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Regional brain axial and radial diffusivity changes during development
Author(s) -
Kumar Rajesh,
Nguyen Haidang D.,
Macey Paul M.,
Woo Mary A.,
Harper Ronald M.
Publication year - 2012
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.22757
Subject(s) - diffusion mri , thermal diffusivity , fractional anisotropy , putamen , nuclear magnetic resonance , psychology , neuroscience , physics , medicine , magnetic resonance imaging , radiology , quantum mechanics
The developing human brain shows rapid myelination and axonal changes during childhood, adolescence, and early adulthood, requiring successive evaluations to determine normative values for potential pathological assessment. Fiber characteristics can be examined by axial and radial diffusivity procedures, which measure water diffusion parallel and perpendicular to axons and show primarily axonal status and myelin changes, respectively. Such measures are lacking from widespread sites for the developing brain. Diffusion tensor imaging data were acquired from 30 healthy subjects (age 17.7 ± 4.6 years, range 8–24 years, body mass index 21.5 ± 4.5 kg/m 2 , 18 males) using a 3.0‐Tesla MRI scanner. Diffusion tensors were calculated, principal eigenvalues determined, and axial and radial diffusivity maps calculated and normalized to a common space. A set of regions of interest was outlined from widespread brain areas within rostral, thalamic, hypothalamic, cerebellar, and pontine regions, and average diffusivity values were calculated using normalized diffusivity maps and these regions of interest masks. Age‐related changes were assessed with Pearson's correlations, and gender differences evaluated with Student's t ‐tests. Axial and radial diffusivity values declined with age in the majority of brain areas, except for midhippocampus, where axial diffusivity values correlated positively with age. Gender differences emerged within putamen, thalamic, hypothalamic, cerebellar, limbic, temporal, and other cortical sites. Documentation of normal axial and radial diffusivity values will help assess disease‐related tissue changes. Axial and radial diffusivities change with age,with fiber structure and organization differing between sexes in several brain areas. The findings may underlie gender‐based functional characteristics, and mandate partitioning age‐ and gender‐related changes during developmental brain pathology evaluation. © 2011 Wiley Periodicals, Inc.