Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heterogeneous bilateral mid and lower lung opacities are likely atelectasis , especially given slightly low lung volumes , although infection or aspiration pneumonitis could have a similar appearance . There may be a small left pleural effusion . There is no pneumothorax . Heart size is normal . The mediastinal contours are normal . Aortic calcifications are seen . Multilevel degenerative changes of the thoracic spine are noted .
    OUTPUT:
    
1 . Low lung volumes with minimal bibasilar atelectasis . A concomitant process at the lung bases , such as pneumonia or aspiration pneumonitis can not be excluded . 2 . Possible small left pleural effusion .