Richard A E
Edden1,2, Derek K. Jones3
1Russell H Morgan Department of
Radiology and Radiological Science, The Johns Hopkins University, Baltimore,
MD, United States; 2FM Kirby Research Center for Functional MRI,
Kennedy Krieger Institute, Baltimore, MD, United States; 3CUBRIC,
School of Psychology,, Cardiff University, Cardiff, Wales, United Kingdom
DTI
provides rotationally invariant information.
Additionally, DTI acquisitions are optimised to ensure that data are
statistically rotationally invariant so that parameter variance is
independent of the orientation of the fibre population within the brain.
Against this backdrop, we focus on skeletonization-based methods for group
comparisons of DTI data and show that they can reintroduce rotational
dependence. Specifically, the power to detect group differences in a fibre
can depend on its orientation. While the cause/solution to this problem are
trivial, the effect on statistical inference is not and should be viewed in
the light of the increasing popularity of skeletonization-based methods.