Table 1.

CT features for lung adenocarcinoma.

Variable	Definition
Type	Central, tumour located in the segmental or more proximal bronchi; peripheral, tumour located in the subsegmental bronchi or more distal airway
Location	The distribution of each lesion in the lung was recorded, including left upper lobe, left lower lobe, right upper lobe, right middle lobe and right lower lobe
Tumour size	Longest diameter of the tumour in MPR images
Texture	Predominantly solid, Tumour solid component/ground glass component > 0.5; Predominantly ground glass opacity, tumour solid diameter/ground glass diameter ≤ 0.5
Ground glass opacity	Ground glass dense nodules with internal vessels and bronchi visible
Mix ground glass opacity	Composition of both ground glass opacity and solid
Pure ground glass opacity	Composition of ground glass opacity only
Shape	Indicated as lobulated, others (round, or oval)
Lobulated	The surface of the tumour showed as multiple arc-shaped projections
Spiculate	Evaluated in the lung window, and indicated as different degrees of spinous or burr-like protrusions at the tumour margin
Margin definition	Evaluated in the lung window, and indicated as well-defined, or poor-defined
Air bronchogram	Tube like or branched air structure within the tumour
Bubble-like lucency	The 1–3 mm of air density area within the mass
Margins	Evaluated in the lung window, and indicated as smooth, or spiculated
Heterogeneity	Evaluated in the soft tissue window, and heterogeneity indicated as the difference of CT values in tumour was greater than 20HU
Pleural attachment	Retraction of the pleura towards the tumour
Thickening of the adjacent pleura	Thickening of the adjacent fissural or peripheral pleura pleura
Pleural effusion	Presence or absence of pleural effusion
Cavitation	Presence or absence of cavitation
Intramodular calcifications	Presence or absence of calcifications
Necrosis	Low-density area in the tumour, without enhancement in enhance CT
Peripheral emphysema	Presence or absence of peripheral emphysema
Peripheral fibrosis	Pulmonary fibrosis around the tumour
Vascular convergence	Convergence of vessels to the tumour, applied to the peripheral tumours
Enhancement	“mild” = 0–20 HU; “moderate” = 20–40 HU, “marked” > 40 HU
Lymphadenopathy	Presence or absence of lymphadenopathy thoracic lymph nodes (hilar or mediastinal) with short-axis diameter greater than 1 cm
Distance metastases	Including metastasis in bone, brain, liver metastasis, etc. Detected at the same time as the diagnosis of primary tumour or occurred within 6 months’ following up after surgery