title: Magnetization transfer attenuation of creatine resonances in localized proton MRS of human brain in vivo.
abstract: To assess putative magnetization transfer effects on the proton resonances of cerebral metabolites in human brain, we performed quantitative proton magnetic resonance spectroscopy (2.0 T, STEAM, TR/TE/TM = 6000/40/10 ms, LCModel data evaluation) of white matter (7.68 mL, 10 healthy young subjects) in the absence and presence of fast repetitive off-resonance irradiation (2.1 kHz from the water resonance) using a train of 100 Gaussian-shaped RF pulses (12.8 ms duration, 120 Hz nominal bandwidth, 40 ms repetition period, 1080 degrees nominal flip angle). A comparison of pertinent metabolite concentrations revealed a magnetization transfer attenuation factor of the methyl and methylene resonances of creatine and phosphocreatine of 0.87 +/- 0.05 (p < 0.01). No attenuation was observed for the resonances of N-acetylaspartate and N-acetylaspartylglutamate, glutamate and glutamine, choline-containing compounds, and myo-inositol. The finding for total creatine is in excellent agreement with data reported for rat brain. The results are consistent with the hypothesis of a chemical exchange of mobile creatine or phosphocreatine molecules with a small immobilized or 'bound' pool.
authors.affiliation: Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, D-37070 Göttingen, Germany. gunther@mrc.ks.se
authors.forename: G
authors.initials: G
authors.lastname: Helms
authors.forename: J
authors.initials: J
authors.lastname: Frahm
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism*; D004151:Dipeptides / Q000378:metabolism; D005260:Female; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D008297:Male
chemical_list: D004151:Dipeptides; C027172:isospaglumic acid; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine