title: Pulmonary emphysema: subjective visual grading versus objective quantification with macroscopic morphometry and thin-section CT densitometry.
abstract: OBJECTIVE
  To compare subjective visual grading of pulmonary emphysema with macroscopic morphometry and computed tomographic (CT) densitometry.
  
  
  METHODS
  In 62 consecutive patients who underwent thinsection CT before surgical lung resection, emphysema was objectively quantified with computer-assisted macroscopic morphometry and CT densitometry. The percentage of lung macroscopically occupied by emphysema was compared with the percentage occupied on CT scans by pixels with attenuation values lower than a predefined threshold (CT densitometry). Three readers with varying degrees of expertise subjectively graded emphysema with visual assessment at two reading sessions. Data from objective quantification and subjective grading were analyzed with correlation coefficients, and interobserver and intraobserver agreement were calculated.
  
  
  RESULTS
  Subjective grading of emphysema showed less agreement with the macroscopic reference standard results (r = 0.439-0.505; P < .05) than with objective CT densitometric results (r = 0.555-0.623; P < .001). The 95% CIs for the intercepts of the linear regression lines were suggestive of systematic subjective overestimation of emphysema by all three readers. Interobserver agreement was moderate (kappa = 0.431-0.589). Intraobserver agreement was good to excellent (kappa = 0.738-0.936). The expertise of individual readers did not substantially influence results.
  
  
  CONCLUSIONS
  Systematic overestimation and moderate interobserver agreement may compromise subjective visual grading of emphysema, which suggests that subjective visual grading should be supplemented with objective methods to achieve precise, reader-independent quantification of emphysema.
authors.affiliation: Department of Radiology, University of Vienna, Austria.
authors.forename: A A
authors.initials: AA
authors.lastname: Bankier
authors.forename: V
authors.initials: V
authors.lastname: De Maertelaer
authors.forename: C
authors.initials: C
authors.lastname: Keyzer
authors.forename: P A
authors.initials: PA
authors.lastname: Gevenois
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000473:pathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed