Chest imaging of H7N9 subtype of human avian influenza

Human infection with avian influenza A H7N9 virus is an acute respiratory infectious disease, which usually causes severe pneumonia with a high mortality. Chest radiographs and Computed Tomography (CT) are principal radiological modalities to assess the lung abnormalities.

The goal of this study was to investigate the chest images characteristic of H7N9 subtype of human avian influenza.

The clinical and imaging data of 11 cases diagnosed as H7N9 subtype of human avian influenza were collected from 4 cities in the southern region of the Yangtze River, China. The chest imaging manifestations were analyzed by the assigned expert group. The analyzed cases include 7 males and 4 females aged from 20 to 84 years, with a mean of 55.6 years. The clinical symptoms were mainly fever (100%, 11/11) and cough (72.7%, 8/11).

Segmental or lobar ground-glass opacity (GGO) or consolidation was shown in 8 cases (72.7% or 8/11). Air bronchogram was found in 7 cases (63.6% or 7/11). The lesions developed into multiple or diffuse in both lungs rapidly at the progressive stage. The reticulation shadows were shown after some lesions absorbed at the stable stage.

The characteristic imaging demonstrations of H7N9 subtype of human avian influenza are segmental or lobar exudative lesions at lungs at the initial stage, which rapidly progress into bilateral distribution at lungs at the progressive stage.