Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A right - sided ventriculoperitoneal shunt courses across the right side of the chest . The cardiac , mediastinal , and hilar contours appear unchanged . Hazy left basilar opacification has resolved . There is a persistent opacity projecting over the left upper lung that has decreased somewhat and may correspond to radiation - related changes , scarring , or atelectasis ; since it has decreased , infection seems less likely though not entirely excluded .
    OUTPUT:
    
No evidence of acute disease .