title: Dynamic metabolic imaging of hyperpolarized [2-(13) C]pyruvate using spiral chemical shift imaging with alternating spectral band excitation.
abstract: OBJECTIVE
  In contrast to [1-(13) C]pyruvate, hyperpolarized [2-(13) C]pyruvate permits the ability to follow the (13) C label beyond flux through pyruvate dehydrogenase complex and investigate the incorporation of acetyl-coenzyme A into different metabolic pathways. However, chemical shift imaging (CSI) with [2-(13) C]pyruvate is challenging owing to the large spectral dispersion of the resonances, which also leads to severe chemical shift displacement artifacts for slice-selective acquisitions.
  
  
  METHODS
  This study introduces a sequence for three-dimensional CSI of [2-(13) C]pyruvate using spectrally selective excitation of limited frequency bands containing a subset of metabolites. Dynamic CSI data were acquired alternately from multiple frequency bands in phantoms for sequence testing and in vivo in rat heart.
  
  
  RESULTS
  Phantom experiments verified the radiofrequency pulse design and demonstrated that the signal behavior of each group of resonances was unaffected by excitation of the other frequency bands. Dynamic three-dimensional (13) C CSI data demonstrated the sequence capability to image pyruvate, lactate, acetylcarnitine, glutamate, and acetoacetate, enabling the analysis of organ-specific spectra and metabolite time courses.
  
  
  CONCLUSIONS
  The presented method allows CSI of widely separated resonances without chemical shift displacement artifact, acquiring multiple frequency bands alternately to obtain dynamic time-course information. This approach enables robust imaging of downstream metabolic products of acetyl-coenzyme A with hyperpolarized [2-(13) C]pyruvate.
authors.affiliation: SRI International, Neuroscience Program, Menlo Park, California, USA; Department of Radiology, Stanford University, Lucas MRI Center, Stanford, California, USA.
authors.forename: Sonal
authors.initials: S
authors.lastname: Josan
authors.forename: Ralph
authors.initials: R
authors.lastname: Hurd
authors.forename: Jae Mo
authors.initials: JM
authors.lastname: Park
authors.forename: Yi-Fen
authors.initials: YF
authors.lastname: Yen
authors.forename: Ron
authors.initials: R
authors.lastname: Watkins
authors.forename: Adolf
authors.initials: A
authors.lastname: Pfefferbaum
authors.forename: Daniel
authors.initials: D
authors.lastname: Spielman
authors.forename: Dirk
authors.initials: D
authors.lastname: Mayer
mesh_terms: D000090:Acetoacetates / Q000378:metabolism; D000108:Acetylcarnitine / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D003287:Contrast Media / Q000737:chemistry; D018698:Glutamic Acid / Q000378:metabolism; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000737:chemistry; D009206:Myocardium / Q000378:metabolism*; D009942:Organometallic Compounds / Q000737:chemistry; D019047:Phantoms, Imaging; D011773:Pyruvates / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D000090:Acetoacetates; D002247:Carbon Isotopes; D003287:Contrast Media; D007773:Lactates; D009942:Organometallic Compounds; D011773:Pyruvates; D018698:Glutamic Acid; C016635:acetoacetic acid; D000108:Acetylcarnitine; D008536:Meglumine; C072417:gadoterate meglumine
keywords: [2-13C]pyruvate; dynamic metabolic imaging; hyperpolarized 13C; spiral CSI