Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There streaky retrocardiac opacity which is similar compared to prior . There is also the subtle increased opacity projecting in the retrocardiac region on the lateral view . Elsewhere , lungs are clear . Cardiomediastinal silhouette is stable . No acute osseous abnormalities .
    OUTPUT:
    
Retrocardiac opacity which could be atelectasis however infection can not be entirely excluded .