C-RADS v2023 (CT Colonography Reporting & Data System)

C-RADS standardizes CT colonography reporting. The 2023 update adds subcategory C2b for mass-like diverticular strictures that are likely benign, and merges extracolonic E1 and E2 into a single E1/E2 category because neither requires work-up. Technically inadequate studies (poor preparation or insufflation) are C0. A normal colon or unequivocally benign findings (diverticula, lipoma, diminutive polyps under 6 mm) are C1. One or two 6-9 mm polyps are C2a; three or more 6-9 mm polyps, any polyp 10 mm or larger, or interval growth of a C2a polyp is C3 and warrants colonoscopy. A polypoid mass 30 mm or larger, a malignant-appearing mass, luminal compromise, or extracolonic invasion is C4. When several findings coexist, the highest category governs. Extracolonic findings are graded E0 (limited exam), E1/E2 (no work-up), E3 (likely unimportant or incompletely characterized; work-up may be indicated), and E4 (potentially important; communicate and work up).