Thyroid Radiofrequency Ablation: Updates on Innovative Devices and Techniques

Thermal ablation for cervical lymph node metastasis from papillary thyroid carcinoma: A meta-analysis

BACKGROUND

Traditionally, surgery has been the standard treatment for cervical lymph node metastasis in patients with papillary thyroid carcinoma (PTC). However, thermal ablation is currently recommended by several guidelines. This study aimed to evaluate the efficacy and safety of thermal ablation for lymph node metastasis in patients with PTC.

METHODS

We searched PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases until March 2022 to collect studies on thermal ablation (including radiofrequency, microwave, and laser ablations) for cervical lymph node metastasis from PTC.

RESULTS

A total of 190 patients were included, ranging from 5 to 39 in each study, with a sex ratio (male/female) ranging from 1/4 to 17/20, an average age ranging from 15.6 ± 3.0 to 62.3 ± 13.2 (yr), and a total of 270 cervical lymph nodes, ranging from 8 to 98. The follow-up results showed that thermal ablation significantly reduced the maximum diameter and volume of metastatic lymph nodes in PTC (P < .01). The pooled complete disappearance rate was 86% (95% confidence interval 79% to 93%). Thyroglobulin levels were significantly lower after surgery (P < .01). No major complications occurred, and the combined voice change rate was as low as 1% [CI 0% to 3%].

CONCLUSION

Our meta-analysis showed that thermal ablation is an effective and safe method for the treatment of cervical lymph node metastases from PTC. Considering the limitations of this study, more prospective, multicenter, large-sample studies are needed in the future.

Rigorous radiofrequency ablation can completely treat low-risk small papillary thyroid carcinoma without affecting subsequent surgical management

OBJECTIVE

Minimally invasive therapies are gaining interest because of the indolence and excellent prognosis of low-risk papillary thyroid carcinoma (PTC). This study aimed to evaluate the outcomes of radiofrequency ablation (RFA) for low-risk PTC and to determine the effects of ablation on subsequent surgical management.

METHODS

A medical record review was conducted including patients with low-risk PTC who underwent surgery after RFA from July 2015 to July 2021. Demographic characteristics, tumor characteristics, ablation procedures, surgical findings, and pathological changes were reviewed for all patients. The primary outcomes were surgical and pathological changes in post-ablation patients.

RESULTS

Of the 10 patients with 11 PTCs, 9 (90%) were women; the median (SD) patient age was 41.5 (8.2) years. The maximum diameter range of PTCs was 3.0-12.0 mm. All 10 patients underwent rigorous RFA procedure involving a four-step approach, and had received surgical management. Intraoperatively, no patients had muscle and nerve injuries, and mild adhesion of the post-ablation lesions with the anterior cervical muscle was observed in two cases. Histopathologically, no residual PTCs were observed in the ablated areas in all patients. Central lymph node metastasis (LNM) was found in three (30.0%, pN1a). Occult PTCs were observed in three cases (30.0%).

CONCLUSIONS

Our findings suggest that low-risk small PTCs can be completely treated with rigorous RFA, which does not affect subsequent surgical management, if necessary. RFA may be a treatment option, but occult PTCs and clinically negative LNMs may be overlooked. Long-term follow-up data are necessary to further identify its efficacy.

KEY POINTS

• RFA can completely treat low-risk small PTC. • RFA does not affect the subsequent surgical management if necessary. • Because occult PTCs and clinically negative LNMs may be overlooked by RFA, long-term follow-up data are necessary to further identify its efficacy.

Review of Radiofrequency Ablation in Tonsillectomy

The most common disease involving the tonsils among children and adults is chronic tonsillitis. There are different surgical techniques described in literature for the treatment of diseases involving the tonsils. Of these, the most routinely performed and the traditional method is conventional dissection tonsillectomy. The main disadvantage of this method is bleeding and postoperative pain. Radiofrequency ablation is found to overcome this limitation due to its mechanism of action. Both monopolar and bipolar radiofrequency ablation can be used in the surgical management. The effectiveness of monopolar radiofrequency has been proved in different fields of medicine. Hence new studies can be directed in comparing monopolar radiofrequency ablation with other techniques of tonsillectomy.

Combination Therapy of Ethanol Ablation and Radiofrequency Ablation to Treat Parathyroid Adenoma in a Case with Primary Hyperparathyroidism

Introduction: Ethanol ablation (EA) and radiofrequency ablation (RFA) are minimal invasive therapeutic modalities to treat primary hyperparathyroidism (PHPT). Case Presentation: A 77-year-old man presented a 3.5-cm parathyroid adenoma with mixed cystic and solid components. He was ineligible for parathyroidectomy because of his age and the surgical history of the coronary artery bypass graft. First, EA was performed to remove cystic component. After that, the volume of parathyroid adenoma was decreased (volume reduction rate: 94%); however, the level of serum parathyroid hormone (PTH) was persistently high (88 pg/mL). Subsequent RFA was performed to remove the remaining parathyroid adenoma. Further, it was completely disappeared on the following ultrasound examination, and PTH was normalized. The results during a 2-year follow-up confirmed clinical success, and no relevant complication was reported. Conclusion: The combination therapy of EA and subsequent RFA is safe and effective as an alternative therapeutic method to treat PHPT in patients ineligible for parathyroidectomy.

Perithyroidal hemorrhage caused by hydrodissection during radiofrequency ablation for benign thyroid nodules: Two case reports

BACKGROUND

Hydrodissection is a widely used technique during radiofrequency ablation (RFA) for benign thyroid nodules. Although it could effectively avoid thermal injury to the surrounding critical structures and achieve complete treatment, routine operation of the remaining needle could cause perithyroidal hemorrhage. In this report, we present 2 cases of perithyroidal hemorrhage during RFA caused by a hydrodissection needle, which have not been reported before.

CASE SUMMARY

A 21-year-old female and a 45-year-old male were admitted for RFA for benign thyroid nodules. Considering that their nodules were adjacent to the recurrent laryngeal nerve, the needle used for hydrodissection was placed and remained between the dorsal capsule of the lateral lobe and the recurrent laryngeal nerve. During the procedure, active bleeding near the needle appeared on ultrasonography (US). Although moderate pressure was quickly applied to the neck for several minutes, contrast-enhanced US (CEUS) still showed an active hemorrhage. A radiofrequency electrode was placed at the bleeding point under the guidance of CEUS to stop the bleeding, and the procedure was finally confirmed to be successful by CEUS, without other complications.

CONCLUSION

Hydrodissection during RFA of benign thyroid nodules was associated with a risk of perithyroidal hemorrhage. The timely recognition of this acute hemorrhage could help in the timely control of the bleeding, and CEUS-guided ablation of the bleeding point could be useful.

