Figure 4.

(a) Illustration of the partial-volume effect region (between arrows) at the colon surface. The white solid line represents the true material surface. The dotted white lines indicate the extent of the partial-volume effect. (b) A region of interest. (c) High values of the gradient magnitude of CT numbers indicate partial-volume region in the region of interest. (d) Lesions that are not connected directly to bowel wall can be excluded immediately as untagged feces (arrow). (e) A pseudolesion (stool) that is connected to the bowel wall through an artificial soft-tissue interface (arrows) due to PVE. (f) The first step of the virtual tagging method (light grey color) indicates the artificial soft-tissue interfaces.