It is an imaging technique that uses a contrast agent to evaluate narrowed blood vessels or blocked arteries of the wrist, arm, upper arm and shoulder. The scan is also used to find out atherosclerosis (depositions of fats or cholesterol in the artery walls) and vasculitis (inflammation of blood vessels). An abnormal result helps in finding out ruptured vessels, aneurysms, stenosis, occlusion, and congenital disabilities.