Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The mediastinal and hilar contours are unchanged . The pulmonary vasculature is normal . Previously demonstrated patchy opacity within the left lower lobe persists , but appears slightly improved compared to the prior exam . The right lung is clear . No pleural effusion or pneumothorax is present .
    OUTPUT:
    
Improved aeration within the left lower lobe with residual patchy opacity likely reflecting improving pneumonia .