title: Handheld electromagnet carrier for transfer of hyperpolarized carbon-13 samples.
abstract: OBJECTIVE
  Hyperpolarization of carbon-13 ((13) C) nuclei by dissolution dynamic nuclear polarization increases signal-to-noise ratio (SNR) by >10,000-fold for metabolic imaging, but care must be taken when transferring hyperpolarized (HP) samples from polarizer to MR scanner. Some (13) C substrates relax rapidly in low ambient magnetic fields. A handheld electromagnet carrier was designed and constructed to preserve polarization by maintaining a sufficient field during sample transfer.
  
  
  METHODS
  The device was constructed with a solenoidal electromagnet, powered by a nonmagnetic battery, holding the HP sample during transfer. A specially designed switch automated deactivation of the field once transfer was complete. Phantom and rat experiments were performed to compare MR signal enhancement with or without the device for HP [(13) C]urea and [1-(13) C]pyruvate.
  
  
  RESULTS
  The magnetic field generated by this device was tested to be >50 G over a 6-cm central section. In phantom and rat experiments, [(13) C]urea transported via the device showed SNR improvement by a factor of 1.8-1.9 over samples transferred through the background field.
  
  
  CONCLUSIONS
  A device was designed and built to provide a suitably high yet safe magnetic field to preserve hyperpolarization during sample transfer. Comparative testing demonstrated SNR improvements of approximately two-fold for [(13) C]urea while maintaining SNR for [1-(13) C]pyruvate.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.|The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Shang
authors.affiliation: GE Healthcare, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Skloss
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Cornelius
authors.initials: C
authors.lastname: von Morze
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Lucas
authors.initials: L
authors.lastname: Carvajal
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Van Criekinge
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.|The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Milshteyn
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.|The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA.
authors.forename: Peder E Z
authors.initials: PE
authors.lastname: Larson
authors.affiliation: GE Healthcare, USA.
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Hurd
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.|The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Vigneron
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D004574:Electromagnetic Fields; D004867:Equipment Design; D008279:Magnetic Resonance Imaging; D019047:Phantoms, Imaging; D051381:Rats; D059629:Signal-To-Noise Ratio
chemical_list: D002247:Carbon Isotopes
keywords: T1 relaxation; dynamic nuclear polarization; hyperpolarized carbon-13 MRI/MRSI; low magnetic field; scalar coupling; urea