What are the imaging findings in case of pleural effusion?

X ray (PA and lateral view reveals 200ml effusion (PA) and 50 ml (lateral)) US (very useful, if multiple punctures, guides the pleural tap (decreasing the risk of iatrogenic pneumothorax)) Chest CT (reveals spots not seen on X ray, provides potential causes of the effusion- white spots are atelectasis- damaged alveoli, shouldn't be punctured!)