Ultrasound-guided percutaneous microwave ablation of benign thyroid nodules: experimental and clinical studies

A Prediction Model for Assessing the Efficacy of Thermal Ablation in Treating Benign Thyroid Nodules ≥ 2 cm: A Multi-Center Retrospective Study

OBJECTIVES

To develop and validate a prediction model utilizing clinical and ultrasound (US) data for preoperative assessment of efficacy following US-guided thermal ablation (TA) in patients with benign thyroid nodules (BTNs) ≥ 2 cm.

MATERIALS AND METHODS

We retrospectively assessed 962 patients with 1011 BTNs who underwent TA at four tertiary centers between May 2018 and July 2022. Ablation efficacy was categorized into therapeutic success (volume reduction rate [VRR] > 50%) and non-therapeutic success (VRR ≤ 50%). We identified independent factors influencing the ablation efficacy of BTNs ≥ 2 cm in the training set using multivariate logistic regression. On this basis, a prediction model was established. The performance of model was further evaluated by discrimination (area under the curve [AUC]) in the validation set.

RESULTS

Of the 1011 nodules included, 952 (94.2%) achieved therapeutic success at the 12-month follow-up after TA. Independent factors influencing VRR > 50% included sex, nodular composition, calcification, volume, and largest diameter (all p < 0.05). The prediction equation was established as follows: p = 1/1 + Exp∑[8.113 -2.720 × (if predominantly solid) -2.790 × (if solid) -1.275 × (if 10 mL < volume ≤ 30mL) -1.743 × (if volume > 30 mL) -1.268 × (if with calcification) -2.859 × (if largest diameter > 3 cm) +1.143 × (if female)]. This model showed great discrimination, with AUC of 0.908 (95% confidence interval [CI]: 0.868-0.947) and 0.850 (95% CI: 0.748-0.952) in the training and validation sets, respectively.

CONCLUSIONS

A clinical prediction model was successfully developed to preoperatively predict the therapeutic success of BTNs larger than 2 cm in size following US-guided TA. This model aids physicians in evaluating treatment efficacy and devising personalized prognostic plans.

Brazilian Consensus on the Application of Thermal Ablation for Treatment of Thyroid Nodules: A Task Force Statement by the Brazilian Society of Interventional Radiology and Endovascular Surgery (SOBRICE), Brazilian Society of Head and Neck Surgery (SBCCP), and Brazilian Society of Endocrinology and Metabolism (SBEM)

There is increasing interest in ultrasound-guided ablation treatments for thyroid diseases, including benign and malignant ones. Surgeons, radiologists, and endocrinologists carry out these treatments, and various organizations within these specialties have recently released multiple international consensus statements and clinical practice standards. The aim of the present consensus statement is to provide guidance, cohesion, and standardization of best practices for thermal ablation procedures of thyroid nodules. The statement includes the indications for these procedures, preprocedural evaluations, technical aspects of the procedures, posttreatment care, follow-up, complications, and training recommendations. This document was written by a panel of specialists from the Brazilian Society of Interventional Radiology and Endovascular Surgery (SOBRICE), the Brazilian Society of Head and Neck Surgery (SBCCP), and the Brazilian Society of Endocrinology and Metabolism (SBEM). The statement does not aim to provide criteria for assessing the capability of specialists to perform the procedure. Instead, it aims to promote the standardization of best practices to reduce potential adverse outcomes. Additionally, it strives to enhance the delivery of high-quality care and the widespread adoption of these technologies on a national level. The recommendations collectively serve as a guidebook for applying best practices in thyroid ablation.

Protect the recurrent laryngeal nerves in US-guided microwave ablation of thyroid nodules at Zuckerkandl tubercle: a pilot study

BACKGROUND

To evaluate the safety and efficacy of US-guided microwave ablation in patients with thyroid nodules at Zuckerkandl tubercle.

METHODS

103 consecutive patients with thyroid nodules at Zuckerkandl tubercle (ZTTN) were enrolled in this study from November 2017 to August 2021. Prior to the surgery or US-guided microwave ablation (MWA), preoperative ultrasound visualization of the recurrent laryngeal nerve (RLN) and ZTTN was performed, the size and the position relationship between them were observed. Patients were followed up at 1, 3, 6, and 12 months after MWA and the volume reduction rates (VRR) of the thyroid nodules were analyzed.

RESULTS

All patients successfully had the RLN and ZTTN detected using ultrasound before surgery or ablation with a detection rate of 100%. For the 103 patients, the majority of ZTTN grades were categorized as grade 2, with the distance from the farthest outside of ZTTN to the outer edge of thyroid ranging between 6.0 and 10.0 mm. The position relationship between ZTTN and RLN was predominantly type A in 98 cases, with type D observed in 5 cases. After MWA, the median nodule volume had significantly decreased from 4.61 (2.34, 8.70) ml to 0.42 (0.15, 1.41) ml and the VRR achieved 84.36 ± 13.87% at 12 months. No nodules regrew throughout the 12-month follow-up period. Of the 11 patients experienced hoarseness due to RLN entrapment before ablation, 7 recovered immediately after separation of the RLN and ZTTN during MWA, 2 recovered after one week, and the other 2 recovered after two months.

