Simultaneous measurement of glutamate, glutamine, GABA , and glutathione by spectral editing without subtraction

Purpose To simultaneously measure glutamate, glutamine, γ‐aminobutyric acid (GABA), and glutathione using spectral editing without subtraction at 7T. Methods A novel spectral editing approach was proposed to simultaneously measure glutamate, glutamine, GABA, and glutathione using a TE of 56 ms at 7T. By numerical optimization of sequence timing in the presence of an editing pulse, the 4 metabolites all form relatively intense pseudo singlets with maximized peak amplitudes and minimized peak linewidths in 1 of the 3 interleaved spectra. For measuring glutamate, glutamine, and glutathione, the editing pulse targets the H 3 protons of these metabolites near 2.12 parts per million. Both GABA H 2 and H 4 resonances are fully utilized in spectral fitting. Results Concentration levels (/[total creatine]) of glutamate, glutamine, GABA, and glutathione from an 8 mL voxel in the pregenual anterior cingulate cortex of 5 healthy volunteers were found to be 1.26 ± 0.13, 0.33 ± 0.06, 0.13 ± 0.03, and 0.27 ± 0.03, respectively, with within‐subject coefficient of variation at 3.2%, 8.2%, 7.1%, and 10.2%, respectively. The total scan time was less than 4.5 min. Conclusions The proposed new technique does not require data subtraction. The 3 major metabolites of the glutamatergic and GABAergic systems and the oxidative stress marker glutathione were all measured in 1 short scan with high precision.