Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: When compared to prior , there has been no significant interval change . Retrocardiac opacity persists , not significantly changed . There is no large pleural effusion or overt pulmonary edema . Cardiac silhouette is enlarged but stable .
    OUTPUT:
    
Retrocardiac opacity likely atelectasis . No definite superimposed cardiopulmonary process .