Differential distribution of NAA and NAAG in human brain as determined by quantitative localized proton MRS

NMR Biomed. 1997 Apr;10(2):73-8. doi: 10.1002/(sici)1099-1492(199704)10:2<73::aid-nbm448>3.0.co;2-4.


Quantitative proton magnetic resonance spectroscopy was performed in frontal, parietal and occipital white and gray matter of young adults with use of a fully relaxed, short-echo time stimulated echo acquisition mode localization sequence at 2.0 T. Separate concentrations of the neuronal compounds N-acetylaspartate (NAA) and N-acetylaspartylglutamate (NAAG) were obtained by user-independent spectral analysis (LCModel). Except for occipital gray matter in which an NAA concentration of 10.1 +/- 1.0 mM correlated with enhanced neuronal density in visual cortex, NAA was found to be homogeneously distributed throughout cortical white and gray matter at a concentration of 8.0-8.9 mM. NAAG concentrations of 1.5-2.7 mM were higher in white matter than levels of 0.6-1.5 mM found in gray matter, contributing up to 25% of total N-acetyl-containing compounds. The frontal to parieto-occipital increase of both gray and white matter NAAG levels is also reflected in the distribution of total NAA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aspartic Acid / analogs & derivatives*
  • Aspartic Acid / metabolism
  • Brain / metabolism*
  • Dipeptides / metabolism*
  • Feasibility Studies
  • Humans
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Spectroscopy / methods*
  • Protons
  • Tissue Distribution


  • Dipeptides
  • Protons
  • isospaglumic acid
  • Aspartic Acid
  • N-acetylaspartate