2.6 Statistical Analysis
Python software (PyRadiomics, v2.1.2) and IBM SPSS Statistics software (version 23.0, IBM Corp.) were used for statistical analysis. A value of p<0.05 was meant statistically significant. To assess the performance of the radiomics features and LR models, the receiver operating characteristic (ROC) curve was used both in training and validation set, and the area under the receiver operator characteristic curve (AUC), sensitivity and specificity were calculated in the two sets respectively. Delong test was used to compare the diagnostic performance of LR model, exponential-skewness and squareroot-skewness based on NP images in both training and validation sets. The Mann–Whitney U-test was used to determine how the most statistically significant features distributed in training and validation sets.