Introduction
Computed tomography (CT) is a useful diagnostic tool for detecting disease and injury. A series of X-rays and a computer are used to create 3D (three-dimensional) images of soft tissue and bone. CT is a painless, non-invasive method for doctors to diagnose medical conditions. One can have a CT scan at a hospital or imaging center. Doctors use computed tomography, also called a CT scan, to look at structures inside the body. A CT scan involves the use of X-rays and a computer to make cross-sectional pictures of the body. It takes images that show thin slices of the muscles, bones, organs, and blood vessels, so the doctor can see the body in detail. Conventional X-ray machines use a fixed tube to focus the X-rays to a point. As X-rays pass directly through the body, they are absorbed in different amounts by various tissues. Dense fabrics produce a whiter image than other fabrics against the film's black background. X-rays produce 2D (two-dimensional) images. A CT scan has a ring-shaped tube that rotates the X-ray beam 360 degrees. The recorded data provides a detailed 3D view of the body.
What Is a CT Angiography?
Doctors use angiography to diagnose and treat diseases and conditions of blood vessels. Angiography produces images of large blood vessels throughout the body. Some tests use a contrast agent. CT angiography is used in the following cases:
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To identify anomalies such as aneurysms in the aorta, both thoracic and abdominal, or other arteries.
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Detects atherosclerosis (plaque) in the carotid arteries (blood vessels in the neck) that can restrict blood flow to the brain and cause stroke.
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To identify arteriovenous malformations in the brain or elsewhere.
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To detect plaque disease that has narrowed arteries to the legs and prepare for angioplasty stent placement or surgery.
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To detect disease in the arteries to the kidneys or visualize blood flow in preparation for kidney transplantation or stent placement. Interventional radiologists and surgeons use it for the implantation of stents or evaluation of stents after implantation.
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To find damage to one or more arteries in the chest, abdomen, neck, pelvis, or limbs after trauma.
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The arteries supplying the tumor are evaluated before surgery or other procedures such as chemoembolization (blockage of blood vessels to cancer) or selective internal radiation therapy.
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To identify the anatomy or division of the thoracic or abdominal aorta or its main branches.
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To indicate the extent and severity of coronary artery disease, its impact, and plan interventions. Coronary artery bypass and stent placement. The pulmonary embolism is checked by examination of the pulmonary arteries of the lungs for a blood clot.
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To watch out for congenital anomalies of blood vessels, especially arteries in children (heart or other vascular anomalies due to congenital heart disease).
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Assessment of vascular stenosis and occlusion.
How Is the CT Angiography Scan Performed?
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A nurse or technician inserts an intravenous (IV) catheter, usually into a vein in the arm or hand. Rarely, a small amount of blood is taken from a catheter or fingertip to test kidney function.
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The technician first places the patient on the table for a CT scan. The patient is supposed to lie on their back.
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Straps and pillows help maintain proper alignment and keep the patient still during the exam.
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An automatic injection pump is connected to the IV and injects contrast at a specific rate.
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In some cases, especially in children and patients with weak and thin veins, the contrast agent can be injected manually using a syringe.
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During the scanning process, the table is positioned at the starting point and moved through the machine aperture while the CT scan is performed.
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A single scan takes about one to two minutes, but multiple scans may be required.
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The technician may ask the patient to hold their breath during the scan. Any movement, including breathing and body movement, can cause image artifacts. This image quality loss is similar to the blur seen in photos of moving objects.
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In some cases, sedation is required to keep the child calm during the scan. The doctor will help determine whether sedation is needed and will arrange for it if necessary. Preparing for sedation may include not eating or drinking for several hours before the test to avoid complications. Also, after the scan, a long period of close observation may be required until the sedation wears off.
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Once the examination is complete, the technician will ask to wait until the radiologist confirms that the image quality is sufficient for accurate interpretation. After the examination has been completed, the technician will bandage the needle site after the removal of the IV catheter.
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The entire CT angiography procedure is completed in seconds. The actual time in the scanner room can be longer, but the technician will position the patient properly on the table, confirm IV line placement, perform preliminary images, and recommend the scanner and the contrast injection pump must be set.
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CT angiography is rarely done in children because children are more sensitive to radiation than adults. In children and adults of reproductive age, radiologists perform low-dose radiation CT scans with dose reduction measures.
What Are the Benefits and Risks of CT Angiography?
The benefits and risks of CT angiography are listed below:
Benefits:
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Angiography can eliminate the need for surgery. If surgery is needed, it can be done more precisely.
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CT scan angiography is fast, non-invasive, may have fewer complications, and is more accurate than conventional angiography.
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CT angiography can provide more detailed anatomical imaging than other angiographic studies, such as magnetic resonance imaging (MRI) and conventional catheter angiography.
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CT angiography does not require sedation or general anesthesia. Cardiac CT angiography is a helpful method for the detection of blocked coronary arteries.
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CT angiography may be less expensive than catheter angiography.
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After a CT scan, no radiation remains in the patient's body.
Risks:
Most patients complete CT angiography without side effects.
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There is always a slight risk of getting cancer from overexposure to radiation. However, the benefits of accurate diagnosis far outweigh the risks associated with CT scans.
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If a patient has a past history of allergy to X-ray contrast agents, their doctor may advise them to take special medications, such as steroids, before the CT angiogram to reduce the chance of getting an allergic reaction. Another option is to have another test that does not require interesting an iodinated contrast agent.
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In patients at risk of renal failure who already have impaired renal function, administration of iodinated contrast media may further impair renal function.
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If an excessive amount of X-ray contrast medium is leaked from the injected vein and spreads beneath the skin where the infusion was performed, it may damage the skin, blood vessels, nerves, etc. If you feel any pain or tingling in this area during or immediately after the contrast injection, let the nurse or technician know immediately.
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A woman should always tell her doctor and her X-ray or her CT technician if she might be pregnant. For more information about pregnancy and X-rays.
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The risk of getting a severe allergic reaction to iodinated contrast media is extremely rare but possible, and hospitals are well prepared to deal with it.
Conclusion
Computed tomography angiography (CTA) involves injecting a contrast agent into blood vessels and using CT scans to diagnose and evaluate vascular diseases or related conditions, such as aneurysms and occlusions. CTA is usually performed in a radiology department or outpatient imaging center. A CT pulmonary angiography is a CT scan that looks for blood clots (also called pulmonary embolism or PE) in the lungs. CT pulmonary angiography acquires pictures of the blood vessels that start from the heart and are directed to the lungs (pulmonary arteries). It is very helpful for emergencies.
