Brain gamma-aminobutyric acid measurement by proton double-quantum filtering with selective J rewinding.
An optimized single-shot proton double-quantum (DQ) filter for the quantification of gamma-aminobutyric acid (GABA) levels in human brain is reported. It is demonstrated that creation of DQ coherences following dual-resonance-selective refocusing gives a theoretical editing efficiency of 50% for the detection of the GABA resonance at 3.01 ppm. The sequence times are optimized with both numerical and experimental analyses of the editing performance, giving an experimental editing efficiency of 42%. It is acknowledged that homocarnosine is partially coedited, leading to a 20% contribution to the edited signal; however, macromolecule contamination is negligible in vivo under these experimental conditions. The GABA concentration in human prefrontal cortex is estimated to be 0.8 +/- 0.1 micromol/g (mean +/- SD, n = 6), with reference to the internal standard creatine at 9 micromol/g.
Choi
Changho
C
Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada.
Coupland
Nicholas J
NJ
Hanstock
Christopher C
CC
Ogilvie
Catherine J
CJ
Higgins
Andrea C M
AC
Gheorghiu
Dan
D
Allen
Peter S
PS
D000328:Adult; D001923:Brain Chemistry; D006801:Humans; D046911:Macromolecular Substances / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D046911:Macromolecular Substances; D005680:gamma-Aminobutyric Acid