Fig. 2

Colour-coded analysis of lung computed tomography (CT) data. Representative CT images taken at the level of carina from three patients with COVID-19 in the supine and prone position, with a very large decrease in the volume of the over-aerated compartment in response to prone positioning. Upper panels: original lung CT images, with aeration shown on a continuous grayscale. Lower panels: using an automated encoding system, we attributed a specific colour to the non-aerated, poorly-aerated, normally-aerated, and over-aerated compartments. The three patients are identified with the same letters as in other figures. With prone positioning, the volume of the over-aerated lung decreased from 318 to 121 ml in patient J; from 738 to 148 ml in patient C; from 503 to 230 ml in patient F