Mapping longitudinal cerebral cortex development using diffusion tensor imaging

Diffusion tensor imaging (DTI) could provide convenient and crucial insights into the underlying age-related biological maturation of human brains, including myelination, axonal density changes, fiber tract reorganization, and synaptic pruning processes. Fractional anisotropy (FA) derived from DTI has been commonly used to characterize cellular morphological changes associated with the development of human brain, due to its sensitivity to microstructural changes. In this paper, we aim to discern the longitudinal neurodevelopmental patterns in typically maturing human brains using 200 healthy subjects from 5 to 22 years of age, based on the FA in cortical gray matter (GM). Specifically, FA image is first aligned with the corresponding T1 image, which has been parcellated into different cortical ROIs, and then the average FA in each ROI is computed. Linear mixed model is used to analyze the FA developmental pattern in each cortical ROI. The developmental trajectory of FA in each ROI across ages is delineated, and the best-fitting models of age-related changes in FA were linear for all ROIs. FA generally increases with the age from 5 to 22 years of age. In addition, males and females follow the similar pattern, with the FA of females being generally lower than that of males in most ROIs. This provides us some insights into the microstructural changes in the longitudinal cerebral cortex development.