Figure 22. Top left -- normal virtual endoscopy view of polyp. Top right -- enhanced visualization of polyp, which was segmented and modeled separately from the colon wall. Bottom left -- transparent view through polyp revealing segmented high density region within polyp. Bottom right -- measurement of diameter and volume of polyp from wire grid surface, also showing dense vascular bed. This capability of virtual endoscopy may be referred to as "virtual biopsy".