Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the prior exam , the medial right base appears slightly more opacified , which is likely due to ___combination of superimposed vasculature , prominent mediastinal fat in this region , and lower lung volumes . There is no abnormality in the right middle lobe on the lateral radiograph to suggest this is ___pneumonia . There is no edema , pleural effusion , or pneumothorax . The mediastinal contours are normal . The heart is mildly enlarged , and unchanged . Old left - sided rib fractures are again noted .
    OUTPUT:
    
No evidence of pneumonia .