3D endoluminal CTC image (A) shows a polypoid lesion, as well as smaller adjacent diminutive foci. Both 3D translucency rendering (B) and 2D correlation (C) show dense internal contrast tagging, easily excluding a polyp. Note that the adherent stool is nondependent on this prone 2D view, which could simulate a true lesion if untagged.
(From Pickhardt PJ, Kim DH. Potential pitfalls at CTC Interpretation, In: CT colonography: principles and practice of virtual colonoscopy. Philadelphia: Saunders; 2010, with permission)