Ultrastructure of Myelinated and Unmyelinated Axons

Reina, Miguel Ángel; Navarro, R.; Mateos, Esther M. Durán

doi:10.1007/978-3-319-09522-6_1

Cited by 1 publication

(3 citation statements)

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“…B: In the presence of myelinated axons, the maximum distance a molecule can travel is bounded by the size of the axon, and the displacement distribution at a given time becomes kurtotic. Figure modelled after (Schneider & Wheeler-Kingshott, 2014), image from (Reina et al, 2015) Figure 3 Mean diffusion kurtosis and the magnetization transfer ratio have a similar spatial profile: A: The distribution of mean kurtosis at 80 µm matches the expected myelin distribution in highly myelinated (Primary motor M1, middle temporal MT), moderately myelinated (Primary vision V1) and lightly myelinated (Piriform cortex, Pir) cortical regions. B: The distribution of MTR is visually similar to MK, especially in high myelin areas.…”

Section: Myeloarchitectural Features (Top Row) Show Strong Congruence...mentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

“…The mean diffusion kurtosis (MK) stemming from restricted diffusion can be estimated across the tissue using multi-shell dMRI acquisition (Jensen et al, 2005) (see Methods). (Schneider & Wheeler-Kingshott, 2014), image from (Reina et al, 2015) We compared the MK mapped across the whole cerebral cortex with the myelin content as estimated by the MTR scan. Since both maps are MRI measures from the same ex-vivo sample, the spatial registration was very precise.…”

Section: Mean Diffusion Kurtosis Tracks Myelin Levelsmentioning

confidence: 99%

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Diffusion kurtosis MRI tracks gray matter myelin content in the primate cerebral cortex

Reveley,

Ye,

Leopold

2024

Preprint

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Diffusion magnetic resonance imaging (dMRI) has been widely employed to model the trajectory of myelinated fiber bundles in white matter. Increasingly, dMRI is also used to assess local tissue properties throughout the brain. In the cerebral cortex, myelin content is a critical indicator of the maturation, regional variation, and disease related degeneration of gray matter tissue. Gray matter myelination can be measured and mapped using several non-diffusion MRI strategies; however, first order diffusion statistics such as fractional anisotropy (FA) show only weak spatial correlation with cortical myelin content. Here we show that a simple higher order diffusion parameter, the mean diffusion kurtosis (MK), is strongly correlated with the laminar and regional variation of myelin in the primate cerebral cortex. We carried out ultra-high resolution, multi-shelled dMRI in ex vivo marmoset monkey brains and compared dMRI parameters from a number of higher order models (diffusion kurtosis, NODDI and MAP MRI) to the distribution of myelin obtained using histological staining, and via Magnetization Transfer Ratio MRI (MTR), a non-diffusion MRI method. In contrast to FA, MK closely matched the myelin content assessed by histology and by MTR in the same sample. The parameter maps from MAP-MRI and NODDI also showed good correspondence with cortical myelin content. The results demonstrate that dMRI can be used to assess the variation of local myelin content in the primate cortical cortex, which may be of great value for assessing tissue integrity and tracking disease in living human patients.

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Section: Myeloarchitectural Features (Top Row) Show Strong Congruence...mentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%