High Resolution Computerized Tomography Evaluation of Influenza H1N1 Infection

Background: H1N1 infection presents with features of predominantly bilateral pneumonia. The findings on plain chest radiograph (CXR) in these patients often fail to correlate with the extensive clinical findings. The study was carried out to bring to light the array of features that can be observed on a computerized tomography (CT) of the thorax. Results: Clinical profile of these patients matched the presentation of acute lower respiratory infection, and seven of ten patients had underlying risk factors such as diabetes, pregnancy, chronic obstructive lung disease and rheumatic valvular heart disease. In all ten patients, HRCT revealed greater number of findings. Lower zones were predominantly involved. Bilateral presentation was seen in eight cases. Consolidation (n = 7) and bilateral ground glass opacities (n = 3), constituted the most common findings. Pleural thickening ( n = 2), septal thickening (n = 2), air trapping (n = 2), mediastinal adenopathy (n = 1), pleural effusion (n = 1), sub-pleural nodules (n = 2) and organizing pneumonia (n = 1) were other notable observations. Chest radiograph (in comparison to HRCT), failed to reveal these heterogenous abnormalities. Conclusion: HRCT of thorax had greater co-relation with clinical findings in H1N1 infection than plain CXR.