Longitudinal changes of pneumonia complicating novel influenza A (H1N1) by high-resolution computed tomography

To assess lung lesions in patients with pneumonia complicating novel influenza A (H1N1) by serial high-resolution computed tomography (HRCT) during the early, progressive and convalescent stages.

Serial HRCT scans in 39 patients with pneumonia complicating novel influenza A (H1N1) were reviewed for predominant patterns of lung abnormalities as well as distribution and extent of involvement. Longitudinal changes were assessed at different time points.

In the early stage, the most common HRCT finding was patchy ground-glass opacity (GGO) (n = 4, 54.7%). In the progressive stage, bilaterally distributed GGO mixed with consolidation was the most commonly observed feature (n = 28, 71.8%). The diffuse pattern deteriorated to a peak (n = 17, 43.6%) at this stage. In the convalescent stage, the most common finding was fibrosis (n = 25, 64.1%). Averagely, fibrosis was observed at d 18.5 ± 6.4 after the onset of symptoms. Three patterns of longitudinal changes of the lesions were observed, including: type 1, improvement after deterioration; type 2, concurrent improvement and deterioration followed by improvement; and type 3, gradual improvement. Type 1 was the more common pattern (n = 27, 69.2%). Complete serial HRCT scans from initial and final scan were obtained in 24 patients, and the mean CT score peaked at d 8-14 of the illness.

HRCT may play a role in detecting and characterizing pulmonary lesions for the cases of pneumonia complicating influenza A. In addition, it may contribute to monitoring longitudinal changes of pneumonia and assessing therapeutic response.