Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a subtle streaky opacity overlying the retrocardiac region which is likely representative of atelectasis . Otherwise , the remainder of the lungs are clear . Cardiomediastinal silhouette is normal . There is no evidence of pneumothorax or pleural effusions . No air is noted under the hemidiaphragms . There are no acute fractures . Mild spurring of the right Acromioclavicular joint is noted .
    OUTPUT:
    
Faint retrocardiac opacity which is likely representative of atelectasis , though given the history , an area of resolving infection is not excluded .