离体猪肝微波消融区的弹性梯度与温度梯度研究

摘要

Objective To explore the characteristics of changes in temperature and stiffness within the microwave-induced ablation region.Methods A type of Thy-ablation microwave antenna was used upon a design of various combination of ablation duration and power to induce heated region in samples of fresh porcine liver.Three special sites were set to assess the corresponding temperature and stiffness in each heated region.The temperature was continuously measured by using electronic thermometer with microwave on going,while stiffness was determined 5min after the ending of ablation by using real-time ultrasonic elastography,strain ratio,a quantitative indicator.Results The SR values and temperature determinations decreased progressively from the central to the peripheral area of the heated region.There was a linear regression between the temperatures (X) and SRs (Y),with Y =0.666 X-37.17.A significant correlation exists between X and Y,with the correlation coefficient being 0.956(P ＜0.001).The stiffness and temperature at the central sites are variable with the changes of both ablation time and power,but little changed at the peripheral sites of heated-region,which we name a phenomenon due to the ending effect of microwave propagation.Conclusions Temperature and stiffness increase considerably following microwave radiation but they are heterogeneously distributed within the ablated region in porcine liver.The characteristic gradient changes are confirmed of both temperature and the elasticity.It is presumable that good recognition and understanding and full utilization of these characteristics are conducive to reasonable control of tumor microwave ablation therapy.%目的 探讨微波消融区组织的弹性分布特征及其与温度分布之间的关系.方法 在离体猪肝上用Thy-ablation微波消融针以变化的消融时间-功率组合制作不同的消融区模型,消融中对消融区的三个特征性位点进行实时电子测温,消融终止5 min后对相应位点的硬度特征采用弹性超声应变率比值(strain ratio,SR)进行定量研究.结果 应变率比值和温度值由消融区的中心向边缘均呈梯度性递减,硬度回落与温度衰落方向性一致,二者间呈线性回归和相关,回归系数b=0.666,相关系数r=0.956(P＜0.001).中心区的温度和硬度受消融时间-功率组合影响变化较为明显,而边缘区受影响甚微,分别具有微波消融区边缘温度趋同效应和边缘硬度趋同效应现象.结论 微波消融区内的温度和硬度均存在明显的不均匀性,但是变化具有梯度性改变的特点.认识和利用这些现象,有助于科学管控肿瘤的微波消融治疗.