title: Regional fractional ventilation mapping in spontaneously breathing mice using hyperpolarized ¹²⁹Xe MRI.
abstract: The feasibility of ventilation imaging with hyperpolarized (HP) (129) Xe MRI has been investigated for quantitative and regional assessment of ventilation in spontaneously breathing mice. The multiple breath ventilation imaging technique was modified to the protocol of spontaneous inhalation of HP (129) Xe delivered continuously from a (129) Xe polarizer. A series of (129) Xe ventilation images was obtained by varying the number of breaths before the (129) Xe lung imaging. The fractional ventilation, r, was successfully evaluated for spontaneously breathing mice. An attempt was made to detect ventilation dysfunction in the emphysematous mouse lung induced by intratracheal administration of porcine pancreatic elastase (PPE). As a result, the distribution of fractional ventilation could be visualized by the r map. Significant dysfunction of ventilation was quantitatively identified in the PPE-treated group. The whole-lung r value of 0.34 ± 0.01 for control mice (N = 4) was significantly reduced, to 0.25 ± 0.07, in PPE-treated mice (N = 4) (p = 0.038). This study is the first application of multiple breath ventilation imaging to spontaneously breathing mice, and shows that this methodology is sensitive to differences in the pulmonary ventilation. This methodology is expected to improve simplicity as well as noninvasiveness when assessing regional ventilation in small rodents.
authors.affiliation: Department of Medical Physics and Engineering, Division of Health Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; Division of Systems Informatics, Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Imai
authors.forename: Hironobu
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Erika
authors.initials: E
authors.lastname: Miyakoshi
authors.forename: Shintaro
authors.initials: S
authors.lastname: Okumura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Atsuomi
authors.initials: A
authors.lastname: Kimura
mesh_terms: D000818:Animals; D008168:Lung / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008810:Mice, Inbred C57BL; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration; D012815:Signal Processing, Computer-Assisted; D014979:Xenon Isotopes
chemical_list: D014979:Xenon Isotopes
keywords: fractional ventilation; hyperpolarized gas; lung MRI; xenon