Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Somewhat linear opacities in the medial right lower lung and left lung base are essentially unchanged compared to ___ There is probably a trace left pleural effusion . No pneumothorax . Heart size is normal . Cardiomediastinal and hilar silhouettes are unremarkable .
    OUTPUT:
    
Unchanged bibasilar opacities could reflect persistent or recurrent infection in the appropriate clinical situation . If treated for pneumonia , recommend repeat radiographs in 6 weeks . If no improvement in 6 weeks , recommend dedicated chest CT .