COVID-19 has emerged as a pandemic leading to a global public health crisis of
unprecedented morbidity. A comprehensive insight into the imaging of COVID-19
has enabled early diagnosis, stratification of disease severity, and
identification of potential sequelae. The evolution of COVID-19 can be divided
into early infectious, pulmonary, and hyperinflammatory phases. Clinical
features, imaging features, and management are different among the three phases.
In the early stage, peripheral ground-glass opacities are predominant CT
findings, and therapy directly targeting SARS-CoV-2 is effective. In the later
stage, organizing pneumonia or diffuse alveolar damage pattern are predominant
CT findings and anti-inflammatory therapies are more beneficial. The risk of
severe disease or hospitalization is lower in breakthrough or Omicron variant
infection compared with nonimmunized or Delta variant infections. The protection
rates of the fourth dose of mRNA vaccination were 34% and 67% against overall
infection and hospitalizations for severe illness, respectively. After acute
COVID-19 pneumonia, most residual CT abnormalities gradually decreased in
extent, but they may remain as linear or multifocal reticular or cystic lesions.
Advanced insights into the pathophysiologic and imaging features of COVID-19
along with vaccine benefits have improved patient care, but emerging knowledge
of post–COVID-19 condition, or long COVID, also presents radiology with
new challenges.
© RSNA, 2023
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