title: Quantitative measurement of cancer metabolism using stimulated echo hyperpolarized carbon-13 MRS.
abstract: OBJECTIVE
  Magnetic resonance spectroscopy of hyperpolarized substrates allows for the observation of label exchange catalyzed by enzymes providing a powerful tool to investigate tissue metabolism and potentially kinetics in vivo. However, the accuracy of current methods to calculate kinetic parameters has been limited by T1 relaxation effects, extracellular signal contributions, and reduced precision at lower signal-to-noise ratio.
  
  
  METHODS
  To address these challenges, we investigated a new modeling technique using metabolic activity decomposition-stimulated echo acquisition mode. The metabolic activity decomposition-stimulated echo acquisition mode technique separates exchanging from nonexchanging metabolites providing twice the information as conventional techniques.
  
  
  RESULTS
  This allowed for accurate measurements of rates of conversion and of multiple T1 values simultaneously using a single acquisition.
  
  
  CONCLUSIONS
  The additional measurement of T1 values for the reaction metabolites provides further biological information about the cellular environment of the metabolites. The new technique was investigated through simulations and in vivo studies of transgenic mouse models of cancer demonstrating improved assessments of kinetic rate constants and new T1 relaxation value measurements for hyperpolarized (13) C-pyruvate, (13) C-lactate, and (13) C-alanine.
authors: Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA.
authors: Christine Leon
authors: CL
authors: Swisher
authors: Peder E Z
authors: PE
authors: Larson
authors: Klaus
authors: K
authors: Kruttwig
authors: Adam B
authors: AB
authors: Kerr
authors: Simon
authors: S
authors: Hu
authors: Robert A
authors: RA
authors: Bok
authors: Andrei
authors: A
authors: Goga
authors: John M
authors: JM
authors: Pauly
authors: Sarah J
authors: SJ
authors: Nelson
authors: John
authors: J
authors: Kurhanewicz
authors: Daniel B
authors: DB
authors: Vigneron
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000465:Algorithms; D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D003198:Computer Simulation; D019344:Lactic Acid / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D019289:Pyruvic Acid / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D002247:Carbon Isotopes; D019344:Lactic Acid; D019289:Pyruvic Acid; D000409:Alanine
keywords: STEAM; cancer; hyperpolarized Carbon-13 MRS; kinetics; metabolism; stimulated echo