title: Pneumonia in novel swine-origin influenza A (H1N1) virus infection: high-resolution CT findings.
abstract: OBJECTIVE
  The purpose of our study was to review the initial high-resolution CT (HRCT) findings in pneumonia patients with presumed/laboratory-confirmed novel swine-origin influenza A (H1N1) virus (S-OIV) infection and detect pneumonia earlier.
  
  
  METHODS
  High-resolution CT (HRCT) findings of 106 patients with presumed/laboratory-confirmed novel S-OIV (H1N1) infection were reviewed. The 106 patients were divided into two groups according to the serious condition of the diseases. The pattern (consolidation, ground-glass, nodules, and reticulation), distribution, and extent of abnormality on the HRCT were evaluated in both groups. The dates of the onset of symptoms of the patients were recorded.
  
  
  RESULTS
  The predominant CT findings in the patients at presentation were unilateral or bilateral multifocal asymmetric ground-glass opacities alone (n=29, 27.4%), with unilateral or bilateral consolidation (n=50, 47.2%). The consolidation had peribronchovascular and subpleural predominance. The areas of consolidation were found mainly in the posterior, middle and lower regions of the lungs. Reticular opacities were found in 6 cases of the initial MDCT scan. The extent of disease was greater in group 1 patients requiring advanced mechanical ventilation, with diffuse involvement in 19 patients (63.3%) of group 1 patients, and only 15/76 (19.7%) of group 2 patients (p<0.01, χ2 test). 20 cases (19%) of the 106 patients had small bilateral or unilateral pleural effusions. None had evidence of hilar or mediastinal lymph node enlargement on CT performed at admission or later.
  
  
  CONCLUSIONS
  The most common radiographic and CT findings in patients with S-OIV infection are unilateral or bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. On HRCT, the ground-glass opacities had a predominant peribronchovascular and subpleural distribution. CT plays an important role in the early recognition of severe S-OIV (H1N1).
authors.affiliation: Department of Radiology, The Second Affiliated Hospital of Harbin Medical University, 246 Xue Fu Road, Harbin 150086, China. pinglee_2000@yahoo.com
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Su
authors.forename: Ji-Feng
authors.initials: JF
authors.lastname: Zhang
authors.forename: Xu-Dong
authors.initials: XD
authors.lastname: Xia
authors.forename: Hong
authors.initials: H
authors.lastname: Sui
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000000981:diagnostic imaging* / Q000821:virology*; D008297:Male; D008875:Middle Aged; D011024:Pneumonia, Viral / Q000000981:diagnostic imaging* / Q000821:virology*; D014057:Tomography, X-Ray Computed / Q000379:methods*