title: Volumetric spiral chemical shift imaging of hyperpolarized [2-(13) c]pyruvate in a rat c6 glioma model.
abstract: OBJECTIVE
  MRS of hyperpolarized [2-(13)C]pyruvate can be used to assess multiple metabolic pathways within mitochondria as the (13)C label is not lost with the conversion of pyruvate to acetyl-CoA. This study presents the first MR spectroscopic imaging of hyperpolarized [2-(13)C]pyruvate in glioma-bearing brain.
  
  
  METHODS
  Spiral chemical shift imaging with spectrally undersampling scheme (1042 Hz) and a hard-pulse excitation was exploited to simultaneously image [2-(13)C]pyruvate, [2-(13)C]lactate, and [5-(13)C]glutamate, the metabolites known to be produced in brain after an injection of hyperpolarized [2-(13)C]pyruvate, without chemical shift displacement artifacts. A separate undersampling scheme (890 Hz) was also used to image [1-(13)C]acetyl-carnitine. Healthy and C6 glioma-implanted rat brains were imaged at baseline and after dichloroacetate administration, a drug that modulates pyruvate dehydrogenase kinase activity.
  
  
  RESULTS
  The baseline metabolite maps showed higher lactate and lower glutamate in tumor as compared to normal-appearing brain. Dichloroacetate led to an increase in glutamate in both tumor and normal-appearing brain. Dichloroacetate-induced %-decrease of lactate/glutamate was comparable to the lactate/bicarbonate decrease from hyperpolarized [1-(13)C]pyruvate studies. Acetyl-carnitine was observed in the muscle/fat tissue surrounding the brain.
  
  
  CONCLUSIONS
  Robust volumetric imaging with hyperpolarized [2-(13)C]pyruvate and downstream products was performed in glioma-bearing rat brains, demonstrating changes in mitochondrial metabolism with dichloroacetate.
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Jae Mo
authors.initials: JM
authors.lastname: Park
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.|SRI International, Menlo Park, California, USA.
authors.forename: Sonal
authors.initials: S
authors.lastname: Josan
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford, California, USA.
authors.forename: Taichang
authors.initials: T
authors.lastname: Jang
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford, California, USA.
authors.forename: Milton
authors.initials: M
authors.lastname: Merchant
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Ron
authors.initials: R
authors.lastname: Watkins
authors.affiliation: Applied Science Laboratory, GE Healthcare, Menlo Park, California, USA.
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Hurd
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford, California, USA.
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: Recht
authors.affiliation: SRI International, Menlo Park, California, USA.|Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, Maryland, USA.
authors.forename: Dirk
authors.initials: D
authors.lastname: Mayer
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Spielman
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000473:pathology*; D002247:Carbon Isotopes / Q000737:chemistry / Q000378:metabolism*; D005910:Glioma / Q000473:pathology*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D059906:Neuroimaging / Q000379:methods*; D019289:Pyruvic Acid / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012815:Signal Processing, Computer-Assisted
chemical_list: D002247:Carbon Isotopes; D019289:Pyruvic Acid
keywords: [2-13C]pyruvate; brain; cancer; glioma; hyperpolarized 13C; mitochondrial metabolism