Angiography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. This is commonly used when there is concern for disease of the lymphatics or when diagnosing pets with portosystemic liver shunts. Angiography is traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy or CT.