129Xe Chemical Shift in Human Blood and Pulmonary Blood Oxygenation Measurement in Humans Using Hyperpolarized 129Xe NMR

Purpose: To evaluate the dependency of the Xe-129-red blood cell (RBC) chemical shift on blood oxygenation, and to use this relation for noninvasive measurement of pulmonary blood oxygenation in vivo with hyperpolarized Xe-129 NMR. Methods: Hyperpolarized Xe-129 was equilibrated with blood samples of varying oxygenation in vitro, and NMR was performed at 1.5 T and 3 T. Dynamic in vivo NMR during breath hold apnea was performed at 3 T on two healthy volunteers following inhalation of hyperpolarized Xe-129. Results: The Xe-129 chemical shift in RBCs was found to increase nonlinearly with blood oxygenation at 1.5 T and 3 T. During breath hold apnea, the Xe-129 chemical shift in RBCs exhibited a periodic time modulation and showed a net decrease in chemical shift of similar to 1 ppm over a 35 s breath hold, corresponding to a decrease of 7-10 % in RBC oxygenation. The Xe-129-RBC signal amplitude showed a modulation with the same frequency as the Xe-129-RBC chemical shift. Conclusion: The feasibility of using the Xe-129-RBC chemical shift to measure pulmonary blood oxygenation in vivo has been demonstrated. Correlation between Xe-129-RBC signal and (129) Xe-RBC chemical shift modulations in the lung warrants further investigation, with the aim to better quantify temporal blood oxygenation changes in the cardiopulmonary vascular circuit. (C) 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.