Table 4. NRI of inter-group comparison for the primary cohort and validation cohort.

Groups	Primary cohort				Validation cohort
	NRI Events	Non-NRI Events	Total NRI Events	NRI Events	Non-NRI Events	Total NRI Events
1 vs. 2	0.244	0.333	0.578	0.022	0.001	0.023
1 vs. 3	0.333	0.533	0.867	0.200	0.267	0.467
3 vs. 4	0.089	0.067	0.156	0.267	0.200	0.467

Note: NRI = Net Reclassification Improvement; NRI Events = Net Reclassification Improvement for events; Non-NRI Events = Net Reclassification Improvement for non-events. Group 1 = non-contrast + 1.25 mm + standard convolution kernel; Group 2 = contrast enhancement + 1.25 mm + standard convolution kernel; Group 3 = non-contrast + 5 mm + standard convolution kernel; Group 4 = non-contrast + 5 mm + lung convolution kernel.