There is currently little understanding of the acute effects of ethanol (EtOH) on the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the antioxidant glutathione (GSH) levels. Previous MRS studies have demonstrated changes in GABA levels in individuals recovering from alcohol use disorder. Alcohol has also been shown to deplete GSH levels, impeding the elimination of reactive oxygen species.
Sequential MEGA-PRESS measurements of GABA, GSH, and EtOH would necessitate 30-min acquisitions, limiting the number of brain regions investigated within a typical 1-hr MR examination and the time resolution of dynamic studies. Muhammad Saleh and colleagues have extended the universal HERMES editing of GABA and GSH to include orthogonal editing of EtOH without an increase in scan time or substantial loss in spectral quality (see figure below). This new sequence is available collaboratively to the community for application in future studies.
a) The separate Experiments A-D are shown: saturated NAA signal in the ON_GABA spectra; saturated water signal in the ON_GSH spectra; and several signals saturated in the vicinity of 3.67 ppm in the ON_EtOH spectra. The saturation range of the editing pulses is shown on each spectrum as a grayscale. b) The Hadamard combinations yield GABA-edited (A+B–C–D), GSH-edited (A+C–B–D), and EtOH-edited (B+C–A–D) spectra.