Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate low lung volumes with increased prominence of the cardiac silhouette and bronchovascular crowding . Mild pulmonary edema is improved . Opacity at the left lung base this likely unchanged , and likely represents atelectasis , although superimposed infection can not be excluded .
    OUTPUT:
    
1 . Improved mild pulmonary edema . 2 . Opacity at the left lung base is likely unchanged and may represent atelectasis , although superimposed infection can not be excluded .