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Table 1 Radiological findings in COVID-19 pneumonia

From: Differential diagnoses of COVID-19 pneumonia: the current challenge for the radiologist—a pictorial essay

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, pleuric effusions, pulmonary nodules
Centroparenchymal (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
  1. COVID-19 pneumonia has been divided into four stages, according to Feng Pan [12], depending on the timing of typical radiological findings occurrence. Spatial distribution of radiological findings and additional findings is of primary importance to reach a correct diagnosis [12, 14, 15]