Direct segmentation of cortical cytoarchitectonic domains using ultra-high-resolution whole-brain diffusion MRI

Area of Science:

• Neuroimaging
• Neuroanatomy

Background:

• Conventional cortical parcellation relies on template warping.
• This method has limitations in accurately defining laminar patterns and areal borders.

Purpose of the Study:

• To evaluate high-resolution mean apparent propagator (MAP) MRI for direct detection of cortical laminar patterns and areal borders.
• To offer an alternative to traditional template-warping methods.

Main Methods:

• Acquired 200 μm resolution MAP-MRI data from a fixed macaque brain.
• Applied a local anisotropic Gaussian filter to enhance sensitivity to cortical layers.
• Clustered all cortical voxels using only MAP-derived microstructural biomarkers.

Main Results:

• MAP-based 3D cytoarchitectonic segmentation revealed laminar patterns comparable to histology.
• MAP-MRI delineated transition regions more accurately than conventional atlas-based parcellation.
• Successfully matched MAP-derived cytoarchitectonic domains across hemispheres.

Conclusions:

• High-resolution MAP-MRI biomarkers effectively delineate 3D cortical cytoarchitectonic domains in individuals.
• Intrinsic microstructural contrasts facilitate the creation of whole-brain mesoscopic cortical atlases.