An Overview of Deep Learning Techniques on Chest X-Ray and CT Scan Identification of COVID-19

Table 2

Comparison of clinical and radiological features of COVID-19, SARS, and MERS [32].

Feature	COVID-19	SARS	MERS
Clinical sign or symptom
Fever or chills	Yes	Yes	Yes
Dyspnea	Yes	Yes	Yes
Malaise	Yes	Yes	Yes
Myalgia	Yes	Yes	Yes
Headache	Yes	Yes	Yes
Cough	Dry	Dry	Dry or productive
Diarrhoea	Uncommon	Yes	Yes
Nausea or vomiting	Uncommon	Yes	Yes
Sore throat	Uncommon	Yes	Yes
Arthralgia		Yes	Uncommon
Imaging finding
Acute phase
Initial imaging
Normal	15–20% of patients	15–20% of patients	17% of patients
Abnormalities
Common	Peripheral multifocal airspace opacities (GGO, consolidation, or both) on chest radiography and CT.	Peripheral multifocal airspace opacities (GGO, consolidation, or both) on chest radiography and CT.	Peripheral multifocal airspace opacities (GGO, consolidation, or both) on chest radiography and CT.
Rare	Pneumothorax	Pneumothorax	Pneumothorax
Not seen	Cavitation or lymphadenopathy	Cavitation or lymphadenopathy	Cavitation or lymphadenopathy
Appearance	Bilateral, multifocal, basal airspace; normal chest radiography findings (15%)	Bilateral, multifocal basal airspace on chest radiography or CT (80%); isolated unilateral (20%)	Unilateral, focal (50%); multifocal (40%); diffuse (10%)
Follow-up imaging appearance	Persistent or progressive airspace opacities	Unilateral, focal (25%); progressive (most common, can be unilateral and multifocal or bilateral with multifocal consolidation)	Extension into upper lobes or perihilar areas, pleural effusion (33%), interlobular septal thickening (26%)
Indications of poor prognosis	Consolidation (vs. GGO)	Bilateral (like ARDS), for or more lung zones, progressive involvement after 12 d	Greater involvement of the lungs, pleural effusion, pneumothorax
Chronic phase	Unknown, but pleural effusion and interlobar septal thickening have not yet been reported
Transient reticular opacities		Yes	Yes
Air trapping		Common (usually persistent)
Fibrosis	More than one-third of patients	Rare	One-third of patients

Note: SARS: severe acute respiratory syndrome; MERS: Middle East respiratory syndrome; COVID-19: coronavirus disease 2019; GGO: ground-glass opacity; ARDS: acute respiratory distress syndrome [32].