CONCLUSIONS

The RLN is closely related to ZTTN and mainly located at the back of ZTTN. The RLN can be separated from ZTTN by hydrodissection during MWA. US-guided MWA is a safe and effective treatment for ZTTN.

Microwave ablation for large benign thyroid nodules: a proposal for a new approach: "the fluid-motion technique"

INTRODUCTION

Most thyroid nodules are benign, and treatment is primarily indicated for patients with symptoms or cosmetic concerns related to nodular volume. Recently, there has been growing interest in nonsurgical and minimally invasive techniques for the treatment of symptomatic benign thyroid nodules, including microwave ablation (MWA).

AIMS

This study aims to evaluate the effectiveness, efficacy, and safety of ultrasound-guided uncooled MWA in the treatment of benign symptomatic thyroid nodules, using a new ablation technique called the "fluid-motion technique."

MATERIALS AND METHODS

From April 2021 to February 2023, a total of 150 patients with benign thyroid nodules were treated using MWA at the Endocrine Surgery Unit of Pederzoli Hospital, Peschiera del Garda (Italy), with 102 of them being followed-up for at least 6 months.

RESULTS

Before treatment, the mean major diameter was 38.4 ± 10.0 mm, and the mean volume was 13.6 ± 10.5 mL. At 1 month, the mean volume was 6.8 ± 6.2 mL, and at 3 months, it was 4.6 ± 4.1 mL. The mean Volume Reduction Rate (VRR) at 3 months was 61.1 ± 22.0%. Of the nodules, 17 (17%), 65 (66%), and 20 (19%) had volumes ≤ 10, 10.1-20, and ≥ 20.1 mL, respectively. For these nodules, the mean VRR at 3 and 6 months was 55.3 ± 16%, 63.4 ± 24.8%, 72 ± 26.9% and 68.0 ± 11.2%, 73.5 ± 18.3%, and 81.6 ± 15.8%, respectively.

CONCLUSION

Our study shows that ultrasound-guided MWA is an effective and safe minimally invasive treatment for benign thyroid nodules. The goal is to achieve a VRR that can reduce symptoms and improve cosmetic appearance.

Minimally Invasive Treatments of Benign Thyroid Nodules: A Network Meta-Analysis of Short-Term Outcomes

Background: Image-guided thermal ablation interventions are novel thermal-based modalities used for the treatment of benign thyroid nodules. Methods: We conducted a systematic review and a Bayesian network meta-analysis, examining studies using thermal ablation interventions in the treatment of benign nodular thyroid disease (PROSPERO CRD42022367680). The primary endpoints included volume reduction rate (VRR), and symptomatic score and cosmetic score improvement. Secondary endpoints included vocal disturbances, laryngeal nerve palsy, hypothyroidism, and nodular regrowth (defined by increased nodular volume of >50% for thermal ablation or new nodules arising in remaining thyroid tissue conventional surgery [CS]). Results: We included 16 studies (3 randomized controlled trials [RCTs] and 13 comparative case series), describing radiofrequency ablation (RFA), laser ablation (LA), microwave ablation (MWA), high-intensity focus ultrasound (HIFU), and CS, respectively. The review included data from 4112 patients followed for a mean of 11.9 months. Meta-analyses showed no significant differences among RFA, LA, MWA, HIFU, and CS regarding any of the primary endpoints of VRR, symptomatic score, and cosmetic score. In examining the surface under the cumulative ranking area (SUCRA) ranking, CS (SUCRA, 98.49), LA (SUCRA, 51.58), and MWA (SUCRA, 57.0) were identified as the three interventions that were most likely to result in the largest VRR, symptomatic and cosmetic score reduction. RFA, relative risk (RR) 0.19 [95% credibility interval (CI): 0.06 to 0.48], LA RR 0.23 [CI: 0.06 to 0.79], and MWA RR 0.25 [CI: 0.09 to 0.60] were associated with the greatest reduction in risk for postintervention vocal complications compared with CS, with RFA (SUCRA, 61.62) being ranked as the highest in safety. RFA RR 0.05 [CI: 0.00 to 0.40] and MWA RR 0.16 [CI: 0.02 to 0.73] were associated with a reduced risk of transient laryngeal nerve injury compared with CS. RFA RR 0.00 [CI: 0.00 to 0.00] and MWA RR 0.00 [CI: 0.00 to 0.03] were associated with a reduced risk of hypothyroidism occurrence compared with CS, with RFA (SUCRA, 99.86) yielding the highest safety ranking. RFA was associated with a reduced risk for nodular regrowth RR 0.09 [CI: 0.00 to 0.85], compared with CS. Conclusion: We have comprehensively reviewed the published literature on the efficacy and safety of thermal ablation modalities for benign thyroid nodules. Important research gaps remain regarding a paucity of both long-term data and high-quality RCTs.

