What is Magnetic Resonance Angiography?

Emma Lloyd

Magnetic resonance angiography (MRA) is a diagnostic medical imaging procedure which is used to generate highly detailed pictures of the body’s major blood vessels. This test can be used to diagnose a large number of diseases and injuries, including those of major organs and body cavities. Magnetic resonance angiography is painless and only minimally invasive, but some discomfort might be experienced by people who are uncomfortable in small spaces. If someone is prone to anxiety or claustrophobia, he or she might be given a sedative to help them relax.

An MRI machine is used for magnetic resonance angiography.
An MRI machine is used for magnetic resonance angiography.

A magnetic resonance imaging (MRI) machine is a cylindrical tube that is surrounded by a large circular magnet. To undergo a magnetic resonance angiography, the patient lies down on a movable table that slides into the cylinder when the test begins. When the machine is operative, it begins to emit radio waves. The combination of the magnetic field and the radio waves causes hydrogen atoms in the body to align themselves in a certain way. The alignment of the hydrogen atoms is detected by the MRI equipment, and a computer uses this information to produce three-dimensional images of the interior of the body.

Images from a magnetic resonance angiogram may be interpreted in real time in order to spot circulation abnormalities.
Images from a magnetic resonance angiogram may be interpreted in real time in order to spot circulation abnormalities.

In magnetic resonance angiography, the patient must undergo some preparation before the test. This involves the insertion of an intravenous line into a vein in the arm or hand. A special dye is injected into the vein via the intravenous line. This dye helps produce higher-contrast images by causing the body’s veins to appear bright white in the MRI images generated by the computer.

This procedure can help diagnose many illnesses. Magnetic resonance angiography can identify aneurysms, atherosclerosis deposits, venous malformations, injuries to arteries and major veins, it can detect blood clots, and it can screen for atherosclerosis and other vascular diseases. In addition to disease diagnosis, this test also can be used as a tool for helping a surgeon prepare for an operation. For example, the test might be used to evaluate the severity of atherosclerotic disease in preparation for a coronary bypass procedure.

There are few serious risks involved with the MRA procedure. It is normal to feel a small amount of discomfort when the intravenous line is inserted and removed. There also might be a small amount of redness, bruising or irritation at the site. There is a small risk of an allergic reaction to the dye used in the intravenous injection. Generally, the allergic reaction is mild.

Another risk is for people with implanted metal devices such as a pacemaker, internal defibrillator or cochlear ear implant. A person with one of these devices might not be able to safely undergo an MRA test. Other devices such as artificial heart valves, artificial limbs, metal screws, pins, stents, plates and other artificial implants might interfere with the test. Anyone with an internal artificial device should ensure that his or her doctor is aware of this fact before undergoing the procedure.

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