Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low resulting in crowding of bronchovascular structures , particularly at the lung bases . The cardiac silhouette is stably enlarged . The lungs are clear . There is no pleural effusion or pneumothorax . Healed left rib fractures are again demonstrated .
    OUTPUT:
    
No acute intrathoracic abnormality .