Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear . The cardiac silhouette is mildly enlarged . The patient has an enlarged right main pulmonary artery . Status post median sternotomy . No pleural effusion or no pneumothorax .
    OUTPUT:
    
Large right pulmonary artery could be from chronic pulmonary hypertension or alternatively pulmonary embolus in the right setting . No pneumonia .