Simultaneous observation of glutamate, gamma-aminobutyric acid, and glutamine in human brain at 4.7 T using localized two-dimensional constant-time correlation spectroscopy.
Localized two-dimensional constant-time correlation spectroscopy (CT-COSY) was used to resolve glutamate (Glu), gamma-aminobutyric acid (GABA), and glutamine (Gln) in the human brain at 4.7 T. In this method, three-dimensional localization was achieved using three radio frequency pulses of the CT-COSY module for slice selection. As this sequence could decouple JHH along the F1 direction, peak resolution of metabolites was improved even on a magnitude-mode display. In experiments on a phantom containing N-acetylaspartate, creatine, Glu, Gln, and GABA with a constant time delay (Tct) of 110 ms, cross peaks of Glu, Gln, and GABA were obtained on a spectrum processed with standard sine-bell windows, which emphasize sine-dependent signals along the t2 direction. In contrast, diagonal peaks of Glu C4H at 2.35 ppm, GABA C2H at 2.28 ppm, and Gln C4H at 2.44 ppm were resolved on a spectrum processed with Gaussian windows, which emphasize cosine-dependent signals along t2. Human brain spectra were obtained from a 27 mL voxel within the parieto-occipital region using a volume transverse electromagnetic (TEM) coil for both transmission and reception. Tct was 110 ms; the total scan time was 30 min. Diagonal peaks of Glu C4H, GABA C2H, and Gln C4H were also resolved on the spectrum processed with Gaussian windows. These results show that the localized two-dimensional CT-COSY method featuring 1H decoupling along the F1 direction could resolve Glu, GABA, and Gln signals in the human brain.
Watanabe
H
H
Environmental Chemistry Division, National Institute for Environmental Studies, Ibaraki, Japan.
Takaya
N
N
Mitsumori
F
F
D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry / Q000528:radiation effects; D003401:Creatine / Q000032:analysis / Q000737:chemistry; D003627:Data Interpretation, Statistical; D004735:Energy Transfer / Q000528:radiation effects; D018698:Glutamic Acid / Q000032:analysis* / Q000737:chemistry; D005973:Glutamine / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D019047:Phantoms, Imaging; D011522:Protons; D011846:Radio Waves; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D005680:gamma-Aminobutyric Acid / Q000032:analysis* / Q000737:chemistry
D011522:Protons; D005973:Glutamine; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C000179:N-acetylaspartate; D003401:Creatine