Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is not engorged . Patchy bibasilar airspace opacities posteriorly are similar when compared to the previous exam , and could reflect areas of atelectasis or aspiration . Small bilateral pleural effusions appear similar . No acute osseous abnormalities demonstrated , and there is no pneumothorax . Metallic biliary stent is noted in the right upper quadrant of the abdomen .
    OUTPUT:
    
Persistent bibasilar airspace opacities posteriorly could reflect aspiration or atelectasis . Trace bilateral pleural effusions .