Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . The heart is mildly enlarged but unchanged . The mediastinal and hilar contours are stable without evidence of pulmonary vascular congestion . Linear opacities in both lung bases are most likely reflective of atelectasis . No pleural effusion or pneumothorax is present . There are mild degenerative changes in the thoracic spine .
    OUTPUT:
    
Mild bibasilar atelectasis .