Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes continue to be low . The cardiac silhouette continues to be enlarged , accentuated by the low lung volumes , and there is crowding of the central bronchovascular structures due to the low lung volumes . There is bilaterally predominately upper lobe airspace opacity , likely reflecting pulmonary edema but infection can not be excluded .
    OUTPUT:
    
Low lung volumes . Bilateral upper lobe airspace opacities likely reflect pulmonary edema but infection can not be excluded .