Abstract:

Objective   To explore imaging characteristics of pneumonia secondary to influenza A (H1N1) virus infection. Methods   Chest X-ray films and CT images were retrospectively reviewed in 27 patients with pneumonia from influenza A (H1N1) virus infection confirmed by laboratory tests. Results   According to the involved area, imaging findings were divided into 3 types:  ① mild degree manifested as scattered ground-glass opacity (GGO) in 10 patients, ② moderate degree manifested as scattered patchy consolidation or nodes in 9 patients, 5 of whom with pleural effusion, ③ severe degree manifested as patchy consolidation with cavity, pleural effusion and compensating emphysema in 8 patients, of whom 2 with mycotic infection,  3 with bronchodilatation, 4 with subcutaneous and mediastinal emphysema. Six patients died of pneumonia-related respiratory failure, including 1 case of mild degree, 1 case of moderate degree and 4 cases of severe degree. Conclusion   Pneumonia secondary to influenza A (H1N1) virus infection presents as multi-segment involved GGO and consolidation. Cavity, broncho-dilatation, pleural effusion, subcutaneous emphysema and mycotic infection, which lead to poor prognosis, are found in severe patients.

Key words: H1N1; Pneumonia; Tomography, X-ray