Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Biapical pleural scarring is noted . There is a subtle retrocardiac airspace opacity , best appreciated on the lateral radiograph . Trace left pleural effusion with adjacent atelectasis is noted . The lungs are otherwise grossly clear without evidence of pneumothorax or overt pulmonary edema . The heart is normal in size . Calcifications are seen within the aortic knob .
    OUTPUT:
    
1 . Subtle , retrocardiac airspace opacity which may represent pneumonia in the appropriate clinical setting . 2 . Trace left pleural effusion with adjacent atelectasis .