血管对肝脏微波消融温度场的影响

为了研究血管对消融温度场的影响,运用离体实验的方法测定距天线不同距离及血流量不同的血管对温度场的影响.实验中采用输液管代替肝动脉,并依据肝动脉的血流速度设定管内的水流速度;利用铜-康铜热电偶测量血管周围的温度场.并在相同的条件下进行微波消融的仿真计算,对比实验与仿真结果的不同.结果显示:当微波天线距血管1.0 cm时,由于血液对流换热的影响,微波消融域并没有关于微波天线对称,在靠近血管的一侧出现了很大的温度梯度,且随着血流量的增大,微波消融域变小;当微波天线距离血管1.5 cm时,微波消融域的形状开始变圆,并且天线两侧相同距离的点的温升曲线的温差也开始减小;当微波天线距离血管2.0 cm时,微波消融域几乎呈圆形,且关于微波天线对称,血管的影响可以忽略.当血流量增大时(从22 cm/s变为55 cm/s),血管对温度场的影响增大(与22 cm/s的温差最大可达10℃),消融温度场进一步减小.当微波天线与血管之间的距离大于2.0 cm时,对于小流量的血管可以忽略其对于温度场的影响,热疗前不用进行血管阻断术.当微波天线与血管之间的距离小于2.0 cm且血流量大于22 cm/s时,为了不影响消融的疗效,建议进行血管阻断术.

Effect of the Blood Vessel on the Microwave Ablation Temperature Field of Liver

To study the effect of the vessel on the ablation field,the temperature field near the blood vessel at different distances from the antenna and different blood flow rates were measured in vitro experiments. Using infusion tube instead of hepatic lartery,and setting the flow rate based on the blood flow velocity of the hepatic artery,copper-constantan thermocouples( TCs) were used to measure the temperature near the blood vessel in vitro experiments,which were compared with the simulation results in the same condition. Experimental results showed that when the microwave antenna was 1. 0 cm away from the vessel,the heating pattern was not symmetrical about the antenna because the heat convective of blood,and large temperature gradient existed in the side of the blood vessel. The greater the blood flow was,the smaller the temperature field of microwave ablation was. When the antenna was 1. 5 cm away from the blood vessel,the heating pattern was more circular,and the temperature contours of two blood flows were almost overlapped. When the antenna was 2. 0 cm away from the blood vessel,the heatingpattern was circle,and almost symmetrical about the microwave antenna. When the blood flow increased( from 22 cm/s to 55 cm/s),vessel influence on the temperature field increased( the temperature difference with 22 cm / s up to 10 ℃),and temperature fields further reduced. The effect of blood on the temperature field could be ignored if the distance between blood vessel and the microwave antenna exceeded 2. 0 cm. When the distance was less than 2. 0 cm and the blood velocity was more than 22 cm /s,in order not to affect the efficacy of the ablation,blood vessel blocking was suggested to implement.