^{129}Xe-Rb Spin-Exchange Optical Pumping with High Photon Efficiency

Area of Science:

• Medical Physics
• Atomic, Molecular, and Optical Physics
• Magnetic Resonance Imaging

Background:

• Hyperpolarized 129Xe gas enables advanced MRI of the lungs, brain, and kidneys.
• Previous methods for producing polarized 129Xe were limited in speed and volume.
• Efficient generation of polarized 129Xe is crucial for widespread clinical adoption.

Purpose of the Study:

• To develop and optimize a Rb-129Xe spin-exchange optical pumping polarizer for rapid, large-volume production of polarized 129Xe.
• To model and experimentally validate the system's performance for maximizing 129Xe nuclear spin polarization.
• To enable on-demand availability of hyperpolarized 129Xe for clinical applications.

Main Methods:

• Utilized Rb-129Xe spin-exchange optical pumping.
• Employed modeling and experimental measurements to optimize Rb vapor density and photon flux.
• Designed a cylindrical optical cell for efficient polarization of 129Xe gas.

Main Results:

• Achieved rapid generation of 300 cm³ polarized 129Xe gas volumes every 5 minutes.
• Measured a 129Xe magnetization production efficiency of 1.8%, approaching the photon efficiency limit.
• Demonstrated a magnetization production rate threefold higher than previously reported, enabling 1013 cm³ of 100% polarized 129Xe per hour.

Conclusions:

• The developed polarizer system significantly enhances the production rate of hyperpolarized 129Xe gas.
• This advancement facilitates routine clinical lung MRI and high-SNR imaging of the brain and kidneys.
• The system provides on-demand availability of polarized 129Xe, paving the way for broader clinical applications of hyperpolarized gas MRI.