Analysis of risk factors for intra-cystic hemorrhage in microwave ablation of partially cystic thyroid nodules

Objective

The aim of this study is to identify risk factors of intra-cystic hemorrhage in microwave ablation of mixed solid and cystic microwave ablation s, and to design a preoperative nomogram to predict the risk value of intraoperative bleeding with the goal of individualizing the surgical approach toward different types of cystic and solid thyroid nodules.

Methods

A total of 241 patients with cystic-solid thyroid nodules who underwent ultrasound-guided percutaneous microwave ablation were retrospectively divided into a bleeding group and a non-bleeding group to compare the diameter, cystic proportion, cystic fluid nature, color Doppler flow imaging, Contrast-enhanced ultrasound (CEUS) findings, and operative methods. Based on univariate and multivariate analysis, the important risk factors of nodular intracapsular hemorrhage in the ablation procedure were projected to a nomogram for predicting the possibility of intraoperative hemorrhage in the thyroid cystic solid nodules.

Results

Intra-cystic hemorrhage was developed in 37 cases during the ablation of mixed thyroid nodules with a total incidence of 15% (37/241). Significant differences were found statistically between the two groups on the diameter of the lesions, CEUS findings, the cystic fluid ratio, and operative methods (P = 0.000, P = 0.001, P = 0.024, P = 0.002). The possibility of intraoperative nodular intracapsular hemorrhage was predicted by the model based on the risk factors with the accuracy of 81% and prediction consistency index (C-index) of 0.78.

Conclusion

A new and efficient prediction model was developed based on the identified risk factors for intracapsular hemorrhage during microwave ablation of mixed thyroid nodules, which will aid in the development of targeted surgical planning for different types of cystic thyroid nodules, thus reducing the risk of hemorrhage during ablation.

Ultrasound-Guided Radiofrequency and Microwave Ablation for the Management of Patients With Benign Thyroid Nodules: Systematic Review and Meta-Analysis

ABSTRACT

Ultrasound-guided thermal ablation has been shown to considerably reduce nodule-related discomfort and cosmetic problems. Hence, this review was done to determine the effectiveness of ultrasound-guided radiofrequency or microwave ablation in the management of benign thyroid nodules. Searches were done in EMBASE, SCOPUS, PubMed Central, Cochrane library, MEDLINE, Google Scholar, ScienceDirect, and Clinicaltrials.gov until August 2022. Meta-analysis was carried out using random-effects model. With 95% confidence intervals (CIs), pooled standardized mean differences, mean differences, and/or odds ratio reported. In total, we analyzed 16 studies, most of them had high risk of bias. The pooled standardized mean difference for symptom score was -1.01 (95% CI, -1.83 to -0.19; I2 = 94.2%), for cosmetic relief was -1.26 (95% CI, -2.27 to -0.24; I2 = 96%), for postoperative nodule volume was -1.77 (95% CI, -3.06 to -0.48; I2 = 94%), for hospital stay was -3.88 (95% CI, -4.58 to -3.18; I2 = 91.1%), for operation time was -3.30 (95% CI, -3.95 to -2.64; I2 = 93.4%). The pooled odds ratio for postoperative pain was 0.04 (95% CI, 0.00-0.35; I2 = 95.1%), for postoperative hypothyroidism was 0.04 (95% CI, 0.01-0.11; I2 = 0%), for postoperative hoarseness was 0.56 (95% CI, 0.22-1.47; I2 = 0%), for postoperative hematoma was 0.57 (95% CI, 0.15-2.22; I2 = 0%). Ultrasound-guided radiofrequency and microwave ablation had better efficacy and safety profile in terms of symptoms, cosmetic relief, complication rate, duration of stay, and operation time when compared with conventional surgery or observation without treatment for patients with benign thyroid nodules.

Initial ablation radio predicting volume reduction from microwave ablation of benign thyroid nodules

OBJECTIVE

Our research sought to investigate the relationship between initial ablation ratio (IAR) and internal composition of benign thyroid nodules treated by microwave ablation (MWA).

MATERIALS AND METHODS

Patients who underwent MWA at the Affiliated Hospital of Jiangsu University from January 2018 to December 2022 were enrolled in our research. All the patients were followed up for at least one year. We analyzed the relationship between IAR at 1 month of solid nodules (solid >90%), predominantly solid nodules (90% >solid > 75%), mixed solid alongside cystic nodules (75% >solid > 50%) as well as volume reduction rate (VRR) at 1, 3, 6 and 12 months follow-up.

