title: STEAM-MiTiS: An MR spectroscopy method for the detection of scalar-coupled metabolites and its application to glutamate at 7 T.
abstract: OBJECTIVE
  We herein present a spectroscopic technique for the detection of scalar-coupled metabolites based on stimulated echo acquisition mode (STEAM). The method is based on the time evolution of scalar-coupled metabolites at different mixing times and a constant echo time. The technique is optimized for targeting the metabolite glutamate at 7T.
  
  
  METHODS
  Numerical simulations were used to optimize the parameters to maximize the chosen metabolite signal. The maximum detection efficiency and metabolite signal as a function of echo time were used to identify the optimal parameters. In vitro and in vivo validations of the method were also performed.
  
  
  RESULTS
  This method canceled all the strong singlet lines and signals from macromolecules and preserved signals originating from the scalar-coupled metabolites. The subtracted spectrum was strongly simplified, but the complete spectral information of the traditional STEAM acquisition was retained in the sum spectrum.
  
  
  CONCLUSIONS
  The simulations performed in this study were in agreement with the experimental results, and a clear detection of the metabolite of interest was obtained. The applicability in vivo was also demonstrated, with the selective detection of glutamate in human brain. This technique is simple, suitable for standard MR systems without sequence programming and could be used to detect other metabolites.
authors.affiliation: INFN and Department of Physics, University of Pisa, Pisa, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Toncelli
authors.affiliation: MR Applications and Workflow Development, GE Healthcare, Berlin, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Noeske
authors.affiliation: Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, University of Pisa, Pisa, Italy.|Fondazione IMAGO7, Pisa, Italy.
authors.forename: Mirco
authors.initials: M
authors.lastname: Cosottini
authors.affiliation: Fondazione IMAGO7, Pisa, Italy.|Laboratorio di Fisica Medica e Biotecnologie per la Risonanza Magnetica IRCCS Fondazione Stella Maris, Pisa, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Costagli
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, University of Pisa, Pisa, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Domenici
authors.affiliation: Fondazione IMAGO7, Pisa, Italy.|Laboratorio di Fisica Medica e Biotecnologie per la Risonanza Magnetica IRCCS Fondazione Stella Maris, Pisa, Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Tiberi
authors.affiliation: Fondazione IMAGO7, Pisa, Italy.|Laboratorio di Fisica Medica e Biotecnologie per la Risonanza Magnetica IRCCS Fondazione Stella Maris, Pisa, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Tosetti
mesh_terms: D000465:Algorithms; D001921:Brain / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods; D018377:Neurotransmitter Agents / Q000378:metabolism; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018377:Neurotransmitter Agents; D018698:Glutamic Acid
keywords: MR spectroscopy; metabolite detection; scalar-coupled metabolites; ultra-high field