Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph provided . A single - lead pacemaker is again seen projecting over the left chest wall and lead extending to the region of the right ventricle . Lung volumes are low . Bronchovascular crowding likely accounts for mild left basilar opacity , though atelectasis versus mild aspiration difficult to exclude in the correct clinical setting . The aorta appears unfolded . The heart size is stable . No definite bony injury is seen .
    OUTPUT:
    
Limited study due to low lung volumes with subtle opacity at the left lung base likely representing atelectasis or bronchovascular crowding , though subtle aspiration difficult to exclude .