title: Double spin-echo sequence for rapid spectroscopic imaging of hyperpolarized 13C.
abstract: Dynamic nuclear polarization of metabolically active compounds labeled with (13)C has been introduced as a means for imaging metabolic processes in vivo. To differentiate between the injected compound and the various metabolic products, an imaging technique capable of separating the different chemical-shift species must be used. In this paper, the design and testing of a pulse sequence for rapid magnetic resonance spectroscopic imaging (MRSI) of hyperpolarized (13)C is presented. The pulse sequence consists of a small-tip excitation followed by a double spin echo using adiabatic refocusing pulses and a "flyback" echo-planar readout gradient. Key elements of the sequence are insensitivity to calibration of the transmit gain, the formation of a spin echo giving high-quality spectral information, and a small effective tip angle that preserves the magnetization for a sufficient duration. Experiments in vivo showed three-dimensional coverage with excellent spectral quality and SNR.
authors.affiliation: Department of Medical Biophysics, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario, Canada. chuck@sri.utoronto.ca
authors.forename: Charles H
authors.initials: CH
authors.lastname: Cunningham
authors.forename: Albert P
authors.initials: AP
authors.lastname: Chen
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Albers
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Hurd
authors.forename: Yi-Fen
authors.initials: YF
authors.lastname: Yen
authors.forename: John M
authors.initials: JM
authors.lastname: Pauly
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nelson
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Vigneron
mesh_terms: D000818:Animals; D002138:Calibration; D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D019289:Pyruvic Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002247:Carbon Isotopes; D019289:Pyruvic Acid