Endocrine Abstracts

Context: Radiofrequency ablation (RFA) was proven as effective in reducing thyroid nodules’ volume. However, whether technical procedure aspects could influence the volume reduction rate (VRR) has not been clarified.

Objective: To analyze the correlation of RFA power, duration and energy with VRR.

Design: Prospective study from June 2018 to December 2019.

Setting: Two primary-care centers using the same RFA procedure.

Patients or other participants: Adult outpatients undergoing a single-session RFA and 1-year post-treatment follow-up.

Intervention: RFA was performed by moving-shot technique with internally cooled 18-gauge electrode having a 10-mm active tip. Main outcome measures The VRR was calculated. Technical parameters were the following: median power (P _median), effective time of treatment (T_eff), energy calculated as P_median × T_eff (E_calc), and energy delivered per ml as Kcal × 4184 × nodule’s volume (E_del). Continuous variables were analyzed by the Mann Whitney test. The correlation of the above parameters with VRR was analyzed by linear regression.

Results: Forty-one nodules were included and their VRR 66.6%. RFA was performed with a P_median of 55 watts, T_eff 10.24 min, E_calc 31380 Joules, E_del 1473 Joules/mL. E_del was significantly correlated with VRR (P = 0.014) while P_median, T_eff and E_calc not. A strong correlation of E_del with VRR was found in nodules <10 ml (P = 0.001) while no significant correlation was observed in nodules >10 ml.

Conclusions: This study showed that the energy delivered with RFA is the only technical parameter significantly correlated with the VRR of thyroid nodules.