Shinkai M, Ueda K, Ohtsu S, Honda H, Kohri K, Kobayashi T
Department of Biotechnology, Graduate School of Engineering, Nagoya University.
Jpn J Cancer Res. 1999 Jun;90(6):699-704. doi: 10.1111/j.1349-7006.1999.tb00803.x.
Magnetic particles (magnetite) were used to make radiofrequency (RF) capacitive hyperthermia effective to a specific site. In an agar phantom experiment, a magnetite-containing agar piece was buried in a large agar phantom and heated by an 8 MHz-RF capacitive heating device. The magnetite-containing agar piece was heated more than the magnetite-free agar phantom, and the specific adsorption rate in the phantom was increased 1.5 times by the magnetite particles. The temperature distribution in the large agar phantom showed that the highest temperature was obtained at the center of the magnetite-containing piece. The rate of temperature increase was approximately proportional to the magnetite concentration to the power 0.8. This method was applied to an in vivo experiment using a pig. Magnetite was prepared as a colloidal material dispersed in a carboxymethylcellulose solution (CMC-Mag) and intramuscularly injected in the pig femur. As a result of 8 MHz-RF heating, the temperature at the CMC-Mag-injected point increased to over 43 degrees C after 7 min, while the temperature at a point without magnetite was under 40 degrees C at the same time. The specific adsorption rate in the magnetite-containing tissue was twice that of the magnetite-free tissue. In addition, the time required to reach a temperature of over 43 degrees C was only 7 min, while it was over 15 min in the case without the CMC-Mag.
磁性颗粒（磁铁矿）被用于使射频（RF）电容式热疗对特定部位有效。在琼脂模型实验中，将含磁铁矿的琼脂块埋入大的琼脂模型中，并通过8兆赫兹的射频电容加热装置进行加热。含磁铁矿的琼脂块比不含磁铁矿的琼脂模型升温更多，并且模型中的比吸收率因磁铁矿颗粒而提高了1.5倍。大琼脂模型中的温度分布表明，含磁铁矿块的中心温度最高。升温速率大致与磁铁矿浓度的0.8次方成正比。该方法应用于使用猪的体内实验。磁铁矿被制备成分散在羧甲基纤维素溶液中的胶体材料（CMC-Mag），并肌肉注射到猪的股骨中。经过8兆赫兹的射频加热后，注射CMC-Mag的点在7分钟后温度升至43摄氏度以上，而同时不含磁铁矿的点温度低于40摄氏度。含磁铁矿组织中的比吸收率是不含磁铁矿组织的两倍。此外，达到43摄氏度以上温度所需的时间仅为7分钟，而在没有CMC-Mag的情况下则超过15分钟。
