Polarizes Water Molecules from Parahydrogen to Intensify Their Nuclear Magnetic Resonance Signals for Detection in Low Magnetic Fields
The use of hyperpolarized water as a contrast agent in magnetic resonance imaging (MRI) could dramatically shorten scanning times for patients, provide new imaging modalities, and avoid the risks associated with conventional contrast agents (e.g. gadolinium). However, the only existing method for making hyperpolarized water, i.e. dynamic nuclear polarization (DNP), requires complex instrumentation incorporating cryogenics, high frequency microwaves, and a powerful superconducting magnet system. In a new process developed at the University of Florida, hyperpolarized liquid water is produced from parahydrogen* by heterogeneous spin conversion catalysis (SCC) at low magnetic field. The key advantages of this parahydrogen-based SCC method include its far greater simplicity, reliability, and scalability. Most importantly, the SCC process can be performed at low magnetic field and does not require a superconducting magnet. In principle, hyperpolarized water can be continuously produced by flowing it over the specially formulated insoluble SCC nanoparticles, rending pure hyperpolarized water that is suitable for in vivo biomedical use. Production of hyperpolarized water by the SCC process has far-reaching implications. Since it is relatively inexpensive and does not require a superconducting magnet, it can be deployed for low-field medical MRI in remote or impoverished regions. *Parahydrogen is a metastable quantum state of molecular hydrogen that can be quickly and inexpensively prepared, stored and transported
Application
A catalytic process that hyperpolarizes a fluid, such as water, ethanol, or methanol, to enhance the molecular nuclear magnetic resonance signals for use in sensitivity-enhanced NMR spectroscopy and MRI at low magnetic fields
Advantages
- Increases the proton spin polarization in water molecules, thereby decreasing the amount of time required for an MRI scan
- Produces hyperpolarized water that yields intense NMR signals, improving the performance of ultra-low field MRI and low-field NMR spectroscopy
- Establishes a continuous, scalable catalysis system that utilizes parahydrogen, providing a fast, flexible, and inexpensive source of hyperpolarized water with improved throughput
- Uses a non-toxic catalyst that is insoluble and easily separates from the water, enabling the production of highly-pure hyperpolarized water suitable for in vivo use as an MRI contrast agent
Technology
This heterogeneous spin conversion catalytic process yields hyperpolarized water from parahydrogen without the use of high magnetic fields or microwave irradiation. The hyperpolarized water is produced by dissolution of parahydrogen gas in a suspension of the specially formulated catalyst, composed of synthesized metallic nanoparticles, which is insoluble in liquid water. The water molecules in hyperpolarized water exhibit strong nuclear magnetic resonance signals, enabling it to function as an intrinsic MRI contrast agent. In addition to water, this same catalytic process can also hyperpolarize other fluids, including ethanol and methanol, for other applications.
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