Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post tracheostomy insertion . The opacity seen on prior exam at the right lung base appears improved . In the setting of low lung volumes this is concerning for atelectasis however pneumonia can not be excluded in the appropriate clinical setting . cardiac size is normal . There is no pneumothorax or pleural effusion .
    OUTPUT:
    
Persistent opacity at the right lung base of unclear etiology in the setting of low lung volumes may be atelectasis however pneumonia can not be excluded in the appropriate clinical setting .