What are the limitations of cardiac MRI or MRA?

These techniques are still considered experimental and are not widely used. Some arteries in the heart cannot be seen with cardiac MRA. To get the best pictures of the heart, you have to hold your breath and lie very still; this can be too hard for some people and, in these cases, the images of the heart may not be good enough to use. During other types of noninvasive testing such as a stress echo, you are hooked up to an ECG so your doctor can monitor your heart's activity. This is difficult to do with cardiac MRI because the magnetic field affects the ECG. There are some safety issues with chemical stress cardiac MRI testing compared with other types of chemical stress tests. The doctor is not in the room with you during the test, and it may not be immediately obvious if you experience problems because you are hidden inside the machine.