Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear within normal limits . There is mild elevation of the left hemidiaphragm and patchy opacification at the left base , but decreased , whereas other portions of the lungs appear clear . However , the left diaphragm is somewhat elevated which may indicate some atelectasis or mild gastric distension , noting new gastric air - fluid levels . There is probably a small pleural effusion on the left , noting posterior costophrenic blunting .
    OUTPUT:
    
Improving left basilar opacification . New gastric air - fluid levels with mild distension .