Colorectal cancer is the 3rd most common type of cancer and the 3rd leading cause of cancer death in the United States. Colonoscopies have long been the standard screening procedure for detecting growths in the colon, but CT Colonography is a comparably accurate, non-invasive alternative. Ask your care provider to refer you to UVA Radiology and Medical Imaging for your CT Colonography.
Understanding Colorectal Cancer
Doctors usually refer to cancer in the colon or rectum as colorectal cancer. Before we talk about what colorectal cancer is and how doctors screen for it, it’s helpful to know where the colon and rectum are and what they do.
The colon (also known as the large intestine) and rectum are the final parts of the body’s digestive system. After food is swallowed it enters the stomach, where digestive juices begin to break it down. A thick slurry of solid food and liquid passes from the stomach to the small intestine, where nutrients are absorbed into the bloodstream. Next, the material moves to the colon, where the liquid is absorbed and the remaining solid material is passed to the rectum. The rectum connects the colon to the anus. It’s where this solid material, or stool, is stored until it is eliminated from the body.
Abnormal collections of cells called polyps can attach to and grow on the inner lining of the colon or rectum. Most polyps are non-cancerous, but colorectal cancer often develops from one particular type of polyp, called adenomas. The goal of a colorectal cancer screening is to detect and remove adenomas and other polyps as early as possible, before they become cancerous.
Who Should Be Screened?
According to the American Cancer Society, everyone aged 45 to 75 should be screened for colorectal cancer. People at a greater risk include anyone over 60 years old, and anyone with a family or personal history of colorectal cancer, inflammatory bowel disease, or cancer of the ovary, breast or endometrium. Smoking cigarettes, drinking alcohol regularly or consuming a high-fat, low-fiber diet also put you at increased risk for colorectal cancer.
Traditional Colonoscopy vs. CT Colonography
A traditional colonoscopy is the most widely known colorectal cancer screening procedure, but many patients are choosing a non-invasive CT (computerized tomography) Colonography instead. A CT Colonography doesn’t require sedation and is just as accurate at detecting most precancerous polyps.
For a traditional colonoscopy, a doctor inserts a flexible metal tube with a camera on the end into the colon through the rectum. The tube is maneuvered through the entire length of the colon, which is usually 5 to 6 feet long. If a doctor finds a polyp during a colonoscopy, he or she can remove it without the need for another procedure. Because the tube is inserted throughout the entire colon, there is a slight risk of colon perforation or bleeding.
During a CT Colonography, a small tube is inserted a few inches into the rectum to gently inflate the colon with gas or air. This helps make the images of the colon clearer. A low-dose radiation CT Scanner then produces images of the entire colon. If polyps are found, however, an additional colonoscopy will be needed to remove them.
Both screening procedures require bowel cleansing to ensure that the colon and rectum are empty.
We’ve created this diagram to show you a few other key differences between a traditional colonoscopy and a CT Colonography:
To schedule a non-invasive CT Colonography, speak with your care provider. To learn more about imaging specialties or procedures performed by the highly skilled radiologists at UVA, visit https://uvahealth.com/services/imaging or call (434) 243-0321.
Infographic Text: Traditional Colonoscopy vs. CT Colonography
Traditional Colonoscopy
45-60 minutes
5-6 feet of tubing
Usually requires sedation
No radiation
Entire colon screened
CT Colonography
15 minutes
2-3 inch probe
No sedation
Low dose of radiation
Entire colon screened. Can also detect other issues in your abdomen.
FAQs
CT colonography has a much lower risk of perforating the colon than conventional colonoscopy. Most people who undergo CT colonography do not have polyps and can be spared having to undergo a full colonoscopy which typically requires sedation.
Which is better, CT colonography or colonoscopy? ›
A drawback of CT colonography is radiation exposure, and finding unrelated abnormalities outside the colon that can lead to unnecessary tests. While CT colonography is about 88.7% accurate at finding certain polyps, it is less accurate than colonoscopy overall.
