Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is slight increased opacity at the left lung base when compared to prior exam which is also seen on the lateral view overlying the spine . Elsewhere , lungs are clear . The cardiomediastinal silhouette is within normal limits . No pneumomediastinum . There is no free intraperitoneal air . No acute osseous abnormalities .
    OUTPUT:
    
Faint left basilar opacity potentially atelectasis . Otherwise unremarkable exam , no evidence of pneumomediastinum or free intraperitoneal air .