Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Chest , PA and lateral . Change in shape since ___ of the large crescentic opacity in the left lower lobe , new since ___ , shows it is largely atelectasis . Right lower lobe opacification is more likely atelectasis than pneumonia . Heart size is top normal . There is no pneumothorax or pleural effusion . Pulmonary vascularity is normal .
    OUTPUT:
    
1 . Heterogeneous opacity in the right lower lobe may represent atelectasis ; however , infection can not be excluded . 2 . Bibasilar atelectasis could be fever souce . 3 . This study does not speak to the possibility of acute pulmonary embolus .