Efficacy, safety and predictors of response to minimally invasive treatments of the thyroid: a prospective study.

PURPOSE: Minimally invasive techniques (MITs), including percutaneous ethanol injection (PEI) and radiofrequency ablation (RFA), are effective non-surgical options for benign thyroid nodules (BTN). However, predictors of response and technical determinants remain incompletely defined.

METHODS

We conducted a prospective single-center study including 120 BTNs (45 PEI, 75 RFA) treated between 2022 and 2025, with 12-month follow-up. The primary objective of this study was to identify clinical and procedural predictors of treatment response following MITs for BTNs. The primary outcome measure was the 12-month volume reduction ratio (VRR). Secondary endpoints included changes in cosmetic and symptomatic scores, thyroid function in autonomously functioning nodules (AFTN), and safety outcomes.

RESULTS

Baseline mean nodule volume was 22.06 mL SD 14.52, cosmetic score 3.39 SD 0.93, and dysphagia score 3.33 SD 1.8. At 12 months, mean VRR was 84.24% overall, 95.9% after PEI, and 77.4% after RFA, achieving therapeutic success in 96.67% of cases (p < 0.001). In AFTN, MITs, comprising 3 predominantly cystic nodules treated with PEI and 10 solid nodules treated with RFA, achieved a mean VRR of 88.17%, with TSH increasing from 0.12 SD 0.13 to 2.17 SD 2.47 mIU/L; 76.9% of these patients were on antithyroid medication prior to ablation, all discontinued post-procedure. Baseline nodule volume independently predicted VRR (β = - 0.237; p = 0.014), while energy density (kcal/mL) predicted RFA efficacy (β = 1.416; p = 0.047). All adverse events were mild and transient, including local pain (27.5%), transient dysphonia (6.7%), and transient cough or vagal reaction. No permanent complications occurred.

CONCLUSION

PEI and RFA are safe and effective minimally invasive options for BTN, achieving durable volume reduction with improved clinical outcomes. Smaller nodules and higher energy delivery/ml predict optimal response.