Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Previous large left basilar consolidation has markedly improved . A residual opacity in the left lower lobe is best seen on the lateral radiograph . Mediastinal contours including left ventricular enlargement and pacemaker leads are stable . The right lungs clear . There is no large pleural effusion or pneumothorax .
    OUTPUT:
    
Previous left lower lung pneumonia has substantially improved .