The British Society of Thoracic Imaging (BSTI) guidelines (attached below) have outlined features that define Classical COVID:

Lower lobe predominant, peripheral predominant, multiple, usually bilateral foci of GGO, Plus or minus the following:

• Crazy-paving
• Peripheral consolidation
• Air bronchograms
• Reverse halo/ perilobular pattern (organising pneumonia pattern)

Radiological Society of North America (RSNA) guidelines (attached below) have outlined features that define Typical COVID:

• Peripheral, bilateral, GGO with or without consolidation or visible intralobular lines (“crazy-paving”)
• Multifocal GGO of rounded morphology with or without consolidation or visible intralobular lines (“crazy-paving”)
• Reverse halo sign or other findings of organizing pneumonia

The RSNA have also provided some guidance on structuring CT reports for Typical COVID:

“Commonly reported imaging features of (COVID-19) pneumonia are present. Other processes such as influenza pneumonia and organizing pneumonia, as can be seen with drug toxicity and connective tissue disease, can cause a similar imaging pattern.”