Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size remains moderately enlarged . Mediastinal and hilar contours are unchanged . There is crowding of the bronchovascular structures without overt pulmonary edema . Retrocardiac patchy opacity may reflect atelectasis , but infection can not be completely excluded . No pleural effusion or pneumothorax is present . Single ___ rod is seen within the thoracolumbar spine which demonstrates moderate S - shaped scoliosis as before .
    OUTPUT:
    
Patchy left basilar opacity , possibly atelectasis but infection can not be excluded .