title: Focal air trapping in patients with HIV infection: CT evaluation and correlation with pulmonary function test results.
abstract: OBJECTIVE
  HIV-positive individuals commonly have symptoms of airway disease. We evaluated thin-section CT scans of HIV-infected individuals during inspiration and expiration for evidence of focal air trapping. We also correlated imaging findings with pulmonary function test results.
  
  
  METHODS
  Fifty-nine subjects, 48 of whom were HIV-positive and 11 of whom were HIV-negative, underwent thin-section CT of the thorax during inspiration and expiration. All subjects also underwent pulmonary function tests. Two radiologists, who were unaware of the subjects' HIV status and smoking history and of the results of pulmonary function tests, evaluated the CT scans for the presence and severity of focal air trapping.
  
  
  RESULTS
  Expiratory CT revealed focal air trapping in 33 subjects: 30 were HIV-positive and three were HIV-negative (p = .0338). The mean values of forced expiratory volume in 1 sec (FEV1), forced mid expiratory flow, and diffusion capacity (DL(CO)) were significantly lower for subjects with focal air trapping (mean = 88.85, 84.52, and 80.80, respectively) than for those with normal findings on CT (mean = 100.84, 99.24, and 95.82, respectively; p = .001, p = .021, and p = .003, respectively). We found no significant differences in smoking history between HIV-positive and HIV-negative subjects. Severe air trapping on expiratory CT scans was seen in three subjects: All three had HIV infection, low CD4 counts, and abnormally decreased FEV1 and DL(CO) values.
  
  
  CONCLUSIONS
  Focal air trapping was a common finding on thoracic CT scans obtained during expiration in HIV-positive subjects. In addition, focal air trapping was associated with significantly lower FEV1, forced mid expiratory flow, and DL(CO) values than those found for subjects in whom CT revealed no focal air trapping. These results suggest that small airways disease may accompany a decline in pulmonary function in HIV-positive individuals.
authors.affiliation: Department of Radiology, The Ohio State University Medical Center, Columbus 43210, USA.
authors.forename: M
authors.initials: M
authors.lastname: Gelman
authors.forename: M A
authors.initials: MA
authors.lastname: King
authors.forename: D E
authors.initials: DE
authors.lastname: Neal
authors.forename: E R
authors.initials: ER
authors.lastname: Pacht
authors.forename: T L
authors.initials: TL
authors.lastname: Clanton
authors.forename: P T
authors.initials: PT
authors.lastname: Diaz
mesh_terms: D000328:Adult; D005260:Female; D005541:Forced Expiratory Volume; D015658:HIV Infections / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D011653:Pulmonary Diffusing Capacity; D015656:Respiratory Mechanics; D014057:Tomography, X-Ray Computed