Magnetic resonance angiography (MRA) is one of the newer innovations in the field of magnetic resonance imaging (MRI). Whereas MRI is used to image various parts of the body-bones and joints, soft tissues, muscles, internal organs, and blood vessels, MRA is specifically intended to show the arteries and veins. MRA enables radiologists to evaluate both healthy and diseased vessels in the brain and neck and to observe the blood flow within them.
MRA can be used to evaluate most major arteries in the body. MRA can be used to examine the carotid arteries in the neck and the cerebral vessels in the brain. MRA can show their shape, size, location, and orientation. With this information, radiologists can diagnose diseases in these vessels and then determine the best way to treat them.
MRA is particularly valuable in screening for atherosclerosis, or hardening of the arteries. Over time, fat can be deposited along the walls of medium and large arteries in the body, causing them to become narrowed or even blocked. This blockage can eventually lead to a transient ischemic attack or even a stroke.
MRA is also performed to detect a brain aneurysm, which is an abnormal widening or ballooning of a cerebral vessel. Brain aneurysms occur when an injury or congenital defect weakens the wall of the vessel. Aneurysms are particularly dangerous because they can burst and cause potentially fatal bleeding.
In addition, MRA is helpful in assessing vascular malformations, which occur when blood or lymph vessels fail to develop normally before birth. The affected vessels become tangled and change the normal flow of the blood through the brain. Some patients have headaches and seizures, but others may be asymptomatic. Vascular malformations can cause hemorrhage and subsequent neurologic damage. Lastly, MRA may aid in evaluating some types of headaches.
Compared with catheter angiography, MRA is less invasive, less expensive, and faster to perform. For conventional angiography, a catheter is inserted though the patient’s groin and threaded up into the artery in the brain. MRA does not require this catheter. As a result, it eliminates related complications such as possible damage to an artery.
In addition, because MRA relies on the natural magnetic properties of hydrogen atoms in the body, injections of contrast material are not always needed. This feature is especially important in patients who have had allergic reactions to contrast agents in the past.
MRA is a painless and noninvasive procedure in which no incisions or arterial catheters are required. With some MRA techniques, contrast agents are not necessary, so no intravenous lines are needed. With other techniques, a small amount of a gadolinium-based contrast agent is added to highlight the blood vessels and enhance the sharpness of the image. This contrast material is infused through an intravenous line placed in your arm. No other preparation is involved.