What is the recommended treatment approach for thermal ablation of thyroid nodules or cancer using radiology?

Thermal Ablation for Thyroid Nodules: Evidence-Based Treatment Approach

Ultrasound-guided thermal ablation is a safe and effective alternative to surgery for carefully selected patients with benign thyroid nodules and select cases of papillary thyroid carcinoma (PTC), offering significant volume reduction with minimal complications while preserving thyroid function. 1

Patient Selection and Mandatory Pre-Procedure Requirements

Pathological Confirmation Required

• All patients must undergo puncture biopsy before thermal ablation to confirm pathological diagnosis 1
• Fine-needle aspiration biopsy (FNAB) is the preferred diagnostic method (strong recommendation, high-quality evidence) 1
• Core needle biopsy (CNB) should be used for FNAB-undiagnosed nodules to improve diagnostic accuracy 1

Indications for Benign Thyroid Nodules

Thermal ablation is appropriate for solid nodules or cystic nodules with ≥10% solid composition that meet ANY of the following criteria 1:

• Nodules causing compression symptoms, cosmetic concerns, or anxiety 1
• Nodules with maximal diameter ≥2 cm that are enlarging gradually 1
• Autonomously functioning thyroid nodules 1
• Recurrent nodules after chemical ablation 1

Indications for Malignant Nodules (Papillary Thyroid Carcinoma)

Thermal ablation can be considered for PTC confirmed by biopsy with cN0M0 status meeting ALL of the following strict criteria 1:

Primary indications:

• Cancer nodule maximal diameter ≤1 cm 1
• Single cancer nodule 1
• No invasion of trachea, large blood vessels, or perithyroid structures 1
• No cervical lymph node metastasis (cN0) 1
• No distant metastasis (cM0) 1

Relative indications (with available medical technical resources):

• Cancer nodule located in isthmus 1
• Cancer nodule adjacent to capsule or with ultrasound-detected capsular invasion 1
• Cancer nodule maximal diameter >1 cm and ≤2 cm 1
• Multiple cancer nodules (≤3 nodules with maximal diameter ≤1 cm) 1

Additional consideration:

• Thermal ablation is optional for patients who cannot tolerate surgery due to comorbidities or refuse surgical resection 1
• Thermal ablation is an option for recurrent thyroid cancer and limited metastatic cervical lymph nodes 1

Absolute Contraindications

Do not perform thermal ablation in patients with: 1

• Severe bleeding tendency 1
• Severe cardiopulmonary insufficiency or systemic diseases preventing tolerance or cooperation 1
• Contralateral vocal cord paralysis on the treatment side 1
• Diffuse sclerosing papillary carcinoma 1
• Malignancies other than PTC 1

Exercise caution in:

• Pregnant and lactating women 1

Pre-Procedure Protocol

Mandatory Laboratory Testing

Complete the following tests before ablation (strong recommendation, moderate-quality evidence) 1:

• Comprehensive blood count 1
• Blood type determination 1
• Coagulation function assessment 1
• Blood biochemistry analysis 1
• Hepatitis B surface antigen, hepatitis C antibodies 1
• Syphilis antibodies, HIV antibody testing 1
• Urinalysis and stool examination 1
• Tumor markers 1
• Thyroid function and calcitonin tests (strong recommendation, moderate-quality evidence) 1

Imaging Evaluation

Ultrasound (US): Routine and preferred method for evaluating thyroid and cervical lymph nodes 1

Contrast-enhanced ultrasound (CEUS): Evaluates blood supply, assists in gauging ablation extent, and confirms complete ablation 1

Neck and chest CT: Defines nodule size and spatial location; neck CT assesses tracheal positioning; chest CT evaluates retrosternal extension and lung metastases 1

Cervical lymph node evaluation: Assess for suspicious features (microcalcification, cystic change, hyperecho, abnormal blood flow, rounded shape, irregular edges) requiring cytological/histological confirmation 1

Patient Preparation

• Discontinue anticoagulant medications (strong recommendation, moderate-quality evidence) 1
• Obtain comprehensive informed consent regarding condition, treatment goals, risks, complications, and alternatives 1
• Fast for 4-6 hours before procedure to prevent aspiration 1
• Establish intravenous access for CEUS and drug administration 1
• Implement multi-parameter vital sign monitoring (blood pressure, heart rate, ECG, oxygen saturation) 1

Procedural Technique

Anesthesia and Approach

• Local anesthesia with 1-2% lidocaine 1
• Needle insertion via isthmus or lateral neck region 1

Available Thermal Ablation Modalities

Multiple techniques are available including radiofrequency ablation (RFA), microwave ablation (MWA), laser ablation (LA), and high-intensity focused ultrasound (HIFU) 1, 2

Expected Outcomes and Efficacy

Benign Nodules

• Volume reduction of 50.7-84.8% at 6 months 3
• Long-term volume reduction of 67-75% at 12 months with single procedure 4
• Volume reduction up to 93.6% with repeat ablations 4
• Significant improvement in clinical symptoms: anterior cervical discomfort (-83.6%), cosmetic complaints (-84.9%), dysphagia (-86.4%) 5
• RFA shows 75% volume reduction; laser ablation shows 83.9% reduction at 18 months 5

Safety Profile

• Complication rate approximately 3% 5
• Most complications are transient and resolve spontaneously 3
• Reported complications include: pain, voice change, hematoma, skin burn, thyrotoxicosis, hypothyroidism, edema, fever 3
• Serious but transient events: recurrent laryngeal nerve palsy (2 cases), hematoma (1 case), abscesses (2 cases) in 166 patients 5

Post-Procedure Follow-Up

• Use CEUS to evaluate treatment effectiveness after ablation 1
• Monitor volume reduction rate (VRR) to assess treatment efficacy 6
• Regrowth rate at 12 months ranges from 0-34% 4

Critical Pitfalls to Avoid

Patient selection errors: The most common pitfall is inadequate patient selection—always confirm benign pathology before treating presumed benign nodules, and strictly adhere to size and staging criteria for malignant nodules 1

Vocal cord assessment: Never proceed without confirming normal contralateral vocal cord function, as this represents an absolute contraindication 1

Incomplete pre-procedure workup: Failure to complete mandatory laboratory testing and imaging evaluation increases procedural risk 1

Operator experience: Thermal ablation is operator-dependent and should only be performed in centers with specific expertise 4