Abstract: A generally non-invasive method of colon examination in which the patient's colon is first inflated with gas, and then a plurality of cross-sectional images of the colon are taken by CT scanning along the longitudinal axis of the abdomen. Sets of data corresponding to each cross-sectional image are stored in computer memory. These sets of data are processed by a first computer program that reconstructs a three-dimensional model of the entire colon. Data corresponding to the reconstructed three-dimensional model of the colon are also stored in computer memory. A second computer program processes the original sets of data and the three-dimensional model data to reconstruct, for successive thin segments along the length of the entire colon, a cross-sectional image for each segment which is perpendicular to the longitudinal axis of the colon lumen.