Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since prior radiograph the interstitial lines representing pulmonary edema have improved . However , opacities at the bilateral lung bases are worsened and could represent pneumonia or aspiration . The cardiomediastinal silhouette is unchanged . No pneumothorax is identified .
    OUTPUT:
    
1 . Bilateral lower lung opacities have worsened , and could represent pneumonia or aspiration . 2 . Interval improvement in severity of pulmonary edema .