Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette size is normal . The aorta is mildly tortuous . Pulmonary vascularity is normal . The hilar and mediastinal contours are otherwise unremarkable . Linear opacities within the left lung base likely reflect atelectasis . No focal consolidation , pleural effusion or pneumothorax is present . There are no acute osseous abnormalities .
    OUTPUT:
    
Mild left basilar atelectasis .