Angiography or arteriography is a medical imaging technique in which an X-ray or MRI picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. An angiogram done with an MRI machine is often referred to as a Magnetic Resonance Angiogram or MRA. Angiography is also commonly performed to identify vessel narrowing in patients with retinal vascular disorders, such as diabetic retinopathy and macular degeneration.