Title |
Whole-Brain In-vivo Measurements of the Axonal G-Ratio in a Group of 37 Healthy Volunteers
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Published in |
Frontiers in Neuroscience, November 2015
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DOI | 10.3389/fnins.2015.00441 |
Pubmed ID | |
Authors |
Siawoosh Mohammadi, Daniel Carey, Fred Dick, Joern Diedrichsen, Martin I. Sereno, Marco Reisert, Martina F. Callaghan, Nikolaus Weiskopf |
Abstract |
The g-ratio, quantifying the ratio between the inner and outer diameters of a fiber, is an important microstructural characteristic of fiber pathways and is functionally related to conduction velocity. We introduce a novel method for estimating the MR g-ratio non-invasively across the whole brain using high-fidelity magnetization transfer (MT) imaging and single-shell diffusion MRI. These methods enabled us to map the MR g-ratio in vivo across the brain's prominent fiber pathways in a group of 37 healthy volunteers and to estimate the inter-subject variability. Effective correction of susceptibility-related distortion artifacts was essential before combining the MT and diffusion data, in order to reduce partial volume and edge artifacts. The MR g-ratio is in good qualitative agreement with histological findings despite the different resolution and spatial coverage of MRI and histology. The MR g-ratio holds promise as an important non-invasive biomarker due to its microstructural and functional relevance in neurodegeneration. |
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Unknown | 31 | 23% |