title: Reduction of pulmonary compliance found with high-resolution computed tomography in irradiated mice.
abstract: OBJECTIVE
  To demonstrate that high-resolution computed tomography (CT) can be used to quantify loss of pulmonary compliance in irradiated mice.
  
  
  METHODS
  Computed tomography images of three nonirradiated (controls) and three irradiated mice were obtained 200 days after a single dose of 16-Gy Co (60) thoracic irradiation. While intubated, each animal was imaged at static breath-hold pressures of 2, 10, and 18 cm H2O. A deformable image registration algorithm was used to calculate changes in air volume between adjacent-pressure CT image pairs (e.g., 2 and 10 cm H2O), and functional images of pulmonary compliance were generated. The mass-specific compliance was calculated as the change in volume divided by the pressure difference between the 2 image sets and the mass of lung tissue.
  
  
  RESULTS
  For the irradiated mice, the lung parenchyma mean CT values ranged from -314 (+/- 11) Hounsfield units (HU) to -378 (+/- 11) HU. For the control mice, the mean CT values ranged from -549 (+/- 11) HU to -633 (+/- 11) HU. Irradiated mice had a 60% (45, 74%; 95% confidence interval) lower mass-specific compliance than did the controls (0.039 [+/- 0.0038] vs. 0.106 [+/- 0.0038] mL air per cm H2O per g lung) from the 2-cm to 10-cm H2O CT image pair. The difference in compliance between groups was less pronounced at the higher distending pressures.
  
  
  CONCLUSIONS
  High-resolution CT was used to quantify a reduction in mass-specific compliance following whole lung irradiation in mice. This small animal radiation injury model and assay may be useful in the study of lung injury.
authors.affiliation: Division of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. tguerrero@mdanderson.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Guerrero
authors.forename: Richard
authors.initials: R
authors.lastname: Castillo
authors.forename: Josue
authors.initials: J
authors.lastname: Noyola-Martinez
authors.forename: Mylin
authors.initials: M
authors.lastname: Torres
authors.forename: Xinhui
authors.initials: X
authors.lastname: Zhou
authors.forename: Rudy
authors.initials: R
authors.lastname: Guerra
authors.forename: Dianna
authors.initials: D
authors.lastname: Cody
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Komaki
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Travis
mesh_terms: D000465:Algorithms; D000818:Animals; D016001:Confidence Intervals; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000528:radiation effects*; D008170:Lung Compliance / Q000528:radiation effects*; D051379:Mice; D011658:Pulmonary Fibrosis / Q000000981:diagnostic imaging; D013990:Tidal Volume; D014057:Tomography, X-Ray Computed / Q000379:methods*