ABSTRACT
In order to assess the effects of radiofrequency-induced local hyperthermia on the normal liver, histopathologic findings and biochemical changes after localized hyperthemia in canine liver were studied. Hyperthermia was externally administered using the Thermotron RF-8 (Yamamoto Vinyter Co., Japan; Capacitive type heating machine) with parallel opposed electrodes. Thirteen dogs were used and allocated into one control group (N=3) and two treatment groups according to the treatment temperature. GroupI(N=5) was heated with 42.5+/-0.5degree C for 30 minutes, and GroupII(N=5) was heated with 45+/-0.5degree C for 15-30 minutes. Samples of liver tissue were obtained through a needle biopsy immediately afterhyperthermia and 7, 14 and 28 days after treatment and examined for SGOT, SGPT and alkaline phosphatase. Although SGOT and SGPT were elevated after hyperthermia in both groups (three of five in each group), there was no liver cell necrosis or hyperthermia related mortality in GroupI. A hydropic swelling of hepatocytes was prominent histologic finding. Hyperthermia with 45degree C for 30 minutes was fatal and showed extensive liver cell necrosis. In conclusion, liver damage day heat of 42.5+/-0.5degree C for 30 minutes is reversible, and liver damage by heat of 45+/-0.5degree C for 30 minutes can be fatal or irreversible. However, these results cannot be applied directly to human trial. Therefore, in order to apply hyperthermic treatment on human liver tumor safely, close observation of temperature with proper thermometry is mandatory. Hyperthermic treatment should be confined to the tumor area while sparing a normal liver as much as possible.