title: Field dependence of T1 for hyperpolarized [1-13C]pyruvate.
abstract: In vivo metabolism of hyperpolarized pyruvate has been demonstrated to be an important probe of cellular glycolysis in diseases such as cancer. The usefulness of hyperpolarized (13)C imaging is dependent on the relaxation rates of the (13)C-enriched substrates, which in turn depend on chemical conformation and properties of the dissolution media such as buffer composition, solution pH, temperature and magnetic field. We have measured the magnetic field dependence of the spin-lattice relaxation time of hyperpolarized [1-(13)C]pyruvate using field-cycled relaxometry. [1-(13)C]pyruvate was hyperpolarized using dynamic nuclear polarization and then rapidly thawed and dissolved in a buffered solution to a concentration of 80 mmol l(-1) and a pH of ~7.8. The hyperpolarized liquid was transferred within 8 s to a fast field-cycling relaxometer with a probe tuned for detection of (13)C at a field strength of ~0.75 T. The magnetic field of the relaxometer was rapidly varied between relaxation and acquisition fields where the sample magnetization was periodically measured using a small flip angle. Data were recorded for relaxation fields varying between 0.237 mT and 0.705 T to map the T(1) dispersion of the C-1 of pyruvate. Using similar methods, we also determined the relaxivity of the triarylmethyl radical (OX063; used for dynamic nuclear polarization) on the C-1 of pyruvate at field strengths of 0.001, 0.01, 0.1 and 0.5 T using 0.075, 1.0 and 2.0 mmol l(-1) concentrations of OX063 in the hyperpolarized pyruvate solution.
authors.affiliation: Imaging Research Laboratory, Robarts Research Institute, Western University, London, ON, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Chattergoon
authors.forename: F
authors.initials: F
authors.lastname: Martínez-Santiesteban
authors.forename: W B
authors.initials: WB
authors.lastname: Handler
authors.forename: J H
authors.initials: JH
authors.lastname: Ardenkjaer-Larsen
authors.forename: T J
authors.initials: TJ
authors.lastname: Scholl
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000494:pharmacology; D006019:Glycolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism* / Q000494:pharmacology*; D011859:Radiography
chemical_list: D002247:Carbon Isotopes; D019289:Pyruvic Acid