This paper discusses about the differences between Computed Tomography Angiography and Conventional Angiography in terms of quality and reliability. The two are compared and contrasted based on their characteristics. At the end of the paper, Computed Tomography is recommended to diagnose many diseases and it shows many advantages over the conventional angiography.
Diseases in blood vessels including those of the brain and the heart can be diagnosed through angiography. Angiography is used to diagnose pathology of blood vessels such as blockage caused by plaque build up (Imaginis, 2006). Traditionally, X-ray or the conventional angiography was used but due to the development of technology, Magnetic Resonance, ultrasound, and Computed Tomography slowly replaced x-ray angiography.
Basically, angiography is a radiographic technique where a radio-opaque contrast material is injected into a blood vessel for the purpose of identifying anatomy on x-ray. This technique is used to image arteries in the brain, heart, kidneys, gastrointestinal tract, aorta, neck or carotids, chest, limbs and pulmonary circuits (On-Line Medical Dictionary, 2006). This technique is carried out in a laboratory by a trained cardiologist or radiologist and technicians. The doctor will first need to insert an intravenous, IV, line into one of the blood vessels of the patient’s arm, chest, neck or groin (Keller, 2004). Then, a catheter is inserted through the IV and into the patient’s blood vessels using x-ray machine that produces real-time pictures. When the catheter is already placed into the blood vessel of interest, contrasts material is injected and pictures are taken. It usually takes time for the doctors to get the catheter into the right spot (Keller, 2004). There are different types of angiography depending on the type of test such as cerebral angiography for the head, extremity angiography for arm or leg, renal angiography for the kidneys and pulmonary angiography for the lungs.
Conventional angiography or cardiac catheterization is the diagnostic of standard for determining the presence, location, and severity of coronary artery disease (Anonymous, 2006). Conventional angiography has long been used in the medical field for its high effectiveness. However, this technique is invasive, labor intensive due to its procedure, costly and has a significant risk of complications. This technique involves passing a catheter onto the right or left side of the heart. It is also used to determine pressure and blood flow in the heart’s chambers, collect blood samples from the heart and examine the arteries of the heart with an x-ray technique called fluoroscopy. Fluoroscopy provides real-time visualization of the x-ray images on a screen and provides a permanent record of the procedure (Keller, 2004).
Conventional angiography carries risks depending on organ undergoing a test. These risks may include bleeding and pain at IV site; a risk that the soft plastic catheters could damage the blood vessels; the risks the blood clot could form on the catheters and later block blood vessels in the body; and the risks that the contrast material could damage the kidneys especially in diabetes patients (Keller, 2004) aside from some discomfort and it mandates routine follow-up care.
On the other hand, there are other angiography techniques that are more advantageous than the conventional type. One of these is the Computed Tomography Angiography, CTA. CTA is replacing conventional angiography because this test is less invasive and easier to perform than conventional angiography while obtaining results just as accurate as the results obtained from conventional angiography. CTA is a three-dimensional technique that provides information about the imaged vessels and adjacent structures (Tins et al, 2001). It enables the display of vascular structures aided by injections of contrast medium. The multislice scanner enables the system to display the entire vascular system including small vascular exits, branches, embolisms or dissection membranes (Siemens, 2006). This is one of the advantages of CTA, with this type of imaging the physician can easily conduct and decide for surgical planning using the image produce through a CTA.
CTA requires only venous vascular access and is an outpatient examination with lesser risks than conventional angiography. At minimum, CTA requires a thin section helical CT acquisition coupled with a power injection of intravenous iodinated contrast medium. A multidetector-row CT or MDCT, that is capable of detecting and reliably diagnosing pathology in the adjacent structures and end organs of the vessel is commonly used and preferred for CTA (CIGNA, 2005). For cardiac and some aortic CTA, an electrocardiograph-gated acquisition should be performed that allows retrospective reconstruction of the scan volume at multiple phases through the cardiac cycle (American College of Radiology, 2005 on CIGNA, 2005).
The advantages of Computed Tomography angiography over conventional angiography were studied by the American Heart Association (Olin et l, 2004) and found out that the advantages and use of CTA varies depending on the type of disease being evaluated. For occlusive disease of the extracranial carotid arteries, CTA has higher degree of accuracy compared with conventional angiography. For thoracic aorta, one major advantage of CTA is the ability to accurately evaluate the surrounding structures within the thorax for pathology that may provide alternative explanations for the patient’s symptoms (CIGNA, 2005) necessary for the treatment. For abdominal aorta diseases, CTA has high accuracy in measuring vessel lengths, diameters and angles. With peripheral arterial disease, CTA can produce image not visualized by conventional angiography aside from the greater longitudinal coverage of multidetector-row CT (CIGNA, 2005).
Generally, CTA has many advantages over the conventional angiography. These advantages include visualization of the anatomy from multiple angles and in multiple planes; improved visualization of soft tissues and other adjacent anatomic structures; less invasiveness and fewer complications. However, it is still a standard for coronary artery diseases to use the conventional angiography or the Cardiac Catheterization because there is still no sufficient evidence to support the use of CTA with suspected coronary artery disease. CTA also involves radiation exposure and the potential for ionated contrast related reaction (CIGNA, 2005) as well as temporal and spatial resolution. Recommendation of the use of either CTA or the conventional angiography depends on the type of the disease to be imaged. However, for its accuracy and advantages over the conventional one, CTA is recommended due to above mentioned characteristics, quality and reliability and due to it less invasiveness than conventional angiography.
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Credit:ivythesis.typepad.com
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