Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded . There is a dense retrocardiac opacity , with obscuration of the margin of the left hemidiaphragm and descending thoracic aorta , suggestive of left basilar consolidation . Cardiac size is moderately enlarged , not significantly changed from prior exam . No large right pleural effusion or pneumothorax . Dense calcifications of the aorta are reidentified . Left deviation of the trachea and prominence of the upper mediastinum on the right is better assessed in prior CT and secondary to tortuosity of the vessels . Right upper quadrant surgical clips .
    OUTPUT:
    
Dense retrocardiac opacity likely represents a combination of pleural effusion and lung consolidation due to atelectasis versus pneumonia .