[Experimental study of ferromagnetic induction heating combined with hepatic arterial embolization for treatment of liver tumors].

The induction heating to ferromagnetic implants (Ferromagnetic Induction Heating: FIH) has been developed for the purpose of selective hyperthermia on deep-seated tumors. In this investigation, the procedure of FIH combined with hepatic arterial embolization (HAE) was experimentally studied on VX2 liver tumor of rabbit. The induction heating unit is composed of radiofrequency generator (500 KHZ, 6-12 KW) and circular applicator (60 cm in diameter). Ferromagnetic implant used was pure iron particles (100 mu in size), which were suspended in tenacious polysaccharide solution to be injectable through a needle. After HAE with gelatin sponge powder had been made, iron particle suspension was injected into the cavity of tumor with subsequent exertion of induction heating (9KW) for 15 minutes. The measurement of temperature was made on the tumor and the liver parenchyma by fluoroptic thermometer with thin, flexible probe which readily passed through a needle. The temperature measured at peripheral area of tumor elevated at range from 2.5 to 7.1 degrees C, corresponding to the dose of iron particles injected; 2.5 degrees C with 1 g, 4.9 degrees C with 2 g, 7.1 degrees C with 3 g. In contrast, the temperature of liver parenchyma elevated at range of less than 2.5 degrees C, to indicate a successful selective heating of liver tumor. An additional experiment for the effect of heat on normal liver of rabbit were made using a microwave heating system. The histological and serologic examinations after heating of below 40 degrees C did not show any abnormal findings. After heating of 42-43 degrees C, however, serum GOT and GPT transiently elevated more than 3 times to that of before heating. Histologically, there were extensive degeneration and necrosis of liver tissue. From the results we concluded that FIH combined with HAE could provide an intensive therapeutic effect for treatment of well-localized liver tumors with minimal damages to the liver parenchyma, because of selective heating of the tumor.