OBJECTIVE

The mean IAR of the solid nodules (solid >90%) was 94.32±7.87%,#x0025;, that of the predominantly solid nodules (90% >solid > 75%) and mixed solid alongside cystic nodules (75% >solid > 50%) were 86.51±6.66% and 75.19±4.97%,#x0025;, respectively. Almost all the thyroid nodules were significantly decreased in size after MWA. After 12 months of MWA treatment, the average volume of the aforementioned thyroid nodules decreased from 8.69±8.79 to 1.84±3.11 ml, 10.94±9.07 to 2.58±3.34 ml, 9.92±6.27 to 0.25±0.42 ml, respectively. The mean symptom and cosmetic scores of the nodules showed significant (p < 0.000) improvement. The rates of the complications or side effects of MWA against the above-mentioned nodule types were 8.3% (3/36), 3.2% (1/31) and 0% (0/36), respectively.

CONCLUSIONS

The application of the IAR to quantify the success rate of thyroid nodule microwaves in the short term demonstrated that IAR was related to the internal components of the nodule. Although the IAR was not high when the thyroid component was mixed solid and cystic nodules (75% >solid > 50%), the final therapeutic effect was still satisfactory.

A systematic review and meta-analysis comparing tumor progression and complications between radiofrequency ablation and thyroidectomy for papillary thyroid carcinoma

BACKGROUND

Papillary thyroid cancer (PTC) is the most frequent thyroid cancers worldwide. The efficacy and acceptability of radiofrequency ablation (RFA) in the treatment of PTC have been intensively studied. The aim of this study is to focus on extra detailed that may influent for PTC or papillary thyroid microcarcinoma (PTMC).

MATERIALS AND METHODS

We identified a total of 1,987 records of a primary literature searched in PubMed, Embase, Cochrane Library, and Google Scholar by key words, from 2000 to 2022. The outcome of studies included complication, costs, and local tumor progression. After scrutiny screening and full-text assessment, six studies were included in the systematic review. Heterogeneity was estimated using I2, and the quality of evidence was assessed for each outcome using the GRADE guidelines.

RESULTS

Our review enrolled 1,708 patients reported in six articles in the final analysis. There were 397 men and 1,311 women in the analysis. Two of these studies involved PTC and four focused on PTMC. There were 859 patients in the RFA group and 849 patients in the thyroidectomy group. By contrast, the tumor progression of RFA group was as same as that surgical groups [odds ratio, 1.31; 95% CI, 0.52-3.29; heterogeneity (I2 statistic), 0%, p = 0.85]. The risk of complication rates was significantly lower in the RFA group than that in the surgical group [odds ratio, 0.18; 95% CI, 0.09-0.35; heterogeneity (I2 statistic), 40%, p = 0.14].

CONCLUSIONS

RFA is a safe procedure with a certain outcome for PTC. RFA can achieve a good efficacy and has a lower risk of major complications.

Meta-analysis of the efficacy and safety of thermal ablation for treating large benign thyroid nodules

OBJECTIVE

Many large benign thyroid nodules have symptoms and cosmetic problems. This study consisted of a meta-analysis to accurately assess the effect of thermal ablation on these nodules.

METHODS

The PubMed, Embase, Web of Science, and Scopus databases were systematically searched for retrospective or prospective studies of thermal ablation since June 1, 2021. The weighted mean differences of the measures were analysed before and after treatment.

RESULTS

A total of 10 eligible studies were included. By comparing the initial nodule volume with the nodular volume after thermal ablation, we found that the volume reduction rate was increased significantly after 1 month (SMD = 0.453, 95% CI: 0.323-0.583, p &lt; .001), 3 months (SMD = 0.655, 95% CI: 0.563-0.747, p &lt; .001), 6 months (SMD = 0.691, 95% CI: 0.607-0.774, p &lt; .001), and 12 months (SMD = 0.694, 95% CI: 0.583-0.803), p &lt; .001). The nodular volume was also found to decrease significantly, after 1 month (SMD = 2.381, 95% CI: 1.278-3.485, p &lt; .001), 3 months (SMD = 5.071, 95% CI: 2.386-7.756, p &lt; .001), 6 months (SMD = 5.363, 95% CI: 2.765-7.962, p &lt; .001), and 12 months (SMD = 8.194, 95% CI: 2.113-14.274), p &lt; .001). Symptom score (SMD = 4.419, 95% CI: 2.573-6.265, p &lt; .001)and cosmetic score (SMD = 4.245, 95% CI: 2.566-5.359, p &lt; .001) were reduced after thermal ablation.

CONCLUSIONS

Thermal ablation could become an alternative to manage large benign thyroid nodules.

