title: High-resolution computed tomography features in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  In recent years, there has been increasing interest in diagnosing various components of chronic obstructive pulmonary disease (COPD) using high-resolution computed tomography (HRCT). The present study was undertaken to evaluate HRCT features in patients with COPD.
  
  
  METHODS
  40 male patients with COPD (age 40 years or older) and with a significant smoking history (20 pack-years or more) were included in the study. They were evaluated for HRCT features including vascular attenuation and distortion, mosaic attenuation pattern, directly visible small airways, low attenuation areas of emphysema and measures of hyperinflation of the lungs: tracheal index, sterno-aortic distance, thoracic cage ratio and thoracic cross-sectional area.
  
  
  RESULTS
  The tracheal index ranged from 0.46 to 0.94; Saber-sheath trachea was found in 14 patients. The mean thoracic cage ratio at two levels, carina and 5 cm below carina, were 0.69 (range 0.61-0.78) and 0.73 (range 0.62-0.83), respectively. Sterno-aortic distance at carinal level ranged from 1.43 to 4.55 cm, with a mean of 3.00 cm. Directly visible small airways was the commonest finding (36 patients), followed by vascular attenuation (25 patients), mosaic attenuation pattern (16 patients) and vascular distortion (8 patients). Among various subtypes of emphysema, centriacinar emphysema was commonest (16 patients), followed by paraseptal (13) and panacinar emphysema (11).
  
  
  CONCLUSIONS
  There are certain specific HRCT features of emphysema and it is possible on HRCT to identify the subtypes of emphysema, such as centriacinar, panacinar and paraseptal emphysema. Various features of hyperinflation can also be well identified and quantified on HRCT.
authors.affiliation: Department of Respiratory Medicine, Postgraduate Institute of Medical Sciences, 9J/17 Medical Enclave, Rohtak 124001, India. gparkas@yahoo.co.in
authors.forename: P P
authors.initials: PP
authors.lastname: Gupta
authors.forename: R
authors.initials: R
authors.lastname: Yadav
authors.forename: M
authors.initials: M
authors.lastname: Verma
authors.forename: K B
authors.initials: KB
authors.lastname: Gupta
authors.forename: Dn
authors.initials: D
authors.lastname: Agarwal
mesh_terms: D000368:Aged; D001991:Bronchitis / Q000175:diagnosis / Q000000981:diagnostic imaging; D002908:Chronic Disease; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*