Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to the prior radiographs , there is no change in the chronic fibrotic changes in the upper lobes and severe emphysema in the lower lobes . Heart size and mediastinal contours are normal . Along the posterior aspect of the left lower lobe , there is new heterogeneous opacification which may correspond to a developing pneumonia . No evidence of pneumothorax or pleural effusion . Osseous structures are intact .
    OUTPUT:
    
1 . New heterogeneous opacification along the posterior aspect of the left lower lobe may represent developing pneumonia . 2 . Stable chronic changes including scarring in the upper lobes and emphysema in the lower lobes .