US-CT fusion-guided percutaneous radiofrequency ablation of large substernal benign thyroid nodules

The aim of the present study was to assess feasibility, safety and outcome of ultrasound (US) guided percutaneous radiofrequency (RF) ablation of large substernal benign thyroid nodules assisted by US-computed tomography (CT) fusion imaging and real-time virtual needle tracking (VT) system. Thirty patients (18 females, mean age 56 y, range 32-76 y) with 35 benign nonfunctioning thyroid nodules (mean volume ± SD 26.8 ± 7.6 mL; range 20-38mL) were selected for CT-US fusion guided RF ablation. Nodules' volume was evaluated before treatment and during 12-months follow-up. Complications' rate was also evaluated. US-CT fusion imaging with VT system was feasible in all cases (feasibility 100%) and it was always possible to complete the procedure as planned (technical success 100%). Minor complications occurred in 2/30 cases (6.6%). No major complications occurred. 50% volume reduction (technique efficacy) was achieved in 93% cases, with a significant mean volume reduction at 12 months follow-up (68.7 ± 10.8%), (p < .001). The VT system could be useful in thyroid nodules ablation procedures assistance being able to track the RF electrode tip even when this is obscured by the bubbles produced by the ablative process. The combination of fusion imaging with VT assisted RF ablation represents a safe, non-surgical treatment option for patients with large substernal benign thyroid nodules.

Minimally Invasive Techniques for the Management of Thyroid Nodules

Image-guided interventional techniques have emerged as promising treatments for thyroid disease. Percutaneous ethanol ablation, radiofrequency ablation, laser ablation, high intensity focused ultrasound, and microwave ablation have shown efficacy in treating benign thyroid disease. There is increasing evidence that these techniques may effectively treat papillary thyroid microcarcinomas, recurrent and metastatic disease, follicular neoplasms, and parathyroid lesions. They are performed in an outpatient setting, well-tolerated, with negligible risk for thyroid hormone supplementation, making them a popular alternative to surgical resection. In this comprehensive review, we discuss the devices, techniques, advantages, and disadvantages of each intervention, and summarize the published outcomes.

High intensity focused ultrasound in the therapy of benign thyroid nodules-first German bicentric study with long-term follow-up

PURPOSE

The study evaluated high-intensity-focused ultrasound (HIFU) for benign thyroid nodules in terms of efficiency, complication rate, influence of preablative nodule size, parameters influencing the therapeutic success and hormonal-thyroid-function.

METHODS

Seventy-two patients with 75 nodules were treated with HIFU at 2 centers from 2014-2019. Median nodule volume was 4.4 ml (range 0.33-53). The therapeutic ultrasound probe (EchoPulse THC900888-H) generated 80-90 °C in the target tissue with 87.6-320.3 J per sonication. Nodal volume was measured at baseline and over 12 months after therapy in a retrospective bicentric-study with long-term follow-up. Hormonal-thyroid function (TSH, T3, T4) was measured before and after ablation. Complications were assessed.

RESULTS

Significant volume reduction (p < 0.05 Wilcoxon-signed-rank test) of thyroid nodules was 38.98% at 3 months, 37.32% at 6 months, 61.54% at 9 months and 60.66% at 12 months. Volume reduction of nodules <3 ml did not differ significantly from nodules >3 ml (p > 0.05 Mann-Whitney test). At 3 months solid nodules had a significant volume reduction of 52.08%, complex nodules of 32.57%, nodules treated under regional anesthesia of 33.07% and under general anesthesia of 49.47%. Hormonal-thyroid function was not influenced significantly by HIFU therapy (p > 0.05 Wilcoxon-signed-rank test). Complication rate was 3.8%. No long-term complications occurred.

CONCLUSION

Significant volume reduction of thyroid nodules up to 12 months after HIFU was shown. All complications were reversible. Therapy was more efficient in solid than complex nodules and in nodules treated under general anesthesia than with regional anesthesia. Hormonal-thyroid-function was not affected.

TRIAL REGISTRAFTION NUMBER

2020-1728-evBO. Date of registration: 16.06.2020. Agency: Ethik-Kommission bei der Landesäztekammer Hessen.

Thermal shielding performance of self-healing hydrogel in tumor thermal ablation

Thermal ablation therapy is widely used in the surgical treatment of tumors. Clinically, normal saline is generally used as an insulator to protect adjacent tissues from local high-temperature burns caused by thermal ablation. However, the flow of saline causes fluid loss, requiring frequent injections and complex operation, which is easy to lead to complications such as secondary injury and hematoma. Here, a self-healing chitosan-PEG (CP) hydrogel was proposed as a protective medium to challenge the clinical preparations. Compared with saline and non-self-healing hydrogel F127, CP hydrogel exhibited outstanding thermal shielding performance in the thermal ablation of thyroid nodule in a Beagle dog model. The transient plane source (TPS) method is used to measure thermal properties, including thermal conductivity, thermal diffusivity and specific heat capacity. The thermal shielding mechanism and clinical advantages including operability, biodegradability, and biological safety of self-healing hydrogel are then revealed in-depth. Therefore, self-healing hydrogel can achieve much better thermal management in tumor thermal ablation.

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.

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.

Factors related to the absorption rate of benign thyroid nodules after image-guided microwave ablation: a 3-year follow-up

PURPOSE

To assess the absorption rate and factors related to the development of benign thyroid nodules (BTNs) following image-guided microwave ablation (MWA).

