Outcomes of Radiofrequency Ablation for Autonomously Functioning Thyroid Adenomas-Mayo Clinic Experience

Abstract

Background: Autonomously functioning thyroid nodules (AFTNs) constitute 5% to 7% of thyroid nodules and represent the second most common cause of hyperthyroidism following Graves' disease. Currently, radioactive iodine (RAI) and surgery are the standard treatment options, and both incur a risk of postprocedural hypothyroidism and other surgery and radiation-related complications.

Methods: This work aimed at assessing the efficacy of radiofrequency ablation (RFA) as an alternative treatment option for resolving hyperthyroidism and the nodule volume rate reduction (VRR) and its associated adverse events.

Results: A total of 22 patients underwent RFA for a solitary AFTN. Seventy-two percent (n = 16) had subclinical hyperthyroidism, 9% (n = 2) had overt hyperthyroidism, and 18% (n = 4) were biochemically euthyroid on antithyroid medication. Average pretreatment TSH was 0.41 mIU/L (SD = 0.98) and free T4 1.29 ng/dL (SD = 0.33). Following a single RFA session, hyperthyroidism resolved in 90.9% (n = 20) and average VRR (61.13%) was achieved within 3 to 6 months following the ablation. Except for 1 nodule, none of the nodules grew during the follow-up period (16.5 months). Two patients (9%) developed transient tachycardia requiring short-term beta-blocker therapy, and 2 developed mild hypothyroidism requiring levothyroxine therapy. Two patients developed recurrent hyperthyroidism and elected to undergo lobectomy and repeat RFA respectively. No serious adverse effects were noted in this cohort.

Conclusion: RAI and/or surgery represent the standard of care for toxic adenomas, but RFA shows excellent efficacy and safety profile. Therefore, at centers with RFA expertise, it should be considered an alternative treatment strategy, avoiding radiation and surgery-related complications.

Keywords: ablation; autonomous; hyperthyroidism; radioactive iodine; radiofrequency; thyroid nodule.

Figure 1.

TSH (mIU/L) vs time (months). Change in TSH (mIU/L) over time in months following a single radiofrequency ablation session with the median TSH represented in solid bold undulating line and the bold parallel lines representing normal TSH range.

Figure 2.

VRR (percent) vs time (months). Change in VRR (percent) over time in months following a single radiofrequency ablation session with the median VRR (percent) represented in solid bold undulating line. Abbreviations: VRR, volume reduction rate.

Figure 3.

Radiofrequency ablation procedure of one study patient. (A) The ultrasound image of thyroid nodule preablation (hypoechoic nodule). (B) The vascularity of the nodule preablation. (C) Percutaneous RFA of the thyroid nodule (moving shot technique). (D) Ongoing RFA causing coagulative necrosis of the thyroid nodule represented as dense area (black arrow) along the needle track. (E) Completion of the RFA procedure (hyperechoic nodule). (F) Reduced vascularity of the nodule post-RFA procedure (in comparison to image B). Abbreviations: RFA, radiofrequency ablation.