Dataset Information

N-acetyl-aspartate levels correlate with intra-axonal compartment parameters from diffusion MRI.

ABSTRACT: Diffusion MRI combined with biophysical modeling allows for the description of a white matter (WM) fiber bundle in terms of compartment specific white matter tract integrity (WMTI) metrics, which include intra-axonal diffusivity (Daxon), extra-axonal axial diffusivity (De||), extra-axonal radial diffusivity (De?), axonal water fraction (AWF), and tortuosity (?) of extra-axonal space. Here we derive these parameters from diffusion kurtosis imaging to examine their relationship to concentrations of global WM N-acetyl-aspartate (NAA), creatine (Cr), choline (Cho) and myo-Inositol (mI), as measured with proton MR spectroscopy ((1)H-MRS), in a cohort of 25 patients with mild traumatic brain injury (MTBI). We found statistically significant (p<0.05) positive correlations between NAA and Daxon, AWF, ?, and fractional anisotropy; negative correlations between NAA and De,? and the overall radial diffusivity (D?). These correlations were supported by similar findings in regional analysis of the genu and splenium of the corpus callosum. Furthermore, a positive correlation in global WM was noted between Daxon and Cr, as well as a positive correlation between De|| and Cho, and a positive trend between De|| and mI. The specific correlations between NAA, an endogenous probe of the neuronal intracellular space, and WMTI metrics related to the intra-axonal space, combined with the specific correlations of De|| with mI and Cho, both predominantly present extra-axonally, corroborate the overarching assumption of many advanced modeling approaches that diffusion imaging can disentangle between the intra- and extra-axonal compartments in WM fiber bundles. Our findings are also generally consistent with what is known about the pathophysiology of MTBI, which appears to involve both intra-axonal injury (as reflected by a positive trend between NAA and Daxon) as well as axonal shrinkage, demyelination, degeneration, and/or loss (as reflected by correlations between NAA and De?, AWF, and ?).

SUBMITTER: Grossman EJ

PROVIDER: S-EPMC4651014 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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N-acetyl-aspartate levels correlate with intra-axonal compartment parameters from diffusion MRI.

Grossman Elan J EJ Kirov Ivan I II Gonen Oded O Novikov Dmitry S DS Davitz Matthew S MS Lui Yvonne W YW Grossman Robert I RI Inglese Matilde M Fieremans Els E

NeuroImage 20150530

Diffusion MRI combined with biophysical modeling allows for the description of a white matter (WM) fiber bundle in terms of compartment specific white matter tract integrity (WMTI) metrics, which include intra-axonal diffusivity (Daxon), extra-axonal axial diffusivity (De||), extra-axonal radial diffusivity (De┴), axonal water fraction (AWF), and tortuosity (α) of extra-axonal space. Here we derive these parameters from diffusion kurtosis imaging to examine their relationship to concentrations o ...[more]

PMID: 26037050

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Dataset Information

N-acetyl-aspartate levels correlate with intra-axonal compartment parameters from diffusion MRI.

Publications

N-acetyl-aspartate levels correlate with intra-axonal compartment parameters from diffusion MRI.

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