Figure 21. Volume renderings of anatomic structures segmented from spiral CT scan of patient with colon cancer. Upper images show transparency and skin removed to reveal sections of bowel selected for segmentation, as well as circumferential rectal cancer (red). Lower images show rotated views. A mid-sigmoid polyp (blue) can be seen in the oblique posterior view of the isolated bowel at lower right. (Scan data courtesy of Dr. Michael Vannier, Washington University.)