Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are low lung volumes . Left base opacity may be due to atelectasis versus pneumonia or aspiration in the appropriate clinical setting . No large pleural effusion is seen although a trace pleural effusion is difficult to exclude . No pneumothorax is seen . Cardiac and mediastinal silhouettes are stable . Right - sided vascular stent is again seen .
    OUTPUT:
    
Low lung volumes . Left base retrocardiac opacity , which could be due to atelectasis , aspiration , and / or pneumonia . Difficult to exclude trace pleural effusion .