CT Colonography

What is CT Colonography?

CT colonography (CTC) is a minimally invasive CT exam that produces a 3D view of the colon. Doctors use this exam to check the colon for polyps. A polyp is an abnormal growth of tissue, which is often not cancer, but some can develop into cancer. This exam does not require sedation and typically takes about 20 to 30 minutes.

CT colonography uses contrast to help us see the images more clearly. There are two kinds: the kind you drink (oral contrast) and the kind you get through an IV (IV contrast). A CT colonography uses oral contrast and may also use IV contrast. The liquids you drink from the pharmacy to prepare for this exam act as the oral contrast during your CT colonography.

The benefits of using contrast typically outweigh any potential risk. We carefully asses your risk before giving you contrast.

How to Prepare for CT Colonography

You can log into Patient Gateway for more details about your specific appointment.
  • When to Arrive - Please arrive 30 minutes before your appointment so we can properly prepare for your imaging.
  • Medication -  Keep taking your medications as prescribed. If you need to take diabetes pills or insulin medicine while preparing for your CT colonography, please talk to the doctor who helps you manage this condition before your appointment.
  • Eating & Drinking - Stop eating solid foods starting at midnight the day before your exam. The only foods you can eat include chicken, beef or vegetable broth, Jello-O, popsicles, clear hard candy or gum. The only drinks you can have include all colors of Gatorade and POWERADE except for the color red. You can drink water, black tea or coffee, Vitamin Water, Crystal Light, apple or white grape juice, soda, iced tea or no-pulp lemonade. Do not drink orange, tomato, grapefruit or prune juice. Your doctor who ordered this exam will provide you with a more detailed guide on what you can and cannot have in preparation for a CT colonography exam.
  • Diabetes - If you are diabetic, talk to your doctor before starting the colon cleaning prep. You may need to change the time when you take your diabetes medicine. You should also test your blood glucose level more frequently during colon cleaning prep. 
  • Clothing - Please wear loose, comfortable clothing that's easy to change in and out of. We will ask you to change into hospital attire for clearer images.
  • Valuables - We suggest you leave your valuables at home so you don’t have to worry about them. You can keep your things with you during your exam.
  • Children - Children are not allowed in the exam room. If you need to bring kids, please bring someone to watch them in the waiting room.

Patient Resources

Use these patient resources to learn more about getting a CT colonography at Mass General Imaging. You can contact us if you have any questions.

How to Prepare for Your CTC
How to Prepare for CT Colonography

How to Prepare for CT Colonography

This guide will help you prepare for your imaging by properly cleaning out your colon.

download ct screening form
CT Screening Form

CT Screening Form

You can print this CT screening form and fill it our before your appointment.

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Checking In

Checking In

Find out what happens when you check in and why we keep asking for your date of birth.

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CT and Radiation

CT and Radiation

We pay special attention to minimizing radiation exposure. Find out how.

order your images
Order Your Images

Order Your Images

You can order your images online or in person.

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Get Your Results

Get Your Results

Most imaging results are in Patient Gateway in about a week. Sign in or sign up now.