Pulmonary embolism, coloured angiogram (blood vessel X-ray). The embolism is affecting the patient's right lung (at left). The pulmonary blood vessels have been highlighted by a contrast medium using a technique called thoraco-pulmonary angiography. A catheter has been inserted into the pulmonary arteries in this anterior view in a 43-year-old man. The embolism has been caused by abnormal blood clotting (thrombosis).