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What is the difference between a cardiac MRI or MRA of the heart?
What is the difference between a cardiac MRI or MRA of the heart? I need to do a follow-up of my heart due to returning of dyspnea symptoms and abnormal ECG's. My last angiogram was in 2007 (was ok) but I heard about cardiac MRI and MRA, but I don't know what is the best option in cases when the doctor suspect a blockage or atherosclerosis of the heart. Can you give some advice on which one is best to do and why?
submitted Giuseppe from Peru, on 1/25/2012
by Texas Heart Institute cardiologist, Jorge F. Guttin, MD
MRI stands for Magnetic Resonance Imaging. MRA stands for Magnetic Resonance Angiogram, meaning it is done with the same type of contrast material that is used in coronary angiograms (done at time of cardiac catheterization). The diagnostic standard to this day (which may change in the future) continues to be coronary arteriography done at the time of cardiac catheterization. Your cardiologist should be the one to decide what diagnostic modality he may want to use, if any, at this time.
by Texas Heart Institute cardiologist, Benjamin Y. Cheong, MD
Technically, MRI is magnetic resonance imaging and this test is to assess the function or "squeeze" of the heart; the size of the ventricles and atria (chambers of the heart); and valve function. When given with contrast like gadolinium (a type of dye that is very safe when used properly), MRI can be used to assess if the heart is damaged (e.g., prior heart attack) and can even be used to perform a "stress" test on the heart.
MRA (magnetic resonance angiography) is an MR test to look at blood vessels, in this case, coronary arteries. There have been good advances in the technology, however, it is also a technically demanding test - despite that the patient "simply" lies still in the scanner for 5-15 minutes. It requires the physician to be knowledgeable about the MR machine (as there are a lot of parameters to optimize); the patient needs to be still and to have a regular breathing pattern and heart rate. If one wants to look at the first 5-10 cm of the coronaries (or longer distance with better scan/equipment), MRA could be a reasonable choice providing your physician is skillful in this area.
So far, there is no data from the medical literature that "routine" looking into the coronary arteries would provide any benefit to the patient, assuming the patient has no symptoms. If symptoms are present that are suggestive of coming from the heart, one may consider a stress test. If the patient can run, an exercise type of stress test can really be helpful to him/her and the clinician, particularly to determine exercise tolerance. Another test is coronary CT angiography. This uses radiation and iodine dye, but takes only 5-8 seconds if the patient is of standard weight and has a good heart rate. If the patient's symptoms are highly suggestive of angina pain, one should consider going directly to coronary angiography, which while more invasive, is still the gold standard for diagnosis.
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Updated January 2012