title: Measurement of transverse relaxation times of J-coupled metabolites in the human visual cortex at 4 T.
abstract: Accurate quantification of (1) H NMR spectra often requires knowledge of the relaxation times to correct for signal losses due to relaxation and saturation. In human brain, T(2) values for singlets such as N-acetylaspartate, creatine, and choline have been reported, but few T(2) values are available for J-coupled spin systems. The purpose of this study was to measure the T(2) relaxation times of J-coupled metabolites in the human occipital lobe using the LASER sequence. Spectra were acquired at multiple echo times and were analyzed with an LCModel using basis sets simulated at each echo time. Separate basis spectra were used for resonances of protons belonging to the same molecule but having very different T(2) values (e.g., two separate basis spectra were used for the singlet and multiplet signal in N-acetylaspartate). The T(2) values for the N-acetylaspartate multiplet (149 ± 12 ms), glutamate (125 ± 10 ms), myo-inositol (139 ± 20 ms), and taurine (196 ± 28 ms) were successfully measured in the human visual cortex at 4 T. These measured T(2) relaxation times have enabled the accurate and absolute quantification of cerebral metabolites at longer echo times.
authors: Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA. deelc001@umn.edu
authors: Dinesh Kumar
authors: DK
authors: Deelchand
authors: Pierre-Gilles
authors: PG
authors: Henry
authors: Kâmil
authors: K
authors: Uǧurbil
authors: Małgorzata
authors: M
authors: Marjańska
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D013654:Taurine / Q000378:metabolism; D014793:Visual Cortex / Q000378:metabolism*
chemical_list: D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline