Undertreated Volume and Tumor Morphology as Predictors of Outcome Following Thermal Ablation of 3-7-cm Hepatocellular Carcinoma

Purpose: To evaluate the association of 3-dimensional (3D) undertreated volume and tumor features to local recurrence and survival in patients with hepatocellular carcinoma (HCC) treated with radiofrequency (RF) ablation. Materials and Methods: A total of 556 patients with well-defined solitary large HCC tumors (3–7 cm) treated with RF ablation alone or RF ablation plus ThermoDox from a multicenter trial between 2014 and 2018 were retrospectively considered for this study. Each patient had pre–RF ablation and 28-day post–RF ablation computed tomography (CT) with sufficient quality. Overall, 185 patients (61 years [SD ± 11]; female, 24%) were included in this study. The mean tumor volume was 31.8 cm3 (SD ± 27.6). The percent of the tumor covered by the ablation zone was determined by semimanual 3D tumor and devascularized ablation zone segmentation with subsequent elastic registration. Tumor and ablation zone overlap and tumor morphology were compared with local recurrence and survival by univariate and multivariate statistical analyses. Results: There was a difference between percent overlap volume, with the RF ablation–alone group showing a higher overlap volume compared with RF ablation + ThermoDox group (73% [SD ± 17] vs 66% [SD ± 22], P = .02). Local recurrence was associated with a larger tumor volume (P = .004) and a higher tumor flatness (P = .034). A modest trend existed between survival and a lower absolute overlap volume (P = .068), lower absolute undertreated volume (P = .063), and lower tumor volume (P = .067). Conclusions: The correlations between tumor-ablation zone overlap and local recurrence and survival suggests that 3D preablation and postablation image registration could aid in verification of adequate treatment coverage or to predict recurrence. Image assessment and registration with ablation may support standardization, tailored treatment approaches, and outcome prediction.