MATERIALS AND METHODS

This retrospective study reviewed nodule efficacy in patients who underwent MWA of BTNs between January 2016 and January 2018. The endpoint was a third-year follow-up. Nodules were categorized into those showing complete absorption (volumes with less than 100% volume reduction ratio (VRR) and those showing partial absorption (100% VRR)). Univariable and multivariable regression analyses were carried out to identify variables that were associated with nodule absorption rates.

RESULTS

A total of 173 BTNs (median volume= 4.23 ml; 25-75 percentiles= 2.27-9.00 ml) from 173 patients were evaluated. 49.7% (86/173) of patients had nodules that became completely absorbed. The mean VRRs of all BTNs were 18.0%, 78.7%, 89.0%, 94.5%, and 97.1% at the 1-, 6-,12-, 24- and 36- month follow-ups. At the 3-year follow-up time point, nodule characteristics related to nodule VRR included nodule volume (adjusted odds ratio [AOR], 1.1 [95% CI: 1.0, 1.2]; p = 0.03) and nodule margin (AOR, 5.3 [95% CI: 1.8, 16.0]; p < 0.01). Treatment-related characteristics included energy per ml in nodular volume (AOR, 1.0 [95% CI: 1.0, 1.0]; p < 0.01) and blockage of peripheral flow (AOR, 3.3 [95% CI: 1.3 8.3]; p = 0.01).

CONCLUSIONS

US-guided image-guided MWA results in satisfactory long-term outcomes for the patients with BTNs. Factors related to nodule absorption rate were the volume and margin of the nodule, energy per ml in nodular volume and blockage of peripheral flow.

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.

Review of clinical tumor ablation advance in Asia

Tumor ablation has been widely applied in Asia, accounting for 44.65% of clinical studies worldwide. We reviewed 5853 clinical studies to provide insight on the advance of tumor ablation in Asia chronologically and geographically among different techniques and organs. Since 1998, tumor ablation application has dramatically evolved in Asia. All kinds of ablation techniques, including percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), microwave ablation (MWA), laser ablation (LA), cryoablation (CA), high-intensity focused ultrasound (HIFU), and irreversible electroporation (IRE), have been applied, with the first application of PEI and the most popular application of RFA. Twenty-five countries and one district in Asia have applied tumor ablation in various organs, including liver, lung, uterus, thyroid, kidney, pancreas, bone, prostate, breast, adrenal gland, lymph node parathyroid, esophagus, etc. Due to the high incidence of tumors as well as advanced economy and technology, East Asia accounted for 93.87% of studies, led by China (45.00%), Japan (32.72%), South Korea (12.10%), and Taiwan (4.03%). With the enrichment of evidence from large-scale multicenter and randomized control studies, China and South Korea have issued several guidelines on tumor ablation for liver, lung, and thyroid, which provided recommendations for global standardization of tumor ablation techniques. Therefore, Asia has made active contribution to global tumor ablation therapy.KeypointsKey point 1: Asia accounted for 44.65% of clinical studies worldwide on tumor ablation.Key point 2: Twenty-five countries and one district in Asia have used tumor ablation in various organs, and East Asia accounted for 93.87% of studies, led by China (45.00%), Japan (32.72%), South Korea (12.10%), and Taiwan (4.03%).Key point 3: China and South Korea have issued several guidelines on tumor ablation for liver, lung, and thyroid, which provided recommendations for global standardization of tumor ablation techniques.

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.

Analysis and evaluation of the efficacy of ultrasound-guided microwave ablation for papillary thyroid microcarcinoma

OBJECTIVE

The choice of the most appropriate therapeutic approach for a diagnosed papillary thyroid microcarcinoma (PTMC) remains controversial. The present study aimed to evaluate the efficacy of microwave ablation (MWA) for unifocal PTMC with a diameter of ≤0.6 cm.

METHODS

A total of 63 consecutive patients with PTMC treated with MWA were studied retrospectively. MWA was performed using the hydrodissection technique and multidimensional fixed-needle principle. We analyzed the absorption of the MWA area and evaluated the prognosis over a follow-up period of 24 months. In addition, 83 patients with PTMC who underwent surgery were selected. The operating room characteristics and procedural complications of the two groups were compared.

RESULTS

In the MWA group, the volume of nodules (p < 0.05) decreased from 0.04 ± 0.03 cm³ to 0.0001 ± 0.0004 cm³ at the 24-month follow-up after MWA, and the volume reduction rate (p < 0.05) was 99.43 ± 1.58%. The incidence of temporary reactive hyperplastic lymphadenectasis was higher and that of other complications was lower in the MWA group than in the surgery group. One percent of the patients in the surgery group had recurrence or metastasis, but none were detected in the MWA group. The loss of thyroid tissue volume (p < 0.001), operating room time (p < 0.001), and the mean length of hospital stay (p < 0.001) were significantly lower in the MWA group than in the surgery group.

CONCLUSION

Ultrasound-guided MWA is an effective treatment strategy for unifocal PTMC with a diameter of ≤0.6 cm.

