Correlation of apparent diffusion coefficient and fractional anisotropy values in the developing infant brain

Area of Science:

• Neuroimaging
• Developmental Neuroscience
• Biomedical Engineering

Background:

• Diffusion tensor imaging (DTI) is crucial for assessing white matter (WM) development in infants.
• Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) are key DTI metrics reflecting tissue microstructure.
• Understanding the relationship between ADC and FA in developing WM is vital for diagnosing neurological conditions.

Purpose of the Study:

• To correlate the decrease in apparent diffusion coefficient (ADC) with the increase in fractional anisotropy (FA) in infant white matter (WM) regions.
• To investigate the influence of fiber architecture (crossing vs. parallel) on the ADC-FA relationship.
• To determine the impact of age on these DTI metric correlations.

Main Methods:

• Performed DTI on 53 infants, measuring FA and ADC in 10 critical WM regions.
• Calculated correlation coefficients (r) and coefficients of determination (r²) for ADC as a function of FA.
• Analyzed group data for WM regions with predominantly crossing versus parallel fibers, adjusting for age.

Main Results:

• Significant correlations between FA and ADC were observed across WM regions (r values from -0.81 to -0.50).
• Higher correlations (r²) were found in WM regions with predominantly crossing fibers compared to parallel fibers.
• After age adjustment, correlations persisted, with partial coefficients showing a more even distribution between fiber types.

Conclusions:

• The evolution of FA and ADC in infant WM regions exhibits varying degrees of correlation.
• Infant age exerts a significant influence on the relationship between FA and ADC.
• DTI metrics provide valuable insights into white matter maturation and microstructure.