MON-406 Efficacy of 7 Versus 10 mm Thyroid Radiofrequency Ablation Active Tips

Abstract Disclosure: Z. Nasrallah: None. M. Morkos: None. Radiofrequency ablation (RFA) is an effective treatment for benign thyroid nodules. The procedure utilizes an internally cooled electrode with an active tip to deliver thermal energy, resulting in coagulative necrosis of the nodule tissue. The active tip length can vary, with 7 and 10 mm being the most common options, but the optimal length remains unclear. In this study, we compared the efficacy of 7 versus 10 mm active tips in terms of volume reduction rates (VRR), defined as the percentage decrease in nodule volume after RFA over 12 months. We conducted a retrospective chart review of adult patients at an academic institution in the US from December 2021 to November 2024 who underwent RFA by a single endocrinologist. We included patients who had confirmed benign thyroid nodules as per the recommended guidelines and excluded those who received ablation for thyroid cancer. We identified 35 patients, of whom 91.4% were female, with a mean age of 50.6±17.5 years, who underwent RFA using either 7 mm (n=22) or 10 mm (n=13) active tips. The initial nodule volumes were similarly distributed between groups (<10 mL: 45.7%, 10-20 mL: 25.7%, ≥20 mL: 28.6%). Volume measurements were performed at baseline and 1, 3, 6, and 12 months after the RFA. When comparing 7 versus 10 mm active tips, we found a statistically significant VRR at every follow-up: 1 month (47.1±24.7% vs. 27.3±28.8%, p=0.044), 3 months (74.1±20.1% vs. 52.0±20.0%, p=0.035), 6 months (74.6±19.0% vs. 54.6±13.6%, p=0.016), and 12 months (85.9±22.4% vs. 59.3±20.0%, p=0.031) respectively. Procedure duration was comparable between both groups (480±259.6 vs. 511.3±286.1 seconds, p=0.742), although the 7 mm tip delivered significantly less energy (10.2±5.0 vs. 22.5±15.6 kJ, p=0.002) compared to the 10mm tip. In conclusion, our study demonstrates that the 7 mm active tip achieved consistently and statistically greater volume reduction rates compared to the 10 mm tip across all thyroid nodule volumes at all follow-up time points while requiring less delivered energy. Notably, the superior efficacy of the 7 mm probe was maintained even in larger nodules (≥10mL), which comprised 54.5% of the 7 mm probe group. These findings suggest that the 7 mm probe may be the preferred option for radiofrequency ablation of benign thyroid nodules across all size categories. Presentation: Monday, July 14, 2025