Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear without infiltrate or effusion . The cardiac silhouette is normal . There is increased opacity in the midline projecting over the heart that could represent a hiatal hernia but comparison is recommended with other studies .
    OUTPUT:
    
opacity in the midline behind the heart . Recommend correlation with other studies not available at the current time . There is no infiltrate