C-RADS Category (CT Colonography)
C-RADS (CT Colonography Reporting and Data System; Zalis 2005, 2023 update) colonic categories — the standardized reporting category for the colonic findings on a CT colonography, completing the RADS family (BI/LI/PI/O/TI/Lung-RADS).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- C-RADS colonic category
- C3 - polyp(s) >= 10 mm, or >= 3 polyps 6-9 mm
Result: C-RADS C3: one or more polyps 10 mm or larger, or three or more 6-9 mm polyps; colonoscopy is recommended.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- C0 / C1
- C0 inadequate study (repeat CTC). C1 normal or benign (routine screening).
- C2a / C2b
- C2a indeterminate 6-9 mm polyps (<3; short-term follow-up). C2b mass-like likely-benign stricture.
- C3 / C4
- C3 polyp(s) >= 10 mm or >= 3 polyps 6-9 mm (colonoscopy). C4 colonic mass, malignant-appearing (urgent).
What you enter
- C-RADS colonic category
How this is calculated
Zalis ME, Barish MA, Choi JR, et al. CT colonography reporting and data system: a consensus proposal. Radiology. 2005;236(1):3-9. Version 2023 Update: Radiology. 2024. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.