Experimental Study On Image-guided Percutaneous Microwave Ablation For Lung Cancer

PART ONEEstablishment of Rabbit Lung VX2 Tumor ModelObjective: To establish rabbit lung tumor model suitable for microwave ablation. Materials and methods: By CT-guided, 36 New Zealand white rabbits were implanted in right lung with hydrogels, which carried VX2 tissue suspension. Results: Fourteen to twenty-six days after implantation, tumors were found in 34 rabbits by CT scan. Twenty-six of them have single nodule in right lung, which diameter wais from 0.5cm to 0.8cm. The achievement ratio of model was 72.2% (26/36). There were multi-nodules in 2 rabbits combined with pleural effusion. Mediastinum was involved in 4 rabbits. Implantation metastases in chest wall were found in 2 rabbits. Conclusion: The rabbit lung VX2 tumor models are established successfully. The volume of solid tumor formed in lung is big enough for study of microwave ablation. The method of establishing model is safe and feasible. PART TWOExperimental Study on Microwave Ablation for Porcine Lung in vitroObjective: To investigate the regularity of temperature rising of lung in vitro produced by microwave ablation, and select power output and time of microwave suitable for animal models. Materials and Methods: The rigid implanted microwave antenna with internally water-cooled were directly implanted into fresh porcine lung in vitro. Microwave frequency was 2450 MHz. Differential irradiation power output were performed 15min and the temperature curves of selected spots were simultaneously recorded by iron-constantan coupletemperature-measuring system. Results: Fifty-six experiments with 224 spots' temperature curves were performed. Four spots (r=5mm, 10mm, 15mm, 20mm) were recorded in each experiment. The shape of curve was as followed: temperature of each spot reached the peak in short time. Then the curve got into the "platform" stage. When microwave ablation stopped, the temperature decreased rapidly. The characteristic of curve became more obvious if the spot was nearer the original point and/or power was higher. When the power output was 30W, 40W and 50W, it took 162s, 126s, and 123s respectively, to reaching 60 ℃ at the spot 10mm far away from original point. Conclusion: The characteristic of temperature curve in lung is different with that in liver. 30W3min power/time combination can meet the need of ablating lung cancer, which diameter is less than 1cm. PART THREEExperimental Study on Percutaneous Microwave Ablation for Rabbits'Lung in vivoObject: To investigate ablation areas in lung in vivo under 30W3min power/time combination, and its security. Materials and Methods: By the guidance of CT, microwave antenna was inserted in the preset position of right lung in 5 New Zealand white rabbits. Ablation was carried out in 30W3min power/time combination. CT scans were performed after microwave ablation instantly, 2 weeks, and 3 months respectively. Results: CT scans showed the ablation areas were from 1.5×1.1cm to 1.6× 1.4cm after ablation instantly. The areas became little less 2 weeks later. After 3 months, the ablation areas became much less even vanished. Slight pneumothorax was found in 1 rabbit and self-cure after 2 weeks without treatment. Conclusion: Percutaneous microwave ablation rabbits' lung is safe. The area of 30W3min power/time combination can meet the need of ablating animal models.PART FOURImage-guided Percutaneous Microwave Ablation for Rabbit LungVX2 Tumor ModelsObjective: To investigate the effectivity and security of percutaneous microwave ablation for rabbit lung tumor model. Materials and Methods: Twenty-six rabbit lung VX2 tumor models were divided into experimental group and control group randomly. Experimental group were performed microwave ablation guided by ultrasound or CT, according to the location of tumor. Enhanced CT scans were carried out before and after ablation instantly in experimental group. Two experimental rabbits were killed after ablation instantly and one week later, respectively. Pathological changes were analyzed. Results: (1) There were 12 animals in control group and 14 in experimental group. Ten animals were performed microwave ablation guided by ultrasound, and other 4 by CT. (2) CT appearance: single nodule could be detected in the lung before ablation. The nodule was lobulated with round shape. The margin was spiculate. After contrast administration, the nodule showed mild to marked enhancement. After ablation, the lesion showed grind glass opacity with blurry margin. The density was heterogeneous. After contrast administration, the central part of the lesion had no enhancement, but the peripheral part shows mild to moderate enhancement. (3) Complications: Pneumothoraxes were found in seven rabbits, one of which was plentiful. Pulmonary hemorrhage was found in one case and mild degree burn of skin in one rabbit. Three to five days later, all animals were self-cure or became better without treatment. (4) Pathological changes: After ablation instantly, the tumor appeared as white nodule. Around tumor were sable coagulation area, salmon pink hyperaemia reaction zone and normal lung tissue one by one. The hyperaemia became lightened one week later. Light microscope findings revealed coagulation necrosis in the center of tumor. The outlines of periphery tumor cellswere maintained. There were plenty erythrocytes in alveolar spaces of reaction zone and plenty effusions in periphery alveolar spaces. One week later, tumor cells appeared coagulation necrosis. Effusions in alveolar spaces became less but lymphocytes were still found. There were plenty inflammatory cells and effusions in bronchial lumen. (5) There were significant different of survival time between experimental and control group (P=0.026). However all animals died of tumor metastases. Conclusion: It is safe and effective of microwave ablation for rabbits' lung cancers and provides experimental evidences for clinical application. PART FIVEDiscovery of Biomarkers in the Serum for Lung Cancer withThe Use of Protein FingerprintingObjective: To investigate the feasibility of screening serum biomarkers for lung cancer by protein fingerprinting. Materials and Methods: The serum proteins of 23 rabbits with implanted tumor and 17 healthy rabbits were detected by surfaced enhanced laser desorption/ionization time of flight mass spectroscopy (SELDI-TOF-MS) and weak cation exchange (WCX2) proteinchip. In 15 of 23 rabbits, CT scan showed that the tumors were formed in lung, which were called cancer group. Other 8 of 23 were not found tumor formation when specimens collected. They were called precancer group, because rumors were found at the follow-up investigation. The data were read with PBSII-C type proteinchip reader and analyzed with Biomarker Wizard and Proteinchip 3.1 Software of Ciphergen Biosystems Company. Results: There were 5 protein contents of the three groups which were significantly different. Among them, 3 proteins were up-regulated and 2 down-regulated. Conclusion: Serum biomarkers, which are correlated with advancement of tumor, can be detected by protein fingerprinting. That could beuse in clinical application to precaution lung cancer or detection earlier.