What does a positive (abnormal) test indicate?
Results so far suggest that women with a positive (abnormal) test have a higher risk of suffering a heart attack or dying from heart disease in the next few years than women with a normal test.1 Your healthcare provider will discuss the tests results with you and may prescribe further tests or treatments.
How accurate is cardiac MRI or MRA?
Cardiac MRI is very accurate if it is done well. The images produced with cardiac MRI are much clearer than those for other noninvasive imaging tests such as echocardiography or a nuclear scan. So far, cardiac MRI appears to work equally well in men and women.
What are the risks of cardiac MRI or MRA?
People with tattoos or permanent makeup may feel some mild discomfort or a burning feeling on their skin during a cardiac MRI caused by the metallic components of the inks. Large or dark tattoos around the scanned area may also cause false shadows to appear on the film produced from the test. MRIs are usually discouraged for up to 6 months after stent placement because the magnetic field could move the stent. If you have had bypass surgery, the surgical clips may distort the MRI image. The contrast dye used in cardiac MRI is less likely to trigger an allergic reaction or damage the kidneys compared with the dyes used in cardiac catheterization. You should still tell your healthcare provider if you have had a reaction to X-ray dye, shellfish, or iodine in the past.
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.4 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.
1. Hundley WG, Morgan TM, Neagle CM, Hamilton CA, Rerkpattanapipat P, Link KM. Magnetic resonance imaging determination of cardiac prognosis. Circulation. Oct 29 2002;106(18):2328-2333.
2. Wahl A, Paetsch I, Gollesch A, et al. Safety and feasibility of high-dose dobutamine-atropine stress cardiovascular magnetic resonance for diagnosis of myocardial ischaemia: experience in 1000 consecutive cases. Eur Heart J. Jul 2004;25(14):1230-1236.
3. Hundley WG, Hamilton CA, Thomas MS, et al. Utility of fast cine magnetic resonance imaging and display for the detection of myocardial ischemia in patients not well suited for second harmonic stress echocardiography. Circulation. Oct 19 1999;100(16):1697-1702.
4. Yang TP, Pohost GM. Magnetic Resonance Coronary Angiography. Am Heart Hosp J. 2003;I:141-148,163.