Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear not significantly changed including mild cardiac enlargement . There is persistent patchy left basilar opacity and a very small pleural effusion . Opacification is perhaps increased slightly in the background of persistent left basilar opacity . There is also slightly increased medial right basilar opacity , probably within the right lower lobe . There is no overt congestive heart failure . No pleural effusion is seen on the right . A mild superior endplate compression along a lower thoracic vertebral body appears unchanged and is likely chronic .
    OUTPUT:
    
Minimal increase in bibasilar opacities of uncertain significance . This appearance may represent waxing and waning atelectasis and change from the prior examination is not striking ; it is difficult to completely exclude pneumonia , however .