Conventional vs. Virtual Colonoscopy
Colon cancer, also referred to as colorectal cancer, is the second leading cancer killer in the United States, and the third most common cancer overall. It usually begins with the development of benign colonic polyps which form when cells lining the colon grow in a disorderly fashion. These growths can become cancerous, invading the wall of the colon and surrounding tissue structures. They can even spread to other parts of the body.
Colon cancer can frequently advance without symptoms. These symptoms may include abdominal pain, weight loss, rectal bleeding, or changes in the consistency and frequency of bowel movements.
Anyone over the age of 50 is at risk for developing colon cancer. Those who have a personal history of colon polyps or a family history of colon cancer are at high risk of developing the disease. In addition, those with a personal history of inflammatory bowel disease or other cancers including ovarian and uterine cancer are at high risk for this disease. This risk is the same among males and females and all racial groups.
Colon cancer can be prevented by early detection and removal of polyps in their benign stage with a procedure called colonoscopy. If detected early enough, even colon cancer can be cured with high rates of survival.
Two popular techniques currently exist for detection of colon polyps and cancer: Conventional vs. virtual colonoscopy (VC). Conventional colonoscopy enables a safe and effective means for visual inspection of the entire large bowel. The process usually begins a day prior to the procedure with a bowel preparation consisting of a liquid diet and use of laxatives. On the day of the procedure, sedation is given for relaxation and comfort through the intravenous route. A colonoscope is then inserted into the rectum and advanced to the end of the large intestine by a trained gastroenterologist or surgeon. The bowel wall is then carefully visualized and inspected. If any polyps are detected, they can usually be removed at that time and sent for evaluation by a pathologist. There is usually no discomfort during or after the procedure. Patients should not be allowed to drive afterwards due to sedation received during the procedure. Compared with other imaging modalities, colonoscopy is especially useful in detecting smaller and flatter polyps. The main advantage of colonoscopy is its direct ability for intervention, since biopsies can be taken and polyps can be removed at the same time. When performed by a trained expert, there is usually no discomfort following the procedure and the risk of complication is very small.
Virtual colonoscopy (VC) refers to using spiral CT or Magnetic Resonance Imaging (MRI) scanning to simulate colonoscopy by generating high-resolution multidimensional views of the colon. As with traditional colonoscopy, the bowel must be prepared and cleared prior to the study. At the time of the scan, a rectal tube is inserted and the colon is filled with air. A specialized computer is used to process the images obtained. Patients usually complain of more pain and discomfort using this modality since no sedation is given. In addition, this technique currently has less accuracy for detection of smaller and flatter polyps. Removal of polyps which are detected will then need to be accomplished by conventional colonoscopy.
It appears that virtual colonoscopy, in its current form, may not be as accurate as conventional colonoscopy. All the cancer and gastrointestinal societies currently endorse conventional colonoscopy as the test of choice in screening for colon cancer. Ultimately, the best approach is to undergo either procedure as they can both be life-saving.