Radiofrequency Ablation and Autonomous Functioning Thyroid Nodules: Review of the Current Literature

Current role of interventional radiology in thyroid nodules

Thyroid nodules are a prevalent health issue in society. Interventional radiological methods are successfully applied for both the diagnosis and treatment of nodules. Diagnostically, a fine-needle aspiration biopsy and a core needle biopsy can be performed to ascertain the benign or malignant nature of a lesion. In recent years, imaging-guided percutaneous treatment methods have become popular in the treatment of thyroid nodules. Aspiration, ablation, and embolization are techniques employed in the treatment process. In this study, we aimed to discuss the current role of interventional radiology in the diagnosis and treatment of thyroid nodules, which occupy an important place in clinical practice.

Thermal Ablation of Thyroid Nodules, From the AJR "How We Do It" Special Series

Ablation has been shown to be an effective option for treatment of well-selected patients with thyroid nodules, particularly benign nodules, and thermal ablation is being increasingly used for this purpose. The general approach to thermal ablation of the thyroid will be familiar to interventional radiologists who perform ablation in other tissues; however, thermal ablation of the thyroid has additional unique considerations. In this review, we provide evidence-based and real-world guidance on the performance of thermal ablation for the treatment of patients with thyroid nodules, drawing on our collective experience and clinical practice. We describe patient selection, ablation modalities, equipment, general procedural approach, additional technical considerations, and postprocedural follow-up. We discuss various clinical scenarios; give tips on performing specific portions of the procedure and highlight a range of relevant anatomic, biochemical, and clinical factors, as a guide for interventional radiologists in establishing a successful thyroid ablation practice.

Image-guided Thermal Ablation as a Promising Approach to Both Nontoxic and Toxic Autonomously Functioning Thyroid Nodules

RATIONALE AND OBJECTIVES

Although thermal ablation has been recommended as an alternative therapy option for autonomously functioning thyroid nodules (AFTN), current clinical evidence mainly focuses on toxic AFTN. This study aims to evaluate and compare the efficacy and safety of thermal ablation (percutaneous radiofrequency ablation or microwave ablation) in treating nontoxic and toxic AFTN.

MATERIALS AND METHODS

AFTN patients who received a single session of thermal ablation with a follow-up period ≥12 months were recruited. Changes in nodule volume and thyroid function, and complications were evaluated. Technical efficacy was defined as the maintenance or restoration of euthyroidism with a volume reduction rate (VRR) ≥80% at the last follow-up.

RESULTS

In total, 51 AFTN patients (age: 43.8±13.9 years, female: 88.2%) with a median follow-up period of 18.0 (12.0-24.0) months were included, where 31 were nontoxic (nontoxic group), and 20 were toxic (toxic group) before ablation. The median VRR was 96.3% (80.1%-98.5%) and 88.3% (78.3%-96.2%) in the nontoxic and toxic groups, respectively, and the respective euthyroidism rates were 93.5% (29/31, 2 evolved to toxic) and 75.0% (15/20, 5 remained toxic). The corresponding technical efficacy was 77.4% (24/31) and 55.0% (11/20, p=0.126). Except for one case of stress-induced cardiomyopathy in the toxic group, no permanent hypothyroidism or other major complications occurred in both groups.

CONCLUSION

Image-guided thermal ablation is efficacious and safe in treating AFTN, both nontoxic and toxic. Recognition of nontoxic AFTN would be helpful for treatment, efficacy evaluation, and follow-up.

Radiofrequency ablation for autonomously functioning nodules as treatment for hyperthyroidism: subgroup analysis of toxic adenoma and multinodular goitre and predictors for treatment success

PURPOSE

Treatment of hyperthyroidism caused by autonomously functioning thyroid nodules (AFTN) with 131I often leads to undesirable hypothyroidism. Radiofrequency ablation (RFA) has emerged as a promising alternative. This retrospective analysis aimed to examine the efficacy of, and postprocedural hypothyroidism after, RFA for AFTN.

METHODS

Patients with hyperthyroidism caused by AFTN and treated with RFA were included if follow-up of at least 1 year was available. Cure was defined as thyroid medication-free biochemical euthyroidism. To predict cure, patient and treatment factors were analysed. A distinction was made between solitary toxic adenoma (STA) and toxic multinodular goitre (TMG).

RESULTS

Forty-eight patients (36 STA, 12 TMG) were included. One year post-RFA cure rate was 72% in STA versus 25% in TMG (p = 0.004). One patient developed hypothyroidism. In 11 patients that remained hyperthyroid, a second RFA was successful in 83% of STA and 40% of TMG patients. At last available follow-up, this amounted to a total cure rate of 81% in STA and 33% in TMG (p = 0.002). In STA, cured patients had a higher baseline TSH and a lower FT3 than non-cured patients (p = 0.026 and 0.031). Cure was observed in 91% of patients when > 2.1 kJ/mL was delivered during RFA, compared to 44% when less energy was administered.

CONCLUSION

The efficacy of RFA was nearly 3 times higher in STA patients compared to TMG. Severity of hyperthyroidism and kJ/mL delivered during RFA predicts cure. Direct comparison to the current standard of care is needed to implement RFA in treatment of hyperthyroidism caused by AFTN.

American Association of Clinical Endocrinology Disease State Clinical Review: The Clinical Utility of Minimally Invasive Interventional Procedures in the Management of Benign and Malignant Thyroid Lesions

OBJECTIVE

The objective of this disease state clinical review is to provide clinicians with a summary of the nonsurgical, minimally invasive approaches to managing thyroid nodules/malignancy, including their indications, efficacy, side effects, and outcomes.

METHODS

A literature search was conducted using PubMed and appropriate key words. Relevant publications on minimally invasive thyroid techniques were used to create this clinical review.

RESULTS

Minimally invasive thyroid techniques are effective and safe when performed by experienced centers. To date, percutaneous ethanol injection therapy is recommended for recurrent benign thyroid cysts. Both ultrasound-guided laser and radiofrequency ablation can be safely used for symptomatic solid nodules, both toxic and nontoxic. Microwave ablation and high-intensity focused ultrasound are newer approaches that need further clinical evaluation. Despite limited data, encouraging results suggest that minimally invasive techniques can also be used in small-size primary and locally recurrent thyroid cancer.

CONCLUSION

Surgery and radioiodine treatment remain the conventional and established treatments for nodular goiters. However, the new image-guided minimally invasive approaches appear safe and effective alternatives when used appropriately and by trained professionals to treat symptomatic or enlarging thyroid masses.