Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: As compared ___ chest radiograph , bilateral asymmetrically distributed alveolar opacities have improved , representing improving interstitial edema . The heart is not enlarged . Small bilateral pleural effusions are unchanged . No pneumothorax .
    OUTPUT:
    
Interval improvement of the interstitial pulmonary edema . Persistent left upper lobe opacity in the left lung although has improved .