Local diffusion homogeneity (LDH): an inter-voxel diffusion MRI metric for assessing inter-subject white matter...

Area of Science:

• Neuroimaging
• Biophysics
• Medical Physics

Background:

• Diffusion MRI parameters like FA and MD assess intra-voxel diffusion properties.
• Current markers primarily analyze diffusion within individual voxels.
• Inter-voxel diffusion relationship metrics remain largely unexplored.

Purpose of the Study:

• Introduce a novel inter-voxel diffusion metric: local diffusion homogeneity (LDH).
• Quantify local coherence of water diffusion in a model-free manner.
• Evaluate LDH as an additional marker for white matter (WM) microstructural properties.

Main Methods:

• Systematically compared LDH with FA/MD across different brain regions and subjects.
• Applied LDH and FA/MD to measure age-related WM changes.
• Assessed distinguishing features and sensitivities of LDH versus FA/MD.

Main Results:

• LDH identified unique inter-subject variability in specific WM regions (e.g., cerebral peduncle, internal capsule).
• LDH and FA/MD showed discrepant results in measuring age-related WM alterations in certain areas.
• Findings suggest LDH and FA/MD are sensitive to distinct WM microstructural properties.

Conclusions:

• LDH is a valuable complement to conventional diffusion MRI markers (FA, MD).
• LDH provides additional insights into inter-subject white matter variability.
• Further research is needed to elucidate the neuronal mechanisms underlying LDH.