Figure 2. A, Coronal image of an isotropic volume data set generated from CT colonographic images in a 70-year-old woman. B, Image of the segmented colon obtained with an application of a segmentation algorithm to the isotropic volume in A. Our segmentation algorithm segments a thick region that contains the entire colon and not only the surface of the colonic wall. A portion of the small intestine (arrow) contiguous to the colon was extracted with the entire colon. Volumetric features used for the detection of polyps were calculated from individual voxels in this thick region.