Biexponential apparent diffusion coefficient parametrization in adult vs newborn brain.

Area of Science:

• Neuroimaging
• Biophysics
• Developmental Neuroscience

Background:

• Water diffusion MRI is sensitive to tissue microstructure.
• Apparent Diffusion Coefficient (ADC) decay curves provide insights into diffusion processes.
• Understanding developmental changes in brain water diffusion is crucial.

Purpose of the Study:

• To characterize the apparent diffusion coefficient (ADC) decay curves in adult and newborn brains over an extended b-factor range.
• To investigate the impact of post-natal brain development on water diffusion parameters.
• To analyze differences in fast and slow diffusion components between adult and newborn brain tissues.

Main Methods:

• Utilized line scan diffusion imaging (LSDI) to measure ADC decay curves at 16 b-factors (100-5000 s/mm(2)).
• Acquired data from 0.09 ml voxels in mid-brain axial slices across three orthogonal directions.
• Applied biexponential fitting models to analyze ADC decay curves in cortical gray matter (CG) and internal capsule (IC) regions of interest (ROIs).

Main Results:

• Newborn brain ROIs exhibited a significantly higher fraction of the fast diffusion ADC component compared to adult ROIs.
• Biexponential fitting yielded distinct fast and slow diffusion coefficients and component amplitudes for CG and IC.
• Significant differences in ADC decay parameters were observed between adult and newborn brains.

Conclusions:

• Post-natal brain development profoundly influences the biexponential parameters characterizing water signal decay.
• The increased fast diffusion component in newborns suggests ongoing microstructural changes.
• These findings highlight the sensitivity of advanced diffusion MRI techniques to developmental processes in the brain.