Ground glass (GG) is the commonest sign. This can be subpleural or bronchocentric, with or without prominent vessels (green arrow), with reticular opacities / septal thickening (blue arrow) giving rise to the “crazy-paving pattern”, as a halo around foci of consolidation (red arrow) or within the centre of a rim of consolidation (red arrow), producing a reverse ground glass halo or “atoll” sign.