Development of a highly efficient implanted thermal ablation device:in vivoexperiment in rat liver

Abstract

Objectives: To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant. Methods: 16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured. Results: During AMF exposure, the implant temperature rose to 127.8¡39.3 u C (mean ¡ standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87¡0.22 mm, 4.15¡0.36 mm, 3.67¡0.58 mm and 3.24¡0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p,0.05) were seen in either cross-sectional area or width of the ablated region. Conclusion: Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.

Shaping and Focusing Magnetic Field in the Human Body: State-of-the Art and Promising Technologies

“…Another possibility for thermal ablation for treating cancer is Microwave ablation (MWA). In this technique, water molecules in the body vibrate under electromagnetic waves in the microwave energy spectrum (300 MHz to 300 GHz) and the frictional heat, produced by this vibration, causes a temperature rise in living tissue [ 33 ].…”