy measures in terms of MA
and FA values in a group of old volunteers (> 60 y) is discussed.