Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low but appear clear . There is no pleural effusion or pneumothorax . The mediastinal and hilar contours are normal . The cardiac silhouette is somewhat enlarged , though exaggerated by low lung volumes .
    OUTPUT:
    
Enlarged cardiac silhouette due to cardiomegaly and / or pericardial effusion . Repeat frontal radiograph at full inspiration may modify that interpretation . The lungs are clear .