 To improve the diagnostic performance of CTC in the prepared colon using improved spatial resolution, advanced image displays, and computer-assisted diagnosis, and to optimize diagnostic performance of CTC in the unprepared colon for colorectal polyp detection using electronic stool subtraction and computer-aided diagnostic techniques. To estimate the sensitivity and specificity of CTC in the unprepared colon for clinically important colorectal neoplasms large adenomas 1 cm and to compare such estimates with colonoscopy. To survey patient acceptance of CTC in the unprepared colon, and to assess implications for health care costs and cost-effectiveness of CTC in the unprepared colon in comparison with other approaches. 