Meta-Analysis of the Application Effect of Different Modalities of Thermal Ablation and Surgical Treatment in Papillary Thyroid Microcarcinoma

Background

Papillary thyroid microcarcinoma (PTMC) refers to papillary thyroid carcinoma (PTC) with a maximum diameter of 10 mm. Thermal ablation, including radiofrequency ablation (RFA), microwave ablation (MWA), and laser ablation (LA), has been applied in the treatment of benign thyroid nodules and captured extensive attention. At present, the application of thermal ablation in PTMC has been extensively reported, but outcomes such as volume reduction rate (VRR), complete remission rate (CRR), and adverse reaction rate (ARR) vary considerably. Therefore, this meta-analysis was performed to evaluate the safety and efficacy of different treatment methods of PTMC.

Methods

We did a systematic review and network meta-analysis. We searched PubMed, EMBase, and Cochrane-Library from the date of inception to January 10, 2022, to retrieve the VRR, CRR, and ARR of MWA, RFA, LA and surgical treatment of PTMC, and a meta-analysis was performed using the R meta-package. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, and sensitivity analyses, cumulative meta-analyses, and publication bias were also performed. Relevant literature was retrieved with keywords; the eligible cohort studies were screened based on the established inclusion and exclusion criteria.

Results

A total of 1515 patients were included in the 12-month follow-up. The overall VRR was 86.25% (95% CI: 77.89, 94.60), and the VRR was RFA > WMA > LA, but the differences were not significant. A total of 1483 patients were included in the last follow-up. The overall VRR was 99.41% (95% CI: 99.11, 99.72), and the VRR was RFA > WMA > LA, but the differences were not significant. A total of 1622 patients showed complete remission at the last follow-up, and the overall CRR was 0.63 (95% CI: 0.46, 0.79). The CRR was RFA > LA > WMA, but the differences were not significant. A total of 1883 patients had adverse reactions at the last follow-up, and the overall ARR was 0.06 (95% CI: 0.03, 0.08). The ARR at the last follow-up was RFA = Surg < LA < WMA. The ARR of the RFA and Surg subgroups was significantly lower than that of the WMA subgroup.

Conclusions

Similar good efficacy and safety profiles were observed in WMA, RFA, LA, and surgical treatment in PTMC, among which RFA showed the best volume reduction, complete remission rate, and adverse reaction reduction. However, there is a slight bias in the limited literature included in this study, and we did not conduct or refer to mechanistic studies to confirm its specific mechanism of action. Clinicians are advised to use their discretion in the choice of treatment.

Residual, regrowth, and new growth of radiofrequency ablation for benign thyroid nodules of different volumes: two-year follow-up results

INTRODUCTION

Radiofrequency ablation (RFA) is recognized as an effective technique for the treatment of benign thyroid nodules (BTNs), although the long-term results are limited. This study aimed to evaluate the residual vital volume increase, regrowth, and new growth over a 2-year period after RFA among different nodule volume groups.

SUBJECTS AND METHODS

This retrospective study evaluated 135 patients with 153 BTNs who underwent ultrasound guided RFA. The BTNs were categorized into small (<10 mL), medium (10-30 mL), and large (>30 mL) according to the initial volume of BTNs prior to ablation. The volume changes of each nodule were analyzed at 1, 3, 6, 12 and 24 months after RFA. New growth was defined as the growth in volume not found in the early follow-up on ultrasonography.

RESULTS

The initial ablation ratio of all BTNs was 99.67%. The mean volume reduction ratio (VRR) of BTNs was 85.53% after 2-year follow-up. The small nodule group showed a lower VRR compared to the other two groups at the 1-month follow-up, and there was no difference of VRR at the subsequent follow-ups. The incidence of residual vital volume increase was 4.58%. The overall incidence of regrowth was 3.92% and the mean timing of regrowth was 16.71 months. New growth occurred in 18.95% of patients. No further treatment was required in the majority of cases.

CONCLUSION

RFA achieved a clinically relevant volume reduction in different sizes of single BTNs which persisted for at least 2 years, thereby preventing the need for retreatment.

A novel parallel overlapping mode for complete ablation of large benign thyroid nodules in a single-session radiofrequency ablation

BACKGROUND

Radiofrequency ablation (RFA) has been widely applied in patients with benign thyroid nodules (BTNs), and complete ablation in a single-session treatment brings great benefits to patients. While how the ablation should be planned and performed to achieve complete ablation in a single-session treatment in large BTNs remains unknown.

PURPOSE

To determine a more suitable ablation strategy for sufficient treatment in a single-session treatment.

MATERIALS AND METHODS

This retrospective study included 108 BTNs receiving RFA treatment. These patients were divided into two groups: group A using one insertion point with a fan-shaped overlapping mode and group B using multiple insertion points with a novel parallel overlapping mode. All the treatments used a hydrodissection approach and moving-shot technique. Contrast-enhanced ultrasonography (CEUS) was used to guide the supplementary ablation. Follow-ups were performed at 1, 3, 6 and 12 months. The rates of supplementary ablation, initial ablation ratio (IAR), the rates of complete ablation (CAR), treatment effects and complications between the two groups were compared.

RESULTS

The group B had larger treated nodules (10.2ml vs 6.4ml, P<0.001) than group A, while group B had a lower rate of supplementary ablation (21.6% vs 75.4%, P<0.001), especially in the BTNs with craniocaudal diameters ≥30mm (22.0% vs 100%, P<0.001). With the assistance of supplementary ablation, both groups achieved similar IAR (100% vs 100%, P=0.372) and CAR (94.7% vs 94.1%, P=1.000). Two groups showed similar VRRs at 12-month follow-up (77.9% vs 77.5%, P=0.894) and similar rates of complications (3.5% vs 2.0%, P=1.000).

CONCLUSIONS

Needle placement using the multiple insertion points with a novel parallel overlapping mode would be easier to achieve complete ablation with less supplementary ablation, especially in large nodules.

Long-term follow-up of the radiofrequency ablation of benign thyroid nodules: the value of additional treatment

PURPOSE

This study aimed to evaluate the efficacy of additional radiofrequency ablation (RFA) treatment for benign thyroid nodules.

METHODS

Electronic medical records at a single institution from September 2008 to August 2016 were searched, and consecutive patients treated with RFA due to benign thyroid nodules with cosmetic or symptomatic problems were enrolled. All patients were followed up for at least 30 months. The nodules were divided into three groups: group 1 included nodules that met the criteria for additional treatment and underwent additional treatment, group 2 included nodules that met the criteria but did not undergo additional treatment, and group 3 included nodules that did not meet the criteria. The ablation results were compared among the three groups in terms of the initial ablation ratio (IAR) and volume reduction ratio (VRR).

