Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are present . The cardiac and mediastinal contours are unchanged , with mild pulmonary vascular congestion again noted , similar compared to the prior exam . Bibasilar airspace opacities may reflect atelectasis but infection is difficult to exclude . Right mid lung field peripheral opacity appears unchanged compared to the prior study and is nonspecific , potentially an area of infection . No pneumothorax is detected . Multiple calcified gallstones are again seen within the right upper quadrant the abdomen .
    OUTPUT:
    
Little interval change compared to the prior study . Persistently low lung volumes with bibasilar airspace opacities , possibly reflecting atelectasis but infection is difficult to exclude . Mild pulmonary vascular congestion . Right peripheral mid lung field opacity may reflect an area of infection or infarction , but is nonspecific .