Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . Mild calcification at the aortic knob is noted . The pulmonary vascularity is normal . Subsegmental atelectasis in the lingula is present . Lungs are otherwise clear . No focal consolidation is visualized . Blunting of the right costophrenic angle posteriorly likely reflects a small pleural effusion . No pneumothorax is present .
    OUTPUT:
    
Small right pleural effusion .