Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: As compared to prior chest radiograph from ___ , the right apical pneumothorax has improved . The distance between the right apical pleura and second rib is 1 .8 cm . Mediastinal structures are midline . There is mild pulmonary edema . Small bilateral pleural effusions remain unchanged . Opacities at lung bases are most readily explained by atelectasis . However , early pneumonia can not be excluded .
    OUTPUT:
    
1 . Improving small right apical pneumothorax . 2 . Bibasilar opacities most readily explained by atelectasis ; however , early pneumonia can not be excluded , and close monitoring is recommended .