内镜超声引导下射频消融离体猪胰腺的实验研究

An experimental study of EUS-guided radiofrequency ablation of porcine pancreas in vitro

目的 探讨不同功率、时间下,射频消融对离体猪胰腺的消融范围,建立关于射频对离体猪胰腺消融的回归方程.方法 在射频消融的两个参数（功率、时间）可取值的范围内（5～20 W,20～240s）,取功率参数4个,时间参数11个,组成44种不同组合,每种组合执行2次,建立一个包含88种参数组合的随机化表,共对离体胰腺进行88次消融实验.观察消融过程中的声像图变化,测量消融灶的宽度（Y）,并行病理学检查.利用逐步回归法对2个参数的9个指数的9个项（时间、功率、时间×功率、时间的平方项、功率的平方项、时间的平方根项、功率的平方根项、时间的对数项、功率的对数项）进行选择,获取最佳模型,并制定回归方程.结果 启动射频消融后,声像图上可见沿导管工作区域逐渐出现长条形的回声增强区域,并逐渐增宽.消融灶形成以消融探头为中心线的近似圆柱体,灰白色,与周边正常胰腺组织境界较清晰,射频功率为15、20 W时可出现碳化坏死组织.最优的逐步回归模型显示,功率的平方项与时间的对数项均与消融宽度呈正线性相关关系,模型的回归决定系数为0.71,拟合图和残差散点图均显示拟合效果较好.最终建立了关于消融宽度的回归方程：Y =0.005×E2＋0.9374×In（t）-0.6943.结论 建立了不同功率、时间参数组合下射频消融效果的具有统计学意义的标准方程式,为临床内镜超声引导下射频消融治疗胰腺肿瘤提供实验基础依据.

Objective To investigate the extent of radiofrequency ablation of pig pancreas in vitro with various power and duration,and to establish the regression equation of radiofrequency ablation of porcine pancreas in vitro.Methods Among the 4 settings of power （from 5 w ～ 20 w） and 11 settings of duration （from 40s ～ 240s）,44 combinations were selected,and every combination was performed twice,then a randomization table including 88 combinations was established,and 88 ablation procedures on porcine pancreases in vitro were performed.The uhrasonography changes were observed,ablation widths （Y） were measured,and pathological examination was performed.In order to construct optimal model and to establish the regression equation of radiofrequency ablation,9 parameters （duration,power,duration × power,the square of duration,the square of power,the square root of duration,the square root of power,the natural logarithm of duration,the natural logarithm of power） derived from duration and power were analyzed via stepwise regression method.Results A rectangular echo enhanced region was observed along the working area of catheter when radiofrequency ablation started,and it gradually became wider during ablation.A hoar-like cylindrical ablation region that was clearly different from surrounding normal pancreatic tissue was formed.Carbonation of necrotic tissue could be observed after radiofrequency ablation under 15 w or 20 w.The optimal model showed a linear positive correlation between ablation width （Y） with the square of power and the natural logarithm of duration.The coefficient of determination of this model was 0.71.Both Fitting curve and Residual scatter diagram showed good fitting effect.Finally,a significant regression equation of radiofrequency ablation was established：Y （mm） =0.005 × E2 ＋ 0.9374 × ln （t）-0.6943.Conclusions A significant regression equation of radiofrequency ablation is established,which provides experimental base for EUS-guided radiofrequency ablation of pancreatic tumors in clinical practice.