title: The effects of dynamic hyperinflation on CT emphysema measurements in patients with COPD.
abstract: OBJECTIVE
  Dynamic hyperinflation (DH) significantly affects dyspnea and intolerance to exercise in patients with chronic obstructive pulmonary disease (COPD). Quantitative computed tomography (QCT) of the chest is the modality of choice for quantification of the extent of anatomical lung damage in patients with COPD. The purpose of this article is to assess the effects of DH on QCT measurements.
  
  
  METHODS
  The study sample comprised patients with Global initiative for Chronic Obstructive Lung Disease (GOLD) stages III and IV COPD referred for chest CT. We examined differences in total lung volume (TLV), emphysema volume (EV), and emphysema index (EI) determined by QCT before and after DH induction by metronome-paced tachypnea (MPT). Initial (resting) and post-MPT CT examinations were performed with the same parameters.
  
  
  RESULTS
  Images from 66 CT scans (33 patients) were evaluated. EV and EI, but not TLV, increased significantly (p<0.0001) after DH induction.
  
  
  CONCLUSIONS
  QCT showed significant increases in EV and EI after MPT-induced DH in patients with GOLD stages III and IV COPD. For longitudinal assessment of patients with COPD using QCT, we recommend the application of a pre-examination rest period, as DH could mimic disease progression. QCT studies of the effects of DH-preventive therapy before exercise could expand our knowledge of effective measures to delay DH-related progression of COPD.
authors.affiliation: Post-graduation Program in Medicine (Radiology), Federal University of Rio de Janeiro, Brazil. Electronic address: grtalves@gmail.com.
authors.forename: Giordano Rafael Tronco
authors.initials: GRT
authors.lastname: Alves
authors.affiliation: Post-graduation Program in Medicine (Radiology), Federal University of Rio de Janeiro, Brazil.
authors.forename: Edson
authors.initials: E
authors.lastname: Marchiori
authors.affiliation: Radiology Department, Liverpool Heart and Chest Hospital, United Kingdom.
authors.forename: Klaus Loureiro
authors.initials: KL
authors.lastname: Irion
authors.affiliation: Pulmonology Department, Federal University of Health Sciences of Porto Alegre, Brazil.
authors.forename: Paulo José Zimmerman
authors.initials: PJZ
authors.lastname: Teixeira
authors.affiliation: Pulmonology Department, Federal University of Rio Grande do Sul, Brazil.
authors.forename: Danilo Cortozi
authors.initials: DC
authors.lastname: Berton
authors.affiliation: Pulmonology Department, Federal University of Health Sciences of Porto Alegre, Brazil.
authors.forename: Adalberto Sperb
authors.initials: AS
authors.lastname: Rubin
authors.affiliation: Post-graduation Program in Medicine (Radiology), Federal University of Rio de Janeiro, Brazil.
authors.forename: Bruno
authors.initials: B
authors.lastname: Hochhegger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000503:physiopathology; D059246:Tachypnea / Q000000981:diagnostic imaging
keywords: Chronic obstructive pulmonary disease; Computed tomography; Lung