Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Both lungs are clear . There are no lung opacities of concern . Very minimal bibasilar opacity is probably attributed to suboptimal inspiratory effort and is likely bibasilar atelectasis . No lung opacities concerning for pneumonia . Left posterior costophrenic angle blunting is likely from combination of effusion and pleural thickening , unchanged since ___ . Top normal heart size , mediastinal and hilar contours are unchanged since ___ .
    OUTPUT:
    
No pneumonia or pulmonary edema .