Table 1.

Demographic characteristics of patients in the primary and validation cohorts

Characteristic	Primary cohort (n = 103)			Validation cohort (n = 44)
	AIS/MIA (n = 60)	IA (n = 43)	P	AIS/MIA (n = 25)	IA (n = 19)	P
Gender			0.037*			0.355
Female	16	20		6	7
Male	44	23		19	12
Age (years)	51.55 ± 9.59	55.91 ± 9.92	0.027*	46.68 ± 12.58	54.37 ± 9.58	0.026*
T stage			<0.001*			0.002*
T1a	36	9		18	4
T1b	24	29		7	13
T1c	0	5		0	2
Shape			0.079			0.009*
Round/oval	37	19		19	7
Irregular	23	24		6	12
Margin			0.041*			0.333
Smooth	17	5		5	1
Coarse	43	38		20	18
Nodule-lung interface			0.803			0.405
Clear	28	19		15	9
Blurry	32	24		10	10
Lobulation			0.017*			0.006*
No	55	32		24	11
Yes	5	11		1	8
Spiculation			0.769			0.999
No	59	41		23	17
Yes	1	2		2	2
Pleural indentation			0.183			0.054
No	45	27		20	10
Yes	15	16		5	9
Air bronchogram			0.007*			0.011*
No	57	32		25	14
Yes	3	11		0	5
Vacuole sign			0.002*			0.074
No	49	23		16	7
Yes	11	20		9	12
Average diameter (mm)	7.95 ± 2.78	12.55 ± 4.39	<0.001*	7.32 ± 2.52	11.97 ± 4.52	<0.001*
Volume (mm3)	494.96 ± 398.68	1727.05 ± 1936.51	<0.001*	438.18 ± 395.12	1669.83 ± 2003.81	0.016*
Mean attenuation (HU)	- 657.39 ± 66.24	- 616.29 ± 73.90	0.004*	- 662.99 ± 65.31	- 621.91 ± 94.88	0.096
FS			<0.001*			<0.001*
AIS/MIA	53	7		23	5
IA	7	38		2	14

AIS/MIA, adenocarcinoma in situ/minimally invasive adenocarcinoma; IA, invasive adenocarcinoma; FS, frozen section. Age, average diameter, volume, mean attenuation are shown in mean ± standard deviation, and other data are the number of nodules. *p < 0.05.