Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . There is a curvilinear lucency projecting along the inferior cardiac border , somewhat unusual , although this may merely reflect aerated lung . The right hemidiaphragm is mild - to - moderately elevated . The lungs appear clear . There are no pleural effusions or pneumothorax .
    OUTPUT:
    
No definite acute process . Somewhat unusual curvilinear opacity projecting along the inferior cardiac border . This is not necessarily a true abnormality , but the possibility of air in the pericardium could be considered . Acquisition of standard PA and lateral radiographs is suggested when clinically appropriate to confirm the probability that this is an artifact .