What are the three methods utilized to distinguish stool from polyps on CTC?
Three Methods to Distinguish Fecal Material from Polyps on CTC
| Attenuation | Fecal material should be immediately characterized on an adequately tagged examination by the presence of high attenuation barium infused within the lesion. Polyps can be identified as soft tissue attenuation masses which may be coated, but not infused, with high attenuation contrast. Pearl: When fecal tagging is suboptimal, the presence of gas within a lesion is diagnostic of fecal material. |
| Mobility | Fecal material will shift with patient positioning, whereas polyps will remain fixed to the colon wall. Pearl: Polyps within intraperitoneal colonic segments located on a mesentery (i.e., sigmoid colon, transverse colon, and cecum) may appear to shift. Careful inspection of multiplanar 2D images should help one to make this distinction. |
| Morphology | Fecal material generally demonstrates angular geographic borders in contrast to polyps which demonstrate smooth borders. Pearl: All lesions detected on 3D images, even those with smooth borders, must be correlated with 2D images. Tagged stool, fecaliths, and submucosal masses such as lipomas may demonstrate smooth walls. |
