Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest demonstrate normal cardiomediastinal silhouette allowing for low lung volumes . There is no pneumothorax , vascular congestion , or large effusion . There may be trace subsegmental atelectasis in the left base .
    OUTPUT:
    
No evidence of pneumonia . Trace subsegmental atelectasis in the left base .