Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal silhouette and pulmonary vasculature are normal . The lungs are clear . There is no large pleural effusion or pneumothorax . There is blunting of the left posterior costophrenic angle posteriorly , which may reflect small pleural effusion or pleural thickening .
    OUTPUT:
    
No definite acute intrathoracic abnormality . Small left pleural effusion versus pleural thickening .