Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-erect chest radiograph ___ at 23 : 12 is submitted .
    OUTPUT:
    
Lung volumes remain low with crowding of the vasculature and bibasilar opacities likely representing atelectasis , although pneumonia or aspiration can not be excluded . Worsening mild perihilar edema . Stable cardiac and mediastinal contours with calcification of the aortic knob . No pneumothorax .