Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to the prior study , the lung expansion has slightly increased . Bilateral lower lobe atelectasis and elevation of the left hemidiaphragm persists . The cardiac and mediastinal contours are stable . Two compression fractures in the lower thoracic spine are unchanged since ___ and may be related to the patient 's history of renal cell carcinoma .
    OUTPUT:
    
Bilateral lower lobe atelectasis is minimally improved since ___ .