Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size remains mildly enlarged . The mediastinal and hilar contours are unchanged . The pulmonary vasculature is not engorged . Patchy opacities in the left lung base likely reflect areas of atelectasis . No focal consolidation , pleural effusion or pneumothorax is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Left basilar atelectasis .