Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Reversal of left mediastinal shift likely reflects improving retrocardiac left lower lobe atelectasis . The linear opacification remaining in the left lower lobe is likely residual atelectasis . There is no pleural effusion or pneumothorax . Cardiomediastinal silhouette is normal size . The tracheostomy tube and PEG tube are in unchanged position . Again seen is an old healed fracture of the right clavicle .
    OUTPUT:
    
Improved left lower lobe atelectasis compared to ___