For a patient with a confirmed benign solid or partially cystic thyroid nodule, how does radiofrequency ablation compare to surgery, laser ablation, percutaneous ethanol injection, and high‑intensity focused ultrasound regarding efficacy, safety, and appropriate indications?

Radiofrequency Ablation vs Other Methods for Thyroid Nodules

For confirmed benign solid or partially cystic thyroid nodules causing symptoms or cosmetic concerns, radiofrequency ablation (RFA) and microwave ablation (MWA) are the preferred thermal ablation techniques, achieving similar clinical results with 60-90% volume reduction, superior safety profiles compared to surgery, and preservation of thyroid function without lifelong medication requirements. 1, 2

Comparative Efficacy of Thermal Ablation Techniques

RFA and MWA: First-Line Thermal Ablation Options

RFA and MWA are the most widely used and effective thermal ablation techniques for thyroid nodules, with comparable clinical outcomes in most studies. 1, 3

• RFA electrodes are sharp and facilitate easy puncturing, making them particularly suited for small to medium nodules (typically <4 cm). 1
• MWA offers stronger vascular coagulation ability, providing clear advantages for highly vascularized tumors—MWA is typically recommended for patients with hyper-vascular nodules. 1
• Both techniques achieve persistent volume reduction rates of 60-90% that remain stable over several years, with overall complication rates of only 2-3%. 2, 4, 5
• The choice between MWA and RFA is typically based on operator preference and available equipment, as efficacy is similar. 1

Laser Ablation: Limited Applications

• Laser ablation (LA) is usually used for papillary thyroid carcinoma (PTC) ablation due to its limited thermal field and lower thermal efficiency compared to RFA and MWA. 1
• LA has proven effective and safe for producing significant volume reduction in solid cold nodules, but has less clinical application than MWA and RFA in thyroid ablation. 1, 2, 6

High-Intensity Focused Ultrasound (HIFU): Least Preferred

• HIFU has a more painful procedure than other ablative techniques, takes longer time to perform, and is highly sensitive to patient movement. 1
• Efficacy of HIFU is less established, with limited thermal efficiency resulting in fewer clinical applications. 1

Percutaneous Ethanol Injection (PEI): Specific Indication

• Percutaneous ethanol injection represents the first-line treatment specifically for thyroid cysts or cystic nodules with solid composition less than 10%. 1, 2
• For solid nodules or cystic nodules with solid composition ≥10%, thermal ablation (RFA/MWA) is more appropriate than chemical ablation. 1

RFA vs Surgery: Safety and Efficacy Comparison

Advantages of RFA Over Surgery

Compared with traditional surgery, thermal ablation has multiple advantages: simple operation, short operation time, no neck scar, lower complication rates, outpatient treatment, preservation of thyroid function, and most patients do not require lifelong medication. 1, 3

• The overall risk of permanent complication or severe injury with RFA is very unlikely, below 1%, compared to higher surgical complication rates. 4
• The overall safety profile of RFA is impressive and superior to that of thyroid surgery, with overall complication risk of 2-3%. 4, 5
• The vast majority of complications related to RFA can be managed conservatively, without need for invasive measures. 4

When Surgery Remains Preferred

• Surgery remains the gold standard for treating all malignant nodules and benign nodules when thermal ablation is contraindicated. 1
• Larger nodules (>4 cm) may require repeated RFA treatments and could be difficult to treat if they extend into the chest—surgery may be more appropriate in these cases. 2
• Surgery is necessary when patients have severe bleeding tendency, severe cardiopulmonary insufficiency, contralateral vocal cord paralysis on the treatment side, or during pregnancy/lactation. 1, 3

Specific Indications for Thermal Ablation

Benign Thyroid Nodules

Thermal ablation is an optional treatment for patients with benign thyroid nodules that meet any of the following criteria: 1, 3

• Nodules causing clinical symptoms such as compression or cosmetic concerns or anxiety problems 1, 3
• Nodules with maximal diameter ≥2 cm and increasing gradually 1, 3
• Autonomously functioning thyroid nodules 1
• Recurrent nodules after chemical ablation 1

Malignant Thyroid Nodules

• Thermal ablation is an optional treatment for recurrent thyroid cancer and metastatic cervical lymph nodes with a limited number. 1
• RFA may serve a curative or palliative role in recurrent well-differentiated thyroid cancers. 7
• For primary papillary thyroid carcinoma (PTC) with diameter less than 1 cm (cT1), thermal ablation has obtained good medium- and long-term treatment effects. 1

Essential Pre-Ablation Requirements

All patients undergoing thermal ablation of thyroid nodules must perform puncture biopsy to confirm the pathological diagnosis—fine-needle aspiration biopsy (FNAB) is the preferred method (strong recommendation, high-quality evidence). 1, 8, 3

• For benign thyroid nodules, cystic and cavernous nodules can undergo FNAB once, while other nodules need to undergo FNAB twice or in combination with core needle biopsy (CNB). 1
• High-frequency ultrasound of the thyroid and cervical lymph nodes is essential for detecting and characterizing nodules before ablation. 3, 9
• Contrast-enhanced ultrasound (CEUS) evaluates vascularity and helps plan ablation strategy. 3

Technical Approach and Follow-Up

Standard Technique

• Local anesthesia, transisthmic approaches, hydrodissection techniques, and the moving-shot and/or fixed electrode technique are recommended as standard techniques (strong recommendation, moderate-quality evidence). 1
• The transisthmic approach is typically preferred over lateral neck insertion. 1, 3
• Hydrodissection technique may be employed to establish safe separation between the ablation zone and vital neighboring structures (recurrent laryngeal nerve, trachea, esophagus, major neck vessels). 1

Immediate Post-Ablation Assessment

• It is recommended to use routine ultrasound combined with CEUS to assess ablation efficacy immediately post-procedure. 1, 3
• Complete ablation is indicated by the absence of enhancement in the ablation zone, with the ablation zone completely covering the intended area. 1

Follow-Up Protocol

• Initial follow-up should begin one month after the procedure, followed by subsequent assessments at 3,6, and 12 months during the first year. 1, 3
• After the initial 12 months, re-evaluate malignant nodules every 6 months and benign nodules annually. 1
• Long-term follow-up is necessary as there can be regrowth of ablated thyroid nodules due to an undertreated nodule margin. 5

Common Pitfalls and Caveats

• RFA is suited for small and medium nodules, while larger nodules may require repeated RFA treatments—set realistic expectations with patients about potential need for multiple sessions. 2
• For nodules extending into the chest, RFA may be technically difficult and surgery may be more appropriate. 2
• Patients with autonomously functioning thyroid nodules may see symptomatic relief with RFA but success rates are variable—thyroid function normalization is not guaranteed. 7
• The role of RFA for thyroid microcarcinomas (<1 cm) remains controversial, and there is little data describing the use of RFA for primary well-differentiated thyroid cancer >1 cm. 7
• Hydrodissection technique, careful patient selection, and experienced operators are critical to prevent complications including vocal cord paralysis, major bleeding, and tracheal or esophageal injury. 3