Thyroid-dedicated internally-cooled wet electrode for benign thyroid nodules: experimental and clinical study

Background To assess the effects of radiofrequency ablation (RFA) using an internally-cooled wet (ICW) electrode in ex vivo bovine liver and evaluate the feasibility of the ICW electrode for benign thyroid nodules. Methods We developed an 18-gauge ICW electrode with a microhole at the distal tip for tissue infusion of chilled (0 - 4 degrees C) isotonic saline (rate = 1.5 ml/min). RFA using ICW and IC electrodes were performed in bovine livers (40 pairs, 1-cm active tip, 50 W, 1-min). We compared the morphological characteristics of ablation zones and presence of carbonization. Twenty patients with benign thyroid nodules larger than 5 ml were prospectively enrolled in a clinical study and underwent ultrasound-guided RFA with ICW electrodes. Ultrasound examinations, laboratory data, and symptom and cosmetic scores were evaluated preprocedure and 1 and 6 months after the procedure. Results In the ex vivo study, the ICW achieved significantly larger ablation zones than the IC (p<.001). In the clinical study, ICW electrodes were tolerable in all patients. At last follow-up, nodule volume had decreased from 15.6 +/- 12.1 ml to 4.1 +/- 4.3 ml (p<.001), and the mean volume reduction ratio (VRR) was 73.3 +/- 13.7% at 6.0 months follow-up. Cosmetic and symptom scores were reduced from 3.52 +/- 1.03 to 2.65 +/- 0.88 and 3.10 +/- 2.17 to 0.85 +/- 0.99 (both p<.001), respectively. After RFA, thyroid function was well preserved in all patients, and mean thyroglobulin level decreased from 36.6 +/- 52.1 ng/ml to 26.9 +/- 62.2 ng/ml. One patient experienced a temporary voice change that recovered within a week. Conclusions We developed a thyroid-dedicated ICW electrode that we showed to be feasible and effective in patients with benign thyroid nodules.

Automated summary

An internally-cooled wet (ICW) electrode was developed and showed to be effective and feasible in the treatment of benign thyroid nodules. It achieved larger ablation zones compared to the conventional internally-cooled electrode (IC) in ex vivo bovine liver. The ICW electrode resulted in significant reduction in nodule volume, improvement in cosmetic and symptom scores, and preservation of thyroid function in patients.