Table 1.

T classification for appearance on chest CT for TNM 8th edition

T classification		T components on CT
Tis (AIS)		Pure GGN ≤ 3 cm
T1	T1mi	≤ 0.5 cm solid part within part-solid tumor total size ≤3 cm
	T1a	0.6–1.0 cm solid part within part-solid tumor total size ≤3 cm
		Pure GGN >3 cm
		≤ 1 cm solid tumor
	T1b	1.1–2.0 cm solid part within part-solid tumor total size ≤3 cm
		>1–2 cm solid tumor
	T1c	2.1–3 cm solid part within part-solid tumor total size ≤3 cm
		>2–3 cm solid tumor
T2	T2a	3.1–4 cm	Involves main bronchus without involvement of carina
	T2b	4.1–5 cm	Total/partial atelectasis
			Total/partial pneumonitis
			Involves hilar fat
			Involves visceral pleura (PL1 or PL2)
T3		5.1–7 cm	Separate tumor nodules in the same lobe as the primary
			Involves parietal pleura (PL3)
			Parietal pericardium
			Chest wall
			Phrenic nerve
T4		>7 cm	Involves diaphragm
			Mediastinal fat or other mediastinal structures (trachea, great vessels, heart, recurrent laryngeal nerve, esophagus)
			Carina
			Vertebral body
			Visceral pericardium
			Separate tumor nodules in the same lung but different lobes as the primary

Source: References (8) and (16).

CT, computed tomography; AIS, adenocarcinoma in situ; GGN, ground-glass nodules; mi, minimally invasive; PL1, tumor invasion of the elastic layer of visceral pleura without reaching the visceral pleural surface; PL2, tumor invasion of the visceral pleural surface; PL3, tumor invasion of the parietal pleura or chest wall.