Table 1.

COVID-19 pneumonia main radiological findings, additional features, and spatial distribution in relation to the four phases defined by Pan F. [13].

Stage	Phase	Timing (Days)	Predominant Radiological Findings	Additional Findings	Spatial Distribution of Radiological Findings
1	Early	0–4	ground glass opacities	peripheral vessel widening halo sign atoll sign or reversed halo sign overlapping of radiological findings in different phases rarity of: lymphadenopathies, pleural effusions, pulmonary nodules	bilateral peripheral/subpleural centro-parenchymal (atypical) lower lobes prevalence
2	Progressive	5–8	crazy paving pattern, ground glass opacities and small consolidations
3	Peak	9–13	consolidative foci
4	Absorption	≥14	ground-glass opacities and linear consolidation

The table was reproduced from Guarnera A, Podda P, Santini E, Paolantonio P, Laghi A. “Differential diagnoses of COVID-19 pneumonia: The current challenge for the radiologist-a pictorial essay”, Insights Imaging. 2021 Mar 11;12 (1):34, under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/ accessed on date 10 June 2021).