Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared with the immediate prior study of ___ , mild pulmonary edema has resolved . Persistent heterogeneous opacification of the left base is most likely atelectasis related to low lung volumes . If infectious symptoms develop , repeat radiographs to assess for developing pneumonia are recommended . There is mild atelectasis at the right base . Multiple , bilateral , old , well healed rib fractures are noted . There is no pleural effusion , pneumothorax , or pulmonary edema . The heart size is stably top - normal .
    OUTPUT:
    
1 . Resolved mild pulmonary edema . 2 . Persistent left base opacification is likely atelectasis , although superimposed pneumonia can not be fully excluded .