Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild bibasilar and retrocardiac atelectasis , but the lungs are clear of focal opacities to suggest infection . No evidence of pneumonia , pleural effusion , pneumothorax or pulmonary edema . Heart size is normal . The aorta is unfolded .
    OUTPUT:
    
Bibasilar atelectasis . No evidence of pneumonia .