Neurite density index is sensitive to age related differences in the developing brain.

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Biomedical Engineering

Background:

• White matter development in youth involves increasing organization and coherence.
• Conventional diffusion tensor imaging (DTI) metrics like fractional anisotropy (FA) are insensitive to specific developmental mechanisms.
• Distinguishing microstructural changes during development requires more sensitive imaging techniques.

Purpose of the Study:

• To investigate the relationship between age and neurite density index (NDI) using neurite orientation dispersion and density imaging (NODDI).
• To compare the age-classification accuracy of NDI with FA in a developmental cohort.
• To assess the utility of NODDI metrics in developmental neuroscience research.

Main Methods:

• Collected diffusion-weighted imaging data from 72 children and adolescents (ages 4-19).
• Compared NODDI metrics (NDI) against conventional DTI metrics (FA, MD, AD, RD) for their relationship with age.
• Utilized Receiver Operating Characteristic (ROC) analysis to evaluate classification accuracy for older versus younger participants.

Main Results:

• NDI showed a stronger relationship with age (median R²=.60) compared to DTI metrics (FA: R²=.27, MD: R²=.39, AD: R²=.14, RD: R²=.35).
• NDI achieved superior age-classification accuracy (median AUC=.89) between older and younger groups.
• MD, FA, and RD showed moderate classification abilities (AUCs ≈ .80), while AD was less effective (AUC=.64).

Conclusions:

• NDI is highly sensitive to age-related microstructural changes in white matter during development.
• NDI demonstrates greater sensitivity to developmental changes than commonly used DTI metrics.
• NODDI metrics are recommended for implementation in future developmental studies due to their enhanced sensitivity.