RESULTS

Ninety nodules from 88 patients were included in the study. At the last follow-up, group 1 showed a significantly smaller nodule volume and larger VRR (2.5 mL and 84.6%, respectively) than group 2 (8.1 mL and 39.8%, respectively, P<0.001), but did not present a significant difference from group 3 (0.9 mL, P=0.347, and 92.8%, P=0.238). The IAR was significantly higher in group 3 (94.5%) than in the other two groups (group 1, 81.1%; group 2, 82.8%; P<0.001).

CONCLUSION

Multiple treatment sessions achieve greater VRR. Therefore, additional treatment could be considered for patients who meet the corresponding criteria.

Uncooled Microwave Ablation as a Treatment Option to Preserve Thyroid Function in Patients with Benign Thyroid Nodules

Objective:

The objective is to evaluate the long-term efficacy and safety of uncooled MWA for the treatment of benign thyroid nodules and its long-term effect on thyroid functions.

Material and Methods:

The study was conducted on 40 patients with 40 nodules. They were treated between September 2019 and December 2020. Nodules’ volumes, thyroid functions (triiodothyronine, free thyroxine, thyrotropin) and anti-thyroid peroxidase and anti-thyroglobulin antibodies were measured before treatment and at 3rd, 6th and 12th month following the treatment. Volume reduction rates and changes in clinical findings were evaluated.

Results:

The mean volume reduction rate was 49.88, 65.3, and 79.06% at 3rd, 6th, and 12th month, respectively. Antibody levels and thyroid function tests have remained within normal limits and were not exhibited significant change during follow-ups (p > 0.05), except for a significant increase in free thyroxin level at 12th-month (p = 0.007). Subjective symptoms and cosmetic scores were significantly improved all follow-up (p < 0.0001). The only complication was a first-degree skin burn in a patient.

Conclusion:

In conclusion, uncooled microwave ablation is an effective and safe method for the treatment of benign thyroid nodules and preserves thyroid function.

Improving Voice Outcomes after Thyroid Surgery and Ultrasound-Guided Ablation Procedures

The field of endocrine surgery has expanded from the traditional open neck approach to include remote access techniques as well as minimally invasive approaches for benign and malignant thyroid nodules. In experienced hands and with careful patient selection, each approach is considered safe, however complications can and do exist. Post-operative dysphonia can have serious consequences to the patient by affecting quality of life and ability to function at work and in daily life. Given the significance of post-procedural dysphonia, we review the surgical and non-surgical techniques for minimizing and treating recurrent laryngeal nerve injury that can be utilized with the traditional open neck approach, remote access thyroidectomy, or minimally invasive thermal ablation.

Thyroid-dedicated internally-cooled wet electrode for benign thyroid nodules: experimental and clinical study

BACKGROUND

To assess the effects of radiofrequency ablation (RFA) using an internally-cooled wet (ICW) electrode in ex vivo bovine liver and evaluate the feasibility of the ICW electrode for benign thyroid nodules.

METHODS

We developed an 18-gauge ICW electrode with a microhole at the distal tip for tissue infusion of chilled (0 - 4 °C) isotonic saline (rate = 1.5 ml/min). RFA using ICW and IC electrodes were performed in bovine livers (40 pairs, 1-cm active tip, 50 W, 1-min). We compared the morphological characteristics of ablation zones and presence of carbonization. Twenty patients with benign thyroid nodules larger than 5 ml were prospectively enrolled in a clinical study and underwent ultrasound-guided RFA with ICW electrodes. Ultrasound examinations, laboratory data, and symptom and cosmetic scores were evaluated preprocedure and 1 and 6 months after the procedure.

RESULTS

In the ex vivo study, the ICW achieved significantly larger ablation zones than the IC (p<.001). In the clinical study, ICW electrodes were tolerable in all patients. At last follow-up, nodule volume had decreased from 15.6 ± 12.1 ml to 4.1 ± 4.3 ml (p<.001), and the mean volume reduction ratio (VRR) was 73.3 ± 13.7% at 6.0 months follow-up. Cosmetic and symptom scores were reduced from 3.52 ± 1.03 to 2.65 ± 0.88 and 3.10 ± 2.17 to 0.85 ± 0.99 (both p<.001), respectively. After RFA, thyroid function was well preserved in all patients, and mean thyroglobulin level decreased from 36.6 ± 52.1 ng/ml to 26.9 ± 62.2 ng/ml. One patient experienced a temporary voice change that recovered within a week.

CONCLUSIONS

We developed a thyroid-dedicated ICW electrode that we showed to be feasible and effective in patients with benign thyroid nodules.

Charge Reversal Polypyrrole Nanocomplex-Mediated Gene Delivery and Photothermal Therapy for Effectively Treating Papillary Thyroid Cancer and Inhibiting Lymphatic Metastasis

As a traditional treatment for papillary thyroid cancer (PTC), surgical resection of diseased tissues often brings lots of inconveniences to patients, and the tumor recurrence and metastasis are difficult to avoid. Herein, we developed a gene and photothermal combined therapy nanosystem based on a polypyrrole (Ppy)-poly(ethylene imine)-siILK nanocomplex (PPR_ILK) to achieve minimally invasive ablation and lymphatic metastasis inhibition in PTC simultaneously. In this system, gelatin-stabilized Ppy mainly acted as a photothermal- and photoacoustic (PA)-responsive nanomaterial and contributed to its well-behaved photosensitivity in the near-infrared region. Moreover, gelatin-stabilized Ppy possessed a charge reversal function, facilitating the tight conjunction of siILK gene at physiological pH (7.35-7.45) and its automatic release into acidic lysosomes (pH 4.0-5.5); the proton sponge effect generated during this process further facilitated the escape of siILK from lysosomes to the cytoplasm and played its role in inhibiting PTC proliferation and lymphatic metastasis. With the guidance of fluorescence and PA bimodal imaging, gene delivery and Ppy location in tumor regions could be clearly observed. As a result, tumors were completely eradicated by photothermal therapy, and the recurrences and metastases were obviously restrained by siILK.

Ultrasound-guided thermal ablation for hyperparathyroidism: current status and prospects

BACKGROUND

Hyperparathyroidism (HPT) is classified into primary HPT (PHPT), secondary HPT (SHPT), tertiary HPT (THPT), and pseudohyperparathyroidism. Parathyroid surgery is generally reserved for patients with symptomatic PHPT and asymptomatic patients who meet the surgical guideline criteria. However, the risk of complications and mortality after parathyroid gland surgery increases with increasing patient age.

AIM

This study aimed to review existing research on laser ablation, radiofrequency ablation, microwave ablation, and high-intensity focused ultrasound in the treatment of HPT and analyze its application prospects.

