Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates low lung volumes with resulting bronchovascular crowding . An area of increased opacification of the left base may represent artifact from patient positioning or atelectasis , however superimposed infection can not be excluded . There is a probable small left - sided pleural effusion . There is no pneumothorax . The cardiomediastinal contours are unchanged .
    OUTPUT:
    
Increased opacification of the left base may represent artifact from patient positioning or atelectasis , however superimposed infection can not be excluded .