Long-Term Outcomes Following Thermal Ablation of Benign Thyroid Nodules as an Alternative to Surgery: The Importance of Controlling Regrowth

Abstract

Thermal ablation (TA) procedures, such as radiofrequency ablation and laser ablation, are used for the treatment of benign thyroid nodules. Short-term studies (<2 years) have demonstrated that TA is an effective and safe procedure to improve cosmetic or symptomatic problems. However, studies including a longer follow-up period show that treated thyroid nodules can increase in size after 2 to 3 years. Several studies suggest that this results from regrowth at the undertreated nodule margins. Here, we review current data on regrowth after TA and describe factors related to it and possible approaches to prevent it.

Keywords: Ablation; Thyroid nodule.

Fig. 1. Ultrasonography of a thyroid nodule: (A) pre-radiofrequency ablation (RFA), (B) 2 months post-RFA, and (C) 9 months post-RFA. (D-F) Diagrams indicate the total volume (Vt), ablated volume (Va), and viable volume (Vv) at these timepoints. Although Vt decreases over time, Vv increased by 2 mL between months 2 and 9, indicating that growth of the residual viable nodule tissue had already begun. In this case, additional RFA was performed 1 month after obtaining the image in C. ^aThe centrally-located hypoechoic area of ablated tissue is indicated.

Fig. 2. (A) An electrode (short arrows) directly ablates the perinodular vein (arrow). Air bubbles are seen inside the venous lumen (arrowheads). (B) After completing venous ablation, compact filling of hot air bubbles is observed (arrowheads).