Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal contours are stable , with a mildly tortuous aorta . The lung volumes appear lower compared to the prior exam ; however , there does appear to be slight interval improvement of the moderate right pleural effusion . There is no evidence of a pneumothorax . There is increased atelectasis at the left lung base , otherwise the left lung is clear . Note is made of an old rib fracture at the posterior sixth rib .
    OUTPUT:
    
Slight interval improvement of the moderate right pleural effusion . No evidence of a pneumothorax .