title: Exchange-linked dissolution agents in dissolution-DNP (13)C metabolic imaging.
abstract: OBJECTIVE
  The use of unlabeled exchange-linked dissolution agents in hyperpolarized metabolic imaging was studied to examine pool size limits and saturation relative to the availability of NADH.
  
  
  METHODS
  Three-dimensional dynamic metabolic images were obtained, and compared following injection of a bolus of hyperpolarized [1-(13)C]pyruvate, prepared with and without unlabeled sodium lactate in the dissolution buffer. Comparisons were made on the basis of apparent rate constants and [1-(13)C]lactate signal-to-noise ratio. Range finding data were obtained for different bolus compositions. Isotope exchange was also probed in the reverse direction, following injection of a bolus of hyperpolarized [1-(13)C]lactate, with and without unlabeled sodium pyruvate in the dissolution buffer.
  
  
  RESULTS
  Liver, kidney, and vascular regions of interest all showed an increase in [1-(13)C]lactate signal with addition of unlabeled sodium lactate in the dissolution buffer. Injection of hyperpolarized [1-(13)C]lactate with unlabeled sodium pyruvate in the dissolution buffer, provided exchange rate constants Klp for kidney and vascular regions of interest.
  
  
  CONCLUSIONS
  These results are consistent with a high level of (13)C-exchange, and with labeling rates that are limited by steady-state pool sizes in vivo.
authors.affiliation: GE Healthcare, California, USA.
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Hurd
authors.forename: Daniel
authors.initials: D
authors.lastname: Spielman
authors.forename: Sonal
authors.initials: S
authors.lastname: Josan
authors.forename: Yi-Fen
authors.initials: YF
authors.lastname: Yen
authors.forename: Adolf
authors.initials: A
authors.lastname: Pfefferbaum
authors.forename: Dirk
authors.initials: D
authors.lastname: Mayer
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000378:metabolism*; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D009928:Organ Specificity; D019289:Pyruvic Acid / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019354:Sodium Lactate / Q000493:pharmacokinetics*
chemical_list: D002247:Carbon Isotopes; D019275:Radiopharmaceuticals; D019289:Pyruvic Acid; D019354:Sodium Lactate