CONCLUSIONS

Thermal ablation is a good alternative treatment for patients with parathyroid hyperplasia who do not meet the criteria or decline surgery. Being a type of minimally invasive treatment, ultrasound-guided thermal ablation has the advantages of easy operation, rapid recovery, and reusability and is used widely.

Long-term outcome of microwave ablation for benign thyroid nodules: Over 48-month follow-up study

OBJECTIVES

The short-term effects of microwave ablation (MWA) for the treatment of benign thyroid nodules (BTNs) were satisfactory in previous studies. However, as a slowly progressing disease, the long-term efficacy of MWA for BTNs at present is not clear. Our study aim was to assess the long-term results of MWA for BTNs after a 48-month follow-up.

METHODS

From June 2015 to September 2017, 148 patients had 148 BTNs. All patients were from the China-Japan Union Hospital of Jilin University. Careful ultrasound examinations were performed 1 day, 1 month, 3 months, 6 months, 12 months, and every 6 months after MWA. The volume, volume reduction rate (VRR), recurrence rate of the ablated area and thyroid function were recorded.

RESULTS

The mean volumes of the 148 nodules were 15.6 ± 9.4 cm³ (range: 1.3-48.9 cm³) and 0.6 ± 0.6 cm³ (range: 0-3.5 cm³) before and 48 months after MWA, respectively, with a nodule VRR of 96.9 ± 2.5% (range: 90.4-100%). Two patients (1.35%) had recurrence after MWA. Compared with thyroid function before MWA, no significant variation was observed after MWA. Five patients experienced complications (3.38%): two patients (1.35%) had bleeding, two patients (1.35%) had ear pain and toothache during MWA, and one patient (0.68%) had hoarseness after MWA. No cases of oesophageal injury, tracheal injury, infection, skin burns, etc., were reported during or after MWA.

CONCLUSIONS

Based on a long-term follow-up, MWA is an effective method for treating BTNs and is expected to be a potential first-line treatment.

Comparison of efficacy, safety, and patient satisfaction between thermal ablation, conventional/open thyroidectomy, and endoscopic thyroidectomy for symptomatic benign thyroid nodules

PURPOSE

Thermal ablation (TA) is a minimally invasive treatment method for symptomatic benign thyroid nodules (BTNs). This study aimed to evaluate the value of TA by comparing the efficacy, safety, and patient satisfaction with conventional/open thyroidectomy (ConT) and endoscopic thyroidectomy (ET) for symptomatic BTNs.

METHODS

Patients with symptomatic BTNs who underwent ConT, ET, or TA therapy between January 2018 and January 2020 were included. Pre-operation data of the two comparisons (TA vs. ConT and TA vs. ET) was balanced using propensity score matching. The technique efficacy (volume reduction ratio ≥50%), nodule disappearance, and regrowth rate were calculated after ablation. The operation and hospitalization time, medical cost, complications, post-operative symptoms, and cosmetic scores were recorded and compared. Patient satisfaction was evaluated using a telephone survey.

RESULTS

After a median 19-month follow-up (range, 12-36 months), the technique efficacy rate, nodule disappearance, and regrowth rate were 93.2% (119/129), 6.8% (10/129), and 0.8% (1/129), respectively. Operation time, hospitalization time, and medical costs were less for patients in the TA group than for patients in the ConT and ET groups (all p < 0.001). The incidence of complications, post-operative symptoms, cosmetic scores, and overall satisfaction were not significantly different among groups (all p > 0.05). Post-operative hypothyroidism was less frequent in the TA group than in the ConT and ET groups (all p < 0.05).

CONCLUSIONS

Compared to ConT and ET, TA has comparable efficacy, safety, and patient satisfaction and exhibits greater protection of thyroid function for the treatment of symptomatic BTNs.

Radiofrequency ablation and thyroid cancer: review of the current literature

BACKGROUND

Thyroid nodules are commonly being diagnosed in general population and have a potential for malignant transformation. Historically, surgery has been considered as the first line treatment for these tumors. However, with passage of time newer minimally invasive techniques such as RFA (radiofrequency ablation) has been adapted. Though, RFA for thyroid tumors has been performed more commonly in Asian and European countries, it is a fairly new technique in North America. The aim of the review is to assess the current data and conclude that whether RFA is likely a valuable option when compared to surgery for treatment of thyroid tumors.

MATERIALS AND METHODS

A Comprehensive PubMed/MEDLINE, Embase and Web of Science search was performed. To expand our search, references of the retrieved articles were also screened for additional data. After selecting the studies that fulfilled the initial screening, authors independently reviewed the selected studies and screened the full texts to identify those that met the inclusion criteria.

RESULTS

The comprehensive literature search from PubMed/MEDLINE, Web of Science, and EMBASE databases revealed 1094 studies (Embase 870, PubMed 200, and Web of Science 24). References were imported for screening. Amongst 1094 studies, 138 duplicates removed, and 956 studies were screened against title and abstract. After these 777 studies were excluded the remaining 179 studies were assessed for full-text eligibility. Amongst them 127 studies excluded due to wrong design or setting. Finally, 18 studies were included in the review.

CONCLUSION

RFA appears to be a safe alternative to surgery in selected cases. However, it is not widely used and there are few randomized controlled trials. Furthermore, it is associated with a low risk profile and has shown promising results in patients who are difficult surgery candidates. Currently large-scale prospective studies are needed in North America to establish the efficacy of RFA and its use as an alternative to surgery for thyroid tumors.

Intraoperative Neuromonitoring: Evaluating the Role of Continuous IONM and IONM Techniques for Emerging Surgical and Percutaneous Procedures

Continuous and intermittent intraoperative nerve monitoring (IONM) has become an important asset for endocrine surgeons over the past few decades. The ability to determine neurophysiologic integrity of the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) on top of identification and meticulous dissection of the nerve in the surgical field, has allowed for advances in technology and improved outcomes when it comes to prevention of vocal fold immobility. This article aims to compare in review continuous and intermittent nerve monitoring (CIONM, IIONM), as well as review the current paradigms of their use. This article will also discuss the future of intraoperative nerve monitoring technologies in scarless thyroid surgery and percutaneous approaches to thyroid pathology in form of radiofrequency ablation (RFA).

Radiofrequency ablation and related ultrasound-guided ablation technologies for treatment of benign and malignant thyroid disease: An international multidisciplinary consensus statement of the American Head and Neck Society Endocrine Surgery Section with the Asia Pacific Society of Thyroid Surgery, Associazione Medici Endocrinologi, British Association of Endocrine and Thyroid Surgeons, European Thyroid Association, Italian Society of Endocrine Surgery Units, Korean Society of Thyroid Radiology, Latin American Thyroid Society, and Thyroid Nodules Therapies Association

BACKGROUND

The use of ultrasound-guided ablation procedures to treat both benign and malignant thyroid conditions is gaining increasing interest. This document has been developed as an international interdisciplinary evidence-based statement with a primary focus on radiofrequency ablation and is intended to serve as a manual for best practice application of ablation technologies.

