# C-RADS — CT Colonography Reporting and Data System version 2023

> Current CT-colonography reporting framework with separate colorectal C and extracolonic E axes. The active colorectal map is C0, C1, C2a, C2b, C3 and C4: C0 is nonassessable rather than low risk; C2a and C2b encode different findings and follow-up logic; and C4 is imaging suspicion rather than histology or pathologic stage.

**Situação:** vigente · **Órgão:** Cólon · **Órgão emissor:** American College of Radiology · **Versão:** v2023 update (published and corrected 2024) · **Ano:** 2024

## Procedência e vigência
- Família: léxico
- Tipo de lógica: flat
- Modalidade: CT
- Fonte primária: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007
- Última verificação: 2026-07-24
- Última checagem: 2026-08-12

## Lógica de decisão
Apply current C-RADS v2023 to one CTC examination, retain lesion-level facts, separate C from E, and never collapse technical inadequacy, imaging suspicion and pathology into one label.

## Categorias

| Código | Rótulo | Critérios | Conduta | Risco | Localizador | Verificado |
| --- | --- | --- | --- | --- | --- | --- |
| C0 | Inadequate examination or comparison pending | Assign C0 when a confident colorectal interpretation is not possible because a technical limitation prevents exclusion of a polyp 10 mm or larger, such as complete segmental collapse, insufficient insufflation or inadequate cleansing, or when a prior study required for comparison is unavailable. A mass-like but interpretable likely benign diverticular segment belongs in C2b rather than C0. | Repeat or complete the CT colonography when visualization is inadequate, consider an alternative colorectal screening test, or amend the report after the required prior examination becomes available. State the exact nonassessable segment and limitation rather than treating C0 as a negative examination. | C0 does not estimate colorectal-neoplasia risk: the relevant colon is not adequately assessable, so an important lesion has not been excluded. It must never be translated into low risk, benignity or a routine negative-screen interval. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C0 section; lines describing the >=10-mm exclusion limit, missing priors, C2b distinction and repeat/alternative/addendum options. | ✓ |
| C1 | Normal colon or benign lesion | Assign C1 only when the entire colon is adequately cleansed and distended and no polyp measures 6 mm or larger. The category may include a normal colon, diminutive nonreportable polyps 5 mm or smaller, diverticula, confidently benign myochosis or muscular hypertrophy, lipoma, and confidently characterized residual fecal material. | Continue routine CT-colonography screening at a 5- to 10-year interval. Any decision to shorten the interval should be justified by the complete clinical and colonic context, such as extensive diverticulosis or inflammatory change, rather than by the C1 label alone. | C1 denotes no colorectal abnormality that increases carcinoma risk in the setting of regular screening, but it is not zero lifetime risk and does not negate interval symptoms or future screening. The classification also does not supply an individualized cancer probability. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C1 section; adequate whole-colon requirement, <6-mm boundary, benign examples and 5-10-year screening recommendation. | ✓ |
| C2a | One or two 6-9 mm polyps | Assign current C2a, formerly C2, when the examination contains one or two colonic polyps and each measures 6-9 mm inclusive. Record each lesion's largest diameter, segment, morphology, measurement method and confidence; unequivocal interval growth at surveillance changes the examination to C3. | Recommend repeat CT colonography in 3 years to assess growth versus optional colonoscopy with polypectomy, using patient age, comorbidities, preferences, reader confidence and local practice to choose the pathway. Low confidence can justify a shorter interval; demonstrated growth is managed as C3. | In cited surveillance series, 22%-35% of 6-9-mm polyps progressed within 3 years and about 10%-14% resolved. These are cohort observations, not this lesion's probability; CT colonography cannot determine dysplasia or histology from the C2a label. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Subcategory C2a section; one-or-two count, 6-9-mm range, 22%-35% growth, 10%-14% resolution and 3-year-versus-colonoscopy guidance. | ✓ |
| C2b | Likely benign mass-like diverticular or muscular lesion | Assign C2b to a soft-tissue mass or mass-like colonic area that is likely benign, including moderate or severe diverticular myochosis, muscular hypertrophy or a stricture in which malignancy is not entirely excluded. Preserved haustra, absent 3D mucosal irregularity, diverticulosis and lack of overhanging shoulders support this category. | When benignity is highly likely, suggest routine CT-colonography follow-up at 5 years. When confidence is lower, use a shortened interval of 3 years or less according to context. If concern for malignancy is high, classify the lesion as C4 and recommend flexible sigmoidoscopy or colonoscopy rather than retaining C2b. | C2b expresses likely benign morphology with residual diagnostic uncertainty; it is not a numerical malignancy-risk band or histologic diagnosis. Risk depends on the complete morphology, positional change, prior stability, symptoms and clinical context, so uncertainty and confidence must be explicit. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Subcategory C2b section including Figures 5-6; morphologic features, prior comparison, 5-year/<=3-year follow-up and C4 escalation. | ✓ |
| C3 | Polyp, multiplicity, growth or subepithelial lesion requiring colonoscopy | Assign C3 for one or more polyps measuring at least 10 mm, three or more polyps each measuring 6-9 mm, unequivocal interval growth of a prior C2a polyp, or a suspected subepithelial lesion measuring at least 10 mm. Preserve which branch triggered the overall category. | Recommend colonoscopic polypectomy. If colonoscopic removal cannot be performed because of distal narrowing or severe tortuosity, short-interval CT colonography within 1 year or surgical referral may be appropriate according to patient age, comorbidities, anatomy and lesion features. | Polyps at least 1 cm have a reported 10%-25% likelihood of high-grade dysplasia or carcinoma, with risk increasing with size. This source range is population context rather than an individual prediction, and C3 does not prove advanced histology or cancer. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C3 section; size, multiplicity, growth, subepithelial-lesion branches, 10%-25% range and colonoscopy/alternative guidance. | ✓ |
| C4 | Polypoid mass at least 30 mm or malignant-appearing mass | Assign C4 for a polypoid soft-tissue mass measuring at least 30 mm or for a malignant-appearing colonic mass. Describe length, morphology, location, obstruction or narrowing, synchronous lesions, nodes and possible distant disease when technically assessable rather than replacing those findings with the code. | Recommend surgical and/or oncologic consultation, with or without preoperative colonoscopic biopsy. Intravenous-contrast CT colonography may contribute to staging, but the C4 label alone does not select an operation, establish resectability or replace tissue diagnosis and formal staging. | C4 represents high imaging suspicion for malignancy, not histologic confirmation, TNM stage, operability or an individualized prognosis. A benign final diagnosis remains possible, so the report must preserve uncertainty and the evidence supporting the malignant appearance. | Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C4 section; >=30-mm polypoid-mass or malignant-appearance definition and surgical/oncologic consultation with optional biopsy. | ✓ |

