Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Overall , the lungs are better aerated compared the prior study and there has been interval decrease in previously seen pulmonary opacities . Subtle patchy left base retrocardiac opacity may be due to atelectasis versus infection or aspiration . No pleural effusion or pneumothorax is seen . The cardiac silhouette is top - normal to mildly enlarged . The main pulmonary artery is mildly prominent . No overt pulmonary edema is seen .
    OUTPUT:
    
Overall , the lungs are better aerated compared the prior study and there has been interval decrease in previously seen pulmonary opacities . Subtle patchy left base retrocardiac opacity may be due to atelectasis versus infection or aspiration .