Three-dimensional (3D) imaging of the large intestine is globally called computed tomography colonography (CTC). CTC has been intensively investigated for application in colorectal cancer screening in Western countries and with the advent of multi-slice CT (MSCT), which provides effective high resolution in 3D CT images, the diagnostic use of CT for colorectal lesions has become a concept widely accepted throughout the world. Computer-aided detection (CAD) for colorectal polyps using digital CT image data and digital pre-processing are also advancing in the West. Compared with colonoscopy, which depends largely on the skill of the performer, CTC produces objective and reproducible diagnostic images and presents a high probability of standardizing examination protocols. Development of effective systems for screening colorectal lesions is expected, leveraging the excellent processing capability of MSCT to enhance 3D visualization and allow efficient detection.