title: Correlation of quantitative CT with selective alveolobronchogram and pulmonary function tests in emphysema.
abstract: BACKGROUND
  Emphysema diagnosed by computed tomography (CT) has been reported to be correlated with morphologic data from autopsied lungs or resected lobes. However, autopsied lungs or resected lobes are quite different from lungs in vivo. We examined the correlation between a quantitative analysis of CT and the in vivo morphologic degree of emphysema (selective alveolobronchography [SAB]) in patients with COPD.
  
  
  METHODS
  We measured the mean attenuation value (MAV) of the lung fields between -700 HU and -1,024 HU to exclude the effect of high-density structures in 21 patients with COPD. Low attenuation, greater than 2 SD below the mean value of five normal healthy subjects, was used as an index of emphysema. To quantitate the amount of emphysema, the relative area of low attenuation to the area of the entire lung field (2SD percent) was measured. The morphologic degree of emphysema was determined from the diameter of ring shadow (DR) of SAB. We also examined the relationship between CT data and pulmonary function tests.
  
  
  RESULTS
  The DR was highly correlated with the CT indexes of MAV and 2SD percent; (r = -0.894, p < 0.001, and r = 0.890, p < 0.001). Both MAV and 2SD percent were correlated with pulmonary function tests such as Dco, FEV1, and residual volume (r > 0.60).
  
  
  CONCLUSIONS
  The MAV and relative area of emphysema obtained from CT density measurements accurately assess the severity of emphysema in patients with COPD as well as SAB.
authors.affiliation: First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Watanuki
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Nishikawa
authors.forename: A
authors.initials: A
authors.lastname: Miyashita
authors.forename: T
authors.initials: T
authors.lastname: Okubo
mesh_terms: D000328:Adult; D000368:Aged; D001995:Bronchography / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D002908:Chronic Disease; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000175:diagnosis* / Q000453:epidemiology; D012129:Respiratory Function Tests / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data