MR Angiography (MRA)

MR Angiography (MRA)

• What is MR Angiography?
• What are some common uses for MRA?
• Who interprets the results and how do I get them?
• What are the limitations of MR Angiography?
• What are the benefits vs. risks?

What is MR Angiography?

Magnetic resonance imaging (MRI) is a method of producing extremely detailed pictures of body tissues and organs without the need for x-rays. The electromagnetic energy that is released when exposing a patient to radiofrequency waves in a strong magnetic field is measured and analyzed by a computer, which forms two- or three-dimensional images that may be viewed on a TV monitor. MR angiography (MRA) is an MRI study of the blood vessels. It utilizes MRI technology to detect, diagnose and aid the treatment of heart disorders, stroke, and blood vessel diseases. MRA provides detailed images of blood vessels without using any contrast material, although a special form of contrast material is often given to make the MRI images even clearer. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind.

What are some common uses for MRA?

• Many patients with arterial disease now have it treated in the radiology department rather than undergoing surgery in an operating room. MRA is a very useful way of finding problems with blood vessels and determining how to best to treat those problems.

• The carotid arteries in the neck that conduct blood to the brain are a common site of atherosclerosis, which may severely narrow or block off an artery, reducing blood flow to the brain and even causing a stroke. If an ultrasound study shows that such disease is present, many surgeons will perform the necessary operation after confirmation with MRA, dispensing with the need for catheter angiography.

• MRA has found wide use in checking patients for diseased intracranial (in the head) arteries, so that only those with positive findings will need to undergo a more invasive catheter study.

• MRA is also used to detect disease in the aorta and in blood vessels supplying the kidneys, lungs and legs.

• Patients with a family history of arterial aneurysm, a ballooning out of a segment of the vessel wall, can be screened with MRA to see if they have a similar disorder that has not produced symptoms. If an aneurysm is found, it may be eliminated surgically, possibly avoiding serious or fatal bleeding.

Who interprets the results and how do I get them?

A neuroradiologist, who is a physician experienced in head, neck and spine MRI examinations will analyze the results and send a report to your physician, along with an interpretation of the findings. Your physician in turn will discuss the MRA findings with you. New technology also allows for distribution of diagnostic reports and referral images over the Internet at some facilities.

What are the limitations of MR Angiography?

MRA does not image calcium, as does CT angiography. The clearness of MRA images does not yet match those obtained with conventional angiography. MRI of small vessels, in particular, may not be adequate for diagnosis and treatment planning. Sometimes it may be difficult to separate images of arteries from veins with MRA.

What are the benefits vs. risks?

Benefits:

• Detailed images of blood vessels and blood flow are obtained without having to insert a catheter directly into the area of interest, so that there is no risk of damaging an artery.

• The procedure itself and the time needed to recover are shorter than after a traditional catheter angiogram.

• MRA is less costly than catheter angiography.

• There is no exposure to x-rays during an MRI study.

• MR angiography (MRA) provides detailed images of blood vessels in the brain and other body parts--oftentimes without the need for contrast material. The risk of an allergic reaction from MRA contrast is extremely low and kidney damage does not occur.

• As with catheter-based angiography or CT angiography, it frequently is possible to defer surgery after getting the results of an MRA study. If surgery remains necessary, it can be performed more accurately.

Risks:

• There are no definite side effects from any type of MRI study, including MR angiography.

• An undetected metal implant may be affected by the magnetic field. The procedure should be avoided in any patient with a pacemaker, implanted neurostimulator, certain types of metallic ear implants or metallic object within the eye socket. It should also be avoided if the patient has a port for delivering insulin or chemotherapy (however, many ports are detachable so patients can safely undergo MRI examinations).

• MRI is generally avoided in the first 12 weeks of pregnancy. Doctors usually use other methods of imaging, such as ultrasound, on pregnant women unless there is a strong medical reason.

• Women who are breast-feeding should inform the radiologist and ask how to proceed. If necessary, they may pump breast milk before the exam for use until the gadolinium contrast material has cleared from the body.

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