Computed tomography angiography

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Computed tomography angiography (also called CT angiography or CTA ) is a computed tomography technique used to visualize arteries and veins throughout the body. These range from arteries that serve the brain to those who carry blood to the lungs, kidneys, arms and legs.

Video Computed tomography angiography

Medical use

CTA can be used to examine blood vessels in many major areas of the body, including the brain, kidneys, pelvis, and lungs.

Coronary CT angiography

Coronary CT angiography (CTA) is the use of CT angiography to assess cardiac coronary arteries. The subjects received intravenous radiocontrasion injection and then cardiac scanning using a high-speed CT scanner, allowing radiologists to assess the occlusion rate in the coronary arteries, usually to diagnose coronary artery disease. CTA has not replaced coronary angiography of invasive catheters. This procedure is able to detect constriction of blood vessels in time for corrective therapy to be performed. This method displays the anatomical details of the blood vessels more precisely than magnetic resonance imaging (MRI) or ultrasound. Currently, many patients can undergo CTA as a substitute for conventional catheter angiograms. CTA is a useful screening tool for arterial disease because it is safer and less time consuming than angiographic catheters and is a cost-effective procedure. There is also a slight discomfort because the contrast material is injected into the blood vessels rather than into the large arteries in the crotch.

Other uses

CTA is usually used for the following purposes:

• CT pulmonary angiogram (CTPA) to check pulmonary artery in the lungs, most commonly to exclude pulmonary embolism, a serious but treatable condition.
• Visualize blood flow in the renal artery (which supplies the kidneys) in patients with high blood pressure and those suspected of having renal impairment. The narrow (stenosis) of the renal artery is the cause of high blood pressure (hypertension) in some patients and can be corrected. Specialized computerized methods for viewing images make renal angiography CT an extremely accurate examination. Also performed on prospective donor kidneys.
• Identify aneurysms in the aorta or other major blood vessels. Aneurysms are diseased areas of weakened blood vessel walls - like bulges in the tires. Aneurysm is life-threatening because it can rupture.
• Identify dissection in the aorta or its main branch. Dissection means that the layers of artery walls are peeling off from one another - like layers of onions. Dissection can cause pain and can be life-threatening.
• Identification of small aneurysm or arteriovenous malformations in the brain that can be life-threatening.
• Detection of atherosclerotic disease that narrows the arteries to the feet.
• Exclude coronary artery disease, especially in patients with low to moderate risk.

Maps Computed tomography angiography

Technique

CT angiography is a contrast CT in which images are drawn with certain delays after radiocontrast injection to produce high radiodensity in attractive blood vessels.

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Risk

CT angiography should not be used to evaluate pulmonary embolism when other tests indicate that there is a low probability of someone who has this condition. A D-dimer test may be the preferred alternative to testing pulmonary embolism, and the test and low clinical prediction score on the Wells test or the Geneva score may exclude pulmonary embolism as a possibility.

Damage to excessive use of CT angiography includes radiation exposure and the possibility of finding then seeking treatment for clinically insignificant lung embolisms that should not be treated.

There is a risk of an allergic reaction, which may be serious, when a contrast material containing iodine is injected. A patient with a history of allergy to x-ray dye may be advised to take a specific drug for 24 hours before CTA to reduce the risk of an allergic reaction or undergo a different examination that does not require contrast injection of the material. CTA should be avoided in patients with severe kidney disease or diabetes, as further x-ray contrast material may compromise renal function. If large amounts of x-ray contrast material leak out under the skin where IV is placed, skin damage may occur. Compared with other imaging modalities, CTA is associated with significant ionizing radiation doses. Depending on the patient's age and examination protocol, CTA may lead to an increased risk of lifelong cancer. However, there are many clinical situations where the benefits of performing a procedure outweigh this risk.

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History

In 1994 CT angiography began replacing conventional angiography in diagnosing and characterizing most cardiovascular disorders. Prior to this, conventional angiography has been used for 70 years.

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See also

• Angiography
• Magnetic resonance angiography

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References

Source of the article : Wikipedia