Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been some interval improvement in previously seen interstitial edema with minimal interstitial edema remaining . Right base opacity is seen which could be due to pneumonia versus atelectasis . No large pleural effusion is seen . There is no pneumothorax . The cardiac and mediastinal silhouettes are grossly stable .
    OUTPUT:
    
Right base opacity could be due to pneumonia and / or atelectasis .