Optical pumping and hyperpolarized spin relaxation

Xizeng Wu

doi:10.1117/12.546114

8 December 2003 Optical pumping and hyperpolarized spin relaxation

Xizeng Wu

Proceedings Volume 5254, Third International Conference on Photonics and Imaging in Biology and Medicine; (2003) https://doi.org/10.1117/12.546114
Event: Third International Conference on Photonics and Imaging in Biology and Medicine, 2003, Wuhan, China

Abstract

Optical pumping is to use light photons to polarize the atomic electron spins first and then the nuclear spins of noble gases get polarized through the spin exchange between atomic electron spins and nuclear spins. Using optical pumping nuclear spins of noble gases such as ³He and ¹²⁹Xe can be polarized to 50% or higher, hundred thousand times higher than the proton polarization in conventional MRI. It has been found in this theoretical work that the conventional spin relaxation equations are not valid for the hyperpolarized spins. We find that hyperpolarization and spin coupling result in the multipole spin orders. These multipole spin orders cross-relax each other. New longitudinal relaxation equations for the dipole-dipole coupled hyperpolarized spins at room temperature have been derived. These new equations predict that the longitudinal magnetization relaxation of hyperpolarized spins is, in general, bi-exponential decay instead of single exponential decay. The potential applications of the findings in quantifying the paramagnetic source in lung and other tissue and in modeling hyperpolarized spin relaxation in bio-compatible media are pointed out as well.

Citation Download Citation

Xizeng Wu "Optical pumping and hyperpolarized spin relaxation", Proc. SPIE 5254, Third International Conference on Photonics and Imaging in Biology and Medicine, (8 December 2003); https://doi.org/10.1117/12.546114

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