Laser-Induced Thermotherapy Combined With Hepatic Arterial Embolization in the Treatment of Liver Tumors in a Rat Tumor Model

Laser-induced thermotherapy (LITT) or interstitial laser thermotherapy is an in situ ablation technique for the treatment of malignant tumors of the liver. 1,2 The potential of LITT is that laser light is directly transmitted through flexible bare fibers into the tumor tissue with high precision. The biologic effect of the laser light is based on the transformation of laser photon energy into heat by the absorption of tissue-specific chromophores. The aim is to induce uniform coagulation necrosis of the treatment volume. 3 Of great importance to the method’s success is the size of the induced coagulation necrosis, which must contain the whole volume of the tumor tissue. This lesion size largely depends on the temperature distribution in the target volume, which is determined partly by the blood perfusion in the target organ. 4,5 In organs with a high blood perfusion, such as the liver, a cooling effect results because of the temperature difference between the hyperthermic area and blood. 6,7 Temporary interruption of hepatic blood flow by occlusion of hepatic inflow vessels (Pringle maneuver) during LITT has been proven to increase its efficacy. 8–11 The Pringle maneuver usually requires laparotomy 10,11 or at least laparoscopy 12 and may therefore be difficult to repeat in cases of insufficient therapy. LITT, however, can be applied percutaneously without laparotomy or laparoscopy and can thus be easily repeated. 1,2 An alternative to the temporary interruption of hepatic arterial blood flow to liver tumors is the application of degradable starch microspheres (DSM), as used for chemoembolization. 13,14 The purpose of this study was to assess the effect of combined LITT and DSM on intrahepatic temperature distribution and tumor response in rats with liver tumors.