Bicomponent Conformal Electrode for Radiofrequency Sequential Ablation and Circumferential Separation of Large Tumors in Solid Organs: Development and In Vitro Evaluation.

Abstract

Complete destruction of large tumors by radiofrequency ablation (RFA) with surrounding tumor-free margin is difficult because of incomplete or nonuniform heating due to both heat-sink effect of circulating blood and limitations of existing RF electrode design. A new RF electrode is described to overcome this limitation. A bicomponent conformal (BCC) RFA probe providing sectorial sequential ablation followed by circumferential cutting is designed and evaluated. Three-dimensional finite-element analysis model was developed with temperature feedback-controlled simulation of RFA for electrode design and optimization. The prototype bipolar BCC probe with three embedded thermocouples was constructed and evaluated in tissue-mimicking phantoms. Maximum tissue temperature was kept <100 ºC with power applied <15 W. A 10-min ablation time was used for each sequence and after four sequential RFA, a large ablation zone of 55 cm³ was achieved. Our experiment confirmed that lesions exceeding 3.7 cm could be ablated and separated from the surrounded tissue. The new BCC probe is, thus, capable of controlled ablation followed by circumferential separation of the lesions, when required. The results of these experiments provide the proof of concept validation that the BCC probe has the potential to ablate by sequential heating tumors in solid organs >3.5 cm then separate them by electrosurgical cutting from the surrounding normal parenchyma. The combined RF ablation and physical separation could completely destroy the cancer cells at the ablation site, thus, avoid any local recurrence of cancer. It requires further in vivo validation studies in large animals.