Radiological presentation of COVID-19 pneumonia

Abstract

Interstitial pneumonia is the main manifestation of the COVID-19 disease. The aim of this paper is to present the spectrum of typical radiological findings (CT - computed tomography, and radiographic) in COVID-19 pneumonia, the different CT examination techniques, the types and evolution of inflammatory lesions in the lungs, the criteria for assessing the probability of COVID-19 pneumonia in comparison to other types of interstitial pneumonia, and the scoring systems for determining the extent of COVID-19 pneumonia, based on CT findings and radiography. The standard CT examination protocol is a native CT examination of the chest, and, due to high sensitivity of low-dose CT protocols for detecting lung lesions, this imaging technique has become widely used in radiological practice during the COVID-19 pandemic. Bilateral, multiple, round or confluent zones of ground-glass density, predominantly localized subpleurally, peripherally and posteriorly, usually most extensive in the lower lobes, represent a typical CT presentation of COVID-19 pneumonia. Consolidations may develop at a later stage. A chest X-ray shows homogeneously reduced transparency in the lateral pulmonary fields, circular and irregular cloudlike shadows, and confluent patchy shadows, usually most extensive basally and laterally. RSNA and CO-RADS criteria are used to assess the probability of COVID-19 pneumonia, based on the criteria of a typical/atypical CT finding. Four stages of COVID-19 pneumonia have been defined, based on the dynamics of inflammatory lung lesion presentation: early, progressive, the phase of consolidation and the phase of organization. To assess the extent and severity of pneumonia, various scoring systems have been proposed, the most widely accepted one being the CT severity scoring system, based on visual semiquantitative assessment of the percentage of lung parenchyma inflammation lesions involvement of each of the five lobes, on a scale of 1 (<5%) to 5 (>75%), whereby the maximum score can be 25.