Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared with the prior chest radiograph , severe cardiomegaly is unchanged , with slightly improved pulmonary edema . Widening of the mediastinal contour is due to low lung volumes and mediastinal lipomatosis is seen on the prior chest CT . The right lung appears slightly better aerated . Bibasilar airspace opacities could reflect atelectasis , infection , or aspiration .
    OUTPUT:
    
Compared with the prior study , interval improvement in the bilateral lung aeration , with persistent bibasilar airspace opacities and low lung volumes .