Got back pain questions? Our Back Wellness Coaches have answers. Text Us Now at 412.419.2225. It's FREE!

7 Things You Need to Know About Having a CAT (CT) Scan

Published May 22, 2017

Have you ever wondered what the difference between a CAT scan and a CT scan are? Maybe you never did until you read this headline, and if so, we won't hold it against you. Actually, the fact that the headline made you want to read this, we are virtually hugging you right now.

To get right to it, let's start at the beginning. 

In the health care arena, a diagnostic test is any kind of medical exam utilized to assist in the diagnosis, detection and illness progression of a specific condition or disease (just like your back pain!)

Various exams include an MRI, X-ray, ultrasound, and CAT/CT scan (among others). We can take how a spine surgeon uses a CT scan to identify a back pain diagnosis as an example of how important tests like these are. You can't fix something if you don't know what's causing it to break. These tests are part of the first steps in properly diagnosing your back pain symptoms. We'll get to the details on how it works in a few more lines. 

Now, maybe you associate a CT scan with a CAT scan. Do you know what they mean? Do you know exactly what they are?

Look no further.

What is a CAT Scan?

By definition, a CAT scan is: an X-ray image of a specific portion of the body made using computerized axial tomography.

What is a CT Scan?

Ironically enough, a CAT scan and a CT scan...

...are the same thing! A CT scan is another term for a CAT scan.

At the start of these diagnostic tests, they weren't referred to as a CAT scan or CT scan at all. They were actually known as an EMI scan, named for the Emergency Medical International (EMI) Company that developed and originated the equipment.

The equipment makes use of computer-processed combinations of many X-ray images taken from various angles to produce cross-sectional (tomographic) images (virtual ‘slices’) of specific areas of a scanned object, allowing the doctor to see inside the object without cutting anything open.

The term CAT was used earlier in history, while CT is the most recent term for the sake of convenience.

The term CT stands for computed tomography and the term CAT stands for computed axial tomography or computerized axial tomography scan. Even though a CT scan is more modern, some medical professionals still use the term CAT scan, according to the CT Manager at Children's Cincinnati in Ohio, Erica L. Gates.

Now that we understand they are referring to the same exam, what can you expect from a CAT/CT scan?

How You Prepare for a CT Scan

Depending on which part of your back or spine is being scanned, you may be asked to:

  • Take off some or all of your clothing and wear a hospital gown
  • Remove metal objects, such as a belt, jewelry, dentures, and eyeglasses, which might interfere with image results
  • Refrain from eating or drinking for a few hours before your scan
  • Contrast material

A special dye called a contrast material is needed for various CT scans. The dye helps to highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures.

A contrast material might be given to you by:

  • Mouth If your esophagus or stomach are being scanned, you may need to swallow a liquid that contains contrast material. This drink may taste unpleasant, but the after taste should only last a few moments.
  • Injection — Contrast agents may be injected into a vein in your arm to help your gallbladder, urinary tract, liver, or blood vessels stand out on the images. You may experience a feeling of warmth during the injection or a metallic taste in your mouth. Both side effects will only last a few minutes as well.
  • Enema — A contrast material may be inserted into your rectum to help visualize your intestines. This procedure can make you feel bloated and uncomfortable. If you are receiving the contrast material via enema, you will want to cancel any plans you may have later that day so you can focus on resting and leave any to-do lists until the following day.

What can I Expect?

You can have a CT scan done in a hospital or an outpatient facility. CT scans are painless. Modern technology has made this exam extremely easy — normally, you are in and out within 30 minutes.

During the CT Scan

CT scanners are shaped like a large doughnut, standing on its side. You would lie on a narrow, motorized table that slides through the opening into a tunnel. It can look a little intimidating but do not be afraid. You guys are Backer warriors after all. Straps and pillows may be used to help you stay in position. During a head scan, the table may be fitted with a special cradle that holds your head still.

While the table moves you into the scanner, detectors and the X-ray tube rotates around you. Each rotation yields several images of thin slices of your body. You may hear buzzing, clicking and whirring noises. Do not be alarmed. That is normal.

You will lay in the scanner alone, but a technologist, in a separate room can see and hear you. You will be able to communicate with the technologist via intercom. If anything scares you, share your fears with the tech.

The technologist may also ask you to hold your breath at certain points to avoid blurring the images. You want to lay extremely still to ensure all photos are properly captured.

Before you know it, you will be done. 

After the CT Scan

After the exam, you can return to your normal routine.

If you were given a contrast material, you may receive special instructions. In some cases, you may be asked to wait for a short time before leaving to ensure that you feel well enough to leave following the exam.

After the scan, you'll likely be told to drink lots of fluids to help your kidneys remove the contrast material from your body.

If you have any questions or are not feeling yourself, ask to talk with the doctor. They will be able to assist in any contrast side effects — if any. Normally, most people are able to return home like it never happened.


CT images are stored as electronic data files and are usually reviewed on a computer screen. A radiologist interprets these images and sends a report to your doctor. Your doctor will be the only person who can give you the diagnosis from the results. If you want your results quickly, feel free to contact your physician's office to expedite your images.

Last change: January 27, 2019