| Part Ⅰ Establishment of Rabbit VX2Soft Tissue Tumor Model and Treatment with Percutaneous Ethanol Injection under the Guidance of Magnetic Resonance ImagingObjective:Establish rabbit VX2soft tissue tumor model,and treat it with percutaneous ethanol injection under the guidance of magnetic resonance imaging.To make ready for the therapeutic evaluation with functional magnetic resonance imaging.Methods and Materials:Fifteen healthy New Zealand white rabbits were included in this study.0.2ml tumor tissue suspensions were injected into the proximate of rabbit posterior limb.14days later, all the rabbits underwent conventional MRI examination.Percutaneous ethanol injection were performed to all the tumors under the guidance of MR in the next day of the examination.T2WI was used as guidance and monitoring means. MR compatible puncture needle with lateral hole was stabed into the lesion center, and injected anhydrous ethanol according to the volume of1ml/cm tumor diameter slowly. To observe the tumors signal characteristics, morphological feature and pathological feature pre-operation and post-operation. Results:All of the15rabbits were established soft tissue tumor model successfully, the success rate is100%. The tumors were oval or round,3-4cm in diam. MRI scanning showed a low signal of the tumor on T1WI and a high signal of the tumor on T2WI before PEI. Percutaneous ethanol injection were performed to all the tumors under the guidance of MR successfully with3.5ml ethanol injected into the tumors.T2WI could monitor the ethanol in dispersion and distribution within the tumors clearly.Histologically, tumors were composed of large, uniform, oval/round cells arranged in solid nests which was intensive in the periphery of tumors. Necrosis was apparent in the center of the tumors.10days after operation, most tissue in the periphery of tumors was coagulative necrosis, only a few tumor cells were residual. Necrosis range in the tumors center were obviously increased compared with preoperative.Conclusion:Rabbit VX2tumor of soft tissue model is suitable for the therapeutic evaluation of tumor.It is an animal model of operation simple and high rate of successful. MR T2WI can monitor the ethanol in dispersion and distribution within the tumors clearly. It is a good guidance and monitoring imaging methods of tumor ablation. Part II The Experimental Study on Diffusion-Weighted Imaging in The Evaluation of Percutaneous Ethanol Injection Therapy Response of Rabbit Soft Tissue VX2TumorObjective:To evaluate the therapy value of percutaneous ethanol injection inVX2soft tissue tumor in the posterior limb of rabbit with Diffusion-Weighted Imaging.Methods and Materials:Fifteen healthy New Zealand white rabbits were included in this study.0.2ml tumor tissue suspensions were injected into the proximate of rabbit posterior limb.All the rabbits underwent conventional MRI and DWI examination after2weeks, with the b values at300,500,700,900s/mm2. Percutaneous ethanol injection were performed to all the tumors under the guidance of MR in the next day of the examination. Conventional MRI and DWI examination were performed to all the rabbits after1、7、10days of PEI. To observe the tumors signal characteristics pre-operation and post-operation, and the ADC values change of the tumor essence, necrotic tissue and normal muscle tissue.Results:MRI scanning showed a low signal of the tumor on T1WI and a high signal of the tumor on T2WI and DWI before PEI. Along with the increased b values,the ADC values of tumor essence, necrotic tissue and normal muscle tissue decreased. There was significant difference between the ADC values of the tumor essence, necrotic tissue and normal muscle tissue under the same b value. The ADC values of tumor essence was smaller than those of the muscle and necrosis tissues. The ADC values of tumor essence had significant statistical difference between pre-PEI therapy and post-PEI therapy on the spots of one,seven and ten days. The signal of tumor essence was lower on DWI than pre-PEI on the spot of10days after therapy.Conclusion:It is possible to apply diffusion-weighted MR imaging to evaluate