title: Earth's magnetic field enabled scalar coupling relaxation of 13C nuclei bound to fast-relaxing quadrupolar 14N in amide groups.
abstract: Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the (13)C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner.
authors.affiliation: GE Global Research, Munich, Germany. enrico.chiavazza@unito.it
authors.forename: Enrico
authors.initials: E
authors.lastname: Chiavazza
authors.forename: Eugen
authors.initials: E
authors.lastname: Kubala
authors.forename: Concetta V
authors.initials: CV
authors.lastname: Gringeri
authors.forename: Stephan
authors.initials: S
authors.lastname: Düwel
authors.forename: Markus
authors.initials: M
authors.lastname: Durst
authors.forename: Rolf F
authors.initials: RF
authors.lastname: Schulte
authors.forename: Marion I
authors.initials: MI
authors.lastname: Menzel
mesh_terms: D000577:Amides / Q000737:chemistry* / Q000528:radiation effects; D002247:Carbon Isotopes / Q000737:chemistry* / Q000528:radiation effects; D018534:Earth, Planet; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D060306:Magnetometry / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D000577:Amides; D002247:Carbon Isotopes; D009584:Nitrogen