title: Measurement of brain glutamate and glutamine by spectrally-selective refocusing at 3 Tesla.
abstract: A new single-voxel proton NMR spectrally-selective refocusing method for measuring glutamate (Glu) and glutamine (Gln) in the human brain in vivo at 3T is reported. Triple-resonance selective 180 degrees RF pulses with a bandwidth of 12 Hz were implemented within point-resolved spectroscopy (PRESS) for selective detection of Glu or Gln, and simultaneous acquisition of creatine singlets for use as a reference in phase correction. The carriers of the spectrally-selective 180 degrees pulses and the echo times (TEs) were optimized with both numerical and experimental analyses of the filtering performance, which enabled measurements of the target metabolites with negligible contamination from N-acetylaspartate and glutathione. The concentrations of Glu and Gln in the prefrontal cortex were estimated to be 9.7+/-0.5 and 3.0+/-0.7 mM (mean+/-SD, N=7), with reference to Cr at 8 mM.
authors.affiliation: Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada. changho.choi@ualberta.ca
authors.forename: Changho
authors.initials: C
authors.lastname: Choi
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Coupland
authors.forename: Paramjit P
authors.initials: PP
authors.lastname: Bhardwaj
authors.forename: Nikolai
authors.initials: N
authors.lastname: Malykhin
authors.forename: Dan
authors.initials: D
authors.lastname: Gheorghiu
authors.forename: Peter S
authors.initials: PS
authors.lastname: Allen
mesh_terms: D000328:Adult; D018698:Glutamic Acid / Q000032:analysis*; D005973:Glutamine / Q000032:analysis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D018377:Neurotransmitter Agents / Q000032:analysis*; D017397:Prefrontal Cortex / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D018377:Neurotransmitter Agents; D005973:Glutamine; D018698:Glutamic Acid