水冷式单针射频热消融系统可消融范围测定的实验研究

目的 通过离体器官和活体动物实验,确定水冷式单针射频消融系统的功率、时间、消融范围的相关曲线,为实际应用提供理论依据.方法 采用水冷式单针射频消融系统分别对新鲜牛肝脏、健康成年新西兰白兔的肝脏和肌肉组织实施射频消融处理,经多路测温系统实时采集消融区域的温度场数据,以50 ℃为温度区域边界确定实际达到的最大消融范围,并计算离体肝脏组织的比吸收率(SAR).结果在100～130 V治疗电压范围内,治疗过程平稳,阻抗无明显变化,最大单次消融直径达51 mm.在140～170 V治疗电压范围内,较短时间即可达到较大的消融范围,但之后阻抗开始上升,组织消融范围不再继续扩大.在180～200 V电压范围内,几乎都出现快速的阻抗超标、射频治疗自动终止而不能正常完成射频消融.实际测得肝脏组织的SAR与理论值相符.病理学观察证实肝脏、肌肉组织发生了典型的凝固性坏死.结论 该水冷式单针射频消融系统在实验过程中,功放、水冷、测温及控制部分均运行平稳,实际消融效果达到了设计要求和临床治疗的需要.

Abstract：

Objective To determine the power-time-ablation scope correlogram of a water-cooled single needle electrode radiofrequency (RF) ablation system and to establish a theoretical basis for its practical application.Methods RF ablations were performed using a water-cooled single needle electrode radiofrequency ablation system developed by the authors using fresh ox liver as well as liver and muscles of healthy adult New Zealand white rabbits.The temperature of the ablation area was monitored using a multichannel thermometric system.The maximum ablation scope was determined by detecting the rim at which the temperature was no less than 50 °C.The specific absorption rate (SAR) of the isolated liver tissue was calculated.Results In the treatment voltage range of 100-130V,the process was smooth and steady.No impedance variation was obvious.The maximum diameter of a single ablation was 51 cm.With the treatment voltage at 140-170 V,a larger ablation area could be reached in less time,but eventually the impedance began to increase while the ablation area was no longer expanded.When the treatment voltage reached the range of 180-200 V the impedance almost always increased rapidly out of limits,and the treatment system stopped automatically.The measured SAR value was consistent with the theoretical value.Pathology confirmed that both liver tissue and muscle tissue manifested typical coagulative necrosis.Conclusions The power amplifier,cooling,thermometric and control sections of the RF ablation system worked stably,and the practical ablation effect met the design and clinical treatment requirements.     

单针水冷式射频消融过程中组织热损伤区域的有限元分析

目的:提出单针水冷式射频消融系统在治疗过程中对生物组织热损伤的仿真分析。方法:建立电-热场耦合有限元模型,描述射频消融的电场强度、特征吸收率以及水冷式射频针周围组织的温度分布。考虑了组织的电导不变及电导随温度变化的两种情况,比较两者的最大电场强度与热损伤区域(超过50℃边界)。结果:在相同的治疗电压和治疗时间下,电导变化模型比电导不变模型的射频最大电场强度增高7.9%,热损伤范围增大19.6%。结论:本文对射频消融术的治疗参数选择有着较好的临床参考价值。