Computed Tomographic Colonography (CTC)

Computed Tomographic Colonography, also known as Virtual Colonoscopy, is a medical imaging procedure used to visualize the colon and rectum. It uses computed tomography (CT) scans to produce high-resolution images of the colon and rectum, allowing for the detection of polyps, tumors, and other abnormalities.

Procedure

The CTC procedure typically involves the following steps:

• The patient is instructed to prepare for the exam by following a special diet and bowel preparation regimen, which may include laxatives or enemas to cleanse the colon.
• The patient lies on a table that slides into the CT scanner, a large, doughnut-shaped machine.
• A small tube is inserted into the rectum to inflate the colon with air or carbon dioxide, which helps to distend the colon and provide clearer images.
• The CT scanner takes a series of X-ray images of the abdomen and pelvis, which are then reconstructed into detailed cross-sectional images of the colon and rectum.
• The procedure typically takes about 10-15 minutes to complete.

Indications

CTC is commonly used for:

• Screening for colorectal cancer in average-risk individuals
• Detecting polyps and tumors in the colon and rectum
• Evaluating symptoms such as abdominal pain, changes in bowel habits, or bleeding
• Monitoring patients with a history of colorectal cancer or polyps

Advantages

The advantages of CTC include:

• Less invasive than traditional colonoscopy
• No sedation required
• Faster procedure time
• Lower risk of complications, such as bleeding or perforation
• Able to visualize the entire colon and rectum, including areas that may be difficult to reach with traditional colonoscopy

Limitations

The limitations of CTC include:

• May not detect small polyps or flat lesions
• Requires bowel preparation and air insufflation, which may cause discomfort
• Exposes patients to radiation, although the dose is typically low
• May require additional testing, such as colonoscopy, if abnormalities are detected

Interpretation

The images obtained from CTC are interpreted by a radiologist, who looks for signs of polyps, tumors, or other abnormalities. The results are typically reported as:

• Normal: No abnormalities detected
• Polyp(s) detected: One or more polyps are present, which may require removal and further evaluation
• Tumor detected: A tumor is present, which may require biopsy and treatment
• Inconclusive: Additional testing, such as colonoscopy, may be required to confirm the diagnosis