Microwave ablation of benign thyroid nodules: 3-year follow-up outcomes

PURPOSE

To evaluate the effectiveness of microwave ablation (MWA) for the treatment of thyroid nodules according to nodule composition.

MATERIALS AND METHODS

This study evaluated 171 patients with 180 benign thyroid nodules (BTNs) that had been treated with ultrasound-guided MWA. The volume reduction rate (VRR) of thyroid nodules and factors, which had an influence on the VRR, were assessed. Therapeutic success was defined as a >50% volume reduction at the 12-month follow-up. Multivariate regression analysis was used to identify independent predictors of VRR for BTNs after MWA treatment.

RESULTS

The mean diameter and volume of the nodules were 4.3 ± 1.3 cm and 18.9 ± 2.1 ml, respectively. The VRRs at the 1-, 3-, 6-, 12-, 24-, and 36-month follow-ups were 47.1%, 68.2%, 79.7%, 87.4%, 90.1%, and 93.2%, respectively. Of the 180 BTNs, there were 87 solid, 74 predominantly solid, and 19 predominantly cystic nodules. Solid nodules showed significantly lower VRRs compared with the predominantly solid and predominantly cystic nodules at the 1-, 3-, and 6-month follow-ups. For the multivariate regression analysis, the cyst component was an active prognostic factor for the VRR at the 1-, 3-, and 6-month follow-ups; the cyst component was not significantly associated with the VRR at the 12-, 24-, and 36-month follow-ups.

CONCLUSION

Our study suggested that ultrasound-guided MWA is an effective and safe procedure for the treatment of BTNs. Solid nodules indicate a lower VRR and less efficient than predominant solid nodules and predominant cystic nodules after MWA.

Modified percutaneous ethanol injection method combined with microwave ablation for the treatment of symptomatic, predominantly cystic, benign thyroid nodules: a retrospective study of 201 cases

OBJECTIVE

Percutaneous ethanol injection (PEI) and microwave ablation (MWA) are both important methods used in treating benign thyroid nodules. This study aimed to investigate the efficacy and safety of a modified PEI method combined with MWA for the treatment of symptomatic, predominantly cystic and benign thyroid nodules.

MATERIALS AND METHODS

This study included 201 patients who underwent treatment in our department between April 2015 and August 2018. Predominantly cystic thyroid nodules were treated by the modified PEI procedure, which included short-term boiling ethanol ablation (STBEA) and was combined with MWA. Complications, the volume reduction ratio (VRR), symptoms and cosmetic scores were recorded at 1, 3, 6 and 12 months after treatment and every 6 months thereafter.

RESULTS

No major complications were observed during or after the treatment. Ten patients (4.8%) experienced temporary voice change, which resolved within 3 months. Of 200 (97.6%) out of 205 nodules showed significant volume reduction at the final follow-up. Recurrence occurred for only 5 (2.4%) nodules. The mean thyroid nodule volume decreased from 17.40 ± 3.21 mL at baseline to 1.17 ± 0.37 mL at 12 months. The greatest VRR was observed within the first 3 months after treatment.

CONCLUSIONS

The modified PEI method combined with MWA is safe and effective for the treatment of predominantly cystic benign thyroid nodules and provides a shorter operating time and lower recurrence rate than traditional treatments.

Symptomatic aseptic necrosis of benign thyroid lesions after microwave ablation: risk factors and clinical significance

BACKGROUND

Symptomatic aseptic necrosis (SAN) followed by nodule rupture is a kind of severe complications after thermal ablation for benign thyroid nodules (BTN). No studies are available to evaluate its pathologic process, clinical manifestations, risk factors and effectiveness of therapies after microwave ablation (MWA).

METHODS

From 2012 to 2019, 398 patients who received MWA for BTN were retrospectively reviewed. Clinical data included baseline patient characteristics, imaging features (internal vascularity and the proportion of the solid component), ablation power and time, complications and prognosis were collected and documented.

RESULTS

Ten patients (2.51%) experienced post-MWA SAN, eight patients with nodule rupture and the other two without. The mean time from MWA to SAN symptom was 8.6 days and to rupture was 16.3 days. The initial symptoms of SAN patients were neck bulging, swelling and discomfort. Patients would go through nodule rupture once the nodule contents extended into the extrathyroidal area with the discontinuity of the anterior thyroid capsule, and fistula formed unavoidably in this condition. Incision drainage was effective for rupture and early treatment of non-steroidal anti-inflammatory drug might cure the early-stage SAN. Multivariate analysis showed sex (OR = 0.13; 95% CI: 0.03, 0.61; p=.03) was the risk factor leading to SAN and males were more vulnerable to SAN.

CONCLUSION

SAN after MWA came earlier and initially illustrated as neck bulging, swelling and discomfort. Early detection and early treatment might prevent the rupture of nodules. Once the breakdown of thyroid capsule occurred, rupture of ablated nodules out of skin was unavoidable and invasive procedures might be the most effective treatment.

