CT Scan

CT stands for computed tomography, and the scan is also called a CAT (computed axial tomography) scan. This technology was developed in the early to mid-1970s and is now widely available. It’s a fast, patient-friendly method of looking at soft tissue, bone and blood vessels.

How does it work?

What to expect

Contrast or dye

What happens during the test

How does it work?
CT combines the use of a computer together with a rotating X-ray device to create detailed cross-sectional images or “slices” of the different organs and body parts, such as the kidneys and blood vessels. CT is one of the best tools for looking at the abdomen and lungs. It’s very helpful in diagnosing cancer and in measuring bone density. It’s also a very good tool for looking at the pelvis and hips, reproductive system and bladder.

What to expect
Patients are encouraged to bring something to read or do in case there are delays. Wear comfortable, loose-fitting clothing. You will be asked to remove any articles of clothing that might interfere with the images such as jewelry, belts, earrings, bras, glasses, dentures, hairpins, zippers or snaps.

The test doesn’t hurt, and people are rarely claustrophobic in the CT scanner. The test takes anywhere between 10 and 45 minutes. You cannot have the test if you are pregnant or think you might be pregnant. If you are nursing, tell your physician.

Contrast or dye
Many CT exams use an oral or IV agent (injected into a vein) to make the image better. If the dye is oral, you’ll have to drink it, and if it’s IV, it will be injected into a vein in your arm. If you have any allergy to shellfish or dye or iodine, or have asthma or hay fever, or if you’ve ever had hives, tell your doctor and the X-ray technician before your test. Also, if you have diabetes or a heart, kidney or thyroid condition, tell your doctor and the X-ray technologist. These conditions might indicate a higher risk of iodine reactions or problems with the iodine after the exam.

If contrast is ordered for you, you may not be able to drink anything for several hours before the exam.

Overall, dye is safe and has been used for many years in millions of CT studies without serious side effects. The dye increases the quality of the test. The most common side effect of iodine is a warm or hot-flushed sensation during the injection and a metallic taste in the mouth, which usually lasts less than a minute or so.

Another mild reaction that can happen after the iodine is itching. This can last for several minutes or even several hours after the injection. Tell the radiologists – there is medication to help.

More serious reactions, although much less likely, include breathing difficulty, swelling of the mouth and throat, or swelling of other parts of the body. These reactions become more serious if not treated immediately.

With newer types of non-ionic dyes, the risk of an allergic reaction can be even less.

What happens during the test
You are positioned on a long, thin table. The area of interest – for example, the kidneys – is positioned inside the CT opening. The scanner is shaped like a giant donut.

Once you are comfortable and correctly positioned, the technologist leaves the room. You may be asked to hold your breath and remain perfectly still for a short time, up to about 30 seconds, while the technologist takes the pictures. During the CT scan, you can talk to the technologist over an intercom. The technologist watches you from a window during the whole procedure.

You should lie still and relax as much as you can during the CT study. You may hear the CT scanner rotating during the study, making a whirring noise. The table will move very slowly, in small increments, during the test. You may see the big donut tilting in either direction. Don’t be alarmed – it’s not going to come anywhere near you.

If contrast is being used, the technologist will now come into the room and give you the dye. The technologist will then take more study pictures, just like before. After the test, the technologist will want to look at the films before you leave, to make sure the pictures are good. Sometimes the images might not turn out well, and the technologist will want to re-take some of the pictures.

When the technologist is sure the pictures are OK, you can get dressed and go. You should drink lots of fluids to help flush the dye from your system. You can return to normal activities immediately.

The technician will not give you the results of your study. The office staff of your urologist will call you with the results.