Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Normal heart size , mediastinal and hilar contours . Lung volumes are low . There is tortuosity of the thoracic aorta . Bibasilar opacities worse on the left than the right may reflect atelectasis in the setting of low lung volumes although superimposed infection is possible . No pleural effusion or pneumothorax . No free intraperitoneal air .
    OUTPUT:
    
Bibasilar opacities may reflect atelectasis , however superimposed pneumonia is possible .