Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP radiograph of the chest demonstrates low lung volumes . The cardiomediastinal silhouette is unremarkable . Bibasilar atelectasis is present and the left lung base is not well visualized , possibly due to atelectasis and portable technique , however an underlying infectious process can not be completely excluded . There is no evidence of overt pulmonary edema . No pneumothorax is present . Multilevel spinal fusion surgical hardware is identified in the thoracolumbar spine .
    OUTPUT:
    
Low lung volumes and bibasilar atelectasis , more prominent on the left . Although opacification of the left lung base may be due to atelectasis , underlying infectious process can not be entirely excluded .