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Effect of lanthanide ions on dynamic nuclear polarization enhancement and liquid‐state T 1 relaxation
Author(s) -
Gordon Jeremy W.,
Fain Sean B.,
Rowland Ian J.
Publication year - 2012
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24207
Subject(s) - lanthanide , polarization (electrochemistry) , gadolinium , paramagnetism , chemistry , holmium , ion , dissolution , materials science , analytical chemistry (journal) , nuclear magnetic resonance , condensed matter physics , chromatography , organic chemistry , optics , laser , physics
In the dynamic nuclear polarization process, microwave irradiation facilitates exchange of polarization from a radical's unpaired electron to nuclear spins at cryogenic temperatures, increasing polarization by >10,000. Doping samples with Gd 3+ ions further increases the achievable solid‐state polarization. However, on dissolution, paramagnetic lanthanide metals can be potent relaxation agents, decreasing liquid‐state polarization. Here, the effects of lanthanide metals on the solid and liquid‐state magnetic properties of [1‐ 13 C]pyruvate are studied. The results show that in addition to gadolinium, holmium increases not only the achievable polarization but also the rate of polarization. Liquid‐state relaxation studies found that unlike gadolinium, holmium minimally affects T 1 . Additionally, results reveal that linear contrast agents dissociate in pyruvic acid, greatly reducing liquid‐state T 1 . Although macrocyclic agents do not readily dissociate, they yield lower solid‐state polarization. Results indicate that polarization with free lanthanides and subsequent chelation during dissolution produces the highest polarization enhancement while minimizing liquid‐state relaxation. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.