A novel variable field system for field-cycled dynamic nuclear polarization spectroscopy

Keerthi Shet, George L Caia, Eric Kesselring, Alexandre Samouilov, Sergey Petryakov, David J Lurie, Jay L Zweier

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Dynamic nuclear polarization (DNP) is an NMR-based technique which enables detection and spectral characterization of endogenous and exogenous paramagnetic substances measured via transfer of polarization from the saturated unpaired electron spin system to the NMR active nuclei. A variable field system capable of performing DNP spectroscopy with NMR detection at any magnetic field in the range 0-0.38T is described. The system is built around a clinical open-MRI system. To obtain EPR spectra via DNP, partial cancellation of the detection field B(0)(NMR) is required to alter the evolution field B(0)(EPR) at which the EPR excitation is achieved. The addition of resistive actively shielded field cancellation coils in the gap of the primary magnet provides this field offset in the range of 0-100mT. A description of the primary magnet, cancellation coils, power supplies, interfacing hardware, RF electronics and console are included. Performance of the instrument has been evaluated by acquiring DNP spectra of phantoms with aqueous nitroxide solutions (TEMPOL) at three NMR detection fields of 97G, 200G and 587G corresponding to 413kHz, 851.6kHz and 2.5MHz respectively and fixed EPR evolution field of 100G corresponding to an irradiation frequency of 282.3MHz. This variable-field DNP system offers great flexibility for the performance of DNP spectroscopy with independent optimum choice of EPR excitation and NMR detection fields.
Original languageEnglish
Pages (from-to)202-208
Number of pages7
JournalJournal of Magnetic Resonance
Issue number2
Early online date31 May 2010
Publication statusPublished - Aug 2010


  • proton MRI
  • EPR imaging
  • free radicals
  • oxygen
  • image co-registration
  • in vivo NMR
  • in vivo EPR
  • Overhauser effect


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