title: Direct imaging of hyperpolarized 129Xe alveolar gas uptake in a mouse model of emphysema.
abstract: MRI of hyperpolarized (129)Xe dissolved in pulmonary tissues, and blood has the potential to offer a new tool for regional evaluation of pulmonary gas exchange and perfusion; however, the extremely short T2* and low magnetization density make it difficult to acquire the image. In this study, an ultrashort echo-time sequence was introduced, and its feasibility to quantitatively assess emphysema-like pulmonary tissue destruction by a combination of dissolved- and gas-phase (129)Xe lung MRI was investigated. The ultrashort echo-time has made it possible to acquire dissolved (129)Xe images with reasonably high spatial resolution of 0.625 × 0.625 mm(2) and to obtain T2* of 0.67 ± 0.30 ms in a spontaneously breathing mouse at 9.4 T. The regional dynamic alveolar gas uptake as well as subsequent transport by pulmonary blood flow was also visualized. The ratio of (129)Xe magnetization that diffused into the septa relative to the gas-phase magnetization F was regionally evaluated. The mean F value of elastase-treated mice was 2.28 ± 0.46%, which was significantly reduced from that of control mice 3.41 ± 0.48% (P = 0.0052). This reflects the reduced uptake efficiency due to alveolar tissue destruction and is correlated with the histologically derived alveolar surface-to-volume ratio.
authors.affiliation: Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iguchi
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Imai
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hori
authors.forename: Junichi
authors.initials: J
authors.lastname: Nakajima
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; D004646:Emphysema / Q000378:metabolism* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008815:Mice, Inbred Strains; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014979:Xenon Isotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D003287:Contrast Media; D014979:Xenon Isotopes