Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Diffuse bilateral alveolar opacities persist with mild improvement on the left greater than the right compared to the preceding chest radiograph . The costophrenic angles are clear without pleural effusions . No pneumothorax is present . The cardiomediastinal silhouette is unchanged and within normal limits .
    OUTPUT:
    
Moderate - to - severe pulmonary edema with mild improvement on the left greater than the right since ___ .