Figure 1.

Examples of artifacts that imitate polyps in laxative-free CTC data. (a) Untagged feces (arrow) can imitate large and small lesions. (b) Partial-volume effect lowers CT numbers of tagged materials which can make the outcome look similar to small polyps (arrow). (c) Partial-volume effects can imitate small polyps. Axial view (larger image) indicates a polyp (white arrow), but coronal view (smaller image) indicates that the lesion is a partial-volume artifact (arrow). (d) In 3D view, multiple solid feces that imitate polypoid shapes distract readers from focusing on true polyps.