Follow-up Aspects of Influenza A (H1N1) Virus-Associated Pneumonia: the Role of High-Resolution Computed Tomography in the Evaluation of the Recovery Phase

The first patient showed ill-defined ground-glass opacity nodules and patchy areas of ground-glass attenuation. The second, with secondary bacterial pneumonia, showed bilateral areas of lobar consolidation and ground-glass opacities. The predominant HRCT findings reported bilateral, peripheral, ground-glass opacities and/or bilateral areas of consolidation. The patients who presented with consolidations had a more severe clinical course. Limited data are available, however, on the tomographic or pathological aspects observed during the recovery phase after H1N1 infection. During the treatment and recovery phases, persistent opacities on radiographs may not be informative enough to distinguish disease progression from healing. HRCT may play a role in the detection and characterization of the disease, in monitoring the disease progress and response to treatment, as well as in the identification of complications. In conclusion, although pulmonary opacities secondary to H1N1 infection usually regress during convalescence, the consolidations may occasionally progress to linear opacities (parenchymal bands). These linear opacities probably represent organizing pneumonia.