Table 1. Comparison of nodule management protocols for three leading LDCT studies.

		Nodule characteristics (attenuation, diameter, volume)		Recommended action		Interval findings		Recommended action
Small	NLST	<4 mm dmax		12 m LDCT
	NEL	<50 mm3 without benign characteristics
	IE	Solid/ part-solid <5 mm dmean;
		non-solid: any size
Intermediate	NLST	Solid 4-10 mm dmax		3-6 m LDCT (may vary up to 24 m according to level of suspicion)		No growth†	→	12 m LDCT
						Growth <7 mm	→	3-6 m LDCT or refer to pulmonologist
						Growth ≥7 mm	→	Refer to pulmonologist
		Pure GGO 4-10 mm dmax		6-12 m LDCT		As per solid 4-10 mm nodules
	NEL	Solid: 50-500 mm3;		3 m LDCT		Growth††	→	Refer to pulmonologist
		Solid, pleural based: 5-10 mm
		Mixed: GGO component: ≥8 mm dmean or solid component: 50-500 mm3
		Pure GGO: ≥8 mm dmean
	IE	Solid/ part-solid 5-15 mm dmean		3 m LDCT (preferred option) or Antibiotics & 3 m LDCT if infection possible or		Growth†††	→	Biopsy
				PET scan if solid/solid component >10 mm		PET scan negative	→	3 m LDCT
Large	NLST	Solid >10 mm dmax		Refer to pulmonologist
		Other suspicious finding
	NEL	Solid: >500 mm3;
		Solid, pleural based: >10 mm
		Mixed, solid component: >500 mm3
	IE	Solid/ Mixed >15 mm dmean

Key: NLST-NLST, NEL-NELSON, IE-I-ELCAP; m, month; d_mean, mean of maximal diameter and width viewed on same CT slice; d_max, maximal diameter on axial CT slice; PET, Positron-emission tomography; GGO, ground glass opacity attenuation nodule; Definitions of growth minimum significant change: ^†, >10% increase in diameter; ^††, ≥25% increase in volume after at least a 3 months interval; ^†††, Minimum change in nodule diameter/solid component of part-solid nodules to define significant growth: for nodules <5 mm in diameter, ≥50%; for nodules 
5-9 mm in diameter ≥30%; for nodules >10 mm in diameter ≥20%. Adapted from NLST (60) NELSON (52), I-ELCAP (61).