### Citações por categoria
- **C0**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C0 section; lines describing the >=10-mm exclusion limit, missing priors, C2b distinction and repeat/alternative/addendum options.
- **C1**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C1 section; adequate whole-colon requirement, <6-mm boundary, benign examples and 5-10-year screening recommendation.
- **C2a**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Subcategory C2a section; one-or-two count, 6-9-mm range, 22%-35% growth, 10%-14% resolution and 3-year-versus-colonoscopy guidance.
- **C2b**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Subcategory C2b section including Figures 5-6; morphologic features, prior comparison, 5-year/<=3-year follow-up and C4 escalation.
- **C3**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C3 section; size, multiplicity, growth, subepithelial-lesion branches, 10%-25% range and colonoscopy/alternative guidance.
- **C4**: Yee J, Dachman A, Kim DH, et al.. CT Colonography Reporting and Data System (C-RADS): Version 2023 Update (2024) — https://pubs.rsna.org/doi/10.1148/radiol.232007 · Yee et al. Radiology 2024, DOI 10.1148/radiol.232007, Table 2 and Category C4 section; >=30-mm polypoid-mass or malignant-appearance definition and surgical/oncologic consultation with optional biopsy.

## Histórico de versões

| Data | Evento | Detalhe | Situação |
| --- | --- | --- | --- |
| 2024-01-30 | revised | C-RADS v2023 became the current corrected release: prior C2 was renamed C2a, new C2b was added for likely benign mass-like diverticular strictures, and the extracolonic E1 and E2 categories were combined as E1/E2. | confirmed |
| 2005-07-01 | published | C-RADS consensus proposal published. | confirmed |


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> Conteúdo de referência reescrito. Confira a publicação primária vigente. Não é dispositivo médico nem substitui o julgamento clínico. O radiologista responsável pelo laudo permanece o autor e o responsável.

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