Multi Detector CT

What is CT Angiography?

CT Angiograhphy uses non-invasive x-rays to visualize blood flow in arterial vessels throughout the body. CT Angiography is used to examine the coronary arteries, pulmonary arteries in the lungs, visualize blood flow in the renal arteries (supplying the kidneys), identify aneurysms in the aorta or other major blood vessels, identify dissection in the aorta or its major branches, identify small aneurysms or arterio-venous malformations inside the brain, detect disease that has narrowed arteries to the legs, carotid arteries and pelvis.

How is CTA used in diagnosis?

• Examine the pulmonary arteries in the lungs to rule out blood clots or pulmonary embolism, a serious but treatable condition.
• Visualize blood flow in the renal arteries (those supplying the kidneys) in patients with high blood pressure and those suspected of having kidney disorders. Narrowing (stenosis) of a renal artery is a treatable cause of high blood pressure (hypertension) in some patients. CTA can also help evaluate the kidneys in prospective kidney donors.
• Identify aneurysms in the aorta or in other major blood vessels. Aneurysms are weakenings in a blood vessel wall causing it to bulge out or ballon. If left untreated, aneurysms can rupture, causing death or severe disability.
• Identify dissection in the aorta or its major branches. Dissection occurs when the layers of an artery wall peel away from each other. Dissection can cause pain and be life-threatening.
• Identify a small aneurysm or arteriovenous malformation (AVM) inside the brain. It may provide a roadmap for the neurosurgeon who may want to operate to remove the aneurysm or AVM.
• Detect atherosclerotic disease that has narrowed the arteries to the heart, brain and extremities. CTA can also be used to non-invasively evaluate the patency of vascular stents which have already been placed to open up these narrowed vessels

What should I expect during the procedure?

Depending on the part of the body to be examined, you may be asked to take only clear liquids by mouth before CTA. (see Patient Preparation) You will be asked whether you have asthma or any allergies to foods or drugs, and what medications you are currently taking. If you are pregnant, you should inform the technologist before the procedure. You probably will not have to undress if you are having an exam of the head, neck, arms, or legs, but you will have to remove any jewelry, hair clips, dentures and the like that could show up on the x-rays and make them hard to interpret.

Immediately prior to the X-ray exposures, a dose of contrast material will be injected into an arm or hand vein to make the blood vessels stand out. An automatic injector is used that controls the timing and rate of injection. You may feel a sensation of warmth in your body and possibly a metallic taste in your mouth during the injection, but this should only last a minute or two. During the examination, the table will move through the scanner opening, and the X-ray tube and detector system will rotate rapidly around your body, taking pictures of the particular region of interest. You may be asked to hold your breath for 10 to 25 seconds to ensure that the images will not be blurred. The real work of CTA comes after the images are acquired, when powerful computer programs process the images and display them in 2D and 3D modes which the radiologist will then interpret. CTA takes about 15 minutes from the time the actual examination begins. You can eat immediately afterward, and we recommend you drink plenty of fluids in the hours after the exam to help flush the contrast material out of the system.