Pulmonary angiography is a medical imaging technique used to visualize the blood vessels in the lungs. It involves injecting a contrast dye into the pulmonary arteries, which helps to highlight any blockages or abnormalities in the blood flow. This procedure is often performed to diagnose conditions such as pulmonary embolism or other vascular diseases affecting the lungs. During the procedure, a thin tube called a catheter is inserted into a blood vessel, usually in the groin or arm, and guided to the lungs. X-ray images are then taken to capture detailed views of the pulmonary arteries, allowing doctors to assess the health of the vascular system in the lungs.