Hyperpolarized 6Li as a probe for hemoglobin oxygenation level

Hyperpolarization by dissolution dynamic nuclear polarization (DNP) is a versatile technique to dramatically enhance the nuclear magnetic resonance (NMR) signal intensity of insensitive long‐T1 nuclear spins such as 6Li. The 6Li longitudinal relaxation of lithium ions in aqueous solutions strongly depends on the concentration of paramagnetic species, even if they are present in minute amounts. We herein demonstrate that blood oxygenation can be readily detected by taking advantage of the 6Li signal enhancement provided by dissolution DNP, together with the more than 10% decrease in 6Li longitudinal relaxation as a consequence of the presence of paramagnetic deoxyhemoglobin. Copyright © 2015 John Wiley & Sons, Ltd. Effect of blood oxygenation on the longitudinal relaxation time of hyperpolarized 6Li. Oxygenated hemoglobin being diamagnetic, it does not affect the 6Li relaxation. In contrast, 6Li T1 is more than 10% shorter in the presence of deoxyhemoglobin because it is paramagnetic.