Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . There is mild pulmonary edema . There is interval increase of the left retrocardiac opacity , likely representing atelectasis , but can not rule out pneumonia . The cardiomediastinal silhouette and hila are normal . Sternotomy wires are seen , as well as moderate degenerative changes at the right glenohumeral joint .
    OUTPUT:
    
Mild pulmonary edema and left retrocardiac opacity , likely atelectasis .