A multisample 7 T dynamic nuclear polarization polarizer for preclinical hyperpolarized MR. (30th January 2020)

• Record Type: Journal Article
• Authors: Cheng, Tian; Gaunt, Adam P.; Marco‐Rius, Irene; Gehrung, Marcel; Chen, Albert P.; van der Klink, Jacques J.; Comment, Arnaud
• Is Part Of: NMR in biomedicine. Volume 33:Number 5(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-30
• Subjects: carbon‐13 -- cryogen‐free -- cryostat -- dynamic nuclear polarization -- hyperpolarization -- hyperpolarizer -- MRI -- MRS; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4264
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : Dynamic nuclear polarization (DNP) provides the opportunity to boost liquid state magnetic resonance (MR) signals from selected nuclear spins by several orders of magnitude. A cryostat running at a temperature of ~ 1 K and a superconducting magnet set to between 3 and 10 T are required to efficiently hyperpolarize nuclear spins. Several DNP polarizers have been implemented for the purpose of hyperpolarized MR and recent systems have been designed to avoid the need for user input of liquid cryogens. We herein present a zero boil‐off DNP polarizer that operates at 1.35 ± 0.01 K and 7 T, and which can polarize two samples in parallel. The samples are cooled by a static helium bath thermally connected to a 1 K closed‐cycle 4 He refrigerator. Using a modified version of the commercial fluid path developed for the SPINlab polarizer, we demonstrate that, within a 12‐minute interval, the system can produce two separate hyperpolarized 13 C solutions. The 13 C liquid‐state polarization of [1‐ 13 C]pyruvate measured 26 seconds after dissolution was 36%, which can be extrapolated to a 55% solid state polarization. The system is well adapted for in vitro and in vivo preclinical hyperpolarized MR experiments and it can be modified to polarize up to four samples in parallel. Abstract : A zero boil‐off 7 T dynamic nuclear polarization (DNP) system that can run continuously in a 24/7 operation mode below 1.4 K without any input of liquid cryogen is presented. The system features an insert suitable for multisample polarization and dissolution. A modified fluid path was designed to produce hyperpolarized solutions with a 13C polarization of up to 55% at the time of dissolution.