优化射频消融术参数设置的离体猪肝实验研究

Experimental Study on Optimal Operating Parameters Setting of Radiofrequency Thermal Ablation in Normal Ex-swine Livers

背景与目的:经皮射频消融术作为一种微创治疗手段,目前广泛应用于肝癌的治疗中。最初的射频技术只能在离体猪肝上取得1.4～1.6cm的消融直径,今经过多方面的改进,射频消融范围明显增大。射频消融范围是否足够、能否完全包围整个肿瘤是治疗成败的关键。本实验通过优化射频工作方式的研究,探讨能增大单针射频消融范围,同时能减少射频进针次数,从而降低针道转移机会,并提高小肝癌射频消融疗效的方法。方法:第一步采用方式A(起始功率为10W,每分钟步升10W)、B(起始功率为50W,每分钟步升10W)和C(起始功率为90W,持续至功率自动下降至10W),对经加工后的共22例离体圆柱形正常猪肝进行消融;第二步采用射频工作方式A,调整针尖到电极板距离分别为3、8和13cm,对22例离体圆柱形正常猪肝进行消融。比较各种参数设置下消融灶的特征(消融灶平衡径、垂直径、类圆率、消融体积、能量输出和消融时间等)。结果:采用方式A进行消融所得消融灶大小平均为2.5cm×2.7cm,比采用方式B和C进行消融时大(方式B、C的消融灶大小分别为1.6cm×1.8cm和2.0cm×1.5cm)。方式A的消融体积是10.0cm3,明显大于方式B和C(分别是3.1cm3和2.1cm3),而消融时间也明显延长(分别是281.9、79.4和61.4s),而且采用方式A消融时所得病灶比方式C更接近圆球形。消?

BACKGROUND & OBJECTIVE: As a non-surgical minimally invasive treatment, percutaneous radiofrequency ablation (PRFA) is widely used to treat hepatocellular carcinoma (HCC). Treatment effect of PRFA depends on extent of ablative zone. Initially, necrosis diameter achieved by RFA in normal ex-swine liver was about 1.4-1.6 cm, but now larger ablative zone can be achieved with recently developed techniques. This study was to explore optimal operating parameters to enlarge ablative zone resulted from a single process, reduce chances of needle seeding via reducing needle insertion times, and improve curative effects. METHODS: The first step: mode A, B, and C (starting power was set to 10 W, 50 W, and 90 W, respectively, output power ascended by 10 W/min till ultimate power of 90 W) were adopted to perform ablation on 8,7,7 normal ex-swine livers,respectively, which were processed to be cylinders. The second step: mode A was adopted to perform ablation on 22 ex-swine liver cylinders, the distances between needle tip and grounding pad were set to 3,8,and 13 cm. Characteristics of ablative zones, such as parallel and vertical diameters, isoperimetric ratio, and volume of ablative zones, ablative energy, and time were analyzed. RESULTS: The average ablative zone achieved by mode A was larger than those achieved by mode B, and C (2.5 cm×2.7 cm vs. 1.6 cm×1.8 cm, and 2.0 cm×1.5 cm, P<0.05); the volume of ablative zone achieved by mode A was larger than those achieved by mode B, and C (10.0 cm3 vs. 3.1 cm3, and 2.1 cm3, P<0.05); the ablative time achieved by mode A was longer than those achieved by mode B, and C (281.9 s vs. 79.4 s, and 61.4 s, P<0.05); the ablative zones achieved by mode A were much like a pellet. Ablative zone volume was strongly correlated with ablative time, and energy output (R2=0.920, and 0.853, P<0.05). When the distances between needle tip and grounding pad were 3, 8, and 13 cm, the achieved ablative zones were 2.5 cm×2.7 cm, 3.8 cm×3.4 cm, and 4.9 cm×4.1 cm, respectively; ablative volumes were 10.0 cm3, 22.9 cm3, and 43.3 cm3, respectively; ablative time were 281.9 s, 495.6 s, and 896.1 s, respectively (P<0.05). CONCLUSION: Adopting lower starting power, and slower power ascending speed may enlarge ablative zone. In a certain extent, distance between needle tip and grounding pad may be positively correlated with ablative volume, and needed ablative time; ablative zone volume may be positively correlated with ablative time, and energy output.