Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lungs are well expanded . Blunting of the right costophrenic angle is unchanged and may reflect chronic pleural thickening . Retrocardiac opacity is likely due to Bochdalek hernia on previous CT . Cardiomediastinal silhouette is otherwise unremarkable .
    OUTPUT:
    
Retrocardiac opacity is likely due to atelectasis and posterior pleural fat / small Bochdalek hernia seen on CT of the chest from ___ . Please see subsequently obtained CTA chest for further details .