Baseline PET/CT Radiomics and Clinical Indicators for Pretreatment Response Prediction in Unresectable Hepatocellular...

IntroductionPretreatment prediction of benefit from targeted therapy plus immunotherapy remains uncertain in unresectable hepatocellular carcinoma (HCC). We developed and internally validated a model integrating baseline 18F-FDG PET/CT radiomics with clinical indicators.MethodsThis single-center retrospective study included 325 patients, comprising a development cohort (n = 182) and an internal validation cohort (n = 143). Clinical/PET, radiomics, and fusion logistic models were developed to predict 12-week objective response assessed according to the modified Response Evaluation Criteria in Solid Tumors. Development-derived preprocessing parameters, coefficients, and cutoffs were applied unchanged to validation. Discrimination was assessed using AUCs with bootstrap 95% confidence intervals and paired patient-level bootstrap comparisons; calibration was assessed using the Brier score, calibration intercept, and calibration slope.ResultsIn the 143-patient internal validation cohort, the clinical, radiomics, and fusion models had AUCs of 0.69 (0.60-0.77), 0.75 (0.67-0.83), and 0.84 (0.78-0.90), respectively. The paired AUC difference was 0.16 (95% CI, 0.05 to 0.26; P = 0.002) versus the clinical model and 0.09 (-0.001 to 0.19; P = 0.053) versus the radiomics model. The fusion-model Brier score was 0.16, calibration intercept was -0.02, and calibration slope was 0.83.ConclusionThe fusion model integrating clinical and radiomics features demonstrated favorable discrimination and calibration for predicting 12-week objective response in patients with HCC. It improved predictive performance compared with the clinical model alone and may provide a noninvasive tool for pretreatment response assessment. Prospective multicenter studies are warranted to evaluate its generalizability and clinical utility.