微波消融灶组织病理变化与超声弹性成像图对照的实验研究

目的研究微波消融灶大体标本不同区域与弹性成像图相应区域问的关系，探讨超声弹性成像评价微波消融组织病理改变的可行性。方法单导水冷2450MHz微波，作用功率50w，作用时间200s，消融离体猪臀部肌组织，消融前、消融后即刻行静态超声弹性检查，分别测量弹性图的蓝色区及蓝色区＋绿色区大小。消融后测量大体标本灰白色＋灰粉色区及灰白色区大小。大体标本常规甲醛固定，石蜡切片，HE染色，光镜下观察各消融区域组织细胞变化，并采用配对t检验比较大体标本测值及镜下检查结果同弹性图相应测值。结果共进行了30次微波消融，形成30个消融灶。所有消融灶最终均能获得满意的弹性成像图。消融后消融灶剖面大体观呈以天线为长轴的椭圆形，由中心向外依次分为：棕黄色区，光镜下肌细胞完全破坏、崩解；灰白色区，硬而致密；光镜下肌细胞凝固性坏死；灰粉色区，光镜下肌细胞形态大致正常，细胞问水肿。消融后，弹性图像显示消融灶呈椭圆形，中心为较均匀蓝色，周边呈宽度较均匀一致绿色，与周围混杂颜色的正常组织分界清楚。弹性图蓝色区＋绿色区（灰白色区＋灰粉色区）长、宽、高测值分别为（3．750±0．289）、（2．773±0．264）、（2．223±0．229）cm，大体标本总消融区长、宽、高测值分别为（3．768±0．277）、（2．668±0．337）、（2．291±0．378）cm。2种方法长、宽、高测值的差异均无统计学意义（t=-0．568、1．994、1．078，P均〉0．05），且有相关性（r=-0．86、0．69、0．62，P均〈0．01）。弹性图蓝色区长、宽、高测值分别为（3．307±0．231）、（2．260±0．269）、（1．827±0．271）cm，大体标本灰白色区长、宽、高测值分别为（3．280±0．273）、（1．980±0．373）、（1．840±0．297）cm。2种方法长、高测值的差异亦无统计学意义（t=0．576、0．238，P均〉0．05），且有相关性（F0．76、0．71，P均〈0．01）。结论微波消融后超声弹性图像的蓝色区＋绿色区与消融灶标本灰白色区＋灰粉色区（凝固性坏死区＋水肿区）相对应，蓝色区与灰白色区（凝固性坏死区）相对应，超声弹性成像可以初步反映组织的热损伤程度。

Comparative research between tissue pathological change and ultrasound elastography image after microwave ablation

Objective To investigate the relationship between different zones of the gross specimen and the corresponding ultrasound elastography image after microwave ablation and investigate the feasibility of evaluating the pathological change of tissue after microwave ablation by ultrasound elastography. Methods At an output power of 50 W, microwave with 2450 MHz was applied for 200 s to ablate in vitro muscular tissue of porcine. Static ultrasound elastography was applied before and immediately after ablation, then the sizes of the blue zone and the blue zone ＋ green zone on elastogram and the off-white zone and off-white zone ＋ the pale pink zone of the gross specimen after ablation were measured. Routine formalin fixation, parraffin embedding, section and HE stain were applied for the gross specimen. Then the cellular structure and changes of each zone were observed under light microscope and the measured values of the gross specimen, and the examination results under microscope were compared with the corresponding measured values of the elastography with paired t-test. Results A total of 30 ablation lesions were formed after 30 times of microwave ablation. The section of the ablation lesion showed an ellipse with the antenna as long-axis. The well-defined zones from center to outside were off-white zone which was hard, pale brown zone in which the muscular cells displayed coagulation necrosis under light microscope and pale pink zone in which the muscular cell shape were roughly normal with intercellular edema under light microscope. After ablation, the elastography showed the ablation lesion as an ellipse with a comparatively uniform blue center, peripheral green zone with uniform width and had a clear boundary with surrounding normal tissue showed as mixed color. The length, width and height of blue ＋ green zone on elastography were （3.750±0.289）, （2.773±0.264） and （2.223±0.229）cm, respectively. The length, width and height of total ablation zone （off-white zone ＋ pale pink zone） were （3.768 ±0.277）, （2.668 ±0.337） and （2.291 ±0.378）cm, respectively. The difference of measured values between the two methods were not statistically significant （t=0.568, 1.994 and 1.078, all P 〉 0.05） and were correlated （r=0.86, 0.69 and 0.62, all P 〈 0.01）. The length, width and height of the blue zone on elastography were （3.307±0.231）, （2.260±0.269） and （1.827±0.271）cm, respectively. The length, width and height of off-white zone of the gross specimen were （3.280±0.273）, （1.980±0.373） and （1.840±0.297）cm, respectively. The length and height of the difference of measured values between the two methods were not statistically significant （t=-0.576 and 0.238, both P 〉 0.05） and were correlated （r=0.76 and 0.71, both P 〈 0.01）. Conclusions The blue zone ＋ green zone after ablation on ultrasound elastography correspond with the off-white zone ＋ pale pink zone （coagulation necrosis and edema zone） of the ablation lesion and the green zone on ultrasound elastography corresponds with the pale pink zone （coagulation necrosis zone）. Ultrasound elastography can initially evaluate the degree of muscular tissue thermal injury.