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Relaxation and exchange dynamics of hyperpolarized 129 Xe in human blood
Author(s) -
Norquay Graham,
Leung General,
Stewart Neil J.,
Tozer Gillian M.,
Wolber Jan,
Wild Jim M.
Publication year - 2015
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.25417
Subject(s) - chemistry , xenon , relaxation (psychology) , hematocrit , nuclear magnetic resonance , reaction rate constant , blood plasma , oxygenation , analytical chemistry (journal) , kinetics , chromatography , anesthesia , biochemistry , medicine , psychology , social psychology , physics , organic chemistry , quantum mechanics , endocrinology
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:r s O 2 = 11.1, a “relaxivity index” characterizing the rate of change of 129 Xe relaxation as a function of blood oxygenation, and 1 / T 1 oHb = 0.13 s −1 and 1 / T 1 dHb = 0.42 s −1 , the 129 Xe relaxation rates in oxygenated blood and deoxygenated blood, respectively. In addition, rate constants,k a = 0.022 ms −1 andk b = 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,r O 2 = 0.075 s −1 mM −1 , and the 129 Xe relaxation rate in isolated plasma (without dissolved O 2 ), 1 / T 1,b 0 = 0.046 s −1 , were also calculated. Finally, intrinsic 129 Xe‐RBC relaxation rates, 1 / T 1 , a oHb = 0.19 s −1 and 1 / T 1 , a dHb = 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 74:303–311, 2015. © 2014 Wiley Periodicals, Inc.