title: Hyperpolarized 129 Xe MRI of the mouse lung at a low xenon concentration using a continuous flow-type hyperpolarizing system.
abstract: OBJECTIVE
  To apply a continuous flow-type hyperpolarizing (CF-HP) system to lung imaging and investigate the feasibility of hyperpolarized (129)Xe MRI at a low xenon concentration.
  
  
  METHODS
  Under two conditions where a 3% or 70% xenon gas mixture was constantly supplied, gas- and dissolved-phase (129)Xe images and diffusion-weighted (129)Xe-gas images were obtained from the mouse lung. Signal-to-noise ratio (SNR) of the (129)Xe images and the apparent diffusion coefficient (ADC) of xenon were compared between the two gas mixtures.
  
  
  RESULTS
  The SNR of gas- and dissolved-phase images were 28.9 +/- 5.2 and 12.0 +/- 2.0, respectively, using the 70% xenon gas mixture, while they were 22.9 +/- 4.8 and 6.8 +/- 0.6, using the 3% mixture. The ADC of xenon using the 3% xenon gas mixture was approximately 1.5 times higher than that using the 70% one. These results indicated that the high ADC increases the apparent replenishment rate of gas-phase magnetization, thus resulting in a reduction of the SNR loss induced by diluting xenon with quenching gases.
  
  
  CONCLUSIONS
  The CF-HP system is useful for lung imaging at an extremely low concentration of xenon, which enables one to fully restrain an anesthetic effect of xenon and to reduce consumption of xenon in a measurement.
authors.affiliation: Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan. waka@sahs.med.osaka-u.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Wakayama
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kitamoto
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ueyama
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Imai
authors.forename: Michiko
authors.initials: M
authors.lastname: Narazaki
authors.forename: Atsuomi
authors.initials: A
authors.lastname: Kimura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Fujiwara
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging; D005240:Feasibility Studies; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D019047:Phantoms, Imaging; D014979:Xenon Isotopes / Q000008:administration & dosage
chemical_list: D014979:Xenon Isotopes