Sjoerd B.
Vos1, Derek K. Jones2, Max A. Viergever1,
Alexander Leemans1
1Image Sciences Institute, University
Medical Center, Utrecht, Netherlands; 2CUBRIC, School of
Psychology, Cardiff University, Cardiff, United Kingdom
Diffusion
tensor imaging has been used extensively to investigate brain aging. Fiber
tractography has shown a relation between age and fractional anisotropy (FA)
along fiber tracts. Partial volume effects are known to affect tractography,
and may also influence FA calculations along tracts. In this study,
simulations and experiments have been performed to test whether tract volume
is a covariate in FA calculations. A strong correlation between tract volume
and FA has been found in both the simulations and experiments, proving that
partial volume effects affect FA calculations, and that size is indeed a
hidden covariate in tractography based FA analyses.