Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours are normal . The pulmonary vasculature is normal . Patchy opacity is demonstrated within the left lung base . Right lung is clear . No pleural effusion or pneumothorax is present . There are no acute osseous abnormalities .
    OUTPUT:
    
Patchy left basilar opacity may reflect atelectasis but infection is not excluded .