Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle increased opacity within the left lung base compared to prior examination , raising concern for the development of aspiration or pneumonia . Subsegmental atelectasis is likely at the right lung base . The patient is rotated making evaluation of mediastinal structures difficult . However , cardiac contours appear similar to prior . There is no pneumothorax .
    OUTPUT:
    
Focal increased opacity within the left lung base possibly due to aspiration or early pneumonia . Follow up radiographs may be helpful if warranted clinically .