title: Chemical shift encoded imaging of hyperpolarized (13) C pyruvate.
abstract: OBJECTIVE
  To demonstrate a reconstruction technique for separating signal from different hyperpolarized carbon-13 metabolites.
  
  
  METHODS
  A reconstruction method is described for chemical shift encoded separation of the signal from pyruvate and its downstream metabolites. This method uses consistency of the data with the signal model rather than an additional free-induction decay (FID) acquisition to estimate the B0 offset. Compressed sensing was also integrated into the reconstruction allowing reconstruction of metabolite images from undersampled datasets. The performance of the reconstruction was assessed using thermal phantoms, digital phantoms, and in vivo hyperpolarized [1-(13) C] pyruvate experiments.
  
  
  RESULTS
  Thermal and digital phantoms indicate that metabolite separation is feasible given Signal-to-noise ratio > 5 and an initial B0 offset estimate within -105 Hz to 90 Hz of the actual B0 offset. In vivo comparisons to an existing FID calibrated reconstruction show improved fidelity in regions with significant field map inhomogeneity provided that these field map variations are accounted for using an additional proton acquisition. Prospectively and retrospectively undersampled studies show acceleration factors of 2 are feasible using compressed sensing.
  
  
  CONCLUSIONS
  A reconstruction framework for the separation of signal from pyruvate and its downstream metabolites is shown. This reconstruction eliminates the need to acquire additional calibration FID acquisition and allows acceleration through compressed sensing.
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Curtis N
authors.initials: CN
authors.lastname: Wiens
authors.affiliation: Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario.
authors.forename: Lanette J
authors.initials: LJ
authors.lastname: Friesen-Waldner
authors.affiliation: Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario.|Robarts Research Institute, University of Western Ontario, London, Ontario.
authors.forename: Trevor P
authors.initials: TP
authors.lastname: Wade
authors.affiliation: Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Sinclair
authors.affiliation: Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario.|Robarts Research Institute, University of Western Ontario, London, Ontario.
authors.forename: Charles A
authors.initials: CA
authors.lastname: McKenzie
mesh_terms: D000465:Algorithms; D000818:Animals; D066241:Carbon-13 Magnetic Resonance Spectroscopy / Q000379:methods*; D005240:Feasibility Studies; D006168:Guinea Pigs; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D009928:Organ Specificity; D019047:Phantoms, Imaging; D019289:Pyruvic Acid / Q000378:metabolism*; D019275:Radiopharmaceuticals / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019289:Pyruvic Acid
keywords: chemical shift encoded imaging; compressed sensing; hyperpolarized carbon-13; metabolite imaging