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

Table 1 Three main chest radiographic scoring systems use for coronavirus disease-2019 and their characteristic features

	Chest Radiography Scoring Systems for COVID-19
Characteristics of Chest Radiography Scoring Systems	Severe Acute Respiratory Infection[48]	Radiographic Assessment of Lung Edema[49]	Chest X-ray Score[51]
Division of Lungs	None	2 lungs	6 zones (3 zones each lung)
Methodology of Score Calculation	Entire lungs scored as one	Each lung scored and totaled	Each zone scored and totaled
Characteristics Scored	Various radiographic findings	1GGOs or consolidation	Various radiographic findings
Scoring Scale	1 = normal; 2 = patchy/hyperinflation/bronchial wall thickening; 3 = focal consolidation; 4 = multifocal consolidation; 5 = diffuse alveolar change	1 ≤ 25%; 2 = 25%-50%; 3 = 50%-75%; 4 ≥ 75%	0 = no abnormalities; 1 = interstitial infiltrates; 2 = interstitial (predominant) & alveolar infiltrates; 3 = interstitial & alveolar (predominant) infiltrates
Designed Specifically for COVID-19 Disease	No	No	Yes

¹Ground glass opacities. Modified based on study from Wasilewski et al[47]. COVID-19: Coronavirus disease-2019; GGO: Ground-glass opacities.

Table 2 Three main chest computed tomography scoring systems use for coronavirus disease-2019 and their characteristic features

	Chest CT Scoring Systems for COVID-19
Characteristics of Chest CT Scoring Systems	Chest Computed Tomography Severity Score[52]	Total Severity Score [53]	Chest Computed Tomography Score [54]
Division of Lungs	20 regions for each lung	5 lobes	5 lobes
Methodology of Score Calculation	Each region scored & amount totaled	Each lobe scored and amount totaled	Each lobe scored and amount totaled
Characteristics Scored	Amount of opacification	% of disease in each lobe (1GGOs, mixed GGOs, consolidation)	% of disease in each lobe (no specific features)
Scoring Scale	0 = 0%; 1 = 1%-50%; 2 = 51%-100%	0 = 0%; 1 = 1%-25%; 2 = 26%-50%; 3 = 51%-75%; 4 = 76%-100%	0 = 0%; 1 ≤ 5%; 2 = 5%-25%; 3 = 26%-49%; 4 = 50%-75%; 5 ≥ 75%
Sensitivity & Specificity	83% & 94%	83% & 100%	80% & 82%
Lowest Score for Severe COVID-19 Cases	19.5	7.5	7
Designed Specifically for COVID-19 Disease	Yes	Yes	Yes

¹Ground glass opacities. Modified based on study from Wasilewski et al[47]. CT: Computed tomography; COVID-19: Coronavirus disease-2019; GGO: Ground-glass opacities.

Table 3 Four most common imaging modalities used in the diagnosis and management of coronavirus disease-2019 and their unique features/findings characterized by organ system

	Characteristic Features of COVID-19 by Imaging Modality
Organ Systems Impacted by COVID-19	1CT	Ultrasound	Magnetic resonance imaging	Chest radiography
Pulmonary	2GGOs and reticular opacities; consolidations; 3crazy paving pattern; multifocal and bilateral in a peripheral, sub-pleural, and posterior distribution	4B-line artifacts; irregularly thickened pleura; sub-pleural consolidations	Similar to CT	Interstitial reticular and reticulonodular patterns; alveolar hazy pulmonary opacities (equivalent to GGOs on CT); consolidations; multifocal & bilateral in a peripheral, sub-pleural, and posterior distribution
Cardiac	Cardiac thromboembolism	Pericardial effusion	Myocarditis; pericardial effusion
Neurological	Stroke (ischemic/thromboembolic)	Venous sinus thrombosis	Stroke (ischemic/thromboembolic); venous sinus thrombosis, hyper-intensities
Gastrointestinal	Wall thickening; edema; fluid filled intestinal lumen; mucosal hyper-enhancement; mesenteric vascular thrombi/ischemia	Portal vein thrombosis
Genitourinary	Perinephric fat stranding	Renal vein/artery thrombosis

Both pulmonary and extrapulmonary manifestations of coronavirus disease-2019 disease are detailed. Items are listed from the most common to the least common for each imaging modality and its associated organ system.

¹Computed Tomography: refers to both computed tomography (CT) and CT angiography.

²Ground-glass opacities (GGOs): ground glass opacities.

³Crazy paving pattern: GGOs with superimposed intralobular lines and interlobular septal thickening.

⁴B-line artifacts: vertically oriented hyperechoic artifacts that originate from the pleura or from areas of consolidation. CT: Computed tomography; COVID-19: Coronavirus disease-2019; GGO: Ground-glass opacities.

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.