Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is marked enlarged , as before . Mediastinal and hilar contours appear stable . Left posterior opacifications suggests atelectasis and possibly pleural effusion although otherwise the lungs appear clear . There is only a small pleural effusion on the right .
    OUTPUT:
    
Unchanged marked cardiomegaly . New retrocardiac opacification suggesting atelectasis , possibly with pleural effusion , although infectious causes not excluded by this study .