Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable including cardiac enlargement . There is a persistent pleural effusion on the left , but with substantial decrease . Parenchymal opacification involving the left lower lobe and probably the lingula persists but similar to improved and not optimally assessed with this technique . The left lung apex , as well as the entirety of the right lung , appear well - aerated and clear , as before . There is no evidence for pleural effusion on the right .
    OUTPUT:
    
Reduced pleural effusion on the left without persistent opacification at the left lung base , compatible with pneumonia in the appropriate setting . However , even if pneumonia were successfully treated , it might take several more weeks for the opacity to clear more definitely . Atelectasis is also a differential diagnosis . Follow - up radiographs are recommended to show clearance within ___ weeks .