Spying on parahydrogen-induced polarization transfer using a half-tesla benchtop MRI and hyperpolarized imaging enabled by automation

Abstract

Nuclear spin hyperpolarization is a quantum effect that enhances the nuclear magnetic resonance signal by several orders of magnitude and has enabled real-time metabolic imaging in humans. However, the translation of hyperpolarization technology into routine use in laboratories and medical centers is hampered by the lack of portable, cost-effective polarizers that are not commercially available. Here, we present a portable, automated polarizer based on parahydrogen-induced hyperpolarization (PHIP) at an intermediate magnetic field of 0.5 T (achieved by permanent magnets). With a footprint of 1 m2, we demonstrate semi-continuous, fully automated 1H hyperpolarization of ethyl acetate-d6 and ethyl pyruvate-d6 to P = 14.4% and 16.2%, respectively, and a 13C polarization of 1-13C-ethyl pyruvate-d6 of P = 7%. The duty cycle for preparing a dose is no more than 1 min. To reveal the full potential of 1H hyperpolarization in an inhomogeneous magnetic field, we convert the anti-phase PHIP signals into in-phase peaks, thereby increasing the SNR by a factor of 5. Using a spin-echo approach allowed us to observe the evolution of spin order distribution in real time while conserving the expensive reagents for reaction monitoring, imaging and potential in vivo usage. This compact polarizer will allow us to pursue the translation of hyperpolarized MRI towards in vivo applications further.

Molecules, up Your Spins!

“…[14,29] While challenges remain in clinical translation, specifically, the ability to control all stages of chemical transformations and fields at each moment of sample transfer, recent advancements have showcased reproducible polarization levels on biologically relevant nuclei, fostering optimism for future developments. [30][31][32] For a comprehensive exploration of hyperpolarization, readers are encouraged to consult recent reviews that delve into the physicochemical principles of these techniques. [33] The semantic breadth of "hyperpolarization" terminology highlights its diverse manifestations which extend beyond simple magnetization to encompass complex spin orders with broad implications for both fundamental research and technological innovation.…”

Molecules, Up Your Spins!

“…PHIP variants like PASADENA, ALTADENA, and SABRE demonstrate remarkable polarization levels (above 50%) on various nuclei [14,28]. While challenges remain in clinical translation, specifically the ability to control all stages of chemical transformations and fields at each moment of sample transfer, recent advancements have showcased reproducible polarization levels on biologically relevant nuclei, fostering optimism for future developments [29][30][31].…”