Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . There is no pleural effusion or pneumothorax . There is a streaky retrocardiac opacity , which is is likely explained by minor atelectasis . Bony structures are unremarkable .
    OUTPUT:
    
Streaky retrocardiac opacity , probably attributable to atelectasis , but if pulmonary symptoms are present , short - term follow - up radiographs may be helpful if needed .