Polarized Xe129 optical pumping/spin exchange and delivery system for magnetic resonance spectroscopy and imaging studies

Abstract

We describe the design and construction of a laser-polarized Xe129 production and delivery system that is used in our in vitro and in vivo magnetic resonance imaging (MRI) experiments. The entire apparatus including lasers and optics, rapidly actuated valves, heating and cooling, and transport tubing lies in the high magnetic field environment of a 2 T MRI magnet. With approximately 7.5% Xe129 polarization, 157 cc atm of xenon gas is produced and stored as xenon ice every 5 min. Large quantities of polarized Xe129 can be obtained by cycling this process. The xenon is subsequently delivered in a controlled fashion to a sample or subject. With this device we have established the feasibility of using laser-polarized Xe129 as a magnetic tracer in MRI. This reliable, effective, and relatively simple production method for large volumes of Xe129 can be applied to other areas of research involving the use of laser-polarized noble gases.