An Interpretable Radiomics Model Based on Multi-DLCT Images for Differentiating Benign and Malignant Solid Solitary Pulmonary Nodules.

[BACKGROUND] Early-stage lung cancer frequently presents as a solitary pulmonary nodule. Compared with subsolid pulmonary nodules, solid pulmonary nodules are associated with greater invasiveness, earlier metastasis, faster growth, and worse clinical outcomes. Therefore, early diagnosis is essential for improving survival and prognosis.

[PURPOSE] To develop an interpretable radiomics model using multi-parametric images derived from dual-layer CT (DLCT) for the non-invasive differentiation of benign and malignant solid solitary pulmonary nodules (SSPNs).

[METHODS] This retrospective study included 236 patients with pathologically confirmed SSPNs who underwent DLCT-enhanced scanning at two centers. Patients from one center were randomly divided into a training cohort (n = 111) and an internal test cohort (n = 48) at a 7:3 ratio, while patients from the other center served as an external test cohort (n = 77). Radiomic features were independently extracted from seven venous-phase image series, including conventional images (CI), iodine density (ID) maps, effective atomic number (Zeff) maps, electron density (ED) maps, virtual monochromatic images (VMI) at 40 and 100 keV, and virtual non-contrast (VNC) images, and were subsequently selected using the Mann-Whitney U test, Spearman correlation analysis, and LASSO. Radiomics models based on individual image series and combined models were constructed using logistic regression, SVM, and XGBoost. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity. SHapley Additive Explanations (SHAP) were applied to interpret the fusion model.

[RESULTS] The SVM-based combined model demonstrated stable diagnostic performance across cohorts (AUC = 0.909, 0.852, and 0.793 for the training, internal test, and external test cohorts, respectively), achieving the highest AUC among all models in the external test cohort. In the external test cohort using the SVM algorithm, the combined model showed a higher AUC than the CI model (AUC = 0.793 vs. 0.667; P = 0.125), with positive NRI and IDI.

[CONCLUSIONS] An interpretable radiomics model based on multi-parametric DLCT images using the SVM algorithm enables accurate and robust noninvasive differentiation of benign and malignant SSPNs.