Computed tomographic manifestations of pulmonary aspergillosis after organ transplantation and differential diagnosis with bacterial infection

Objective To summarize the computed tomographic (CT) manifestations of pulmonary aspergillosis after organ transplantation and compare different signs between pulmonary aspergillosis and bacterial pneumonia. Methods CT images of pulmonary aspergillosis (n=62) and bacterial pneumonia (n=68) in post-transplantation patients were reviewed. The signs were categorized with consolidation, mass, large nodule (≥1cm), small nodule and bud-in-tree pattern. Some detailed useful differentiating signs such as halo sign, air bronchogram sign, reversed halo sign, hypodensity sign and cavitation were also analyzed. Results CT patterns of pulmonary aspergillosis included consolidation, mass, large nodule, small nodule and bud-in-tree pattern. The most common was large nodule (75.8%), followed by consolidation (48.4%) and mass (29.0%). And small nodule (16.1%) and bud-in-tree (12.9%) patterns were concurrent. For consolidation pattern, the proportion of bacterial pneumonia (69.1%) was the larger; For mass pattern, the proportion of pulmonary aspergillosis (29.0%) was the larger. For large nodule pattern, there was no difference. The detail sign of large nodule in two groups had no difference. In detailed signs of consolidation pattern, air bronchogram sign was more often seen in bacterial pneumonia while cavitation was more frequently found in pulmonary aspergillosis. In detailed signs of mass pattern, pulmonary aspergillosis often has single lesion (66.7%), cavitation (83.3%)and air crescent sign (77.8%) is more common. The proportion of halo sign was 30.7%. Conclusions CT manifestations of pulmonary aspergillosis are diverse after organ transplantation. There is some difference and yet overlap with bacterial pneumonia. Key words: Organ transplantation; Pulmonary aspergillosis; Computer tomography