What is Computed Tomography?
Computed tomography, or CT, scanning is a popular and effective way of examining any part of the body to detect the presence or absence of disease. It is extremely useful in the evaluation of acute injuries to the head, chest, abdomen, spine and pelvis. It is a valuable tool for cancer patients in determining the size and location of tumors as well as response to treatment. Many new uses of computed tomography have been developed such as detecting kidney stones without the use of injected contrast material ("x-ray dye"), diagnosing appendicitis, as well as special studies of the blood vessels that don't require the surgical placement of a catheter into the blood vessel. New uses for computed tomography continue to be developed, an example of which is CT Coronary Angiography, a less invasive alternative to traditional coronary angiography. 

A Radiologic Technologist with special training in computed tomography will perform your CT scan. At the start of the procedure the technologist will explain the procedure to you and answer any questions that you have. The technologist will operate the CT scanner from a separate control room but remain in contact with you using a two-way intercom and monitor you through an observation window. To begin the study you will lay on a table connected to the CT scanner. The part of your body being scanned will be positioned in the middle of the large, doughnut-shaped scanner.

Present day scanners have a wide opening that does not feel confining, so you should not feel claustrophobic. The machine will not touch you and you will not feel the x-rays.

Some CT scans require the use of an iodine contrast material, "x-ray dye". The contrast material is used to highlight certain body tissues and structures. One type is given prior to the exam by mouth (usually for abdomen or pelvis scans) to define the intestines. A different contrast material is given by I.V. injection and is used to enhance structures of the body and improve the detection of abnormalities.

During the CT scan, a thin beam of x-rays circles completely around the body, collecting a 360-degree view of the area being examined. This information is fed into a computer system that produces a two dimensional cross sectional "slice" of a portion of the body. Multiple slices are taken to cover the area of the body to be examined.

These studies enable the radiologist to see structures inside the body, which makes diagnosis and treatment more accurate.

Is the exam safe?
Millions of CT exams are done every year in the United States. The x-rays used involve a small dose of radiation.

Efforts are always being made to reduce the amount of radiation in these studies and are a special concern for children and women of childbearing age due to risk to a fetus. Generally the small risks of the radiation are outweighed by the potential benefits of the information gained by the study.

Intravenous iodine contrast material is often used depending on the type of exam. These contrast agents are generally safe, but, like all medications, side effects can occur. The incidence of side effects has decreased considerably over the years as newer contrast medicines have been developed. However, a small percent of patients may be allergic to the intravenous agent.

Allergic reactions are usually mild (itching, flushing) but occasionally may be severe. If you have had allergic reactions to these agents before, or if you have asthma or multiple allergies, you may be at higher risk for a reaction. Let your doctor know if you have any of these conditions that would increase your risk.  If a patient has an allergic reaction during the exam, our radiologists are prepared to deal with these situations.

Iodine contrast can also rarely cause kidney toxicity in people with certain medical conditions, which include but are not limited to: kidney failure, diabetes, multiple myeloma, severe dehydration, hyperuricemia (seen with gout), and heart failure. If you fall into one of these categories, or if you are over the age of 55, a blood test will be needed prior to the study to measure your kidney function.

What preparation is needed?
For a head, chest, abdomen or pelvic scan, take nothing by mouth other than required oral contrast material if needed four hours before the exam and nothing to drink two hours before the exam. Otherwise no special preparation is necessary.  You can pick up the oral contrast material any time prior to your scheduled exam and the staff will provide you directions.

What should I wear?
For some of the scans you will be asked to change into a gown. Wear something that is comfortable and easy to remove.

How long will it take?
Allow approximately 30 minutes for this exam, though most of this time is preparatory. The amount of time the machine is actually scanning is usually less than a minute.

What can I expect after the exam?
You should be able to return to your normal activities.

When will my physician get the results?
A HVI radiologist will study the images and provide a written report which includes a description of the findings, any diagnosis that can be made from the exam, as well as a recommendation for further studies if needed. Our reports are usually available within 24 hours of completion of the examination, and are generally received by your physician within that same 24 hour period. A report may be delayed if we are awaiting studies from an outside facility for comparison purposes. If the results are urgent or if you are seeing your doctor on the same day as your exam, our radiologist will provide a preliminary report that will be faxed to your doctor, or in some cases, discussed directly with your doctor.