Interventional procedure overview of percutaneous ultrasound-guided microwave ablation for symptomatic benign thyroid nodules

If treatment of a thyroid nodule is planned with surgical/non-radioiodine ablation therapy, fine-needle aspiration cytology is required prior to treatment in the following situations and must show benign cytology (according to Bethesda class I, II) with reliable/sufficient diagnostic value (at least 6 groups of follicular cells with 10–15 cells each).

In nodules with low risk of malignancy (completely cystic, mixed cystic and solid isoechoic, spongiform, isoechoic appearance, nodule with smooth margins) a single fine-needle biopsy is required.

In nodules with higher probability of malignancy (intermediate risk according to TIRADS, EU-TIRADS), 2 fine-needle biopsies are necessary. In contrast, autonomously functioning nodules do not require a fine-needle biopsy.

Pre-and post-interventional, all patients who are planned for a local-ablative procedure must be examined as accurately as patients who undergo surgery. Calcitonin-screening is mandatory as is laryngoscopy prior to and after the procedure.

The performing institution must be able to treat complications (bleeding, infection) in case of Radiofrequency ablation (RFA), Percutaneous Microwave Ablation (PMWA), and Laser Thermal Ablation (LTA).

In symptomatic predominantly cystic thyroid nodules, image-guided thermal ablation should be considered as an option when local symptoms persist after ethanol ablation.

A double cytological confirmation of benignity should be obtained prior to image-guided thermal ablation of thyroid nodules.

Thermal ablation may be proposed as a first-line treatment for solid non-functioning thyroid nodules that are benign at cytology when they become symptomatic.

Thermal ablation may be proposed as a treatment for non-functioning benign multinodular goitre only in patients who refuse or who cannot undergo surgery.

Thyroid nodules treated with thermal ablation should be routinely followed-up with clinical and US examination.

In case of incomplete symptom resolution, symptom relapse, or nodule regrowth, a re-treatment with thermal ablation may be considered.

Thermal ablation may be proposed as a treatment option for AFTN in patients who refuse or cannot undergo traditional treatments with radioiodine or surgery.

Small size AFTN can be treated with thermal ablation when the preservation of normal thyroid tissue function is a priority and it is reasonable to expect at least 80% nodule volume ablation.