title: A trial to measure local lung volume changes during respiration with CT.
abstract: OBJECTIVE
  To evaluate changes in volume and the CT attenuation value of the pulmonary lobes and peripheral small lung tissue at full inspiration and expiration.
  
  
  METHODS
  We designated (1000+CT insp)/(1000+CT exp)(1000+CT insp)/(1000+CT exp) as CT volume ratio, a new parameter to represent volume changes in lung tissue, and V insp/V exp as actual volume ratio: CT insp, exp: CT attenuation value of measured lung at inspiration and expiration; V insp, exp: actual lung volume measured with CT at inspiration and expiration. Ten normal healthy volunteers were investigated with 5 mm collimation CT in the supine position.
  
  
  RESULTS
  The CT volume ratio and actual volume ratio of each lung lobe were well correlated. The CT volume ratios of small lung tissues were significantly larger in the dependent region than in the nondependent region when measured in the supine position at five levels, except at the level of the aortic arch (P<0.05).
  
  
  CONCLUSIONS
  We advocated a new parameter (CT volume ratio) for representing lung tissue volume changes during respiration. The CT volume ratio might be a new noninvasive method to measure local volume changes in lung during respiration.
authors.affiliation: Department of Radiology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Fujimura
authors.forename: Fumikazu
authors.initials: F
authors.lastname: Sakai
authors.forename: Kaori
authors.initials: K
authors.lastname: Fujimura
authors.forename: Norio
authors.initials: N
authors.lastname: Mitsuhashi
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D012119:Respiration; D012143:Respiratory Physiological Phenomena; D014057:Tomography, X-Ray Computed / Q000379:methods*