Why Use Virtual Colonoscopy?
The first question that needs to be asked and answered is: “Why consider virtual colonoscopy at all?” After all, there are other techniques available to evaluate the colon, including fecal occult blood testing, sigmoidoscopy, barium enema, and conventional colonoscopy. (See section of this website entitled "Traditional Methods of Colorectal Screening: Advantages, Problems, and Comparisons.")
Like conventional colonoscopy, virtual colonoscopy allows for the evaluation of the entire surface of the colon for polyps and cancers. So far, virtual colonoscopy has shown promise in detecting 75 to 100 percent of polyps and cancers of the colon and rectum that are 10 mm in diameter or wider (1, 3, 25-31). In addition, a recent study showed that among potential patients considering colon cancer screening, 60.2 percent favored the idea of virtual colonoscopy, 25.7 percent preferred the idea of conventional colonoscopy, and 14.1 percent had no preference (32). However, in this same study, physicians generally favored conventional colonoscopy because it allowed direct visualization of the mucous membrane of the colon and rectum with the opportunity to excise and biopsy suspicious lesions.
So returning to the original question: “Why should we pursue the clinical evaluation of virtual colonoscopy?” Colorectal cancer is preventable or curable if detected early. Yet there are limitations to the current available screening options and many patients are reluctant to undergo colorectal screening. The disease still affects an unnecessarily large number of people (150,000/year) and many die from it (60,000/year). If virtual colonoscopy can prove effective in detecting precancerous lesions it would aid in the ability to screen the large number of patients who are currently eligible for screening. In addition to its use as a screening test, there are numerous other potential clinical uses for virtual colonoscopy. These include evaluating the colon after an incomplete traditional colonoscopy examination or near an obstructing cancer, in elderly patients, in patients with another serious illness, and in patients who are unable to tolerate sedation.