Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . Opacities in the right middle lobe and lingula have improved since the prior study and appear very similar to the earlier comparison examination suggesting chronic abnormality . Superimposed infection is difficult to exclude , however . There is no pleural effusion or pneumothorax . A Port - A - Cath terminates in the lower superior vena cava .
    OUTPUT:
    
Persistent right basilar opacity which has improved since the last study and may be compatible with chronic background finding ; superimposed infection is not excluded however .