title: Using [1-(13) C]lactic acid for hyperpolarized (13) C MR cardiac studies.
abstract: OBJECTIVE
  Hyperpolarized [1-(13) C]lactate in solution may be a clinically relevant and safe substrate for real time MR investigations of key metabolic pathways. The potential of using hyperpolarized [1-(13) C]lactate for magnetic resonance studies of cardiac metabolism in vivo was explored.
  
  
  METHODS
  Neat [1-(13) C]lactic acid was hyperpolarized using the dynamic nuclear polarization process. Cardiac MR spectroscopy experiments were performed in vivo using hyperpolarized [1-(13) C]lactate and [1-(13) C]pyruvate in solutions.
  
  
  RESULTS
  A high degree of polarization was achieved for [1-(13) C]lactate in solution (16.7%). (13) C-bicarbonate was observed in rat hearts in vivo after either hyperpolarized [1-(13) C]lactate or hyperpolarized [1-(13) C]pyruvate was infused, but lower (13) C-bicarbonate to substrate ratio was observed with hyperpolarized [1-(13) C]lactate infusions. The response of (13) C-bicarbonate signal as a function of hyperpolarized [1-(13) C]lactate doses was also investigated and a saturation of (13) C-bicarbonate signal was observed at the highest dose of [1-(13) C]lactate used (0.69 mmol/kg).
  
  
  CONCLUSIONS
  This study demonstrated that the use of neat [1-(13) C]lactic acid as the DNP sample is a potential alternative to [1-(13) C]pyruvic acid for cardiac hyperpolarized (13) C MR studies. Hyperpolarized [1-(13) C]lactate may enable noninvasive assessment of cardiac PDH flux in cardiac patients in the near future.
authors.affiliation: GE Healthcare, Toronto, Canada.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Chen
authors.affiliation: Department of Medical Biophysics, University of Toronto, Toronto, Canada.|Imaging Research, Sunnybrook Research Institute, Toronto, Canada.
authors.forename: Justin Y C
authors.initials: JY
authors.lastname: Lau
authors.affiliation: Department of Chemistry, University of Toronto, UTM, Mississauga, Canada.
authors.forename: Rohan D A
authors.initials: RD
authors.lastname: Alvares
authors.affiliation: Department of Medical Biophysics, University of Toronto, Toronto, Canada.|Imaging Research, Sunnybrook Research Institute, Toronto, Canada.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Cunningham
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002247:Carbon Isotopes; D019344:Lactic Acid / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009206:Myocardium / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001639:Bicarbonates; D002247:Carbon Isotopes; D019344:Lactic Acid; D019289:Pyruvic Acid
keywords: 13C MRS; DNP; heart; lactic acid; metabolism