剪切波弹性成像评价离体猪肝微波消融实验的初步研究

Preliminary Study of Shear Wave Elastography in Evaluating Microwave Ablation of In Vitro Pork Livers

目的微波消融术已广泛用于临床,但目前尚无较好的能够术中或术后即刻评估疗效的方法,本文探讨剪切波弹性成像对其评估的价值。材料与方法对30个离体猪肝进行微波消融,在消融过程中对4个特殊位置(a、b、c、d点)进行实时电子测温,消融前后分别行弹性检查,对不同消融部位行病理学检查,并对4个位点在消融结束即刻的温度值与杨氏模量值进行相关性分析。结果术后各点之间的温度值及弹性值比较,差异有统计学意义(P<0.01);c点术前、术后的剪切波弹性成像杨氏模量值比较,差异有统计学意义(P<0.01);而d点术前、术后的剪切波弹性成像杨氏模量值比较,差异无统计学意义(P>0.05)。消融即刻消融灶内的杨氏模量值与温度值从消融灶中心向消融灶边缘呈同一趋势递减,两者呈线性回归和相关,回归系数1.15,相关系数0.948。当以22.5 k Pa为消融灶边界组织凝固性坏死的弹性阈值时,鉴别组织凝固性坏死与否的敏感度和特异度分别为86.7%、73.3%,阳性预测值为0.823。结论 a、b点为消融的有效区域,c点为模糊区域,d点为安全区域;a、b、c、d点的温度值与弹性值呈同一趋势递减;消融灶边界组织凝固性坏死的弹性阈值为22.5 k Pa。剪切波弹性成像可以较准确地评估离体猪肝微波消融效果。

Purpose Although microwave ablation has been widely used for clinical purposes, assessment of intra- or post-operative efficacy still keeps controversial. The purpose of this study is to explore the significance of shear wave elastography in evaluating microwave ablation of in vitro pork livers. Materials and Methods Microwave ablation was performed on 30 in vitro pork livers. Real temperature was measured at four（a, b, c and d） special sites during ablation. Elastic examination was made before and after ablation. Pathological examination was performed at the different ablation locations. Correlation between temperature and young modulus of the 4 sites was analyzed at the end of ablation. Results There was a statistic difference between the temperature and elastic value of each point after ablation（P〈0.01）. Young modulus values of site c were different before and after procedure（P〈0.01）, but not at site d（P〈0.05）. The mean young modulus values and temperature determinations decreased gradually from the central to the peripheral area after ablation. There were linear regression and linear correlation between the temperatures and the mean young modulus with coefficient of regression of 0.948 and correlation coefficient of 1.15. The sensitivity and specificity at the threshold of 22.5 k Pa for detecting tissue necrosis were 86.7% and 73.3%, respectively, and the positive predictive value was 0.823. Conclusion Site a and b are the effective areas of ablation, while site c is the fuzzy region, and site d is the safe area. The young modulus values and temperature for the 4 different sites decreased gradually from site a to site d. The elasticity threshold of the coagulation necrosis is 22.5 k Pa. Shear wave elastography could quantitatively evaluate the effect of microwave ablation in vitro pork livers.