Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A tracheostomy is unchanged in position . Again seen are low lung volumes with bilateral heterogeneous opacities likely representing mild pulmonary edema superimposed on a background of chronic interstitial lung disease . No pleural effusion or pneumothorax . Heart size , mediastinal contour , and hila are unremarkable .
    OUTPUT:
    
Mild pulmonary edema superimposed on background of chronic interstitial lung disease . No definite pneumonia .