METHODS

A comprehensive literature review was conducted to guide statement development and generation of best practice recommendations. Modified Delphi method was applied to assess whether statements met consensus among the entire author panel.

RESULTS

A review of the current state of ultrasound-guided ablation procedures for the treatment of benign and malignant thyroid conditions is presented. Eighteen best practice recommendations in topic areas of preprocedural evaluation, technique, postprocedural management, efficacy, potential complications, and implementation are provided.

CONCLUSIONS

As ultrasound-guided ablation procedures are increasingly utilized in benign and malignant thyroid disease, evidence-based and thoughtful application of best practices is warranted.

Radiofrequency ablation of recurrent thyroid cancers: anatomy-based management

Although differentiated thyroid cancer has an excellent prognosis and low mortality, its recurrence rate has been reported to be very high. While surgery is recommended as the standard treatment for recurrent thyroid cancer, reoperation may increase the incidence of complications due to fibrosis and anatomical distortion. In patients with high surgical risk or those who refuse repeated surgery, ultrasonography-guided ablation techniques including radiofrequency ablation, ethanol ablation, and laser ablation are suggested as alternative treatments. In this manuscript, we introduce an anatomy-based management concept for radiofrequency ablation for recurrent thyroid cancer, and present a review of the relevant literature, including indications, basic techniques, clinical outcomes, and complications.

Ultrasound-Guided Thermal Ablation of Thyroid Nodules: Technicalities Progress and Clinical Applications, Especially in Malignant Thyroid Nodules

Thyroid nodules are commonly encountered in health care practice. They are usually benign in nature, with few cases being malignant, and their detection has increased in the adult population with the help of ultrasonography. Thyroidectomy or surgery is the first-line treatment and traditional method for thyroid nodules; however, thyroidectomy leaves permanent scars and requires long-term use of levothyroxine after surgery, which makes patients more reticent to accept this treatment. Thermal ablation is a minimally-invasive technique that have been employed in the treatment of benign and malignant thyroid nodules nodules, and have been shown to be effective and safe. Several studies, including long-term, retrospective, and prospective studies, have investigated the use of ablation to treat benign thyroid nodules and malignant thyroid nodules, including papillary thyroid carcinoma. Here, we review the recent progress in thermal ablation techniques for treating benign and malignant nodules, including their technicalities, clinical applications, pitfalls and limitations, and factors that could affect treatment outcomes. Special in-depth elaboration on the recent progress of the application of thermal ablation therapy in malignant thyroid nodules.

Efficacy on radiofrequency ablation according to the types of benign thyroid nodules

Percutaneous radiofrequency ablation (RFA) has been recommended as minimally invasive treatment for patients with symptomatic benign thyroid nodules (BTNs) because of the large number of clinical applications. This retrospective observational study sought to evaluate the clinical outcomes of RFA for BTNs. From 2014 to 2019, a sample size of 1289 patients treated by RFA were 262 ones with solid nodules and 1027 ones with cystic-solid nodule, respectively. The efficacy including the nodule maximal diameter reduction ratio (MDRR), the volume reduction ratio (VRR) and the cosmetic scores reduction ratio (CSRR). The results of the nodule MDRR and VRR in the cystic-solid nodule group were significantly better than those in the solid nodule group at the 3rd and 6th month, and the CSRR in the two groups showed statistically significant difference at the 3rd month. In a word, RFA is an effective method for symptomatic benign solid or cystic-solid nodules. The achieved MDRR and VRR in the cystic-solid nodule group were significantly better than those in the solid nodule group at the 3rd and 6th month.

A comprehensive review of interventional ablation techniques for the management of thyroid nodules and metastatic lymph nodes

Thyroidectomy remains the gold standard treatment for benign, symptomatic, or enlarging thyroid nodules, malignant nodules, and metastatic lymph node disease. However, in the past 2 decades, image-guided interventional techniques have emerged as promising alternative treatments for these conditions. Percutaneous ethanol ablation is now an accepted first-line treatment for recurring cystic thyroid nodules. Thermal ablation techniques such as high-intensity focused ultrasound, laser ablation, radiofrequency ablation, and microwave ablation have shown efficacy in producing a nodular volume reduction of greater than 50% that is maintained for several years with resolution of local compressive symptoms. There is also increasing evidence that these techniques can effectively treat papillary thyroid microcarcinomas and recurrent metastatic lymph node disease. Because these interventional ablation techniques are performed safely in an outpatient setting, are well tolerated, and the risk for needing thyroid hormone supplementation is negligible, they are becoming a popular alternative treatment to surgical resection. In this comprehensive review, we discuss each of these percutaneous interventions: the devices and techniques, the advantages and disadvantages of each energy, and summarize the outcomes published in the literature.

Continuous, Large-Volume Hydrodissection to Protect Delicate Structures around the Thyroid throughout the Radiofrequency Ablation Procedure

INTRODUCTION

Small-volume hydrodissection liquid dissipates rapidly and confers only short-term protection during radiofrequency ablation (RFA) of benign thyroid nodules. The aim of this study was to establish a safe method for continuous, large-volume hydrodissection.

METHODS

A long needle was inserted and positioned outside the thyroid capsule; 5% glucose was injected to maintain a 3- to 5-mm continuous safety buffer. From October 2015 to July 2020, 166 patients underwent hydrodissection with different volumes, and ablation efficacy and complications associated with different liquid volumes (≤40 mL vs. >40 mL) were compared at 1-month postprocedure. Moreover, 20 mL liquid (equivalent to 250 mL in the human body) was injected around the thyroid of a rhesus monkey, after which CT scans were used to visualize the liquid's fate and verify its safety.

RESULTS

The 51 patients with 10-40 mL injections and 116 patients with larger injections (45-450 mL) showed similar complete ablation rates (88.46% vs. 90.44%, p = 0.582), comparable 6-month VRR (82.79% vs. 76.62%, p = 0.079), and complication incidences, although the latter group had larger nodules (9.11 mL vs. 13.79 mL, p = 0.003), more energy delivered (3.44 kcal vs. 6.04 kcal, p < 0.001), and longer operation times (51.37 min vs. 69.2 min, p < 0.001). In the animal experiment, the 20 mL of liquid diffused quickly (within 10 min) from the vicinity of the thyroid to the mediastinum and retropharyngeal space. It was observed in the kidneys at 10 min and disappeared from the neck and chest space by 24 h.

