Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since prior radiograph acquired ___ hours apart , bilateral , diffuse and confluent opacities show asymmetric changes with mild improvement in the right and worsening in left lung , overall unchanged in severity . Heart size and mediastinal contours are normal .
    OUTPUT:
    
Since prior radiograph acquired ___ hours apart , bilateral , extensive , pulmonary opacities concerning for pulmonary edema / ARDS / hemorrhage is overall unchanged in severity . A concurrent infection can not be ruled out .