Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable AP upright chest radiograph demonstrates mild cardiomegaly . Opacity at the left lung base is present as is streaky opacity at the right lung base . While findings may reflect sequela of atelectasis , infectious process can not be entirely excluded . There is mild central vascular engorgement without overt pulmonary edema . There is no pneumothorax . There is no large pleural effusion , of the left costophrenic angle partially imaged .
    OUTPUT:
    
Bibasilar opacities which may be atelectatic in etiology although infectious process is not entirely excluded . Minimal central vascular engorgement without overt pulmonary edema .