# RSNA COVID — RSNA chest CT reporting categories for acute COVID-19 pneumonia

> Standardizes the typicality of acute chest CT patterns potentially attributable to COVID-19 pneumonia. It is a communication lexicon, not a viral diagnostic test, severity score, screening indication or post-COVID follow-up framework.

**Situação:** vigente · **Órgão:** Tórax · **Órgão emissor:** RSNA / STR / ACR · **Versão:** 2020 acute-pneumonia reporting consensus · **Ano:** 2020

## Procedência e vigência
- Família: léxico
- Tipo de lógica: flat
- Modalidade: CT
- Fonte primária: Simpson S, Kay FU, Abbara S, et al.. Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19 (2020) — https://doi.org/10.1148/ryct.2020200152
- Última verificação: 2026-07-24
- Última checagem: 2026-08-12

## Lógica de decisão
Use this as a morphology communication lexicon for acute chest CT, never as a binary SARS-CoV-2 test or severity score. Preserve timing, laboratory context, mixed processes, complications and the 2025 post-COVID terminology boundary.

## Categorias

| Código | Rótulo | Critérios | Conduta | Risco | Localizador | Verificado |
| --- | --- | --- | --- | --- | --- | --- |
| typical | Typical appearance | Typical appearance requires a characteristic acute-pneumonia pattern: peripheral bilateral or multifocal rounded ground-glass opacity, with or without consolidation or visible intralobular lines/crazy paving, and/or an organizing-pneumonia pattern such as reverse halo. Preserve a mixed atypical component separately rather than hiding it behind the category. | Use the standardized reporting phrase, describe distribution and extent, and correlate with symptoms, exposure, local viral testing and infection-control policy. CT is not a screening or stand-alone first-line diagnostic test, and this label alone must not trigger or withhold treatment. | This is a morphology/typicality category, not a positive virologic diagnosis, probability estimate or severity grade. Its positive predictive value changes with prevalence, vaccination and circulating variants, and similar organizing-pneumonia patterns occur with other infections, drug toxicity and inflammatory disease. | Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Typical appearance' and pp. 3-5 distribution/morphology discussion; Polyakov et al. 2023, DOI 10.1148/radiol.220680, abstract/results for vaccination-, variant- and prevalence-dependent performance. | ✓ |
| indeterminate | Indeterminate appearance | Indeterminate appearance applies when typical features are absent but ground-glass opacity with or without consolidation remains compatible yet nonspecific: multifocal, diffuse, perihilar or unilateral disease without a rounded peripheral pattern, or only a few small nonrounded and nonperipheral ground-glass opacities. | State the nonspecific imaging pattern and relevant alternatives, then integrate timing, clinical findings and viral testing. Do not promote the label to probable COVID-19, and do not derive isolation, therapy, admission or follow-up solely from this category. | The imaging overlap is broad, including edema, hemorrhage, other infection, drug reaction and inflammatory lung disease. Both false-positive and false-negative interpretation are possible, especially with limited, early, treated or technically degraded examinations. | Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Indeterminate appearance' and accompanying discussion of nonrounded, nonperipheral, unilateral, perihilar and diffuse ground-glass patterns. | ✓ |
| atypical | Atypical appearance | Atypical appearance requires absence of typical and indeterminate patterns plus features uncommon for the original acute COVID-19 phenotype, such as isolated lobar or segmental consolidation without ground-glass opacity, discrete centrilobular/tree-in-bud nodules, cavitation, or smooth septal thickening with pleural effusion. | Describe the dominant alternative pattern and surface urgent or treatable differentials such as bacterial infection, aspiration, edema or cavitating infection. Continue clinical and laboratory assessment when COVID-19 remains plausible; an atypical CT label does not exclude infection. | Calling the pattern atypical can create false reassurance because COVID-19 may coexist with a second process or present outside the consensus phenotype. Mixed findings must retain both components, and CT morphology alone cannot assign a competing diagnosis. | Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Atypical appearance' and pp. 4-5 examples of lobar consolidation, tree-in-bud nodules, cavitation and smooth septal thickening with effusion. | ✓ |
| negative | Negative for pneumonia | Negative for pneumonia means no parenchymal abnormality attributable to pneumonia on the examined CT: no relevant ground-glass opacity or consolidation. Incidental or chronic abnormalities may still be present and should be reported separately. | Use the negative-for-pneumonia phrase only for the CT appearance and continue symptom-, exposure- and test-directed clinical evaluation when infection is suspected. A normal CT must not cancel viral testing, infection precautions or clinical reassessment. | A negative CT does not exclude early, mild or otherwise occult COVID-19 and is not equivalent to a negative viral test. Technical limitation or incomplete lung coverage should produce a limited/unclassifiable result rather than false reassurance. | Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Negative for pneumonia' and discussion that CT may be normal early in infection and is not a screening test. | ✓ |

### Citações por categoria
- **typical**: Simpson S, Kay FU, Abbara S, et al.. Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19 (2020) — https://doi.org/10.1148/ryct.2020200152 · Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Typical appearance' and pp. 3-5 distribution/morphology discussion; Polyakov et al. 2023, DOI 10.1148/radiol.220680, abstract/results for vaccination-, variant- and prevalence-dependent performance.
- **indeterminate**: Simpson S, Kay FU, Abbara S, et al.. Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19 (2020) — https://doi.org/10.1148/ryct.2020200152 · Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Indeterminate appearance' and accompanying discussion of nonrounded, nonperipheral, unilateral, perihilar and diffuse ground-glass patterns.
- **atypical**: Simpson S, Kay FU, Abbara S, et al.. Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19 (2020) — https://doi.org/10.1148/ryct.2020200152 · Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Atypical appearance' and pp. 4-5 examples of lobar consolidation, tree-in-bud nodules, cavitation and smooth septal thickening with effusion.
- **negative**: Simpson S, Kay FU, Abbara S, et al.. Radiological Society of North America expert consensus statement on reporting chest CT findings related to COVID-19 (2020) — https://doi.org/10.1148/ryct.2020200152 · Simpson et al. 2020, DOI 10.1148/ryct.2020200152, Table 1 'Negative for pneumonia' and discussion that CT may be normal early in infection and is not a screening test.

## Histórico de versões

| Data | Evento | Detalhe | Situação |
| --- | --- | --- | --- |
| 2020-03-25 | published | RSNA, STR and ACR published the four-category acute chest CT reporting consensus for findings potentially attributable to COVID-19 pneumonia. | 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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