With optical pumping mechanisms, large amounts of nuclear spin-hyperpolarized noble gases can be stored and accumulated for future applications. It has been demonstrated that these strongly polarized gases may be useful in medical imaging. We are exploring the feasibility of using absorbed, spin-hyperpolarized, 129Xe (Xe acts as an anesthetic) in medical imaging. First, T1's of 129Xe in biological fluids will be measured; as a short T1 is an obvious limiting factor in using spin-hyperpolarized signal sources. Second, we will verify that we can produce adequate amount of spin-hyperpolarized 129Xe. Third, a mechanism for Xe transfer to the imagining subject will be developed. Eventually, we will image Xe inhaled by a mouse in the NMRFAM's small-bore imaging system using the 23Na imaging probe. Because of the increased magnetization gained by the hyperpolarization, the signal-to-noise ratio (S/N) should be on the order of the S/N of 1H imaging currently performed in medical applications. Inhaled Xe gas will diffuse throughout the body and provide an interesting compliment to 1H imaging. Xe's NMR properties (chemical shift, and relation times) vary over a large range in different biological environments thus allowing for interesting image contrast. Possible applications for spin-hyperpolarized 129Xe imaging include: lung airspace imaging; lung tissue imaging; cerebral blood flow measurements; protein tracer studies; and probing anesthetic action.
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