1993 Volume 11 Pages 25-32
In order to obtain more large coagulation area by percutaneous microwave tissue coagulation in liver, the combination method of microwave tissue coagulation (MTC) and radiofrequency hyperthermia (RFH) was examined experimentally. The THERMOTORON-RF8 (Yamamoto-vinita Ltd.) was used as the RFH system in this study. Alternative irradiation between MTC (70 watt) abd RFH (peak: 900 watt) every 30 seconds was performed as the combination method (MTC-RFH). As the control experiments, every 30 seconds intermittent irradiation of the MTC or RFH was performed, respectively.
The phantom study in agar revealed that (1) the temperature near the needle-electrode of the MTC was expressly raised by RFH in spite of the absence of microwave irradiation, and that (2) at the point of 25mm distance from the needle-electrode of the MTC the most rise in temperature was obtained by MTC-RFH. In the experiment on liver tissue under anesthetized pig (body weight 20kg), (3) the bullet shaped coagulation area which the diameter was about 30 mm width was found in the MTC-RFH, while the teardrop shaped coagulation area was found in the MTC.(4) It was found the skin where the needle-electrode of the MTC penetrated it was burned maybe due to heat in the needle-electrode induced by RFH.
Accordingly the combination of MTC and the RFH can enlarge the tissue coagulation area, but the problem to control heating around the needle-electrode of the MTC induced by RFH is remained.
