超声、CT、MRI对离体动物肾脏射频消融效果评估的价值

目的 了解超声、CT、MRI在离体动物肾脏即刻射频消融效果评估中的价值。方法 取新鲜离体猪肾4个，在其上、下极和中部进针1cm，共12个靶点进行消融，消融前后分别进行CT、磁共振扫描（MRI）、实时超声和4h后超声测量消融灶大小，并和大体病理进行对比。结果 超声消融灶为不规则的强回声，后方轻度声衰减。周围不规则。CT平扫实验前后影响学无明显改变。消融灶MRI表现为稍长T1，短T2信号，边界清晰。肉眼观察消融灶呈棕褐色类圆形的凝固性坏死，周围绕有0．3～0．5cm的淡红色环。实时超声明显大于肉眼测定值，4h后超声明显小于肉眼测定值（P〈0．05）。MRI和肉眼测得值相似（P〉0．05）。结论 超声无法精确预测消融效果。MRI显示消融灶边界清晰，能精确评估消融效果。CT平扫对消融灶的判断无意义。

Value of ultrasonography, CT, MRI to radiofrequency thermoablation in vitro animal kidney

Objective] To evaluate the action of ultrasonography(US),CT and MRI in judgment the effect of radio-frequency ablation(RFA)shortly in vitro for animal kidney.Methods] Four porcine kidneys away from body were elected,a 8-electrode dry radiofrequency thermal ablation probe was inserted into superior pole,lower pole and middle part of each kidney at the depth of 1 cm from surface,respectively.Then the probe was deployed to a diameter of 2 cm.The ablation lesion was monitored with US during and after experiment and CT and MRI was examined before and after experiment.The size and shape of the lesions were measured and examined histologically and contrasted with different image method.Results] US confirmed probe placement but did not monitor lesion progression,the irregular hyperechogenicity was shown on ultrasound screen.There was not image change on CT general scan before and after experiment.In gross examination,all lesion were rounded brown after ablation,in contrast to the normal pink appearance of untreated parts.The lesion was characteristically shown altered signal on both longer T1-and shorter T2-weighted images,and the regular edge was shown on MRI.The real-time ultrasound measuring value were bigger than the gross examination and after 4 hours RFA the value were smaller than the gross examination(P <0.05).But there was not significant difference for the value between MRI and the gross examination(P >0.05).Conclusion] In the porcine kidney away from body RFA created rapid and completely devitalized lesion of consistent size and shape.It was particular useful that decreased signal on T2-weighted images as a marker for estimated size of lesion.The value of the ablative lesion in real-time and delay ultrasonography wasn't reliable.General CT scan was useless for estimating the ablative lesion.