title: Confirmed swine-origin influenza A(H1N1) viral pneumonia: computed tomographic findings in the immunocompetent and the immunocompromised.
abstract: OBJECTIVE
  This study aimed to retrospectively evaluate the computed tomographic (CT) appearance of cases of swine-origin influenza A(H1N1) viral infection (S-OIV) in immunocompetent and immunocompromised patients confirmed with reverse transcription-polymerase chain reaction and to determine whether the timing of CT relative to the onset of symptoms affected the overall imaging appearance [corrected].
  
  
  METHODS
  A total of 23 patients (15 men and 8 women) from 2 tertiary care centers formed the final study population. Patients were divided into 2 groups based on their immune status: group 1 (n = 14) were patients who were immunocompromised, whereas group 2 (n = 9) were patients who were immunocompetent. The radiologic appearances of pulmonary abnormalities, distribution, and extent of involvement on the initial chest CT scan were documented, and correlation with the onset of symptoms was performed.
  
  
  RESULTS
  The most common CT pattern in both groups of S-OIV patients was ground-glass opacities and consolidation (group 1, 86%; group 2, 71%) in a bilateral, subpleural, and peribronchovascular pattern. Small airways disease [corrected] was seen only in a minority of patients (group 1, 7%; group 2, 11%. Onset of symptoms to time of CT showed a mean duration of 9.7 days in group 1 and 6.7 days in group 2 and did not affect the overall imaging appearance.
  
  
  CONCLUSIONS
  The most common abnormalities on CT scans of both immunocompetent and immunocompromised S-OIV patients were ground-glass opacities and consolidation in a bilateral, subpleural, and peribronchovascular distribution, resembling organizing pneumonia. This appearance was seen regardless of the timing of CT relative to the onset of symptoms.
authors.affiliation: Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada. chandler.tracy@gmail.com
authors.forename: Tracy M
authors.initials: TM
authors.lastname: Chandler
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
authors.forename: Savvas
authors.initials: S
authors.lastname: Nicolaou
authors.forename: Brendan
authors.initials: B
authors.lastname: Quiney
authors.forename: Marc
authors.initials: M
authors.lastname: Romney
authors.forename: Nestor L
authors.initials: NL
authors.lastname: Müller
authors.forename: Amr M
authors.initials: AM
authors.lastname: Ajlan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000821:virology*; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D011024:Pneumonia, Viral / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000821:virology*; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol