4.

Calibration curves of the radiomics model prediction. (A) Calibration curve in the derivation cohort (Hosmer-Lemeshow test; P=0.276); (B) Calibration curve in the internal validation cohort (Hosmer-Lemeshow test; P=0.132); (C) Calibration curve in the independent validation cohort (Hosmer-Lemeshow test; P=0.132). Calibration curves depict the calibration of the radiomics prediction model in terms of the agreement between the predicted probability of perineural invasion (PNI) and observed rate of PNI. The Y-axis represents the actual observed PNI rate whereas the X-axis represents the model predicted PNI probability. The diagonal blue dash line represents a perfect prediction by an ideal model. The dashed smooth curve reflects the relation between observed rate of PNI and predicted probability of PNI using the radiomics prediction model. Triangles indicate the incidence of PNI in quintiles of patients with similar predicted probabilities. Spikes at the bottom represent distribution of predicted probabilities of PNI.