title: High-resolution computed tomography findings of influenza virus pneumonia: a comparative study between seasonal and novel (H1N1) influenza virus pneumonia.
abstract: OBJECTIVE
  To evaluate the high-resolution computed tomography (HRCT) findings of novel influenza virus (n-IFV) pneumonia and compare them with the findings for seasonal (s-IFV) pneumonia.
  
  
  METHODS
  We evaluated 29 cases of pure IFV pneumonia that occurred between 1990 and 2010. We evaluated the existence, extent, and patterns of HRCT findings and compared these features between s-IFV and n-IFV.
  
  
  RESULTS
  Consolidation was less frequent in s-IFV than in n-IFV (40.0 vs. 84.2%, respectively; p = 0.014). Consolidation with a loss of volume was frequent in n-IFV (62.5%). There was no significant difference in the occurrence of ground-glass opacity (GGO) between s-IFV and n-IFV (100 vs. 84.2%, respectively). GGO with reticular opacities was more frequent in s-IFV than in n-IFV (70.0 vs. 25.0%, respectively; p = 0.024). The frequency of nodules was not significantly different between the two groups. The mosaic pattern was more frequent in s-IFV than in n-IFV patients (80.0 vs. 15.8%, respectively; p = 0.0007). Mucoid impaction was more frequent in patients with n-IFV than with s-IFV (52.6 vs. 10.0%, respectively; p = 0.025).
  
  
  CONCLUSIONS
  Consolidation and mucoid impaction were more frequent in n-IFV, whereas GGO with reticular opacities and a mosaic pattern occurred more frequently in s-IFV; otherwise, there were no significant differences between the two groups.
authors.affiliation: Department of Radiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan. nbtanaka@yamaguchi-u.ac.jp
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Tanaka
authors.forename: Takuya
authors.initials: T
authors.lastname: Emoto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Suda
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Kunihiro
authors.forename: Naofumi
authors.initials: N
authors.lastname: Matsunaga
authors.forename: Shunji
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Ichiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000000981:diagnostic imaging*; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011024:Pneumonia, Viral / Q000000981:diagnostic imaging* / Q000821:virology; D014057:Tomography, X-Ray Computed; D055815:Young Adult