**1. Introduction**

Colorectal carcinoma ranks as the third most commonly diagnosed cancer and the second leading cause of death from cancer in the United States [1]. It is estimated that more than 150,000 new cases are diagnosed with more than 50,000 dying from the disease yearly in the U.S. alone [1]. Similar to other cancers, it is often diagnosed at advanced stage, after the patient has developed symptoms. Many colon cancer deaths can be avoided because mostly they arise from adenomatous polyps, which may be detectable years before malig‐ nant transformation.

Since the first report of a complete examination of the entire colon using a flexible endo‐ scope, optical colonoscopy (OC) has evolved to be the current gold standard for evaluation of the colon [2]. OC has several limitations and drawbacks as a population-based screening tool. It is an invasive procedure requiring sedation. An escort is usually required to take the patient home, which increases the cost of the procedure from a societal perspective. OC also carries a small but significant risk of perforation and death. The risk of colonic perforation is about 1 per 1,000 cases and death is approximately 1 in 5,000 cases [3-5]. Failure to reach the cecum (5-10%) and missed polyps (10-20%) also are known limitations of the current gold standard test [6-9].

Computed tomographic colonography (CTC), also known as "virtual colonoscopy" was first described more than a decade ago [10]. In the early 1990's, several pilot studies evaluated the feasibility of (CTC) [11]. The advantages of developing a computerized-based screening tool includes: increased accessibility, non-invasiveness, and no sedation required [12]. These advantages of CTC may help to increase compliance with current screening recommenda‐ tion guidelines [13].

© 2013 Richards and Liang; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
