Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Overall aeration of the right lower lobe appears significantly improved compared to prior . Complete opacification of the left lower lobe appears unchanged and may reflect atelectasis or pneumonia . There is no interstitial pulmonary edema . A component of the left basilar opacity may be due to a small effusion . No pneumothorax is evident . Surgical clips are visualized within the left lower quadrant .
    OUTPUT:
    
Improved aeration of the right lower lobe though with persistent opacification of the retrocardiac region .