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Updated: Apr 25, 2026
Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
Relaxation and exchange dynamics of hyperpolarized 129Xe in human blood
Graham Norquay1, General Leung1, Neil J Stewart1
1Unit of Academic Radiology, Department of Cardiovascular Science, University of Sheffield, Sheffield, South Yorkshire, UK.
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: rsO2 = 11.1, a "relaxivity index" characterizing the rate of change of (129) Xe relaxation as a function of blood oxygenation, and 1/T1oHb = 0.13 s(-1) and 1/T1dHb = 0.42 s(-1) , the (129) Xe relaxation rates in oxygenated blood and deoxygenated blood, respectively. In addition, rate constants, ka = 0.022 ms(-1) and kb = 0.062 ms(-1) , were determined for xenon diffusing between red blood cells (RBCs) and plasma (hematocrit = 48%). The (129) Xe-O2 relaxivity in plasma, rO2 = 0.075 s(-1) mM(-1) , and the (129) Xe relaxation rate in isolated plasma (without dissolved O2 ), 1/T1,b0 = 0.046 s(-1) , were also calculated. Finally, intrinsic (129) Xe-RBC relaxation rates, 1/T1,aoHb = 0.19 s(-1) and 1/T1,adHb = 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.
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