Hyperpolarized orthohydrogen (
Hyperpolarized orthohydrogen (
- NSF-PAR ID:
- 10390922
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie
- Volume:
- 135
- Issue:
- 8
- ISSN:
- 0044-8249
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract o ‐H2) is a frequent product of parahydrogen‐based hyperpolarization approaches like signal amplification by reversible exchange (SABRE), where the hyperpolarizedo ‐H2signal is usually absorptive. We describe a novel manifestation of this effect wherein large antiphaseo ‐H2signals are observed, with1H enhancements up to ≈500‐fold (effective polarizationP H≈1.6 %). This anomalous effect is attained only when using an intact heterogeneous catalyst constructed using a metal–organic framework (MOF) and is qualitatively independent of substrate nature. This seemingly paradoxical observation is analogous to the “partial negative line” (PNL) effect recently explained in the context of Parahydrogen Induced Polarization (PHIP) by Ivanov and co‐workers. The two‐spin order of theo ‐H2resonance is manifested by a two‐fold higher Rabi frequency, and the lifetime of the antiphase HPo ‐H2resonance is extended by several‐fold. -
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Abstract Signal Amplification By Reversible Exchange in SHield Enabled Alignment Transfer (SABRE‐SHEATH) is investigated to achieve rapid hyperpolarization of13C1spins of [1‐13C]pyruvate, using parahydrogen as the source of nuclear spin order. Pyruvate exchange with an iridium polarization transfer complex can be modulated via a sensitive interplay between temperature and co‐ligation of DMSO and H2O. Order‐unity13C (>50 %) polarization of catalyst‐bound [1‐13C]pyruvate is achieved in less than 30 s by restricting the chemical exchange of [1‐13C]pyruvate at lower temperatures. On the catalyst bound pyruvate, 39 % polarization is measured using a 1.4 T NMR spectrometer, and extrapolated to >50 % at the end of build‐up in situ. The highest measured polarization of a 30‐mM pyruvate sample, including free and bound pyruvate is 13 % when using 20 mM DMSO and 0.5 M water in CD3OD. Efficient13C polarization is also enabled by favorable relaxation dynamics in sub‐microtesla magnetic fields, as indicated by fast polarization buildup rates compared to the
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Abstract The growing interest in magnetic resonance imaging (MRI) for assessing regional lung function relies on the use of nuclear spin hyperpolarized gas as a contrast agent. The long gas‐phase lifetimes of hyperpolarized129Xe make this inhalable contrast agent acceptable for clinical research today despite limitations such as high cost, low throughput of production and challenges of129Xe imaging on clinical MRI scanners, which are normally equipped with proton detection only. We report on low‐cost and high‐throughput preparation of proton‐hyperpolarized diethyl ether, which can be potentially employed for pulmonary imaging with a nontoxic, simple, and sensitive overall strategy using proton detection commonly available on all clinical MRI scanners. Diethyl ether is hyperpolarized by pairwise parahydrogen addition to vinyl ethyl ether and characterized by1H NMR spectroscopy. Proton polarization levels exceeding 8 % are achieved at near complete chemical conversion within seconds, causing the activation of radio amplification by stimulated emission radiation (RASER) throughout detection. Although gas‐phase
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Purpose The purpose of this study was to investigate the feasibility of in vivo13C‐>1H hyperpolarization transfer, which has significant potential advantages for detecting the distribution and metabolism of hyperpolarized13C probes in a clinical MRI scanner.
Methods A standalone pulsed13C RF transmit channel was developed for operation in conjunction with the standard1H channel of a clinical 3T MRI scanner. Pulse sequences for13C power calibration and polarization transfer were programmed on the external hardware and integrated with a customized water‐suppressed1H MRS acquisition running in parallel on the scanner. The newly developed RF system was tested in both phantom and in vivo polarization transfer experiments in1JCH‐coupled systems: phantom experiments in thermally polarized and hyperpolarized [2‐13C]glycerol, and1H detection of [2‐13C]lactate generated from hyperpolarized [2‐13C]pyruvate in rat liver in vivo.
Results Operation of the custom pulsed13C RF channel resulted in effective13C‐>1H hyperpolarization transfer, as confirmed by the characteristic antiphase appearance of1H‐detected,1JCH‐coupled doublets. In conjunction with a pulse sequence providing 190‐fold water suppression in vivo,1H detection of hyperpolarized [2‐13C]lactate generated in vivo was achieved in a rat liver slice.
Conclusion The results show clear feasibility for effective13C‐>1H hyperpolarization transfer in a clinical MRI scanner with customized heteronuclear RF system.
