Thoracic CT scan findings in 2009 Influenza A (H1N1) virus pandemic in Isfahan

Pandemic 2009 H1N1 influenza A virus arrived to Isfahan in August, 2009. The virus is still circulating in the world. The abnormal thoracic computerized tomographic (CT) scan findings vary widely among the studies of 2009 H1N1 influenza. We evaluated the thoracic CT findings in patients with 2009 H1N1 virus infection to describe findings compared to previously reported findings, and to suggest patterns that may be suggestive of 2009 influenza A (H1N1) in the appropriate clinical setting. We retrospectively reviewed the archive of all patients with the diagnosis of 2009 H1N1 influenza A, in Alzahra hospital in Isfahan, central Iran, between September 23, 2009 to February 20, 2010. From 216 patients with confirmed 2009 influenza A (H1N1), 26 cases with abnormal CT scan were enrolled the study. Radiologic findings were characterized by type and pattern of opacities and zonal distribution. Patchy infiltration (34.6%), lobar consolidation (30.8%), and interstitial infiltration (26.9%) with airbronchogram (38.5%) were the predominant findings in our patients. Bilateral distribution was seen in 80.8% of patients. Only one patient (3.8%) showed ground-glass opacity, the predominant radiographic finding in the previous reports, and severe acute respiratory syndrome (SARS). The most common thoracic CT findings in pandemic H1N1 were Patchy infiltration, lobar consolidation, and interstitial infiltration with airbronchogram and bilateral distribution. While these findings can be associated with other infections, they may be suggestive of 2009 influenza A (H1N1) in the appropriate clinical setting. Various radiographic patterns can be seen in thoracic CT scans of the influenza patients. Imaging findings are nonspecific.