Comparison of NAA measures by MRS and HPLC

Acta Neurochir Suppl. 2000;76:35-7. doi: 10.1007/978-3-7091-6346-7_7.


This work investigates the accuracy of an in vivo estimation of absolute N-acetyl aspartate (NAA) concentrations by magnetic resonance spectroscopy (MRS) using cerebral water as an internal reference standard. Single-voxel, proton spectroscopy was carried out in two groups of rats (normal and diffuse head injury), using a PRESS sequence with TR = 3 s, TE = 135 ms. Fully relaxed water spectra and water-suppressed proton spectra were obtained from a 7 x 5 x 5 mm3 volume of tissue. MRI-based brain water content measurements were also performed. Following MRS, HPLC determinations of NAA were carried out. In the normal rats the MRS yielded 10.98 +/- 0.83 mmol/kg w.w. vs 10.76 +/- 0.76 for HPLC with a mean absolute difference of 0.8. In the injured rats the corresponding results were 9.41 +/- 1.78 (MRS) and 8.16 +/- 0.77 (HPLC) with a mean absolute difference of 1.66. The in vivo absolute method accurately documented the temporal NAA changes compared to the NAA/Cr approach.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Aspartic Acid / analogs & derivatives
  • Aspartic Acid / metabolism*
  • Brain Concussion / diagnosis
  • Brain Concussion / physiopathology*
  • Brain Edema / diagnosis
  • Brain Edema / physiopathology*
  • Chromatography, High Pressure Liquid*
  • Creatine / metabolism
  • Energy Metabolism / physiology*
  • Extracellular Space / physiology
  • Magnetic Resonance Spectroscopy*
  • Predictive Value of Tests
  • Rats


  • Aspartic Acid
  • N-acetylaspartate
  • Creatine