Regional Metabolite Concentrations in Human Brain as Determined by Quantitative Localized Proton MRS

The regional distribution of brain metabolites was studied in several cortical white and gray matter areas, cerebellum, and thalamus of young adults with use of quantitative single-voxel proton MRS at 2.0 T. Whereas the neuronal compound N-acetylaspartate is distributed homogeneously throughout the brain, N-acetylaspartylglutamate increases caudally and ex-hibits higher concentrations in white matter than in gray mat-ter. Creatine, myo-inositol, glutamate, and glutamine are less concentrated in cortical white matter than in gray matter. The highest creatine levels are found in cerebellum, parallel to the distribution of creatine kinase and energy-requiring pro-cesses in the brain. Also myo-inositol has highest concentra-tions in the cerebellum. Choline-containing compounds ex-hibit a marked regional variability with again highest concentrations in cerebellum and lowest levels and a strong caudally decreasing gradient in gray matter. The present find-ings neither support a metabolic gender difference (except for a 1.3-fold higher myo-inositol level in parietal white matter of female subjects) nor a metabolic hemispheric asymmetry. Key words: proton spectroscopy; brain metabolism; cerebral metabolite distribution