Synchrotron X-ray micro-CT as a validation dataset for diffusion MRI in whole mouse brain

Area of Science:

• Neuroimaging
• Biophysics
• Materials Science

Background:

• Diffusion MRI is a key tool for mapping white matter tracts in the brain.
• Current validation methods like histology have limitations in scale and processing.
• Natively isotropic, nondestructive 3D imaging is needed for advanced validation.

Purpose of the Study:

• Introduce synchrotron X-ray microcomputed tomography (microCT) as a validation tool for diffusion MRI.
• Demonstrate its utility in whole, fixed mouse brains.
• Compare microCT with diffusion MRI for white matter pathway validation.

Main Methods:

• Acquired postmortem diffusion MRI and synchrotron microCT data from the same mouse brain.
• Processed diffusion MRI using constrained spherical deconvolution.
• Analyzed microCT data (1.17 μm isotropic voxel size) using structure tensor analysis for fiber orientation.
• Developed a pipeline for spatial registration and comparison of fiber geometries.
• Performed whole-brain deterministic tractography using fiber orientations from both modalities.

Main Results:

• Successfully extracted fiber orientation distribution functions from the entire microCT dataset.
• Spatial registration between microCT and diffusion MRI was simplified due to whole-brain coverage.
• Demonstrated good agreement in fiber orientations and tract pathways between the two modalities.
• Validated long-range white matter pathways using deterministic tractography.

Conclusions:

• Synchrotron microCT is a valuable new tool for multi-scale diffusion MRI validation.
• It offers comparable value to optical histology while overcoming key limitations.
• This nondestructive, isotropic 3D modality facilitates easier data acquisition and processing for neuroscience studies.