title: Large production system for hyperpolarized 129Xe for human lung imaging studies.
abstract: OBJECTIVE
  Hyperpolarized gases such as (129)Xe and (3)He have high potential as imaging agents for functional lung magnetic resonance imaging (MRI). We present new technology offering (129)Xe production rates with order-of-magnitude improvement over existing systems, to liter per hour at 50% polarization. Human lung imaging studies with xenon, initially limited by the modest quantity and quality of hyperpolarized gas available, can now be performed with multiliter quantities several times daily.
  
  
  METHODS
  The polarizer is a continuous-flow system capable of producing large quantities of highly-polarized (129)Xe through rubidium spin-exchange optical pumping. The low-pressure, high-velocity operating regime takes advantage of the enhancement in the spin exchange rate provided by van der Waals molecules dominating the atomic interactions. The long polarizing column moves the flow of the gas opposite to the laser direction, allowing efficient extraction of the laser light. Separate sections of the system assure full rubidium vapor saturation and removal.
  
  
  RESULTS
  The system is capable of producing 64% polarization at 0.3 L/hour Xe production rate. Increasing xenon flow reduces output polarization. Xenon polarization was studied as a function of different system operating parameters. A novel xenon trapping design was demonstrated to allow full recovery of the xenon polarization after the freeze-thaw cycle. Delivery methods of the gas to an offsite MRI facility were demonstrated in both frozen and gas states.
  
  
  CONCLUSIONS
  We demonstrated a new concept for producing large quantities of highly polarized xenon. The system is operating in an MRI facility producing liters of hyperpolarized gas for human lung imaging studies.
authors.affiliation: Department of Physics, University of New Hampshire, 131 Main Street, Nesmith Hall, Durham, NH 03824, USA. herman@unh.edu
authors.forename: F William
authors.initials: FW
authors.lastname: Hersman
authors.forename: Iulian C
authors.initials: IC
authors.lastname: Ruset
authors.forename: Stephen
authors.initials: S
authors.lastname: Ketel
authors.forename: Iga
authors.initials: I
authors.lastname: Muradian
authors.forename: Silviu D
authors.initials: SD
authors.lastname: Covrig
authors.forename: Jan
authors.initials: J
authors.lastname: Distelbrink
authors.forename: Walter
authors.initials: W
authors.lastname: Porter
authors.forename: David
authors.initials: D
authors.lastname: Watt
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Ketel
authors.forename: John
authors.initials: J
authors.lastname: Brackett
authors.forename: Aaron
authors.initials: A
authors.lastname: Hope
authors.forename: Samuel
authors.initials: S
authors.lastname: Patz
mesh_terms: D004867:Equipment Design; D006801:Humans; D007834:Lasers; D008171:Lung Diseases / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D055095:Optics and Photonics; D014979:Xenon Isotopes / Q000737:chemistry*
chemical_list: D014979:Xenon Isotopes