Predictive Value of Ablative Margin Assessment After Microwave Ablation for Local Tumor Progression in Medium and Large Hepatocellular Carcinoma: Computed Tomography–Computed Tomography Image Fusion Method Versus Side-by-Side Method

Objective This study aimed to explore the feasibility and predictive value for local tumor progression (LTP) of the computed tomography (CT)–CT image fusion method versus side-by-side method to assess ablative margin (AM) in hepatocellular carcinoma ≥3 cm in diameter. Materials and Methods We selected patients with hepatocellular carcinoma ≥3 cm in diameter who underwent microwave ablation and had complete tumor ablation. We used the CT-CT image fusion method and side-by-side method to assess AM separately and divided the lesions into 3 groups: group I, minimum ablative margin (min-AM) <0 mm (the ablation zone did not fully cover the tumor); group II, 0 mm ≤ min-AM <5 mm; and group III, min-AM ≥5 mm. Results A total of 71 patients involving 71 lesions were included. The κ coefficient for the agreement between the CT-CT image fusion method and the side-by-side method in assessing min-AM was 0.14 ( P = 0.028). Cumulative LTP rate was significantly different between groups by min-AM from the CT-CT image fusion method ( P < 0.05) but not by min-AM from the side-by-side method ( P = 0.807). Seventeen of the 20 LTP lesions were located at min-AM on fused CT images, with consistency rate of 85%. Conclusions Compared with the side-by-side method, the CT-CT image fusion method is more accurate in assessing the AM of eccentrically ablated lesions and shows better predictive value for LTP. The min-AM based on CT-CT image fusion assessment is an important influencing factor for LTP.