Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . Mildly hyperinflation is unchanged . There is no focal consolidation , pleural effusion , or pneumothorax . Mildly increased opacity at the left lung base is atelectasis . Heart size is normal . The mediastinal silhouette and hilar contours are normal . Aortic knob calcifications are redemonstrated . Mild degenerative changes in the thoracic spine are unchanged .
    OUTPUT:
    
No pneumonia , edema or effusion .