2.

Prediction model developed based on the derivation cohort

Intercept and predictors	β	OR	95% CI	P
CEA, carcinoembryonic antigen; OR, odds ratio; 95% CI, 95% confidence interval; The predicted probability of perineural invasion (PNI) can be calculated using the following formula: P (PNI) = 1/{1 + exp [– (0.504 + 1.683 × radiomics signature + 0.755 × CEA level)]}. Predictor value is one when PNI is positive and zero when negative.
Intercept	0.504			0.171
Radiomics signature	1.683	5.382	3.310, 8.747	<0.0001
CEA level	0.755	2.128	1.136, 3.980	0.018