Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear unchanged . There is again mild - to - moderate relative elevation of the left hemidiaphragm with associated atelectasis . There is no evidence for pulmonary edema . On the left , a small pleural effusion layers along the posterior costophrenic angle , however . There is no evidence for pleural effusion on the left . Surgical clips again project along the mediastinum .
    OUTPUT:
    
Small pleural effusion on the left , but no evidence of parenchymal edema . Persistent volume loss at the left lung base .