NMR OF LASER-POLARIZED XENON IN HUMAN BLOOD

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude, The enhanced polarization has allowed advances in nucle ar magnetic resonance (NMR) spectroscopy and magnetic resonance imagin g (MRI), including polarization transfer to molecules and imaging of l ungs and other void spaces, A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization , Described herein is an efficient method for the introduction of lase r-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR/MRI signals. Using this m ethod, we have made the first observation of the time-resolved process of xenon penetrating the red blood cells in fresh human blood-the xen on residence time constant in the red blood cells was measured to be 2 0.4+/-2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR/MRI is discus sed in light of their respective relaxation and partitioning propertie s.