Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The aorta is mildly tortuous . The mediastinal and hilar contours are otherwise unremarkable . Pulmonary vasculature is not engorged . Linear opacities in the lung bases , more pronounced on the left , likely reflect areas of subsegmental atelectasis . No definite large pleural effusion or pneumothorax is present . There are no acute osseous abnormalities detected .
    OUTPUT:
    
Bibasilar subsegmental atelectasis .