Publication Date:
2014-08-29
Description:
Purpose 129 Xe-blood NMR was performed over the full blood oxygenation range to evaluate 129 Xe relaxation and exchange dynamics in human blood. Methods Hyperpolarized 129 Xe was equilibrated with blood and isolated plasma, and NMR was performed at 1.5 T. Results The 129 Xe relaxation rate was found to increase nonlinearly with decreasing blood oxygenation. Three constants were extrapolated: = 11.1, a “relaxivity index” characterizing the rate of change of 129 Xe relaxation as a function of blood oxygenation, and = 0.13 s −1 and = 0.42 s −1 , the 129 Xe relaxation rates in oxygenated blood and deoxygenated blood, respectively. In addition, rate constants, 0.022 ms −1 and = 0.062 ms −1 , were determined for xenon diffusing between red blood cells (RBCs) and plasma (hematocrit = 48%). The 129 Xe-O 2 relaxivity in plasma, = 0.075 s −1 mM −1 , and the 129 Xe relaxation rate in isolated plasma (without dissolved O 2 ), = 0.046 s −1 , were also calculated. Finally, intrinsic 129 Xe-RBC relaxation rates, = 0.19 s −1 and = 0.84 s −1 , in oxygenated blood and deoxygenated blood, respectively, were calculated. Conclusion The relaxation and exchange analysis performed in this study should provide a sound experimental basis upon which to design future MR experiments for dissolved xenon transport from the lungs to distal tissues. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.
Print ISSN:
0740-3194
Electronic ISSN:
1522-2594
Topics:
Medicine
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