Virtual Colonoscopy: A Comprehensive Guide to CT Colonography for Colorectal Cancer Screening

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• What is Virtual Colonoscopy?
• How Virtual Colonoscopy Works
• Patient Preparation and Experience
• Benefits of CT Colonography
• Virtual Colonoscopy vs Regular Colonoscopy
• Full Transcript

What is Virtual Colonoscopy?

Virtual colonoscopy, also known as CT colonography (CTC), is a modern, minimally invasive medical imaging procedure. Dr. Perry Pickhardt, MD, a leading gastrointestinal radiologist, describes it as a specialized CT scan designed to examine the colon and rectum. The primary purpose of CT colonography is colorectal cancer screening and the detection of precancerous polyps. This makes it a powerful tool for the early prevention of colorectal cancer, which is the second leading cause of cancer death.

How Virtual Colonoscopy Works

The CT colonography procedure begins after the patient's colon has been prepared and distended. A CT scanner then captures detailed images of the entire large intestine in a single breath-hold. Dr. Perry Pickhardt, MD, explains that these images are processed using advanced CT colonography software. Radiologists use this system to perform a virtual "fly-through" of the colon, employing both 2D and 3D imaging methods to meticulously inspect the colon lining for any abnormalities, including polyps and cancers.

Patient Preparation and Experience

Patient preparation for a virtual colonoscopy involves a bowel cleansing regimen and colon distention. Dr. Perry Pickhardt, MD, notes that the bowel preparation for CT colonography is typically a low-volume solution. This is generally much better tolerated by patients than the standard preparation required for a traditional optical colonoscopy. For distention, carbon dioxide is gently pumped into the colon. This method is very safe and performed at low pressure, maximizing patient comfort during the procedure.

Following the quick CT scan, which is completed in a matter of seconds, the patient's role is complete. Dr. Anton Titov, MD, highlights one of the key advantages: patients can immediately return to their regular daily activities without the need for sedation recovery.

Benefits of CT Colonography

The benefits of virtual colonoscopy extend beyond its non-invasive nature. Its high accuracy in detecting significant precancerous polyps makes it an excellent screening tool for preventing colorectal cancer. Furthermore, as Dr. Perry Pickhardt, MD, points out, the CT scan captures images of areas outside the colon. This means a virtual colonoscopy can incidentally detect other cancers and conditions within the abdomen, providing additional value to the patient.

Virtual Colonoscopy vs Regular Colonoscopy

When comparing virtual colonoscopy vs regular colonoscopy, several key differences emerge. The patient experience is often superior with CT colonography due to the easier bowel prep and the absence of sedation. However, a crucial distinction is that a traditional colonoscopy is both a diagnostic and therapeutic procedure; if a polyp is found, it can be removed during the same session. A finding on a virtual colonoscopy would typically require a follow-up procedure for removal. Dr. Anton Titov, MD, and Dr. Perry Pickhardt, MD, discuss how both methods are vital in the fight against a largely preventable disease.

Full Transcript

Dr. Anton Titov, MD: Leading gastrointestinal radiologist discusses CT colonography, or virtual colonoscopy. What exactly is virtual colonoscopy? How does virtual colonoscopy help to find early colorectal cancer?

Let's start the discussion with the virtual colonoscopy definition. Colon cancer is the second most common cancer in the world. Almost 1.5 million people are diagnosed with colorectal cancer every year. Yet colon cancer is entirely preventable if everyone was screened for it.

Today, virtual colonoscopy is becoming the colon cancer screening method of choice. It is also called computed tomography colonography, or CT colonography.

You are one of the world's foremost experts on virtual colonoscopy. What is virtual colonoscopy? How can it help in effective screening for colorectal cancer?

Dr. Perry Pickhardt, MD: Sure! As you pointed out, colorectal cancer is the second leading cause of cancer death in the U.S. Unlike the other major cancer killers, it is largely preventable. You prevent colon cancer through prevention and screening. Prevention is detection of precancerous lesions.

CT colonography, CTC, virtual colonoscopy, VC—I will use those terms interchangeably. It is really nothing more than a CT scan with a twist.

The patient has undergone some form of bowel preparation and colonic distention. The bowel preparation is generally a low volume bowel preparation. It is much better tolerated than the typical colonoscopy bowel preparation.

The bowel distention is done with carbon dioxide. It is very safe and low pressure bowel distention. The CT scans are performed in a breath-hold. After that, the patient's part is done.

They can basically go back to their regular activities. At that point, the CT images are sent to a specialized visualization system. It is called a CT colonography software system. We fly through the colon. We do a number of 2D and 3D imaging methods to look for polyps and cancers.

Dr. Anton Titov, MD: Virtual colonoscopy is quite easy and straightforward. How does virtual colonoscopy work? Virtual colonoscopy, or CT colonography, is the best screening method for colorectal cancer. Virtual colonoscopy also detects cancers outside the large bowel. Virtual colonoscopy versus regular colonoscopy can provide better patient experience and less inconvenience before and during the procedure.