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Abstract #3660

Tract-specific g-ratio using COMMIT: comparison with conventional g-ratio tractometry

Wen Da Lu1,2, Mark C. Nelson2,3, Simona Schiavi4, Jennifer S.W. Campbell2, Ilana R. Leppert2, Christopher D. Rowley5, G. Bruce Pike6, Alessandro Daducci7, and Christine L. Tardif1,2,3
1Biomedical Engineering, McGill University, Montreal, QC, Canada, 2McConnell Brain Imaging Centre, Montreal Neurological Institute-Hospital, Montreal, QC, Canada, 3Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada, 4ASG Superconductors S.p.A., Genoa, Italy, 5Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada, 6Departments of Radiology and Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, 7Department of Computer Science, University of Verona, Verona, Italy

Synopsis

Keywords: Microstructure, Microstructure

Motivation: Tractometry is used to estimate the microstructural properties of white matter tracts from volumetric images. However, it has significant limitations due to multi-fiber voxels that bias tract measurements.

Goal(s): We aim to estimate the tract-specific g-ratio, a ratio of the inner and outer radius of the myelin sheath.

Approach: Building on the COMMIT framework, we disentangle the microstructural features of individual white matter tracts to estimate tract-specific g-ratio.

Results: Tract-specific g-ratio had higher contrast between tracts and had a stronger correlation with tract caliber (i.e. the axonal cross-sectional area between two nodes derived from COMMIT) and length in comparison to tractometry.

Impact: By using this novel COMMIT-based pipeline to analyze diffusion and myelin-sensitive MRI data, we anticipate that tract-specific g-ratio measures will be more sensitive to subtle differences in g-ratio across tracts and individuals due to the elimination of partial volume effects.

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Keywords

tracttractscalibermyelinwhitecommit