Top: two-dimensional (2D) (left) and three-dimensional (3D) (middle) images from the initial CT colonography screening in 2004 show a subtle flat lesion (arrows) was missed in the ascending colon just distal to the ileocecal valve (*). The specific colonic location is indicated on the colon map (right) by the red dot. Little or no contrast material coating of the polyp surface is seen. Bottom: 2D (left) and 3D (middle) images from repeat CT colonography screening in 2009 show the same flat lesion (arrows), which measured 12 mm without significant change in size from 2004. The lesion now demonstrates subtle contrast coating, which increases conspicuity and reader confidence. The polyp was confirmed (arrow) and removed at same-day colonoscopy (right) and proved to be a sessile serrate polyp at pathologic evaluation. The asterisk indicates ileocecal valve.
From Pickhardt PJ, Pooler BD, Mbah I, et al. Colorectal Findings at Repeat CT Colonography Screening after Initial CT Colonography Screening Negative for Polyps Larger than 5 mm. Radiology 2017;282:139-48; with permission.