Stages of COVID-19 on chest CT

Early stage (0–2 days)
Approximately 50% of patients have negative chest CT
The remaining have ground-glass opacities (44%) and consolidation (17%), more often unilateral
The less pulmonary consolidation identified on CT, the greater the probability of initial negative reverse transcriptase polymerase chain reaction results11
Intermediate stage (3–5 days)
9% of patients have negative chest CT
88% have ground-glass opacities with or without crazy paving (a sign of progression or peak stage), and 55% have consolidation (bilateral in 76%, peripheral in distribution in 64% with rounded morphology)12
Late phase (6–12 days)
Most patients have positive CT findings
Progressive consolidation, evolving linear consolidation, and organizing pneumonia
Reverse-halo appearance (a sign of healing or evolving lesion)12
Ground-glass opacities in 88% with or without crazy paving
Severe phase
Massive pulmonary consolidation and “white lungs”
Recovery phase
Parenchymal abnormalities resolve with residual linear opacities (Figure 6)
  • Based on information from references 5 and 1114.