Reporting of COVID-19 Chest CT Findings

Radiology report

Plain radiograph

The British Society of Thoracic Imaging (BSTI) has published a reporting proforma for the plain chest radiographic appearances of potential COVID-19 cases ¹⁶⁸. 

• classic/probable COVID-19

  • lower lobe and peripheral predominant multiple opacities that are bilateral (>> unilateral)

• indeterminate for COVID-19

  • does not fit classic or non-COVID-19 descriptors

• non-COVID-19

  • pneumothorax / lobar pneumonia / pleural effusion(s) / pulmonary edema / other

• normal

  • COVID-19 not excluded

CT

The Radiological Society of North America (RSNA) has released a consensus statement endorsed by the Society of Thoracic Radiology and the American College of Radiology (ACR) that classifies the CT appearance of COVID-19 into four categories for standardized reporting language ⁹⁹:

• typical appearance

  • peripheral, bilateral, GGO +/- consolidation or visible intralobular lines (“crazy paving” pattern)

  • multifocal GGO of rounded morphology +/- consolidation or visible intralobular lines (“crazy paving” pattern)

  • reverse halo sign or other findings of organizing pneumonia

• indeterminate appearance

  • absence of typical CT findings and the presence of

    • multifocal, diffuse, perihilar, or unilateral GGO +/- consolidation lacking a specific distribution and are non-rounded or non-peripheral

    • few very small GGO with a non-rounded and non-peripheral distribution

• atypical appearance

  • absence of typical or indeterminate features and the presence of

    • isolated lobar or segmental consolidation without GGO

    • discrete small nodules (e.g. centrilobular, tree-in-bud) 

    • lung cavitation

    • smoother interlobular septal thickening with pleural effusion

• negative for pneumonia: no CT features to suggest pneumonia, in particular, absent GGO and consolidation

A study evaluating the RSNA chest CT classification system for COVID-19 against RT-PCR results found moderate interobserver agreement. Using a cohort of 96 patients, it reported that 76.9-96.6% of "typical" scans, 51.2-64.1% of "indeterminate" scans, 2.8-5.3% "atypical" scans and 20-25% of "negative" scans returned a RT-PCR confirming COVID-19 ^99,147.