Fig. 2

Computed tomography (CT) images for the three patterns of COVID-19 pneumonia. The pulmonary opacities are classified into peripheral, multifocal, and diffuse patterns. a In the peripheral pattern, parenchymal opacification appears in the inner peripheral zone. b In the multifocal pattern, parenchymal opacification is apparent in the central and peripheral regions. c The diffuse pattern reveals generalized pulmonary involvement, with regional inhomogeneity. d–f Semi-automated segmentation using Thoracic VCAR software (GE Healthcare, USA). Blue areas represent normal lung parenchyma in the -501, -900 HU interval; light blue areas represent hyperinflated lung in the -901, -1000 HU; yellow areas represent poorly aerated lung in the -500, -100 HU interval; and red areas represent non-aerated lung in the 100, -100 HU interval. COVID-19, coronavirus disease 2019; HU, Hounsfield unit; VCAR, Volume Computer-Assisted Reading