微波与射频对离体猪股骨干骺端制热效应的对照研究

Swine femoral metaphysis ablation experiment in vitro:a comparative study of heating effects between microwave and radiofrequency ablation

目的比较微波与射频对离体猪股骨干骺端的制热效应,以指导临床应用。方法取20条新鲜成年猪股骨,根据数据随机法分成微波组与射频组2组,每组10个股骨样本分别采用微波和射频进行加热凝固。加热功率为60 W,加热时长为300 s,旁开加热点5、10、15 mm测温,比较两种热疗技术的凝固范围和形状以及温度分布和变化趋势。结果 60 W·300 s微波和射频凝固的纵径分别为37.1±3.2 mm,28.3±2.5 mm,前者明显大于后者(P<0.05),横径分别为21.3±1.6 mm,19.8±1.4 mm,前者明显大于后者(P<0.05)。微波消融后出现明显的炭化带,凝固区及充血带分布,射频消融后仅可观察到明显的凝固区。射频形成的凝固体较微波更接近球形。微波和射频的中心温度分别为126.2±1.51℃,100.2±0.70℃,前者明显高于后者(P<0.05),旁开10 mm处温度分别为91.5±3.7℃,58.3±2.4℃,前者明显高于后者(P<0.05)。射频消融与微波消融各测温点分别在210 s与255 s内达到稳态,二者距离加热中心越近温度越高,上升速度越快。微波消融中心温度可达到120℃以上,射频消融中心温度不超过100℃。结论微波和射频对离体猪股骨干骺端凝固形状及凝固范围存在差异,中心温度和旁开10 mm处温度,微波显著高于射频。微波较射频热场温度高,凝固范围大,在较大骨肿瘤的治疗中宜选用微波,射频消融较微波有更好的温控性。了解各自的制热特性有利于两种技术的合理选择。

Objective To compare the heating effects between microwave and radiofrequency ablation in porcine femoral metaphysis. Methods Microwave and radiofrequency were applied for 300 seconds at 60 Watts in 20 porcine femoral metaphysis. Thermo sensors were placed at 5, 10 and 15 mm from the electrodes, and temperatures were recorded using an advanced temperature monitor system. The diameter, shape and temperature in the ablation zone, the pathologic appearance of the ablation zone and the distribution and variation tendency of temperature were compared between microwave and radiofrequency ablation. Results The longitudinal diameters of lesions ablated with microwave and radiofrequency were （ 37.1±3.2 ） mm and （28.3±2.5） mm respectively, and the former was significantly longer than the later （P〈0.05 ）. The transverse diameters were （ 21.3±1.6 ） mm and （ 19.8±1.4 ）mm respectively, and the former was significantly longer than the later （ P〈0.05 ）. The carbonized zone, coagulation zone and hyperemia zone could be found apparently from the microwave group, but only the coagulation zone could be found from the radiofrequeney group. The radiofrequency induced more spherical lesions than microwave did. The central temperatures of microwave and radiofrequeney were （ 126.2±1.51 ） ℃ and （ 100.2±0.70 ） ℃ respectively, and the former was significantly higher than the later （ P〈0.01 ）. The temperatures 10mm from the centers of microwave and radiofrequency were （ 91.5±3.7 ） ℃ and （ 58.3±2.4 ） ℃ respectively, and the former was significantly higher than the later （ P〈0.01 ）. The microwave and radiofrequency groups could reach the steady-state at 210 s and 255 s independently. The shorter the distance to the heating point, the higher the temprature rdached, and faster the temprature rose. The heating center temperature of microwave could reach over 120 ℃, while the heating center temperature of radiofrequency could reach a point below 100 ℃. Conclusions Lesions induced by radiofrequency and microwave have some differences in shape and temperature distribution. The temperature of the heating zone and the boundary of microwave are higher and larger than that of radiofrequency. Microwave is a better choice for larger bone tumors. Compared with microwave, the ternprature of radiofrequency group could be better controlled. The understanding of these differences will help us better use these ablation techniques.