Abstract:
: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.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Gordon JW,Fain SB,Rowland IJdoi
10.1002/mrm.24207subject
Has Abstractpub_date
2012-12-01 00:00:00pages
1949-54issue
6eissn
0740-3194issn
1522-2594journal_volume
68pub_type
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