It won't give better results, it will give different information basically. A myocardial perfusion scan (Thallium) basically tests how well your heart muscle is being supplied with blood at rest and during exercise. It looks at how well your heart pumps and looks at the flow of blood to the walls of the heart muscle- this will give your doctor more detailed information on blood flow and the heart’s pumping action. Angiography is more useful at determining the degree of occlusion, location and severity of blockages in blood vessels. Both tests are done to identify coronary artery disease and/or the source of any chest pain. These tests are used along side other tests to evaluate your over all condition and decide which is the best treatment option for you. The CPS will not show or explain the degree of blockage. It will only show if the heart is receiving enough blood from the arteries or not and general health of the heart muscle. As I said above, the angiogram will give a clearer picture of where the blockage is and the degree of occlusion.