Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours are normal . Pulmonary vasculature is normal . Streaky opacities are demonstrated within both lower lobes , more so on the left . While prior exams did demonstrate bibasilar opacities , the opacity within the left lung base appears to have progressed . No pleural effusion or pneumothorax is present . There are no acute osseous abnormalities .
    OUTPUT:
    
Streaky bibasilar opacities , slightly progressed on the left . Findings may reflect left lower lobe atelectasis or infection superimposed upon chronic bibasilar scarring .