Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear unchanged . There is a patchy left basilar opacity obscuring the left cardiac border , probably within both the left lower lobe and lingula but not significantly changed and accordingly perhaps chronic . It is difficult to exclude a recurrent opacity at the same location , however . There is no definite pleural effusion or pneumothorax .
    OUTPUT:
    
Persistent left basilar opacities , possibly due to chronic scarring or atelectasis noting the lack of change , although it is difficult to exclude the possibility of recurring infection at the same location as before .