活体猪椎体多极射频消融的热场分布

The thermal field distribution in swine vertebral body created by multi-polar radiofrequency ablation:an experimental study in vivo

目的通过对活体猪椎体进行射频消融(RFA),观察热场分布,探讨RFA时电极针在椎体中的位置与脊髓的安全性关系以及椎体周围有无软组织损伤。方法取2头小型香猪,1头消融2个椎体后即刻取标本制作病理切片;另1头消融10个椎体,每周消融2个椎体,完成后第6周取标本制作病理切片。每个椎体消融时按预先设计的测温点测"0"时刻、消融5、10、15、20 min各测温点的温度值。结果各测温点"0"时刻温度值差异无统计学意义(P>0.05)。当消融5 min后电极针尖温度达到90℃以上时,各测温点的温度值差异有统计学意义(P<0.05)。电极针尖及椎体骨质内深1 cm位置的温度在消融5 min后所测得的值明显高于椎体后壁及椎体的骨皮质表面,但各测温点的温度均高于"0"时刻各测温点的温度值。椎体骨质内深1 cm位置的温度在消融5 min后4个记录时刻比较差异有统计学意义(P<0.05),温度总体上呈渐升过程。椎体后壁及椎体骨皮质表面的温度在消融5 min后4个记录时刻的温度比较差异无统计学意义(P>0.05)。结论在对椎体行RFA时,椎管内流动的脑脊液及椎体骨质内流动的血液会带走部分热量;骨皮质具有一定的隔热作用,对椎体后壁保持完整的椎体转移性肿瘤RFA治疗安全、可靠。

Objective To observe the thermal field distribution by ablating swine vertebral bodies with multi-polar radiofrequency technique, to explore the relationship between the electrode position in the vertebral bodies and the safety of the spinal cord and to clarify whether soft tissues around the vertebral bodies would be impaired. Methods Two miniature swines were used for this study. In one swine, after radiofrequency ablation was performed in two vertebrae, the specimens were immediately cut off and sent for pathological examination. In the other swine, two vertebrae were radiofrequency ablated each week, and a total of ten vertebrae were ablated in five weeks. At the sixth week, the animal was sacrificed and the pathological sections of the specimens were prepared. The baseline temperature as well as the temperature measured at 5, 10, 15 and 20 minutes after the start of ablation at pre-designed temperature measurement points in each vertebra were recorded. The results were analyzed. Results The differences in the baseline temperature between the pre-designed temperature measurement points were not statistically significant （P 〉 0.05）. Five minutes after the ablation, when the temperature at electrode tip reached 90~C, the differences in temperature between the pre-designed temperature measurement points became statistically significant （P 〈 0.05）. Five minutes after starting ablation the temperatures measured at the electrode tip and at the center of vertebra （one cm underneath the vertebral bone） were markedly higher than those determined at the posterior wall of the vertebral body and at the surface of vertebral bone cortex, although the temperatures at all the pre- designed temperature measurement points were higher than the corresponding baseline temperatures.Significant differences in the temperatures at the center of vertebra （one cm underneath the vertebral bone） existed between 5, 10, 15 and 20 minutes measurements （P 〈 0.05）.Generally, the temperatures at these t points went up with the increase of time. No significant differences in the temperatures at the posterior wall of the vertebral body as well as at the surface of vertebral bone cortex existed between 5, 10, 15 and 20 minutes measurements （P 〉 0.05）. Conclusion During the performance of radiofrequency ablation for vertebra, the flowing cerebrospinal fluid within the spinal canal and blood flow in the vertebrae can carry away some amount of heat. The bone cortex has some heat insulation effect. Radiofrequency ablation is quite safe and reliable for the treatment of vertebral metastases if the posterior walls of the involved vertebral bodies remain intact.（J Intervent Radial, 2013, 22： 050-053）