title: Hyperpolarized [1-(13) C]pyruvate MRI for noninvasive examination of placental metabolism and nutrient transport: A feasibility study in pregnant guinea pigs.
abstract: OBJECTIVE
  To test the feasibility of hyperpolarized [1-(13) C]pyruvate magnetic resonance imaging (MRI) for noninvasive examination of guinea pig fetoplacental metabolism and nutrient transport.
  
  
  METHODS
  Seven pregnant guinea pigs with a total of 30 placentae and fetuses were anesthetized and scanned at 3T. T1 -weighted (1) H images were obtained from the maternal abdomen. An 80 mM solution of hyperpolarized [1-(13) C]pyruvate (hereafter referred to as pyruvate) was injected into a vein in the maternal foot. Time-resolved 3D (13) C images were acquired starting 10 seconds after the beginning of bolus injection and every 10 seconds after to 50 seconds. The pregnant guinea pigs were recovered after imaging. Regions of interest (ROIs) were drawn around the maternal heart and each placenta and fetal liver in all slices in the (1) H images. These ROIs were copied to the (13) C images and were used to calculate the sum of the pyruvate and lactate signal intensities for each organ. The signal intensities were normalized by the volume of the organ and the maximum signal in the maternal heart.
  
  
  RESULTS
  No adverse events were observed in the pregnant guinea pigs and natural pupping occurred at term (∼68 days). Pyruvate signal was observed in all 30 placentae, and lactate, a by-product of pyruvate metabolism, was also observed in all placentae. The maximum pyruvate and lactate signals in placentae occurred at 20 seconds. In addition to the observation of pyruvate and lactate signals in the placentae, both pyruvate and lactate signals were observed in all fetal livers. The maximum pyruvate and lactate signals in the fetal livers occurred at 10 seconds and 20 seconds, respectively.
  
  
  CONCLUSIONS
  This work demonstrates the feasibility of using hyperpolarized [1-(13) C]pyruvate MRI to noninvasively examine fetoplacental metabolism and transport of pyruvate in guinea pigs. Hyperpolarized (13) C MRI may provide a novel method for longitudinal studies of fetoplacental abnormalities.
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
authors.forename: Lanette J
authors.initials: LJ
authors.lastname: Friesen-Waldner
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
authors.forename: Kevin J
authors.identifier: http://orcid.org/0000-0002-5203-7484
authors.initials: KJ
authors.lastname: Sinclair
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.|Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
authors.forename: Trevor P
authors.initials: TP
authors.lastname: Wade
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
authors.forename: Banoub
authors.initials: B
authors.lastname: Michael
authors.affiliation: GE Healthcare, Toronto, Ontario, Canada.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynaecology, University of Western Ontario, London, Ontario, Canada.|Children's Health Research Institute, London, Ontario, Canada.|Lawson Research Institute, London, Ontario, Canada.
authors.forename: Barbra
authors.initials: B
authors.lastname: de Vrijer
authors.affiliation: Department of Obstetrics and Gynaecology, University of Western Ontario, London, Ontario, Canada.|Children's Health Research Institute, London, Ontario, Canada.|Lawson Research Institute, London, Ontario, Canada.|Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Timothy R H
authors.initials: TR
authors.lastname: Regnault
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.|Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.|Children's Health Research Institute, London, Ontario, Canada.|Lawson Research Institute, London, Ontario, Canada.
authors.forename: Charles A
authors.initials: CA
authors.lastname: McKenzie
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D005260:Female; D005333:Fetus / Q000000981:diagnostic imaging; D006168:Guinea Pigs; D021621:Imaging, Three-Dimensional; D019344:Lactic Acid / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D010920:Placenta / Q000000981:diagnostic imaging* / Q000378:metabolism; D011247:Pregnancy; D019289:Pyruvic Acid / Q000737:chemistry*; D012815:Signal Processing, Computer-Assisted
chemical_list: D019344:Lactic Acid; D019289:Pyruvic Acid
keywords: fetus; hyperpolarized carbon-13; magnetic resonance imaging; metabolism; nutrient transport; placenta