CTA of the Head or Neck
by Dr. L.P. Riccelli, MD
how it works: CT angiography (CTA) evaluates the major vessels of the head, neck or both. An iodine based contrast agent is rapidly injected through an IV placed in a vein, usually in the arm. A CT scan uses x-rays to acquired images as the contrast bolus passes through the arteries. The data can then be reviewed in multiple planes, and 3 dimensional images can also be created for review.
Equipment: Most commonly, a 64 channel Philips CT scanner is used, however, in some situations a 16 or 256 channel CT scanner may be used. OHSU is an ACR accredited CT facility.
Benefits: CT angiography is a fast and minimally invasive method of evaluating vessels for abnormalities such as narrowing, blockage, aneurysms, and other vascular malformations.
Exam Preperation: The technologist will interview you prior to the scan to make sure you do not have contraindications to the injection of intravenous contrast, such as contrast allergy or kidney problems. If you have had an allergy to iodine based contrast in the past, you should discuss this with your physician before the study. In some situations, an alternative imaging method may be considered, or you may receive medication that needs to be taken before the study to reduce your risk of reaction. In some situations, kidney function labs may also be checked before your study. An IV will be placed, usually in the arm.
What to expect: Once you are positioned on the scanner table and the contrast injector tubing is attached to your IV, a localizer scan will be taken, which takes a few seconds. Contrast will be rapidly injected into a vein, and the actual CTA scan takes about 10 seconds or less, depending on coverage. It is very important to remain still during the scan time. You may have a warm, flushed feeling and a metallic taste during the injection of contrast. The technologist will check the images before you leave the room. After you have left, additional multiplanar and 3D reconstructions will be created, and a board certified neuroradiologist will review the study.
Adverse reactions to contrast materials are uncommon, but can range from mild to severe. Severe reactions are very uncommon. Further information about the risks and benefits of x-rays and contrast material can be found at http://www.radiologyinfo.org/en/safety/index.cfm
Louis P. Riccelli, MD
Associate Professor of Neuroradiology