This test is done in the hospital. You will be asked to lie on the X-ray table. Your head is positioned and immobilized by using a strap, tape, or sandbags. Electrocardiogram (ECG) leads are taped to your arms and legs to monitor your heart during the test. The area where the contrast medium will be introduced is shaved and cleansed. The site is usually in the leg. You are given a local anesthetic, the artery is punctured, and a needle is inserted into the artery.
The catheter (a long, narrow, flexible tube) is inserted through the needle and into the artery. It is then threaded through the main vessels of the abdomen and chest until it is properly placed in the arteries of the neck. This procedure is monitored by a fluoroscope (a special X-ray that projects the images on a TV monitor). The contrast medium is then injected into the neck area through the catheter, and the X-ray pictures are taken. The catheter is kept open by flushing it periodically with a saline solution containing heparin, which will keep the blood in the catheter from clotting. Your pulse, blood pressure, and breathing are monitored during the procedure.
After the X-rays are taken, the needle and catheter are withdrawn. Pressure is immediately applied on the leg at the site of insertion for 10 to 15 minutes to stop the bleeding. After that time, the area is checked and a tight bandage is applied. Your leg should be kept straight for 12 hours after the procedure.
Digital Subtraction Angiography (DSI) uses a computer to "subtract" out the bones and tissues in the region viewed such that only the vessels filled with contrast are seen.
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