Optimized Continuous Application of Hyperpolarized Xenon to Liquids

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Medical Imaging
• Chemical Engineering

Background:

• Hyperpolarized (HP) xenon NMR shows promise for direct observation of metabolic processes.
• Dissolving HP xenon gas efficiently in liquids is a key challenge for its application.
• Functionalized host structures like cryptophanes are used for xenon-based imaging.

Purpose of the Study:

• To develop and demonstrate an improved, controlled method for dissolving HP xenon in aqueous solutions.
• To enhance the stability and duration of HP xenon signals for advanced NMR experiments.
• To reduce polarization losses during gas dissolution and transfer.

Main Methods:

• Utilized a novel apparatus combining a polarization-preserving compressor and a hollow fiber membrane unit for gas dissolution.
• Tested two types of compressors and optimized system parameters using physical models.
• Dissolved HP xenon in an aqueous solution of cryptophane-A-(OCH2COOH)6.

Main Results:

• Achieved continuous, controlled dissolution of HP xenon in aqueous liquids without bubble or foam formation.
• Maintained stable HP xenon signals for over 35 minutes, limited only by gas reservoir size.
• Enabled detailed study of xenon chemical exchange within cryptophane structures using 2D NMR.
• Determined an average xenon residence time within cryptophane of 44.5 ± 2.7 ms.

Conclusions:

• The developed HP xenon dissolution system significantly improves stability and duration for NMR imaging.
• This method facilitates advanced NMR studies, such as chemical exchange and residence time measurements.
• The technology holds potential for enhanced molecular imaging of metabolic processes.