title: α-trideuteromethyl[15N]glutamine: A long-lived hyperpolarized perfusion marker.
abstract: We characterized the performance of a novel hyperpolarized perfusion marker, α-trideuteromethyl[15N]glutamine, for direct comparison with a 13C-based hyperpolarized perfusion marker, [13C, 15N2]urea.
  
  
  
  A hardware platform and pulse sequence for in vivo 15N experiments were established. Hyperpolarized solutions of α-trideuteromethyl[15N]glutamine and [13C, 15N2]urea were injected into healthy male Lewis rats. Kidney slice images were acquired using a single-shot spiral readout. Both compounds were compared to determine in vivo signal lifetime and tracer distribution. Mass spectrometry was performed to evaluate excretion of the compound.
  
  
  
  Compared with 13C-labeled urea, a significantly increased signal lifetime was observed. While the urea signal was gone after 90 s, decay of the glutamine compound was sufficiently slow to obtain a quantifiable signal, even after 5 min. The glutamine derivative showed strong localization in the kidneys with little background signal. Effective T1 of α-trideuteromethyl[15N]glutamine was approximately eight-fold higher than that of urea. Mass spectrometry results confirmed rapid excretion within the time scale of the measurement.
  
  
  
  Hyperpolarized α-trideuteromethyl[15N]glutamine is a highly promising candidate for renal studies because of its long signal lifetime, strong localization and rapid excretion. Magn Reson Med 76:1900-1904, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: IMETUM, Technical University of Munich, Garching, Bavaria, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Durst
authors.affiliation: University of Torino, Turin, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Chiavazza
authors.affiliation: IMETUM, Technical University of Munich, Garching, Bavaria, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Haase
authors.affiliation: University of Torino, Turin, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.affiliation: Technical University of Munich, München, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.affiliation: GE Global Research, Garching, Germany.
authors.forename: Rolf F
authors.initials: RF
authors.lastname: Schulte
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D005973:Glutamine / Q000493:pharmacokinetics*; D007668:Kidney / Q000378:metabolism*; D007677:Kidney Function Tests / Q000379:methods*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D057054:Molecular Imaging / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D011917:Rats, Inbred Lew; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea / Q000493:pharmacokinetics*
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D019275:Radiopharmaceuticals; D005973:Glutamine; D014508:Urea
keywords: hyperpolarized 15N; kidney; perfusion