Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared with the immediate prior study , lung volumes are significantly lower causing bibasilar atelectasis and bronchovascular crowding . Allowing for differences in lung volumes , left lung base airspace opacities are likely unchanged . The cardiomediastinal silhouette is stable .
    OUTPUT:
    
Low lung volumes causing bronchovascular crowding and atelectasis . Allowing for this difference , left lung base very sparse opacities are likely unchanged .