Diffusional anisotropy of the human brain assessed with diffusion-weighted MR: relation with normal brain development...

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Biophysics

Background:

• White matter development involves myelination, a crucial process for neuronal function.
• Diffusional anisotropy, measurable by diffusion-weighted MR imaging, reflects white matter microstructure and myelination.
• Understanding age-related changes in diffusional anisotropy is key to assessing brain development.

Purpose of the Study:

• To quantitatively analyze age-dependent changes in diffusional anisotropy in human frontal and occipital white matter using diffusion-weighted MR imaging.

Main Methods:

• Diffusion-weighted MR imaging was performed on neonates, infants, children, and adults.
• Apparent diffusion coefficients parallel (||) and perpendicular (⊥) to nerve fibers were calculated.
• The anisotropic ratio (||/⊥) was computed and analyzed as a function of age.

Main Results:

• Frontal white matter showed significantly higher anisotropic ratios in neonates compared to other age groups, with a rapid decrease within the first six months.
• Occipital white matter also exhibited higher ratios in neonates, though less pronounced than in the frontal lobe.
• A significant difference in anisotropic ratios between frontal and occipital lobes was observed only in neonates.

Conclusions:

• Diffusion-weighted imaging indicates that myelination initiates earlier in the occipital lobe than the frontal lobe.
• The observed changes in white matter diffusional anisotropy are largely completed within six months post-birth.
• Diffusion-weighted imaging enables earlier detection of brain myelination compared to conventional MRI sequences.