Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded and clear . There is no pleural effusion or pneumothorax . The cardiomediastinal silhouette is top normal in size , which may represent a possible non-hemodynamically significant pericardial effusion .
    OUTPUT:
    
Top - normal size of the cardiomediastinal silhouette , which may represent possible non-hemodynamically significant pericardial effusion .