the PEI therapy value of VX2soft tissue tumor in the posterior limb of rabbit.The ADC values change markedly at the prophase after PEI therapy. Part III The Experimental Study on T2*First Perfusion Weighted Imaging in The Evaluation of Percutaneous Ethanol Injection Therapy Response of Rabbit Soft Tissue VX2TumorObjective:To evaluate the therapy value of percutaneous ethanol injection in VX2soft tissue tumor in the posterior limb of rabbit with T2*first perfusion weighted imaging.Methods and Materials:Fifteen healthy New Zealand white rabbits were included in this study.0.2ml tumor tissue suspensions were injected into the proximate of rabbit posterior limb. after2weeks, All the rabbits underwent conventional MRI and PWI examination with GD-DTPA injected into the rabbits’ear marginal vein(0.2ml/kg,1.5ml/s). Percutaneous ethanol injection were performed to all the tumors under the guidance of MR in the next day of the examination. Conventional MRI and PWI examinations were performed to all the rabbits after7、10days of PEI.To observe the tumors signal characteristics pre-operation and post-operation, to contrast the time in tensity curve (TIC) of tumor with normal muscle tissue preoperative and postoperative, to calculate the perfusion parameter values of pre-operation and post-operation:negative enhancement integral (NEI) and maximum slope of decrease (MSD).Results:MRI scanning showed a low signal of the tumor on T1WI and a high signal on T2WI before PEI.The tumor’s TIC shows that it’s signal was decreased quickly in the first phase,but the normal muscle tissue’s TIC is flat. After7and10days of PEI,the tumor’s TIC was changed to flat than pre-operation. The tumor’s NEI and MSD (1145.53±69.79,1145.53±17.69) were larger than normal muscle’s (763.26±72.57,763.26±25.58)(P<0.05).7and10days after operation, NEI and MSD of tumor were lower than that of before operation, the difference was statistically significant (P<0.05).ConcIusion:It is possible to apply T2*first perfusion weighted imaging to evaluate the PEI therapy value of VX2soft tissue tumor in the posterior limb of rabbit.The perfusion parameter values change markedly at the prophase after PEI therapy. Part IV The Experimental Study on1H-MRS in The Evaluation of Percutaneous Ethanol Injection Therapy Response of Rabbit Soft Tissue VX2’TumorObjective:To evaluate the therapy value of percutaneous ethanol injection in VX2soft tissue tumor in the posterior limb of rabbit with1H-MRS.Methods and Materials:Fifteen healthy New Zealand white rabbits were included in this study.0.2ml tumor tissue suspensions were injected into the proximate of rabbit posterior limb. after2weeks, All the rabbits underwent conventional MRI and1H-MRS(TR/TE:1500/144, NEX:8) examination.Percutaneous ethanol injection were performed to all the tumors under the guidance of MR in the next day of the examination. Conventional MRI and1H-MRS examinations were performed to all the rabbits after7、10days of PEI. To observe the tumors signal characteristics pre-operation and post-operation, to analysis the tumors’MRS spectrum characteristics preoperative and postoperative, to calculate the Cho/Lipid peak value before operation and after operation.Statistical analysis was used with SPSS17.Results:MRI scanning showed a low signal of the tumor on T1WI and a high signal of the tumor on T2WI before PEI. Before operation, Cho peak(3.2ppm) of the tumor was the first peak, Lipid peak(1.4ppm) was the second peak and Cr peak(3.02ppm) was minimum; However, after operation, the Lipid peak changed into the first peak, Cho peak went down and became the second peak. Cho/Lipid values of pre-operation (1.2539±0.3537,1.1357±0.2684) were higher than those of post-operation(0.3027±0.1132,0.2589±0.1086;0.3125±0.1087,0.2673±0.1145).the difference was statistically significant (P<0.05).Conclusion:It is possible to apply1H-MRS to evaluate the PEI therapy value of VX2soft tissue tumor in the posterior limb of rabbit. Cho peak decreased obviously and Cho/Lipid values were significantly lower than pre-operation at the prophase after PEI therapy. |
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