Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . Pulmonary vascularity is not engorged . There are linear bibasilar airspace opacities most compatible with subsegmental atelectasis or scarring . No focal consolidation , pleural effusion or pneumothorax is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Bibasilar subsegmental atelectasis versus scarring .