A method for extracting a colonic centerline includes segmenting a colon from a digital image of a patient's abdomen, selecting one extreme point of the colon as a source point, calculating a first distance transform of every point in the colon that is a distance of a point to the source point, and calculating a second distance transform of every point in the colon, that is a shortest distance of a point to a wall point of the colon. A centerline path is generated through the colon using the first and second distance transforms, starting from a point with a greatest distance to the source point as determined by the first distance transform, and adding points to the centerline path by selecting points with a greatest distance to the source point that are farthest from the wall of the colon using the second distance transform.