Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . The pulmonary vascularity is normal . Linear and patchy opacities in the left lung base most likely reflect atelectasis though pneumonia is not completely excluded . Right lung is clear . No pleural effusion or pneumothorax is present . No acute osseous abnormalities are visualized .
    OUTPUT:
    
Left basilar linear and patchy opacities likely reflect atelectasis though infection can not be completely excluded .