CONCLUSIONS

Continuous, large-volume hydrodissection can protect the delicate structures around the thyroid throughout the RFA procedure and might be beneficial in large thyroid nodule ablation.

One year follow-up of US-Guided radiofrequency ablation for low-risk papillary thyroid microcarcinoma: The first experience in Taiwan

BACKGROUND

The incidence of papillary thyroid microcarcinoma (PTMC) has increased rapidly in recent decades, with a favorable overall prognosis. We aimed to evaluate the efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treating low-risk PTMC in Taiwan.

METHODS

This prospective study included patients with PTMC who were ineligible or refused surgery and underwent US-guided RFA between October 2018 and June 2020. US and computed tomography (CT) were performed before RFA to assess tumor lesions and exclude cervical lymph node metastasis. Sequential US follow-up following RFA was performed after 1, 3, 6, and 12 months, and yearly thereafter. Volume reduction ratio (VRR) and complete disappearance rate of tumor at one year were evaluated.

RESULTS

13 PTMCs in 12 patients were enrolled with a mean follow-up of 16.2 ± 8.1 months (range, 1-24 months). The median largest tumor diameter and tumor volume before RFA were 0.76 cm and 0.15 ml (range, 0.02-0.37 ml). The median (interquartile range, IQR) volume and VRR at 12 months post-RFA were 0 (0, 0.03) ml (p = 0.033) and 100% (84.26%, 100%) (p = 0.008). Eight tumors (61.54%) were completely disappeared at 12 months post-RFA and no tumor recurrence, lymph nodes, or distant metastasis were noted. All tumors were successfully treated without complications.

CONCLUSION

Minimally invasive US-guided RFA is an effective and safe alternative for low-risk PTMC, resulting a satisfied VRR.

Computer-Analyzed Ultrasound Predictors of the Treatment Efficacy of Radiofrequency Ablation for Benign Thyroid Nodules

AIM

Radiofrequency ablation (RFA) is a relatively safe and efficient alternative to surgery for patients with benign thyroid nodules. We investigated predictive factors associated with volume reduction using digital imaging analysis.

METHODS

In this retrospective study, a prospectively maintained database containing the data of patients who received treatment from April 2019 to March 2020 was analyzed. Computerized analysis for quantitative measurement of echogenicity, heterogeneity, and the proportion of cystic components was performed on ultrasonographic images. The volume reduction rate (VRR) was calculated during follow-up. Treatment efficacy was defined as a volume reduction greater than 50% of baseline volume.

RESULTS

The median volume of 58 benign thyroid nodules before RFA was 22.7 mL. Of 53 nodules with sufficient follow-up, the median VRR was 46.4%, 61.5%, 63.4%, and 67.4% at 1, 3, 6, and 12 months, respectively. Overall, at one-year follow-up, treatment efficacy was achieved in 39 (74%) nodules. In a multivariate regression analysis, the proportion of cystic components and RFA treatment time were independently associated with treatment efficacy. A subgroup analysis focusing on solid nodules indicated a negative correlation between echogenicity and VRR.

CONCLUSIONS

The proportion of cystic components in thyroid nodules is the main predictor of RFA treatment efficacy. In solid nodules, higher echogenicity is associated with a lower volume reduction.

Lidocaine-induced systemic toxicity complicating radiofrequency ablation of benign thyroid nodule procedure: A case report and review of literature

The systemic toxicity of lidocaine is an extremely rare complication of thyroid RFA procedure, and it can be life-threatening. The quick recognization of its symptoms and intravenous use of lipid emulsion are essential to preventing mortality.

The Role of CEUS in the Evaluation of Thyroid Cancer: From Diagnosis to Local Staging

Ultrasound often represents the first diagnostic step for thyroid nodule evaluation in clinical practice, but baseline US alone is not always effective enough to achieve thyroid nodule characterization. In the last decades new ultrasound techniques, such as CEUS, have been introduced to evaluate thyroid parenchyma as recommended by EFSUMB guidelines, for use in clinical research field, although its role is not yet clear. Several papers show the potential utility of CEUS in the differential diagnosis of benign and malignant thyroid nodules and in the analysis of lymph node involvement in neoplastic pathology. Therefore, we carried out an evaluation of the literature concerning the role of CEUS in three specific areas: the characterization of the thyroid nodule, the evaluation of minimally invasive treatment and loco-regional staging of the lymph node in proven thyroid cancer. According to evidence reported, CEUS can also play an operative role in nodular thyroid pathology as it is able to guide ablation procedures on thyroid nodule and metastatic lymph nodes, to assess the radicality of surgery, to evaluate disease relapse at the level of the margins of ablated regions and to monitor the clinical evolution of necrotic areas in immediate post-treatment setting.

Tracheal necrosis following thyroid radiofrequency ablation

INTRODUCTION

Radiofrequency ablation for benign thyroid nodules has a low rate of complications in experienced hands for selected indications, but tracheal necrosis is a major complication.

CASE REPORT

A 60 year-old female patient underwent percutaneous radiofrequency ablation of an unesthetic benign isthmic thyroid nodule. The procedure was performed with a cooled electrode, using the "moving shot" technique on a trans-isthmic approach, under general anesthesia. Postoperative course was complicated by dysphonia and cervical pain implicating a third-degree skin burn of the medial cervical region progressing to severe soft-tissue and cervical tracheal necrosis.

DISCUSSION

Risk factors in the present case included the general anesthesia, isthmic location and thyroid nodule volume. To avoid this kind of complication, the procedure should be performed under local anesthesia, using cooled dextrose solution hydrodissection between trachea, thyroid and skin. Ahead of radiofrequency ablation, patients should be informed of possible major complications, especially if the indication is cosmetic.

Safety and Efficacy of Radiofrequency Ablation of Thyroid Nodules-Expanding Treatment Options in the United States

CONTEXT

Radiofrequency ablation (RFA) has only recently gained popularity in the United States for treatment of thyroid nodules (TNs), with a limited number of patients having undergone the procedure in this country.

OBJECTIVE

To evaluate the safety and efficacy of RFA of TNs performed in an outpatient setting in the United States.

METHODS

This is a retrospective, single-center study of 53 patients who underwent RFA of 58 TNs between November 2018 and January 2021. The reduction in volume of nodule, cosmetic and symptomatic improvement, effect on thyroid function, and complications following RFA were assessed.

