COVID-19 imaging: Diagnostic approaches, challenges, and evolving advances

Table 4 Two main standardized reporting systems used for coronavirus disease-2019 compared by their characteristic features

	Standardized CT Imaging Reporting Systems for COVID-19
Characteristics of the Reporting System	Coronavirus Disease 2019 Reporting and Data System[118]-Dutch Radiological Society	Consensus Statement on Reporting Chest CT Findings for COVID-19-Radiological Society of North America[120]
Type of Reporting System	Quantitative	Qualitative
Components & Relationship Between Both Reporting Systems	0 = inadequate or suboptimal imaging	No equivalent
	1 = very low suspicion for COVID-19 with findings of non-infectious etiology	Negative for pneumonia = no CT features to suggest pneumonia
	2 = low suspicion of COVID-19 with infectious findings not typical for COVID-19	Atypical appearance = absence of typical or indeterminate features & the presence of lobar or segmental consolidation, but no GGOs or centrilobular nodules
	3 = equivocal scan with common findings of COVID-19	No equivalent
	4 = high suspicion of COVID-19 with typical features that overlap with other viral pneumonias	Indeterminate appearance = absence of typical features and the presence of multifocal, diffuse, or unilateral GGOs with or without consolidation in a non-specific distribution
	5 = very high suspicion of COVID-19 with typical findings of disease in typical locations	Typical appearance = peripheral and bilateral GGOs with or without consolidations/crazy paving pattern
	6 = RT-PCR positive COVID-19	No equivalent
Inter-observer agreement	Absolute agreement between 68.2% of observers; > 80% observer agreement on COVID-19 being low to very low or high to very high	No data

CT: Computed tomography; COVID-19: Coronavirus disease-2019; GGO: Ground-glass opacities; RT-PCR: Real time-polymerase chain reaction.