Synopsis

Keywords: Contrast mechanisms: Hyperpolarization

Hyperpolarization is a powerful technique that enhances NMR signal intensity, and it can be implemented using various methods. This presentation provides an overview of hyperpolarization for medical applications, with a particular focus on dynamic nuclear polarization (DNP), which is now utilized in clinical research. The presentation outlines the fundamentals of hyperpolarization and discusses the necessary components for hyperpolarized magnetic resonance imaging. Additionally, prospects for the field are presented in the hopes of inspiring further research efforts.

Hyperpolarization-enhanced Magnetic Resonance Imaging (HP-MRI) is a cutting-edge imaging technique that has recently gained popularity in the field of medical research. It involves a process of increasing the polarization of specific molecules, such as 13C, which allows them to emit a stronger signal when scanned by an MRI machine. The principle of HP-MRI involves increasing the polarization, or the alignment of nuclear spins of specific molecules, such as of 13C, before they are introduced into the living body. The increased polarization allows the molecules to emit a stronger signal when scanned by an MRI machine to develop a highly informative image of specific tissues or structures. There are several methods for hyperpolarizing molecules, such as dynamic nuclear polarization (DNP)1, parahydrogen-induced polarization (PHIP)2, or spin exchange optical pumping (SEOP)3 in which the target molecules are processed into a specialized machine or device to modify their physical and chemical characteristics responsible for the increase in their polarization. One of the key advantages of HP-MRI is its ability to provide real-time information about metabolic processes. By tracking the movement and metabolism of polarized molecules in the body, it is possible to gain valuable insights into the function of various organs and tissues, which would be very useful in studying specific disease characteristics such as cancer, where changes in metabolic activity are often an early indicator of tumor growth. One of the significant limitations of HP-MRI is its short imaging time period. The polarization of the molecules typically lasts only for a few seconds to minutes, which requires immediate imaging with great precision. This can be challenging for researchers, requiring specialized equipment and expertise. Despite its limitations, HP-MRI is a promising technique that has the potential to revolutionize the field of medical imaging. With continued advancements in technology and methodology, it may become a valuable tool for diagnosing and treating various diseases. This presentation will provide an overview of hyperpolarization, to enhance understanding of HP-MRI used in the medical field.

Acknowledgements

This work was supported by AMED under Grant Number JP22dk0207063, JSPS under the Joint Research Program implemented in association with SNSF (JRPs) under Grant number JPJSJRP 20221510, and KAKENHI grant number 22K19393.

References

1) Ardenkjaer-Larsen, J. H., et al. Proceedings of the National Academy of Sciences, 100(18), 10158-10163(2003). 2) Bowers, C. R., et al. Journal of the American Chemical Society, 107(18), 5546-5547(1985). 3) Walker, T. G. Reviews of Modern Physics, 69(2), 629-642(1997).