Chest radiographs and CT

Early in the course of illness, chest radiographs show bilateral reticular opacities, commonly with Kerley B (septal) lines. There is rapid progression over hours or days to small nodules or areas of parenchymal consolidation with peripheral sparing. CT scans demonstrate bilateral areas of ground-glass attenuation, interlobular septal thickening, and parenchymal consolidation. Unilateral or bilateral pleural effusions are present at some point during the course of illness in all patients. The radiologic findings in AEP are similar to those of pulmonary edema, but other considerations in the radiologic differential diagnosis include diffuse alveolar damage (DAD), pulmonary hemorrhage, and viral or atypical bacterial pneumonia.