Quantitative Brain Diffusion Metrics are Fragile to Voxel Size: A Prospective Volunteer Study Calling for Protocol Standardization

Motivation: The quantitative brain diffusion metrics showed potential to provide functional information about diseases, but their robustness must be established before their implementation in clinical practice. Goal(s): To evaluate the variability and reproducibility of quantitative brain diffusion metrics. Approach: Fourteen volunteers prospectively underwent brain diffusion spectrum imagingusing a protocol designed to investigate the impact of scan-rescans, voxel size, coils on twenty-five quantitative diffusion metrics. Two observers drew thirteen regions of interests for metrics calculation. Results: The voxel size has a greater influence on reproducibility of quantitative diffusion metrics than scan-rescans and coils. The reproducibility within an observer was higher than that between two observers. Impact: Quantitative brain diffusion metrics, as promising tools for providing functional information of diseases, should be interpreted with caution because they are fragile to voxel size, which calls for standardization of scan protocols before prior to their implementation in clinical practice.