RESULTS

Eleven out of 53 patients were excluded from the analysis. A total of 47 benign TNs (23 nonfunctioning thyroid nodules [NFTNs] and 24 autonomously functioning thyroid nodules [AFTNs]), were assessed after RFA. The median reduction in volume was 70.8% after a median follow-up period of 109 days, with symptomatic and cosmetic improvement (P < 0.0001). Compared with larger nodules, smaller nodules had greater volume reduction (P = 0.0266). RFA improved thyrotropin (TSH) in AFTNs (P value = 0.0015) and did not affect TSH in NFTNs (P value = 0.23). There were no major complications; however, 1 patient had self-limited local bleeding and another had transient voice change that recovered in 6 months.

CONCLUSION

RFA is a safe and efficacious treatment for symptomatic NFTNs and AFTNs in our population and is especially effective for smaller nodules. RFA should be considered an alternative for TNs in patients who cannot or do not want to undergo surgery.

Ultrasound-guided radiofrequency ablation for the treatment of primary hyperparathyroidism: An efficacy and safety study

OBJECTIVE

To evaluate the efficacy and safety of radiofrequency ablation (RFA) for the treatment of primary hyperparathyroidism (pHPT).

METHODS

25 patients who were treated with RFA for pHPT from September 2015 to January 2020 were enrolled in our study. The serum intact parathyroid hormone (iPTH), calcium and phosphate levels were tested within 1 week before RFA and at 1 day, 1 month, 3months, 6months and 12months after ablation. The ablation areas were evaluated by US at 1, 3, 6 and 12 months after RFA. Postoperative complications including voice hoarseness, hematoma, postoperative pain, incision infections, hypoparathyroidism and hypocalcemia were recorded.

RESULTS

A total of 25 pHPT patients (53.9 ± 10.9 years, 22 women and 3 men) with 29 enlarged parathyroid glands were treated by RFA. 22 of them were treated in one session and the other three were treated in two sessions. Serum iPTH and calcium levels decreased significantly at 1 day after RFA (all P < 0.05). 21 patients had normal levels of serum iPTH and calcium after RFA, with a cure rate of 84%. 26 treated parathyroid glands exhibited a volume reduction rate greater than 70% at the 12 months follow-up. There were only some minor complications, including four postoperative pain (4/25, 16%) and one mild postoperative transient hypocalcemia (1/25, 4%).

CONCLUSIONS

US-guided RFA is an effective and safe technique for the treatment of carefully selected patients with pHPT. Larger sample size and longer follow-up are still need to further confirm its clinical value.

Is partial ablation appropriate for benign thyroid nodules? A retrospective study with long-term follow-up after microwave ablation

OBJECTIVE

This retrospective study aimed to investigate the efficacy and safety of partial ablation (PA) for benign thyroid nodules (BTNs) using microwave ablation (MWA) in a long-term follow-up.

MATERIALS AND METHODS

Between February 2015 and April 2019, 236 patients with 236 BTNs (maximum diameter ≥2 cm) treated with ultrasound-guided MWA were enrolled. Contrast-enhanced ultrasound (CEUS) was performed within 3 d after ablation to determine whether there was residual tissue according to which the patients were assigned PA or complete ablation (CA). The volume reduction ratio (VRR) and complications were evaluated during follow-up.

RESULTS

Eighty-two patients were enrolled in the PA group, and 154 were enrolled in the CA group. Both groups achieved continuous reductions in nodule volume and increases in VRR within 2 years after ablation. Although the VRR of the PA group at 4 years was lower than that of the CA group (65.54 vs. 95.08%; p<.05), PA still achieved 'technical efficacy' with a volume reduction of more than 50%. The complication and side effect rates between the two groups showed no significant difference (p>.05).

CONCLUSIONS

Both PA and CA were safe and effective in reducing the volumes of BTNs in the long-term follow-up. For nodules with a large initial volume and dangerous location, PA with a small amount of residual tissue may be acceptable.

Radiofrequency ablation versus reoperation for benign thyroid nodules that developed after previous thyroid surgery

PURPOSE

To compare the clinical outcomes of radiofrequency ablation (RFA) versus reoperation for benign thyroid nodules that developed after previous thyroid surgery.

METHODS

A total of 53 patients with 53 benign nodules developed after previous thyroid surgery were evaluated in this retrospective study. Eighteen patients were treated by RFA (RFA group) and 35 patients underwent reoperation (reoperation group). The efficacy, safety, thyroid function, blood loss, hospitalization, total treatment time, and cost were compared between the two groups.

RESULTS

In the RFA group, the mean volume decreased significantly from 12.78 ± 17.57 ml to 0.94 ± 1.01 ml (p = 0.043) with a volume reduction rate of 85.27 ± 14.35% and significant improvement in symptom and cosmetic scores (all p = 0.001). Therapeutic efficacy was achieved with a single session in all thyroid nodules. The total treatment time (6.12 ± 3.17 min vs. 110.26 ± 44.41 min, p < 0.001), blood loss (0 ml vs. 82.58 ± 105.55 ml, p < 0.001) and hospitalization(0 days vs. 9.66 ± 4.28 days, p < 0.001) were significantly lower in the RFA group than those in reoperation group, but the costs of treatment were similar(2262.12 ± 221.54 USD vs. 2638.04 ± 1062.90 USD, p = 0.081). The incidence of complications was significantly higher in the reoperation group than in the RFA group(31.43 vs. 0%, p < 0.001). Furthermorre, 65.17% of patients developed hypothyroidism after reoperation, whereas the thyroid function of the patients in the RFA group was unaffected.

CONCLUSION

For patients with benign thyroid nodules developed after previous thyroid surgery, RFA can be considered as a safe and effective alternative to reoperation with advantages of maintenance of intact thyroid function and low incidence of complications.

Ultrasound-guided thermal ablation for papillary thyroid microcarcinoma: a multicenter retrospective study

PURPOSE

Ultrasound-guided thermal ablation (including microwave ablation [MWA] and radiofrequency ablation [RFA]) has emerged as a remarkable technology for the treatment of benign and malignant diseases. The objective of this multicenter study was to assess the efficacy and safety of thermal ablation in a large cohort of patients with papillary thyroid microcarcinoma (PTMC).

MATERIALS AND METHODS

Retrospective study of 725 patients who underwent MWA/RFA at 11 centers between March 2015 and March 2020. The mean age of patients was 46 ± 11 years (range, 22-81); the mean follow-up time was 21 ± 13 months (range, 6-60). Changes in size of tumor, the rates of tumor disappearance, disease progression, and complications were assessed.

RESULTS

From 6 months post-ablation, the size of tumors was significantly reduced compared with those recorded pre-ablation (p < 0.001 for all). Five hundred and fifteen (71.0%) PTMCs had completely disappeared as assessed by ultrasound examination. Six (0.8%) patients developed disease progression post-ablation; of these, 5 (0.7%) patients developed new PTMCs, while one (0.1%) patient developed cervical lymph node metastasis. Nineteen (2.6%) patients developed complications post-ablation; of these 14 (1.9%) patients developed voice hoarseness, 4 (0.6%) developed hematoma, and one (0.1%) patient developed cough.

