Clinicopathologic features and treatment outcomes
The clinicopathologic characteristics of the study participants are listed in Table 1. The predominant FIGO stage was IB1 (n = 43 [56.6%]), followed by IB2 (n = 14 [18.4%]), IIB (n = 10 [13.2%]), and IIA (n = 9 [11.8%]). The histologic cervical cancer types were as follows: squamous cell carcinoma (n = 91 [66.9%]), adenocarcinoma (n = 37 [27.2%]), and adenosquamous carcinoma (n = 8 [5.9%], Table 1). The median ITB counts (range) were 3.5 (0-40), and the median PTB counts (range) were 4 (0-44), respectively. ITB was observed in 47 patients (61.8%), and PTB in 62 patients (81.6%), respectively.
Comparison of metabolic parameters and radiomics features of 18F-PET/CT according to TB status
The median SUVmax significantly higher in positive ITB group than in negative ITB group (11.35 vs. 8.37, p = 0.0406; Figure 1). However, the median SUVmax was not different according to the PTB status. Among the radiomics features, EntropyGLCM (GLCM, p = 0.0111), Coarseness (NGLDM, p = 0.0497), Low Gray-level Run Emphasis / Long-Run Low Gray-level Emphasis (GLRLM, p = 0.0189 and p = 0.0101, respectively), Low Gray-level Zone Emphasis / Short-Zone Low Gray-level Emphasis / Zone Length Non-Uniformity Zone (GLZLM, p = 0.0137, p = 0.0154, and p = 0.0056, respectively), Sphericity / Compacity (Shape and Size, p = 0.0065 and p = 0.0108, respectively), and Kurtosis / EntropyHist / EnergyHist (Histogram, p = 0.0267, p = 0.0130, and p = 0.0200) had significant different levels according to the ITB status. However, there was no significant different radiomics findings according to the PTB status (Table 2).
Multiple logistic regression analysis for ITB status
Univariate and multivariate analysis were performed for evaluation of correlation between 18F-FDG PET/CT values and ITB status using multiple logistic regression analysis (Table 3). Among the significant parameters of conventional metabolic parameters (SUVmax, MTV, and TLG) and each radiomics findings (GLCM, NGLDM, GLZLM, Shape and Size, and Histogram) in univariate analysis, the most significant parameters (the lowest p value) were included to multivariate analysis for inhibition of conflicting each parameters. In univariate analysis, SUVmax (OR, 3.34; 95% CI, 1.27-8.79; p = 0.0146), TLG (OR, 4.42% CI, 1.33-14.72; p = 0.0154), EntropyGLCM (OR, 5.36; 95% CI, 1.95-14.69; p = 0.0011), Coarseness (OR, 3.94; 95% CI, 1.41-11.03; p = 0.0090), Low Gray-level Run Emphasis (OR, 3.45; 95% CI, 1.26-9.47; p = 0.0161), Long-Run Low Gray-level Emphasis (OR, 3.34; 95% CI, 1.27-8.79; p = 0.0146), Low Gray-level Zone Emphasis (OR, 4.05; 95% CI, 1.52-10.82; p = 0.0052) Short-Zone Low Gray-level Emphasis (OR, 3.94; 95% CI, 1.41-11.03; p = 0.0090), Zone Length Non-Uniformity Zone (OR, 9.16; 95% CI, 1.27-8.79; p = 0.0146), Sphericity (OR, 6.09; 95% CI, 2.15-17.28; p = 0.0007), Compacity (OR, 8.73; 95% CI, 2.48-30.76; p = 0.0007), Kurtosis (OR, 3.96; 95% CI, 1.38-11.38; p = 0.0106), EntropyHist (OR, 5.98; 95% CI, 2.12-16.86; p = 0.0007), and EnergyHist (OR, 5.98; 95% CI, 2.12-16.86; p = 0.0007) were significant parameters which correlated with positive ITB. Multivariate analysis with the enter methods showed only Compacity (OR, 5.00; 95% CI, 1.16-21.53; p = 0.0305) remained independent parameter correlated with positive ITB (Table 3).
Predicting model for ITB status usingradiomics features of 18F-FDG PET/CT
A total of 48 features were significant parameters in t-test and were subjected to further selection step by the LASSO regularization (Figure 1). Among them, the final 27 remaining features (SUVmax, MTV, SUV_Skewness, discretized_SUVmax, discretized_SUV_Skewness, discretized_SUV_Kurtosis, discretized_SUVpeak_Sphere, discretized_HISTO_ExcessKurtosis, GLCM_Entropy_log2, GLCM_Dissimilarity, GLRLM_LRE, GLRLM_LGRE, GLRLM_SRHGE, GLRLM_LRLGE, GLRLM_GLNU, GLRLM_RLNU, NGLDM_Contrast, NGLDM_Busyness, GLZLM_SZE, GLZLM_LZE0, GLZLM_LGZE, GLZLM_HGZE, GLZLM_SZLGE, GLZLM_SZHGE, GLZLM_LZLGE) were selected. Figure 2 shows the ROC curves of the prediction models by three machine learning algorithms in training and test dataset. The AUC values of the prediction models constructed by the RF, SVM, and NN were 1.000, 0.951, and 1.000, respectively, in the training dataset and 0.752, 0.784, 0.752, respectively, in the test dataset.