Interpretable habitat radiomics model based on multi-sequence MRI for risk prediction of metachronous liver metastasis in rectal cancer: a multicenter study.

backgroundAccurate prediction of metachronous liver metastasis (MLM) within the 24 months remains a clinical challenge in rectal cancer. While radiomics offers noninvasive insights into tumor characteristics, few studies have investigated multi-sequence MRI-based habitat radiomics with interpretable modeling strategies.

methodsThis retrospective study enrolled 391 patients with pathologically confirmed rectal cancer. K-means clustering was applied to pretreatment T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) MRI to generate tumor subregions. Radiomic features were extracted from both sequences, and clinical variables were also included. Support vector machine (SVM) classifiers were used to construct radiomics, habitat, and combined models. Model performance was assessed using area under the ROC curve (AUC) and decision curve analysis (DCA). SHapley Additive exPlanations (SHAP) were employed to interpret the contribution of individual features.

resultsThe habitat model demonstrated superior predictive performance compared to conventional radiomics, achieving AUCs of 0.875 in the training cohort, 0.829 in the internal validation cohort, and 0.810 in the external test cohort. The combined model, incorporating clinical variables and habitat features, achieved the highest performance in the validation cohort (AUC = 0.870) and external test cohort (AUC = 0.862). SHAP analysis revealed complementary contributions from T1WI and T2WI features, highlighting the intratumoral heterogeneity interpretability of the multi-sequence habitat approach.

conclusionMulti-sequence MRI-based habitat radiomics demonstrated strong performance in predicting MLM, and the integration with clinical variables further improved accuracy, providing a practical tool for individualized risk assessment and treatment planning.