Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is within normal limits . The mediastinal and hilar contours are unremarkable . The lung volumes are low with bibasilar atelectasis . There is no large pleural effusion or pneumothorax .
    OUTPUT:
    
Basilar atelectasis , although in the appropriate clinical setting , an underlying pneumonia can not be excluded .