title: Low-dose volumetric computed tomography for quantification of emphysema in asymptomatic smokers participating in an early lung cancer detection trial.
abstract: OBJECTIVE
  High-resolution computed tomography (CT) is a validated method to quantify the extent of pulmonary emphysema. In this study, we assessed the reliability of low-dose volumetric CT (LDCT) for the quantification of emphysema and its correlation with spirometric indices of airway obstruction.
  
  
  METHODS
  The study population consisted of 102 consecutive current and former smokers participating in a lung cancer screening trial. All subjects underwent spirometry testing and LDCT at entry and a LDCT after 12 months. The extent of emphysema was estimated by 2 techniques; by using the lung attenuation threshold analysis and by visual assessment of the 2 independent radiologists. The reproducibility of these determinations was assessed using test-retest reliability and kappa coefficient of agreement. The correlation of LDCT-based emphysema determinations with indices of airway obstruction on spirometry was also calculated.
  
  
  RESULTS
  Eighty percent of the participants were male, with a mean (standard deviation) age of 54.5 (7.5) years, and median pack-years (interquartile range) of 20 (24). Test-retest reliability of all LDCT-based emphysema determinations was very good (intraclass correlation coefficient of 0.92 for the volume of emphysema, and 0.93 for the emphysema index or emphysema volume/total lung volume). Similarly, there was an excellent interrater agreement for visual assessment of emphysema (kappa coefficient=0.91). Higher volumes of emphysema measured quantitatively or visually significantly correlated with spirometric markers of airway obstruction.
  
  
  CONCLUSIONS
  Volumetric LDCT is a reliable and valid technique for the quantification of emphysema in asymptomatic smokers.
authors.affiliation: Department of Radiology, University of Navarra, Pamplona, Spain. bastarrika@unav.es
authors.forename: Gorka
authors.initials: G
authors.lastname: Bastarrika
authors.forename: Juan P
authors.initials: JP
authors.lastname: Wisnivesky
authors.forename: Jesús C
authors.initials: JC
authors.lastname: Pueyo
authors.forename: Lourdes
authors.initials: L
authors.lastname: Díaz
authors.forename: María
authors.initials: M
authors.lastname: Arraiza
authors.forename: Alberto
authors.initials: A
authors.lastname: Villanueva
authors.forename: Ana B
authors.initials: AB
authors.lastname: Alcaide
authors.forename: Arantza
authors.initials: A
authors.lastname: Campo
authors.forename: Luis
authors.initials: L
authors.lastname: Seijo
authors.forename: Juan P
authors.initials: JP
authors.lastname: de Torres
authors.forename: Javier J
authors.initials: JJ
authors.lastname: Zulueta
mesh_terms: D055088:Early Detection of Cancer; D004646:Emphysema / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*