Reasons you may not be able to have the test or why the results may not be helpful include:
Pregnancy. Although the strong magnetic field used for an MRA does not appear to be harmful, MRA usually is not done when you are pregnant. If a view of your belly is needed and you are pregnant, an ultrasound test may be done instead.
You are using a medical device that contains metal, such as an IUD, a pacemaker, some types of artificial limbs, or medicine infusion pumps. These devices can malfunction or cause problems during an MRA scan.
Not being able to lie still during the test. The results of MRA may not be accurate if you can't remain still during the test.
Being overweight and not fitting into the opening of some MRI scanners.
What To Think About
While MRA is a safe and valuable test for looking at blood vessels inside the body, it is more expensive than other imaging techniques, and it may not be available in all medical centers.
An advantage of MRA is that no radiation is involved.
You may be able to have your MRA in an open MRI machine that doesn't enclose your entire body. But open MRI machines aren't available everywhere. The pictures from an open MRI may not be as good as those from a standard MRI machine. Also, these machines may not be able to do all the studies needed to check for problems.
Open MRI is useful for people who are claustrophobic or obese.
Conventional angiogram or a CT angiogram (computed tomography angiogram) may be done to double-check abnormal results from the MRA in some types of blood vessels such as the aorta. These tests might be an option especially if surgery is being considered to treat the problem.
MRA results may show an aneurysm is present when it is not (false-positive). It also may show no aneurysm when one is present (false-negative). MRA is most accurate for larger blood vessels.
You may need to wait about 6 weeks before having an MRA if you have had a stent put in your coronary arteries. This helps decrease the chances of movement of the stent by the magnet used in the MRA.