In Vivo Detection of Glutamate, Glutamine, and Glutathione at 3 T via Difference Editing of Aspartyl Resonances

Motivation: Glutamate and NAA-CH2 signals interfere with the detection of glutamine and glutathione at 3 T. Goal(s): To enhance glutamine and glutathione detection by reliably quantifying NAA-CH2 and improving the resolution of glutamate and glutamine. Approach: A novel NAA-CH2 difference editing technique was introduced for accurate spectral isolation of NAA-CH2 and optimal spectral resolution of glutamate and glutamine. Results: NAA-CH2, glutamine, and glutathione were successfully resolved at 3 T. 13C turnover of spectrally resolved glutamate following oral administration of [U-13C]glucose was detected using spatially localized proton MRS at 3 T. Impact: Time-course spectra following oral administration of [U-13C]glucose demonstrate, for the first time, the feasibility of measuring 13C turnover of spectrally resolved glutamate at 3 T with the high sensitivity and spatial resolution of proton MRS.