| Introduction: High intensity focused ultrasound (HIFU ) is one means of extracorporeally inducing coagulation necrosis without requiring surgical exposure of the organs. The targeted zone can be precisely aimed and destroyed under diagnostic imaging guidance without harming intervening structures.The potential use of HIFU as a noninvasive local therapy for human cancers has attracted considerable interest. Many animal studies have demonstrated that this method is effective ^ feasible and safe in the treatment of tumors. But there has not been report on FflFU therapy of lung carcinoma.Objective: The project is to investigate the efficacy and feasibility of HIFU for ablating advanced stage vx2 implanted in the rabbit lung , which can provide experimental date for future clinical research of HIFU ablating lung cancer.The study was divided into two parts .Part one: The establishment of transplanted lung tumor model in therabbit suitable for HIFU therapy .Methods: The VX2 tumors were implanted into 40 rabbits lung tissues to establish the transplanted lung tumor model .The biological features were observed .Result: The tumorigenic rate was 100% . Mean survival time of lung tumor model was approximately 38.3 ± 9.7 days. Tumor diamater was 12.3±3.5mm after 3 week transplation. Light microscopy showed tumor infiltrated into the lung tissue on 3rd days. Mediastinal lymph nodes were infiltrated by tumor after 7rd day implantion. The following days tumor metastasized to lymph nodes of axilla.The mass of the inoculating lung tissues were replaced by tumor tissues when rabbits were dead .Conclusion: The result showed the biological feature of this model was stable and had a short growth period which was similar to VX2 tumor rabbit model transplanted into other oranges.The model can develop large volume tumor in a short time suitable for study on HIFU ablating lung tumors.Part two: The efficacy and feasibility of the HIFU therapy on the transplanted lung tumor in the rabbit were observed .1 Methods: To assess the pathological changes of HIFU therapy on lung tumors, 12 rabbits with lung tumors were treated by HIFU three weeks after implantation.The pathological changes of the group after sonication were examined. The treatment of HIFU with a frequency of 1.6MHz ,at intensity of 10100 W/cm 2 .Rabbits were killed from 2h to 7 days following treatment. The lung tumors were performed histological examination and electron microscope at scheduled times (2h, 24h, 3rd, 3rd, 7rd) after HIFU sonication.Result: A well defined area of lung tumors damage was indentified that corresponding to the regions ablated by HIFU. Pathological findings revealed coagulation necrosis of targeted tumor tissues were seen and tumor cells were irreversible death. There was demarcated area of coagulation necrosis after 24h. The damaged tumor area showed cell debris, pyknotic nuclei, karyorrrhexis. Many polymorphonuclear leucocytes cells(PMNs) and lymph cells were around the boundary of the necrotic area. On 3rd day, The destroyed cells continued dissolved . The resorption of some karyorrhexis was seen in the necrotic area. Granulation tissue was found in the form of young fibroblasts and new capillaries around the edges of injured area. Some PMNs appeared in the treated area. On 5~7rd day, more fibrous tissues were at the edges of the injured area. Electron microscopy exhibited severe destruction of tumor cell organelles. The membranes of the organelles were broken up. The morphology of destroyed cells was pyknotic, karyorrhexis, epicyte, cytoplasmic disruption, chromatin margination.2 Methods: The efficacy and feasibility of HIFU therapy on late stage lung tumor were evaluated. 20 rabbits with lung tumors were divided into 2 groups: The treated group (n=10) and the control group (n=10). The treated group received HIFU therapy three weeks after implantation. The treatment of HIFU with a frequency of 1.6MHz ,at intensity of 10100 W/cm 2 . The mean exposure duration was 138.1 + 18.9 seconds . The control group did not receive...
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