Gas Flow MRI Using Circulating Laser-Polarized129Xe

✍ Scribed by E. Brunner; M. Haake; L. Kaiser; A. Pines; J.A. Reimer

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 227 KB
• Volume: 138
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1998.1675

✦ Synopsis

We describe an experimental approach that combines multidimensional NMR experiments with a steadily renewed source of laser-polarized 129 Xe. Using a continuous flow system to circulate the gas mixture, gas phase NMR signals of laser-polarized 129 Xe can be observed with an enhancement of three to four orders of magnitude compared to the equilibrium 129 Xe NMR signal. Due to the fact that the gas flow recovers the nonequilibrium 129 Xe nuclear spin polarization in 0.2 to 4 s, signal accumulation on the time scale of seconds is feasible, allowing previously inaccessible phase cycling and signal manipulation. Several possible applications of MRI of laser-polarized 129 Xe under continuous flow conditions are presented here. The spin density images of capillary tubes demonstrate the feasibility of imaging under continuous flow. Dynamic displacement profiles, measured by a pulsed gradient spin echo experiment, show entry flow properties of the gas passing through a constriction under laminar flow conditions. Further, dynamic displacement profiles of 129 Xe, flowing through polyurethane foams with different densities and pore sizes, are presented.