title: Anisotropic diffusion of metabolites in peripheral nerve using diffusion weighted magnetic resonance spectroscopy at ultra-high field.
abstract: Although the diffusivity and anisotropy of water has been investigated thoroughly in ordered axonal systems (i.e., nervous tissue), there have been very few studies on the directional dependence of diffusion of metabolites. In this study, the mean apparent diffusion coefficient (Trace/3 ADC) and fractional anisotropy (FA) values of the intracellular metabolites N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), choline (Cho), taurine (Tau), and glutamate and glutamine (Glx) were measured parallel and perpendicular to the length of excised frog sciatic nerve using a water suppressed, diffusion-weighted, spin-echo pulse sequence at 18.8T. The degree of anisotropy (FA) of NAA (0.41+/-0.09) was determined to be less than tCr (0.59+/-0.07) and Cho (0.61+/-0.11), which is consistent with previously reported human studies of white matter. In contrast, Glx diffusion was found to be almost isotropic with an FA value of 0.20+/-0.06. The differences of FA between the metabolites is most likely due to their differing micro-environments and could be beneficial as an indicator of compartment specific changes with disease, information not readily available with water diffusion.
authors.affiliation: Department of Biomedical Engineering, University of Alberta, 1098 Research Transition Facility, Edmonton, Alta., Canada T6G 2V2.
authors.forename: Jacob
authors.initials: J
authors.lastname: Ellegood
authors.forename: Ryan T
authors.initials: RT
authors.lastname: McKay
authors.forename: Chris C
authors.initials: CC
authors.lastname: Hanstock
authors.forename: Christian
authors.initials: C
authors.lastname: Beaulieu
mesh_terms: D000818:Animals; D016880:Anisotropy; D004058:Diffusion; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D018377:Neurotransmitter Agents / Q000032:analysis*; D012584:Sciatic Nerve / Q000737:chemistry* / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D018377:Neurotransmitter Agents