An MRA, or magnetic resonance angiogram, is a type of MRI scan that uses MRI's magnetic fields and radio waves to produce pictures of blood vessels inside the body, allowing doctors to locate problems that may cause reduced blood flow. An MRI, or magnetic resonance imaging, is the technology behind an MRA, and it is used to examine soft ligament tissues and tendon injuries. Both scans are generally safe for most patients and do not expose them to ionizing radiation.
|Radiation exposure||None. MRI machines do not emit ionizing radiation.||None. MRAs do not emit ionizing radiation.|
|Acronym for||Magnetic Resonance Imaging.||Magnetic Resonance Angiography.|
|Effects on the body||No biological hazards have been reported with the use of MRI. However, some may be allergic to the contrast dye, which is also inappropriate for those suffering from kidney or liver disorders.||No biological hazards have been reported with the use of MRI/MRA. However, some may be allergic to the contrast dye, which is also inappropriate for those suffering from kidney or liver disorders.|
|Application||Suited for Soft tissue evaluation, e.g., ligament and tendon injury, spinal cord injury, brain tumors, etc.||Because MRA scans look at the body's blood vessels, they are well suited to examining arteries in the brain, neck, chest, and abdomen.|
|Cost||MRI costs range from $1,200 to $4,000 (with contrast), which is usually more expensive than CT scans and X-rays, and most examining methods.||MRA costs are usually $1,000 and up, with scans that require contrast dye costing more.|
|Time taken for complete scan||Depending on what the MRI is looking for, and where it is needing to look, the scan may be quick (finished in 10-15 minutes) or may take a long time (2 hours).||Depending on what the MRA is looking for, and where it is needing to look, the scan may be quick (finished in 10-15 minutes) or may take a long time (2 hours).|
|Intravenous Contrast Agent||Very rare allergic reaction. Risk of reaction in those who have or have a history of kidney or liver disorders.||Very rare allergic reaction. Risk of reaction in those who have or have a history of kidney or liver disorders.|
|Comfort level for patient||Anxiety, especially anxiety caused by claustrophobia, is common, as is tiredness or annoyance over having to stay still on a hard table for a long period of time.||Anxiety, especially anxiety caused by claustrophobia, is common, as is tiredness or annoyance over having to stay still on a hard table for a long period of time.|
MRI and MRA Uses
X-rays, ultrasounds, and CT scans cannot reveal the same information that MRI scans provide. Physicians use MRI scans to discover, treat, and monitor diseases, as these scans are very good at looking at the anatomy of muscles, tendons, ligaments, and internal organs, such as the liver, kidneys, heart, brain, and spine. Moreover, surgeons can use MRIs to assist in surgical planning.
MRI scans are most commonly used for the following reasons:
- To find aneurysms.
- To evaluate bone and joint disorders, such as arthritis, and locate bone infection or tumors.
- To better understand disorders of the eye and inner ear.
- To monitor multiple sclerosis.
- To discover or help treat spinal cord injuries.
- To see if a patient has had a stroke.
- To locate tumors or cancers inside many of the body's organs.
- To help detect breast cancer in women who have dense breast tissue or who are at high risk of the disease.
- To assess heart function, such as the size and health of heart chambers, thickness and movement of heart walls, extent of damage caused by a heart attack or heart disease, structural problems in the aorta, and/or inflammation or blockages in heart blood vessels.
Because MRA scans look at the body's blood vessels, they are well suited to examining arteries in the brain, neck, chest, and abdomen and stomach. MRA scans are typically used for the following reasons:
- To find bulges (aneurysms), clots, or buildups of fat and calcium deposits in the blood vessels leading to the brain.
- To find aneurysms or tears in the aorta, which carries blood from the heart to the rest of the body.
- To find blood clots in arteries and veins.
- To see if any blood vessels leading to the heart, lungs, kidneys, or legs are narrowing. Narrowing blood vessels can lead to hypertension, painful walking, and non-healing ulcers.
Prior to an MRA or MRI, patients should tell their doctors their full medical history, as this will help determine the complete safety and comfort of either scan. Patients with certain devices, like pacemakers, cochlear implants, or IUDs (intrauterine devices), or health problems, like liver or kidney diseases, may not be the right candidates for MRA and MRI scans. Those who are claustrophobic can still have a scan but may require a sedative.
For both types of scan, patients need to remove all metal objects, like jewelry or hearing aids, from their bodies, as the magnetic nature of the scans will pull at them. This means the scans may also be inappropriate for those who have metal pins or other metal pieces inside the body.
How the Scans Are Done
In MRI and MRAs, patients lie flat on a table inside a large, tunnel-like tube; this tube is where pictures of the body are taken. A dye, called a contrast, is sometimes added to the bloodstream via an intravenous needle (IV) to help create clearer pictures of blood vessels.
The head, chest, and/or arms may be strapped down to keep them still during the procedure, as movement during either scan affects image quality. Also, patients will sometimes have to hold their breath for a short period of time to ensure image quality. Inside the scanner, it feels like a fan is blowing, and there are loud thumping sounds which may be better tolerated with earplugs. Though a technologist cannot always be present in the testing room, he or she is always nearby, usually watching the scanner and patient from the window of another room; patients are able to speak to the technologist at all times via an intercom device inside the scanner.
Depending on what the scanner is looking for, and where it is needing to look, MRA and MRI scans may be quick to do (finished in 10-15 minutes) or may take a long time (2 hours).
Side Effects and Risks
Anxiety, especially anxiety caused by claustrophobia, is common, as is tiredness or annoyance over having to stay still on a hard table for a long period of time. The use of a sedative or an open MRI machine (as opposed to the standard, closed MRI machine) may help. In rare cases, patients may feel a tingling sensation in the mouth if they have metal dental fillings. Some may feel warmth in the area of the body that is being examined; this is normal, but patients should tell the technologist if it leads to any nausea, dizziness, pain, headache, burning, or breathing problems.
For those who are approved for MRA or MRI scans, there are relatively few risks involved. One of the biggest risks, which is still small, comes from the contrast dye, which a few patients will be allergic to and which those with kidney disease should avoid. Medical patches can cause a burn if they are not removed prior to the scan.
Scan results are presented as either being "normal" or "abnormal." Normal results are those that find no problems and reveal healthy blood flow and no abnormal clots or growths. Abnormal results are those that find problems. Patients should feel comfortable asking questions about their results, whether normal or abnormal, so that doctors and technologists can clear up any confusion or concerns.
In the U.S., pricing of these scans varies wildly from one city or hospital to another, and what health insurance covers of this cost depends on coverage deductible and a variety of other details. However, most scans in the U.S. will cost over $1,000, much more than they do in other developed nations. A scan by itself will be cheaper than a scan that requires the use of a contrast dye.
Video Explaining the Differences
- Am I exposed to any radiation during an MRI scan? - About.com Multiple Sclerosis
- Magnetic resonance angiography - NIH.gov
- MRA Information - WebMD
- MRI of the Head - WebMD
- MRI Scan: How It Is Performed - NHS.uk
- Why an MRI costs $1,080 in America and $280 in France - The Washington Post
- Wikipedia: Magnetic resonance angiography
- Wikipedia: Magnetic resonance imaging