title: Repeated low-dose computed tomography in current and former smokers for quantification of emphysema.
abstract: OBJECTIVE
  To quantify different emphysema evolution in current and former smokers.
  
  
  METHODS
  We retrospectively analyzed low-dose computed tomography scans from a lung cancer screening study of 59 current and 75 former smokers. The quantitative emphysema analysis was performed using a home-built software (YACTA version 0.9), yielding the parameters lung volume, emphysema volume (EV), emphysema index (EI), mean lung density, and 15th percentile.
  
  
  RESULTS
  The baseline EV and EI were significantly different (median EVformer =422 mL vs EVcurrent =249 mL, P = 0.0003; and median EIformer =7.6 % vs EIcurrent =4.1 %, P = 0.0001, respectively). On the annual repeat scan, the median EI and EV for former smokers had decreased significantly (ΔEIformer = -0.257%, P = 0.004; and ΔEVcurrent = -0.203 mL, P = 0.020), whereas there was no emphysema change in current smokers.
  
  
  CONCLUSIONS
  We were able to demonstrate different emphysema evolution in current versus former smokers; emphysema parameters decreased in the former smokers and remained stable in current smokers.
authors.affiliation: Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: McGregor
authors.forename: Heidi C
authors.initials: HC
authors.lastname: Roberts
authors.forename: Zhi
authors.initials: Z
authors.lastname: Dong
authors.forename: Ravi
authors.initials: R
authors.lastname: Menezes
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Oliver
authors.initials: O
authors.lastname: Weinheimer
authors.forename: Claus Peter
authors.initials: CP
authors.lastname: Heussel
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000473:pathology; D011829:Radiation Dosage; D012189:Retrospective Studies; D012907:Smoking; D012984:Software; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*