Multiple applicator hepatic ablation with interstitial ultrasound devices: theoretical and experimental investigation.
Multiple applicator hepatic ablation with interstitial ultrasound devices: theoretical and experimental investigation.
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DOI：
10.1118/1.4765459
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发表时间：
2012-12
期刊：
影响因子：
3.8
通讯作者：
P. Prakash;V. Salgaonkar;E. Clif Burdette;C. Diederich
中科院分区：
文献类型：
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作者：
P. Prakash;V. Salgaonkar;E. Clif Burdette;C. Diederich
目的：评价多探头植入配置的间质超声装置用于肝肿瘤大体积消融的效果。方法采用有限元法建立三维生物声学-热模型，以评估多个施用器植入物配置用于组织间超声能量热消融。组织间施源器由最多4个10 mm长的管状超声换能器组成的线性阵列组成，每个换能器均处于单独的动态功率控制下，封闭在水冷输送导管（2.4 mm OD）内。作者考虑使用两个和三个施源器（集群配置）的平行植入物，间隔2-3 cm，以模拟开放手术放置。此外，作者考虑了两个施源器植入物，施源器以20°、30°和45°的角度会聚和发散，以模拟经皮放置。进行加热实验（10-15分钟），并与采用相同实验参数的模拟进行比较。为了评估在体内环境中并行、多个施用器配置的性能，进行了模拟，考虑了可能发生在不同血管分布的肿瘤中的血液灌注水平范围（0、5、12和15 kg m（-3）s（-1））。探讨了沿施加器长度沿着向各个换能器元件供应的功率的影响，用于以非平行（会聚和发散）配置插入的施加器。热剂量（t（43）> 240 min）和温度阈值（T > 52 °C）用于定义消融区，模型中包含组织声学和热特性的动态变化。结果在离体牛肝中的实验产生了横截面范围为4.0-5.6 cm × 3.2-4.9 cm的消融区。消融区尺寸预测模拟与实验相似的参数是在密切的协议（5毫米内）。体内加热模拟显示，需要15分钟加热和小于3 cm的消融器间距才能获得连续、完整的消融区。通过沿施源器长度沿着调整施加的功率水平，说明了为非平行植入物创建完整消融区轮廓的能力。结论：由三角形配置的三个组织间超声施源器组成的平行植入物在加热15分钟后可产生6.2 cm × 5.7 cm的完整消融区。在较大的消融器间距下，肿瘤中的血液灌注水平可能会沿消融区的周边产生沿着凹痕。沿施源器的长度定制施加的功率沿着可以适应非平行植入物，而不会影响安全性。
PURPOSE To evaluate multiple applicator implant configurations of interstitial ultrasound devices for large volume ablation of liver tumors. METHODS A 3D bioacoustic-thermal model using the finite element method was implemented to assess multiple applicator implant configurations for thermal ablation with interstitial ultrasound energy. Interstitial applicators consist of linear arrays of up to four 10 mm-long tubular ultrasound transducers, each under separate and dynamic power control, enclosed within a water-cooled delivery catheter (2.4 mm OD). The authors considered parallel implants with two and three applicators (clustered configuration), spaced 2-3 cm apart, to simulate open surgical placement. In addition, the authors considered two applicator implants with applicators converging and diverging at angles of ∼20°, 30°, and 45° to simulate percutaneous placement. Heating experiments (10-15 min) were performed and compared against simulations employing the same experimental parameters. To estimate the performance of parallel, multiple applicator configurations in an in vivo setting, simulations were performed taking into account a range of blood perfusion levels (0, 5, 12, and 15 kg m(-3) s(-1)) that may occur in tumors of varying vascularity. The impact of tailoring the power supplied to individual transducer elements along the length of applicators is explored for applicators inserted in non-parallel (converging and diverging) configurations. Thermal dose (t(43) > 240 min) and temperature thresholds (T > 52 °C) were used to define the ablation zones, with dynamic changes to tissue acoustic and thermal properties incorporated within the model. RESULTS Experiments in ex vivo bovine liver yielded ablation zones ranging between 4.0-5.6 cm × 3.2-4.9 cm, in cross section. Ablation zone dimensions predicted by simulations with similar parameters to the experiments were in close agreement (within 5 mm). Simulations of in vivo heating showed that 15 min heating and interapplicator spacing less than 3 cm are required to obtain contiguous, complete ablation zones. The ability to create complete ablation zone profiles for nonparallel implants was illustrated by tailoring applied power levels along the length of applicators. CONCLUSIONS Parallel implants consisting of three interstitial ultrasound applicators in a triangular configuration yield complete ablation zones measuring up to 6.2 cm × 5.7 cm after 15 min heating. At larger interapplicator spacing, the level of blood perfusion in the tumor may yield indentations along the periphery of the ablation zone. Tailoring applied power along the length of the applicator can accommodate for nonparallel implants, without compromising safety.