Improving radiofrequency ablation outcomes in large thyroid nodules: superiority of adjustable tip needles

Approximately 10-12% of thyroid nodule radiofrequency ablations (RFA) result in failure or regrowth, particularly for nodules larger than 20-30 mL. Adjustable-tip needles (ATN) have recently been introduced to allow tailored heat distribution, although current literature does not demonstrate clear advantages over fixed-tip needles (FTN). This study aimed to assess the efficacy of ATNs in nodules with baseline volume >20 mL.

This retrospective, monocentric observational study included 75 patients (38 FTN, 37 ATN) who underwent RFA for benign thyroid nodules >20 mL, with at least 12 months of follow-up. All patients had confirmed cytological benignity, negative serum calcitonin, normal thyroid function, and ENT evaluation. Technical parameters (energy, duration), volume reduction ratio (VRR), and Compressive/Cosmetic scores were collected at 1, 6, and 12 months. Therapeutic success was defined as VRR ≥50%.

ATNs yielded greater and sustained volume reduction (VRR at 12 months: 60.5% vs 52.4%, p = 0.004; final volume: 14.1 vs 18.4 mL, p = 0.012; AUC_VRR p = 0.019; AUC_Vol p = 0.040), with a progressive time-related effect (p _{GROUP: TIME} = 0.001; β = 1.12). ATNs were associated with higher 12-month success rates (84% vs 55%, OR 4.18 (1.42-12.35), p = 0.015). Energy deposition was significantly higher. The volumetric cutoff for achieving 75% success shifted from 35 mL (FTN) to 80 mL (ATN).

In benign thyroid nodules >20 mL, RFA with ATNs proved more effective than FTNs, thanks to a higher energy deposition. This could suggest a shift in the eligibility threshold for RFA up to 80 mL.