Andrada Ianuș1, Noam Shemesh2, Daniel C. Alexander1, and Ivana Drobnjak1
1CMIC, University College London, London, United Kingdom, 2Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal
Microscopic anisotropy
disentangles the effects of pore shape from orientation distribution,
and thus can serve as a valuable metric for underlying
microstructural configurations. Recent developments in diffusion MRI
proposed different approaches to acquire and analyse data for
extracting information regarding microscopic anisotropy. This work
compares in simulation two recently introduced metrics of microscopic
anisotropy: fractional eccentricity (FE), derived from
double-diffusion-encoding (DDE) sequences and microscopic fractional
anisotropy (μFA), derived from a combination of sequences with
isotropic and directional diffusion weighting. We find that
DDE-derived metrics are more reliable for quantifying underlying
microstructures if diffusion is restricted, while μFA is closer to
the ground truth values when individual micro-domains feature Gaussian
diffusion.
