Top: two-dimensional (2D) (left) and three-dimensional (3D) (middle) images from the initial CTC screening in 2005 show a diminutive lesion (arrowhead for 2D, arrow for 3D) measuring less than 5 mm in the proximal transverse colon. The specific colonic location is indicated on the colon map (right) by the red dot. We do not report isolated diminutive lesions at CT colonography screening.
Bottom: 2D (left) and 3D (middle) images from repeat CT colonography screening in 2011 show that the sessile polyp has grown in the intervening 6 years, now measuring 7 mm (arrowhead for 2D, arrow for 3D). The polyp was confirmed (arrow) and removed at same-day colonoscopy (right) and proved to be a tubular adenoma at pathologic evaluation. The vast majority of diminutive lesions do not progress to non-diminutive size.
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.