High-resolution computed tomography findings of influenza virus pneumonia: A comparative study between seasonal and novel (H1N1) influenza virus pneumonia

Abstract

Purpose 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. Materials and 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. © 2011 Japan Radiological Society.