Colorectal cancer is the third most common cancer in the United States, with early detection being crucial for improved treatment outcomes and survival rates1. While colonoscopy remains the gold standard for screening, Computed tomography (CT) scans have emerged as a valuable tool in detecting colorectal cancer, especially when colonoscopy is not feasible or for patients at higher risk2.
CT colonography, or virtual colonoscopy, offers a less invasive alternative to traditional colonoscopy. It can detect abnormalities inside and outside the colon, including early-stage malignancies in other organs3.
A computed tomography (CT) scan is a diagnostic imaging procedure that uses X-ray technology and computer processing to create detailed cross-sectional images of the body4. It produces more detailed images than standard X-rays, allowing healthcare professionals to visualize internal structures such as bones, muscles, organs, and blood vessels.
CT scans are advanced medical imaging techniques that use X-rays and computer processing to create detailed cross-sectional images of the body. The technology involves a rotating X-ray tube and detectors that measure X-ray attenuation through different tissues5. These measurements are then processed using tomographic reconstruction algorithms to produce virtual “slices” of the body.
The CT machine consists of a motorized table that moves the patient through a circular opening called the gantry6. Inside the gantry, an X-ray source and detector assembly rotate around the patient, typically completing a rotation in less than a second. As the X-rays pass through the body, detectors register the radiation that emerges, creating snapshots from various angles. The computer then reconstructs these snapshots into cross-sectional images or slices of the internal organs and tissues.
CT scans offer several benefits for colon cancer detection.
CT colonography demonstrates high accuracy in detecting colorectal cancer and large polyps. Studies have shown:
CT colonography is less invasive than traditional colonoscopy. No sedation is required, so patients can return to normal activities immediately after, and a lower risk of bowel perforation (1 in 3,000 cases for CT vs. higher risk of colonoscopy)9,10.
CT scans are also quick and painless, typically taking between 15 and 30 minutes in total.
While colonoscopy remains the gold standard for colorectal cancer screening, CT colonography offers a viable alternative, especially for patients who cannot undergo or do not wish to have a colonoscopy. CT colonography has shown higher detection rates for advanced growths in the colon than a single round of fecal immunochemical testing (FIT)11. It also performs about as well as a partial colonoscopy (sigmoidoscopy) in finding potentially dangerous growths.
CT colonography is recommended for several groups of individuals:
It should be noted that while CT colonography is a valuable screening tool, it should be used in conjunction with other screening methods as recommended by healthcare providers.
Proper preparation is essential for a successful CT scan.
If your scan requires it, you may have to fast for four hours before your appointment time15. You can drink clear fluids and take medications as normal10. Diabetic patients can have a light snack if necessary but should avoid large meals. If contrast material is needed, you might be asked to drink water or a special liquid contrast.
You will likely be asked to change into a hospital gown for the scan. Remove any metal items, including jewelry, from the area being scanned. Wear comfortable, loose-fitting clothing to your appointment.
If your CT requires contrast, an IV line may be placed in your arm or hand to inject the contrast dye16. You might be given an oral contrast to drink, which helps highlight your digestive tract. Before contrast is administered, you should inform your healthcare provider if you have any allergies, especially to iodine or contrast materials.
You should inform your doctor if you’re pregnant or think you might be. Tell your healthcare provider about any medical conditions, recent illnesses, or medications you’re taking. If you’re taking metformin for diabetes, you may be asked to temporarily stop this medication17.
A CT scan is a quick and painless imaging procedure that provides detailed images of your internal organs and structures. The entire CT scan process usually takes between 15 and 30 minutes, with the actual scanning time being 10 to 15 minutes. You’ll lie on your back on a table that moves through the CT scanner, which looks like a large doughnut. The table will slowly slide you into the scanner, and you’ll need to remain still during the imaging process.
As the table moves through the scanner, you’ll hear whirring or buzzing noises from the X-ray machine rotating around you. The radiographer will operate the scanner from another room but can see and communicate with you via an intercom. You may be asked to hold your breath briefly at certain points to ensure clear images. If you feel anxious, inform the radiographer, who can advise you on staying calm. For those prone to claustrophobia, it’s reassuring to know that the CT scanner doesn’t completely enclose your body, reducing the likelihood of feeling confined.
CT scans are considered safe and use low levels of radiation18. The procedure is painless and non-invasive. While lying still might be uncomfortable for some, the scan itself doesn’t cause physical discomfort.
Remember, your radiographer ensures your comfort and safety throughout the procedure. Don’t hesitate to communicate any concerns you may have during the scan.
CT scans can often differentiate between diverticulitis and colon cancer, but there is some overlap in their imaging appearance. Studies have shown that CT scans can achieve up to 96 percent accuracy in making a correct, unequivocal diagnosis19. In some cases, an experienced radiologist can make a definitive diagnosis with nearly 100 percent accuracy. However, there is still an overlap in about 10 percent of patients.
The cost of CT colonography can vary depending on several factors. The average cost ranges from $330 to $1,081, depending on the scenario and site of service. Including associated services, referrals, and potential complications, the total cost can increase to $1,44020. In comparison, traditional colonoscopy prices can range from $997 to $10,54121.
CT colonography offers a reliable, non-invasive alternative for colorectal cancer screening, making it particularly valuable for patients unable or unwilling to undergo traditional colonoscopy. With high accuracy, reduced risks, and shorter procedure times, it effectively identifies cancer, large polyps, and other abnormalities. Proper preparation and understanding of the procedure enhance its success, providing patients with a safe and painless diagnostic experience. While CT colonography cannot entirely replace traditional colonoscopy, it plays a crucial role in early detection and comprehensive screening strategies.
If you want to be proactive about your health, why not book an Ezra Full-Body Plus scan? We combine MRI with low-dose CT to catch abnormalities earlier, leveraging AI through the screening process to make it more efficient, affordable, and faster.
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