Extending the Lifetime of Hyperpolarized Propane Gas through Reversible Dissolution.

Hyperpolarized (HP) propane produced by the parahydrogen-induced polarization (PHIP) technique has been recently introduced as a promising contrast agent for functional lung magnetic resonance (MR) imaging. However, its short lifetime due to a spin-lattice relaxation time T ₁ of less than 1 s in the gas phase is a significant translational challenge for its potential biomedical applications. The previously demonstrated approach for extending the lifetime of the HP propane state through long-lived spin states allows the HP propane lifetime to be increased by a factor of ∼3. Here, we demonstrate that a remarkable increase in the propane hyperpolarization decay time at high magnetic field (7.1 T) can be achieved by its dissolution in deuterated organic solvents (acetone- d ₆ or methanol- d ₄ ). The approximate values of the HP decay time for propane dissolved in acetone- d ₆ are 35.1 and 28.6 s for the CH ₂ group and the CH ₃ group, respectively (similar values were obtained for propane dissolved in methanol- d ₄ ), which are ∼50 times larger than the gaseous propane T ₁ value. Furthermore, we show that it is possible to retrieve HP propane from solution to the gas phase with the preservation of hyperpolarization.