Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Right infrahilar and right lower lobe masses are minimally more prominent since chest radiograph of ___ . There are persistent opacities in the right upper lobe . Known silicone bronchial stent is not well visualized . Right mainstem bronchus appears patent . There is no pleural effusion or pneumothorax . The heart is not enlarged .
    OUTPUT:
    
Silicone stent is not well visualized , however the right mainstem bronchus appears patent .