Why a CT scan instead of a colonoscopy? ›
CTC works by taking hundreds of x-ray 'slices' through the body which are then processed by a computer to create a 'virtual' 3D image of the inside of the bowel, similar to what is seen during colonoscopy. CTC is a less uncomfortable test and, unlike colonoscopy, patients do not need to be sedated.
What can a colonoscopy see that a CT Cannot? ›
CT scans utilize X-rays to form images of organs and tissues inside the body (for example, abdominal organs, brain, chest, lungs, heart) while colonoscopy is a procedure that can visualize only the inside surface of the colon.
What is the best screening test for colon cancer? ›
Colonoscopy is one of the most sensitive tests currently available for colon cancer screening. The doctor can view your entire colon and rectum. Abnormal tissue, such as polyps, and tissue samples (biopsies) can be removed through the scope during the exam.
How reliable is a CT colonography? ›
Colorectal cancer is the 3rd most common type of cancer and the 3rd leading cause of cancer death in the United States. Colonoscopies have long been the standard screening procedure for detecting growths in the colon, but CT Colonography is a comparably accurate, non-invasive alternative.
What is the best imaging for colon mass? ›
CT is the mainstay for colon cancer locoregional staging and MRI is the mainstay for rectal cancer locoregional staging.
Why do doctors avoid CT scan? ›
CT does expose patients to ionizing radiation, which may marginally increase their lifetime cancer risk. But your physician considers this very small risk to be outweighed by the importance of discovering cancer or another potentially serious problem. Women who are pregnant or breastfeeding should avoid CT.
Why was my CT colonography so painful? ›
You may have some bloating or pain in your abdomen after the test. This is due to the carbon dioxide or air put into the bowel. This should go away shortly afterwards. There is a small risk of a tear (perforation) in your bowel.
What is the new procedure instead of a colonoscopy? ›
Virtual colonoscopy is a special X-ray examination of the colon using low dose computed tomography (CT). It is a less invasive procedure than a conventional colonoscopy. A radiologist reviews the images from the virtual colonoscopy to look for polyps on the inside of the colon that can sometimes turn into colon cancer.
Alternatives to colonoscopy include sigmoidoscopy, which is a less invasive form of colonoscopy, and noninvasive methods, such as stool sample testing.
Do colon polyps show up on a CT scan? ›
In a number of studies, CT colonography has displayed results equivalent to colonoscopy in both cancer and polyp detection. CT colonography has been shown to rapidly and effectively examine the entire colon for lesions.
Do you need bowel prep for CT colonography? ›
What do I have to do before my CT Colonography? To enable the doctor to have a clear view of your bowel lining, your bowel will need to be prepared before the test. To do this we will ask you to drink a liquid called Gastrografin and to follow a limited diet the day before the test.
What is the most reliable test for bowel cancer? ›
The main test for bowel cancer is a colonoscopy. This is where a thin, flexible, tube with a camera is used to look inside your bowel. It may be uncomfortable but it should not be painful. You'll be offered a sedative and painkillers to help make you feel more comfortable.
What is the new screening for colon cancer? ›
On July 29, the FDA approved the Shield blood test for primary screening of colorectal cancer, according to test manufacturer Guardant Health. The test could be available in doctor's offices within a week, and the test should be covered by Medicare.
What are the two most commonly used screening methods for colon cancer? ›
Studies show that some screening tests for colorectal cancer help find cancer at an early stage and may decrease the number of deaths from the disease. The following types of tests are used to screen for colorectal cancer: Fecal occult blood test. Sigmoidoscopy.
Is CT colonography more expensive than colonoscopy? ›
Because of the higher participation rates, CT colonography screening for colorectal cancer is more cost-effective than colonoscopy screening.
What are the advantages of CT colonography? ›
CT colonography provides clearer and more detailed images than a conventional barium enema x-ray examination. CT colonography can detect abnormalities outside of the colon, including early-stage malignancies in other organs and potentially dangerous conditions, such as abdominal aortic aneurysms.
How painful is a CT colonography? ›
You may feel uncomfortable and bloated. Rarely, people have pain. This 2 minute video shows how you have a CT colonography.
