ACR's CT Colonography Imaging Reporting & Data System, for describing colorectal and extra-colonic findings


Colonic findings

Is any of the following true about this study?

C0 = Inadequate Study

No Recommendation

C0 = Awaiting prior comparisons

No Recommendation
Which abnormalities have you identified? (select all that apply)

C1 = Normal Colon or Benign Lesion

Recommendation: Continue routine screening every 5-10 years

C2 = Intermediate Polyp or Indeterminate Finding

Recommendation: Surveillance or colonoscopy. Evidence suggests surveillance can be delayed at least 3 years, subject to individual patient circumstance.

C3 = Polyp, Possibly Advanced Adenoma

Recommendation: Surveillance or colonoscopy every 5-10 years

C4 = Colonic Mass, Likely Malignant

Recommendation: Surgical consultation. Subject to local practice, endoscopic biopsy may be indicated.

Extra-colonic findings

The scoring of extracolonic findings per C-RADS is very straightforward. Please refer to the following table:

E0 = Limited examCompromised by artifact; evaluation of extracolonic soft tissues is severely limited.No recommendations.
E1 = Normal exam or anatomic variantNo extracolonic abnormalities visible.
Anatomic Variant: eg, retroaortic left renal vein
No recommendations.
E2 = Clinically unimportant findingExamples:
a. Liver, Kidney: simple cysts
b. Gallbladder: cholelithiasis without cholecystitis
c. Vertebra: hemangioma
No work-up indicated.
E3 = Likely unimportant finding or incompletely characterizedExamples:
a. Kidney: minimally complex or homogeneously hyperattenuating cyst
Subject to local practice and patient preference,
work-up may be indicated.
E4 = Potentially important finding


a. Kidney: solid renal mass
b. Lymphadenopathy
c. Vasculature: aortic aneurysm
d. Lung: non-uniformly calcified parenchymal nodule ≥1 cm

Communicate to referring physician as per accepted practice guidelines.


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