Measurement of brain glutamate using TE-averaged PRESS at 3T.
A method is introduced that provides improved in vivo spectroscopic measurements of glutamate (Glu), glutamine (Gln), choline (Cho), creatine (Cre), N-acetyl compounds (NAtot, NAA + NAAG), and the inositols (mI and sI). It was found that at 3T, TE averaging, the f1 = 0 slice of a 2D J-resolved spectrum, yielded unobstructed signals for Glu, Glu + Gln (Glx), mI, NA(tot), Cre, and Cho. The C4 protons of Glu at 2.35 ppm, and the C2 protons of Glx at 3.75 ppm were well resolved and yielded reliable measures of Glu/Gln stasis. Apparent T1/T2 values were obtained from the raw data, and metabolite tissue levels were determined relative to a readily available standard. A repeatibility error of <5%, and a coefficient of variation (CV) of <10% were observed for brain Glu levels in a study of six normal volunteers.
GE Medical Systems, Menlo Park, California, USA. ralph.hurd@med.ge.com
Ralph
R
Hurd
Napapon
N
Sailasuta
Radhika
R
Srinivasan
Daniel B
DB
Vigneron
Daniel
D
Pelletier
Sarah J
SJ
Nelson
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001923:Brain Chemistry; D002794:Choline / Q000032:analysis; D003401:Creatine / Q000032:analysis; D004151:Dipeptides / Q000032:analysis; D005260:Female; D005583:Fourier Analysis; D018698:Glutamic Acid / Q000032:analysis*; D005973:Glutamine / Q000032:analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007294:Inositol / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009479:Neuropeptides / Q000032:analysis; D015203:Reproducibility of Results
D004151:Dipeptides; D009479:Neuropeptides; D005973:Glutamine; C027172:isospaglumic acid; D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline