title: CT quantification of emphysema in young subjects with no recognizable chest disease.
abstract: OBJECTIVE
  The purpose of this prospective study was to evaluate volumetric CT emphysema quantification (CT densitovolumetry) in a young population with no recognizable lung disease.
  
  
  METHODS
  A cohort of 30 nonsmoking patients with no recognizable lung disease (16 men, 14 women; age range, 19-41 years) underwent inspiratory and expiratory CT, after which the data were postprocessed for volumetric quantification of emphysema (threshold, -950 HU). Correlation was tested for age, weight, height, sex, body surface area (BSA), and physical activity. Normal limits were established by mean +/- 1.96 SD.
  
  
  RESULTS
  No correlation was found between the measured volumes and age or physical activity. Correlation was found between BSA and normal lung volume in inspiration (r = 0.69, p = 0.000), shrink volume (i.e., difference in total lung volume in inspiration and in expiration) (r = 0.66, p = 0.000), and percentage of shrink volume (r = 0.35, p = 0.05). For an alpha error of 5%, the limits of normality based on this sample are percentage of emphysema in inspiration, 0.35%; percentage of emphysema in expiration, 0.12%; and maximum lung volume in expiration, 3.6 L. The maximum predicted percentage of shrink volume can be calculated as %SV = 29.43% + 16.97% x BSA (+/- 1.96 x 7.61%).
  
  
  CONCLUSIONS
  Young healthy nonsmokers with no recognizable lung disease can also show a small proportion of emphysematous-like changes on CT densitovolumetry when a threshold of -950 HU is used. Reference values should be considered when applying the technique for early detection or grading of emphysema and when studying aging lungs.
authors.affiliation: Department of Radiology, Liverpool Heart and Chest Hospital, NHS Trust, Thomas Dr., Liverpool L143PE, United Kingdom. klaus.irion@lhch.nhs.uk
authors.forename: Klaus Loureiro
authors.initials: KL
authors.lastname: Irion
authors.forename: Edson
authors.initials: E
authors.lastname: Marchiori
authors.forename: Bruno
authors.initials: B
authors.lastname: Hochhegger
authors.forename: Nelson da Silva
authors.initials: Nda S
authors.lastname: Porto
authors.forename: Jose da Silva
authors.initials: Jda S
authors.lastname: Moreira
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Anselmi
authors.forename: John Allen
authors.initials: JA
authors.lastname: Holemans
authors.forename: Paulo Oliveira
authors.initials: PO
authors.lastname: Irion
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging*; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*