Simultaneous quantification of glutamate and glutamine by J-modulated spectroscopy at 3 Tesla

Magn Reson Med. 2016 Sep;76(3):725-32. doi: 10.1002/mrm.25922. Epub 2015 Sep 12.


Purpose: The echo time (TE) averaged spectrum is the one-dimensional (1D) cross-section of the J-resolved spectrum at J = 0. In multiecho TE-averaged spectroscopy, glutamate (Glu) is differentiated from glutamine (Gln) at 3 Tesla (T). This method, however, almost entirely suppresses Gln resonance lines around 2.35 ppm, leaving Gln undetermined. This study presents a novel method for quantifying both Glu and Gln using multi-echo spectral data.

Methods: A 1D cross-section of J-resolved spectroscopy at J = 7.5 Hz-referred to as J-modulated spectroscopy-was developed to simultaneously quantify Glu and Gln levels in the human brain. The transverse relaxation times (T2 s) of metabolites were first determined using conventional TE-averaged spectroscopy with different starting echo time and then incorporated into the spectral model for fitting J-modulated data.

Results: Simulation and in vivo data showed that the resonance signals of Glu and Gln were clearly separated around 2.35 ppm in J-modulated spectroscopy. In the anterior cingulate cortex, both Glu and Gln levels were found to be significantly higher in gray matter than in white matter in healthy subjects (P < 10(-10) and < 10(-5) , respectively).

Conclusion: Gln resonances can be clearly separated from Glu and N-acetyl-aspartate around 2.35 ppm using J-modulated spectroscopy. This method can be used to quantitatively measure Glu and Gln simultaneously at 3T. Magn Reson Med 76:725-732, 2016. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Keywords: J-resolved spectroscopy; TE-averaged spectroscopy; glutamate; glutamine; human brain; one-dimensional cross-section; quantification.

Publication types

  • Evaluation Study

MeSH terms

  • Algorithms*
  • Brain Chemistry*
  • Female
  • Glutamic Acid / analysis*
  • Glutamine / analysis*
  • Humans
  • Image Interpretation, Computer-Assisted / methods
  • Magnetic Resonance Imaging / methods*
  • Magnetic Resonance Spectroscopy / methods*
  • Male
  • Middle Aged
  • Molecular Imaging / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Tissue Distribution


  • Glutamine
  • Glutamic Acid