CONCLUSIONS

Ultrasound-guided thermal ablation represents an effective and safe treatment for patients with PTMC besides active surveillance and surgery.

Analyzing the adoption of radiofrequency ablation of thyroid nodules using the diffusion of innovations theory: understanding where we are in the United States?

Thyroid nodules are very common and found in up to 68% of the general U.S. population on ultrasound. Although thyroidectomy has long been the mainstay of treatment for malignant and symptomatic benign thyroid nodules, various interventional ablative techniques have emerged in the last couple of decades as alternative non-surgical treatment options. Globally, the most widely adopted technique has been ultrasound-guided radiofrequency ablation (RFA). RFA of thyroid nodules was first performed in 2002, and there has been an expanding body of evidence since 2006 showing that RFA and other interventional ablative techniques are effective treatments for benign solid thyroid nodules, toxic adenomas, and thyroid cysts. More recently, evidence has emerged that these techniques may be effective treatment for low-risk thyroid cancer and recurrent disease. Despite these findings, the United States has been slow to adopt these techniques, with only a single publication on RFA more than a decade after the first series was published. EM Rogers’ Diffusion of Innovation Theory provides us the appropriate lens to carefully analyze the process of adoption of RFA for thyroid nodules-to understand where we are currently, as well as, the important next steps that must be accomplished in order for RFA and other ablative techniques to be successfully adopted into the management algorithm of thyroid nodules in the United States.

Residual vital ratio: predicting regrowth after radiofrequency ablation for benign thyroid nodules

PURPOSE

To determine a novel quantitative index, residual vital ratio(RVR) by contrast-enhanced ultrasound(CEUS) with conventional Ultrasound(US), to early predict nodule regrowth after radiofrequency ablation (RFA)for benign thyroid nodules.

METHODS

This retrospective study evaluated 186 patients with 206 benign thyroid nodules underwent RFA. Patients were followed at 1, 3, 6, 12 months and every 12 months thereafter by conventional US, CEUS and clinical evaluation. RVR was defined as the initial ratio of residual vital volume to the total volume calculated by CEUS and conventional US at the first follow-up period after RFA. The relationship between RVR and regrowth was investigated.

RESULTS

The mean volume of thyroid nodules was 10.09 ± 12.90 ml (range 0.40-71.39 ml), which decreased significantly to 2.33 ± 4.65 ml (range 0-36.75 ml) (p < .001) after a mean follow-up time of 22.50 ± 13.29 months (range 6-68 months) with a mean VRR as 85.26 ± 15.02% (range 32.23-100%). The overall incidence of regrowth was 12.62% (26/206) and the mean timing of regrowth was 20.77 ± 12.03 months (range 6-48 months). Multivariate logistic regression revealed that RVR (OR = 1.050, 95%CI 1.025-1.075), initial volume(OR = 1.033, 95%CI 1.000-1.066), location close to critical structures (OR = 5.967, 95%CI 1.898-18.760) and vascularity (OR = 2.216, 95%CI 1.185-4.143) were independent factors associated with regrowth. According to receiver-operating characteristic curve, the area under curve for RVR to regrowth was 0.819 (95% CI 0.740-0.897, p < .001) with the optimal cutoff value of 44.5% (sensitivity 80.8%, specificity 74.7%).

CONCLUSION

RVR was not only an independent factor but also an early quantitative predictor for regrowth. If RVR was larger than 44.5%, the nodule tended to regrowth in the follow-up.

Radiofrequency Ablation of Benign Thyroid Nodules: Recommendations from the Asian Conference on Tumor Ablation Task Force - Secondary Publication

Radiofrequency ablation (RFA) is a thermal ablation technique widely used for the management of benign thyroid nodules. To date, five academic societies in various countries have reported clinical practice guidelines, opinion statements, or recommendations regarding the use of thyroid RFA. However, despite some similarities, there are also differences among the guidelines, and a consensus is required regarding safe and effective treatment in Asian countries. Therefore, a task force was organized by the guideline committee of the Asian Conference on Tumor Ablation with the goal of devising recommendations for the clinical use of thyroid RFA. The recommendations in this article are based on a comprehensive analysis of the current literature and the consensus opinion of the task force members.

European Thyroid Association and Cardiovascular and Interventional Radiological Society of Europe 2021 Clinical Practice Guideline for the Use of Minimally Invasive Treatments in Malignant Thyroid Lesions

The growing detection of papillary thyroid microcarcinomas (PTMCs) is paralleled by an increase in surgical procedures. Due to the frequent indolent nature, cost, and risk of surgery, active surveillance (AS) and ultrasound-guided minimally invasive treatments (MITs) are in suitable cases of incidental PTMC proposed as alternatives to thyroidectomy. Surgery and radioiodine are the established treatments for relapsing cervical differentiated thyroid carcinoma (DTC) metastases. But radioiodine refractoriness, risk of surgical complications, adverse influence on quality of life, or declining repeat surgery have led to AS and MIT being considered as alternatives for slow-growing DTC nodal metastases. Also, for distant radioiodine-refractory metastases not amenable to surgery, MIT is proposed as part of a multimodality therapeutic approach. The European Thyroid Association and the Cardiovascular and Interventional Radiological Society of Europe commissioned these guidelines for the appropriate use of MIT. Based on a systematic PubMed search, an evidence-based approach was applied, and both knowledge and practical experience of the panelists were incorporated to develop the manuscript and the specific recommendations. We recommend that when weighing between surgery, radioiodine, AS, or MIT for DTC, a multidisciplinary team including members with expertise in interventional radiology assess the demographic, clinical, histological, and imaging characteristics for appropriate selection of patients eligible for MIT. Consider TA in low-risk PTMC patients who are at surgical risk, have short life expectancy, relevant comorbidities, or are unwilling to undergo surgery or AS. As laser ablation, radiofrequency ablation, and microwave ablation are similarly safe and effective thermal ablation (TA) techniques, the choice should be based on the specific competences and resources of the centers. Use of ethanol ablation and high-intensity focused ultrasound is not recommended for PTMC treatment. Consider MIT as an alternative to surgical neck dissection in patients with radioiodine refractory cervical recurrences who are at surgical risk or decline further surgery. Factors that favor MIT are previous neck dissection, presence of surgical complications, small size metastases, and <4 involved latero-cervical lymph nodes. Consider TA among treatment options in patients with unresectable oligometastatic or oligoprogressive distant metastases to achieve local tumor control or pain palliation. Consider TA, in combination with bone consolidation and external beam radiation therapy, as a treatment option for painful bone metastases not amenable to other established treatments.