Feasibility and efficacy of a thermal ablation device utilizing a nitinol-based coil

BackgroundA fibrous actuator, composed of a nitinol-based coil memory alloy, functions as a flexible coil under normal conditions. It contracts and generates heat when activated with an electric current. This property makes it a promising candidate for use as an interventional thermal device.PurposeTo evaluate the thermal effects of a nitinol coil ablation device on liver tissue and the intrahepatic portal vein.Material and MethodsAn in vitro experiment using bovine resected liver was performed. Ten Japanese white rabbits were divided equally into two groups (0.6-W and 1.1-W) based on electric power settings. Ablation was performed in three liver regions for each rabbit. Ablated areas were measured using fat-suppressed T1-weighted imaging following gadolinium administration and histological examination with hematoxylin and eosin staining. For the intrahepatic portal vein ablation, nine rabbits were assigned to the ablation group and eight rabbits served as controls. Portography was conducted before and after the procedure.ResultsIn vitro, temperature increases at ablation site and at 5-, 10-, and 15-mm distances and ellipsoid-shaped ablated area were proportional to electric power. In the in vivo experiment, the 1.1-W group exhibited significantly greater ablation effects compared to the 0.6-W group, as measured by magnetic resonance imaging (50.6 vs. 22.7 mm²; P <0.001) and histopathology (38.9 vs. 21.7 mm²; P = 0.001). Nearly complete occlusion (>80% stenosis) was more frequently observed in the ablation group (72.2% vs. 22.2%; P = 0.007).ConclusionThe thermal ablation device utilizing a nitinol coil demonstrated effective liver ablation. Furthermore, it shows potential for customization in endovascular ablation applications.