title: Hyperpolarized 129Xe phase-selective imaging of mouse lung at 9.4T using a continuous-flow hyperpolarizing system.
abstract: The use of hyperpolarized (HP) 129Xe magnetic resonance (MR) imaging to regionally evaluate gas diffusion and perfusion processes as well as ventilation in the lung has been expected. In this study, we used a continuous-flow hyperpolarizing (CF-HP) system to acquire gas- and dissolved-phase 129Xe images from mouse lung, employing standard gradient echo sequence equipped with chemical shift selective excitation and 90 degrees flip angle. The character of non-recoverable HP magnetization enabled the use of a phase (frequency)-selective 90 degrees pulse for direct visualization of only a given-phase 129Xe magnetization replenished into the slice during repetition time (TR). We combined gas- and dissolved-phase 129Xe images to map the ratio of dissolved- to gas-phase 129Xe replenished into the slice during TR (Mdissolved/Mgas) and found it to be approximately 0.05 to 0.08 in the peripheral regions of mouse lungs. This result suggested that replenishment of dissolved-phase 129Xe magnetization by gas diffusion and pulmonary perfusion would be faster than that of gas-phase by ventilation. The use of a CF-HP system that allows the application of relatively long TR to HP 129Xe imaging using a phase-selective 90 degrees pulse would be useful in evaluating gas transport mechanisms in the lung.
authors.affiliation: Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan. wakayama_tetsuya@yahoo.co.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Wakayama
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: D000280:Administration, Inhalation; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012680:Sensitivity and Specificity; D055672:Static Electricity; D014979:Xenon Isotopes / Q000008:administration & dosage*
chemical_list: D003287:Contrast Media; D014979:Xenon Isotopes