Table 1.

Nodule semantic features and their descriptions

Semantic feature	Description
Air-bronchogram	Presence of visible air-filled bronchi within the lesion. Measured as being present or absent.
Ground-glass component	Presence of hazy attenuation, higher than background, but not sufficiently high to obscure bronchial and vascular margins within the lesion.21
Location	Central or peripheral, based on whether the tumour was closer to the hilum than the nearest segmental bronchus or not.
Margins	Irregular, smooth, or lobulated. Lobulation was defined as the presence of at least three undulations with a height of more than 2 mm.21
Pleural indentation	Retraction of pleura near the tumour margin.22
Satellite nodules	Presence of smaller nodules in the immediate vicinity of the main lesion.
Spiculation	The presence of linear strands at least 2 mm thick extending from tumour margin into adjacent parenchyma.21,23
Cavitation	Presence of a round lucency inside the lesion, usually within the centre of the lesion and larger than pseudo cavitation; suggests necrosis.21
Pseudocavitation	Presence of bubble-like areas of low attenuation within the nodule.