<scp>MRI</scp> ‐Based Score to Predict Retreatment Response for Viable Hepatocellular Carcinomas After Transarterial Chemoembolization

BACKGROUND & AIMS: Predicting retreatment response of viable tumours after transarterial chemoembolization (TACE) is critical for personalised treatment and prognosis assessment in hepatocellular carcinoma (HCC). We aimed to develop an MRI-based prediction model for viable tumour response. METHODS: This retrospective multicentre study included patients with HCC who presented with viable tumours 1 month after initial TACE between February 2015 and October 2022. In addition, data from a prospective clinical trial were reanalyzed as an external validation cohort. All patients underwent contrast-enhanced MRI at baseline (for initial HCC assessment), at 1 month (for evaluation of viable tumour characteristics) and at 6 months (for assessment of treatment response). The training set (n = 167) and test set (n = 59) were used to build lesion- and patient-level models predicting retreatment response at 6 months via logistic regression. Risk groups were stratified by the Youden index and analysed across retreatment subgroups. RESULTS: The Viable tumour Imaging Traits for Assessing Likelihood of response (VITAL) model incorporated four features: diffusion restriction (p = 0.050; 1 point), peritumoral hyperenhancement (p = 0.002; 1 point), heterogeneity (p < 0.001; 2 points) and mural nodule (p = 0.004; 2 points if absent). The model achieved AUCs of 0.821 (95% CI: 0.760-0.882) and 0.733 (95% CI: 0.602-0.865) in training and test cohorts. The patient-level VITAL-P Score was calculated as: 1 × (largest viable tumour size + viable tumour number) + 3 × VITAL Score. High-risk patients (VITAL-p ≥ 16) had significantly shorter overall survival (OS) in the overall cohort (p = 0.021) and shorter progression-free survival (PFS)and OS compared with low-risk patients in the locoregional therapy subgroup (p = 0.021 and 0.002, respectively). CONCLUSIONS: The prediction model based on imaging features of post-TACE viable HCCs demonstrates strong predictive power for tumour retreatment response at 6 months and correlates well with prognosis.