Subsecond Three-Dimensional Nitrogen-15 Magnetic Resonance Imaging Facilitated by Parahydrogen-Based...

Area of Science:

• Medical Imaging
• Nuclear Magnetic Resonance
• Pharmacology

Background:

• Conventional proton MRI is limited for real-time metabolism studies due to abundant water and fat signals.
• Heteronuclear MRI with hyperpolarization offers a solution to overcome these signal limitations.

Purpose of the Study:

• To develop and demonstrate hyperpolarized 15N MRI for non-invasive, real-time metabolic imaging.
• To visualize the distribution of a drug (fampridine) in vivo using advanced MRI techniques.

Main Methods:

• Polarization of 15N nuclei in [15N1]fampridine using spin-lock-induced crossing and signal amplification by reversible exchange.
• Acquisition of three-dimensional 15N MRI with high signal-to-noise ratio.
• Comparison of NMR signal enhancements between 15N-enriched and naturally abundant fampridine.

Main Results:

• Achieved 4% polarization of 15N nuclei in NMR experiments and 0.7% in MRI studies.
• Acquired 3D 15N MRI of hyperpolarized fampridine in 0.1 seconds with a signal-to-noise ratio of 70.
• Observed and explained differences in NMR signal enhancement between enriched and natural abundance 15N fampridine.

Conclusions:

• Hyperpolarized 15N MRI enables rapid, high-contrast imaging of metabolic processes.
• This technique overcomes the limitations of conventional MRI for observing real-time metabolism.
• The developed method holds promise for in vivo drug monitoring and metabolic research.