Hyperpolarization without persistent radicals for in vivo real-time metabolic imaging

Area of Science:

• Biomedical Imaging
• Chemical Physics
• Medical Diagnostics

Background:

• Hyperpolarized substrates are crucial for metabolic MRI in diagnosing diseases like cancer and cardiac failure.
• Current methods rely on toxic persistent radicals for substrate hyperpolarization, posing safety concerns.
• Existing techniques require extensive filtering and safety testing for clinical use.

Purpose of the Study:

• To develop a safer, simpler method for preparing hyperpolarized agents for in vivo metabolic MRI.
• To eliminate the need for toxic radicals in the hyperpolarization process.
• To facilitate faster and more accessible clinical translation of hyperpolarized MRI.

Main Methods:

• Utilizing UV light irradiation of frozen pyruvic acid to induce radical formation.
• Employing dissolution dynamic nuclear polarization (DNP) with photo-induced radicals.
• Analyzing the (13)C polarization enhancement of pyruvic acid.
• Assessing the endogenous nature of the final solution post-dissolution.

Main Results:

• Successful generation of sufficient photo-induced radicals in pyruvic acid using UV light.
• Significant enhancement of (13)C polarization via DNP.
• Formation of a solution containing only endogenous products after radical recombination upon dissolution.
• Demonstrated feasibility of in vivo metabolic hyperpolarized (13)C MRI with high spatial resolution.

Conclusions:

• A novel, safe, and efficient method for preparing hyperpolarized (13)C pyruvic acid using UV light and DNP has been established.
• This approach avoids toxic radicals and simplifies the preparation process, removing the need for filtering and extensive safety tests.
• The method enables straightforward preclinical and clinical applications of metabolic hyperpolarized MRI, improving sensitivity and accessibility.