Effects of energy-based ablation on thyroid function in treating benign thyroid nodules: a systematic review and meta-analysis

BACKGROUND

Whether thyroid function would be affected by ablation remains controversial. This systematic review and meta-analysis aimed to investigate the effects of energy-based ablation on thyroid function in treating benign thyroid nodules.

METHODS

EMBASE, PubMed, Cochrane Library, and Web of Science databases were searched. The mean difference (MD) or standard MD (SMD) was applied to assess changes in thyroid function, thyroglobulin (Tg), and antibodies after ablation. RevMan version 5.3 was used for data synthesis.

RESULTS

Forty-two studies involving 6380 patients were eligible. The pooled results revealed significant decrease of 1-day thyroid-stimulating hormone (95% CI, -0.67 to -0.14), significant increase of 1-day, 1-week, and 1-month free thyroxine (95% CI, 1.57 to 5.28; 95% CI, 0.61 to 2.42; 95% CI, -0.76 to -0.15), 1-day and 1-week Tg level (95% CI, 0.40 to 0.81; 95% CI, 0.21 to 1.29), 6-month anti-thyroglobulin antibodies (95% CI, 0.02 to 0.26), 1- and 3-month thyroperoxidase antibody (95% CI, 0.02 to 0.22; 95% CI, 0.17 to 0.43), and 1-day, 1-, and 3-month thyrotrophin receptor antibody (95% CI, 0.10 to 0.43; 95% CI, 0.00 to 0.30; 95% CI, 0.13 to 0.36) after ablation. No statistically significant differences were found in these six indicators in the longer term. The results of subgroup analysis were similar to the pooled results. No significant publication bias was found.

CONCLUSIONS

Energy-based ablation was more likely to have negative effects on thyroid function and antibodies and led to transient increase in Tg level in the short term. However, most of the patients would not develop any thyroid dysfunction in the long-term follow-up.

Predictor Analysis in Radiofrequency Ablation of Benign Thyroid Nodules: A Single Center Experience

Purpose

To confirm the efficacy of ultrasound (US) guided radiofrequency ablation (RFA) in the treatment of benign thyroid nodules, we evaluated as primary outcome the technical efficacy and clinical success in a single center dataset. The secondary outcome was to find a correlation between nodules' pre-treatment features and volume reduction rate (VRR) ≥75% at 12 months after RFA and during follow-up period.

Methods

This retrospective study included 119 consecutive patients (99 females, 20 males, 51.5 ± 14.4 years) with benign thyroid nodules treated in our hospital between October 2014 and December 2018 with a mean follow-up of 26.8 months (range 3-48). Clinical and US features before and after RFA were evaluated by a US examination at 1, 3, 6, 12 months and annually thereafter up to 48 months.

Results

The median pre-treatment volume was 22.4 ml; after RFA we observed a statistically significant volume reduction from the first month (11.7 ml) to the last follow-up (p < 0.001 for all follow-up times). The median VRR was 47.1, 55.3, 61.2, 67.6, 72.8, 71.3, and 62.9% at 1, 3, 6, 12, 24, 36, and 48 months of follow-up respectively, showing a progressive significant improvement up to 24 months (VRRs 1 vs 3 months, 3 vs 6 months and 6 vs 12 months p < 0.001, 12 vs 24 months p = 0.05) while no differences at 24 vs 36 and 36 vs 48 months were observed. Symptoms improved significantly (complete resolution 64.35%, partial resolution 35.65%), and neck circumference was reduced as compared to pre-treatment (p < 0.001). Lower pre-treatment neck circumference (37.5 vs 36.0 cm, p = 0.01) was a positive predictor of VRR ≥75% at 12 months. Macrocystic echostructure (HR 2.48, p 0.046) and pre-treatment volume >22.4 ml (HR 0.54, p 0.036) were found to be independent positive and negative predictors of VRR ≥75% respectively. One-month post RFA VRR ≥50% represented the best positive predictor of technical success.

Conclusions

This study confirmed the efficacy of RFA in the treatment of benign thyroid nodules. In particular we show that by selecting macrocystic nodules smaller than 22.4 ml better long-term response can be achieved, which is predicted by an early shrinkage of the nodule.

Microwave ablation of symptomatic benign thyroid nodules: Short- and long-term effects on thyroid function tests, thyroglobulin and thyroid autoantibodies

OBJECTIVE

Microwave ablation therapy has been attracting great attention due to its advantages such as low complication rate, good cosmetic results and effective nodule shrinking. Although the effect of thermal ablation therapy on the nodule volume reduction rate has been shown several studies, a limited number of papers have been reported for the effects of microwave ablation (MWA) on thyroid function tests. The aim of this study was to investigate the short- and long-term effects of MWA therapy on thyroid function tests (TFTs), thyroglobulin (Tg) and thyroid autoantibodies in euthyroid patients.

DESIGN, PATIENTS AND MEASUREMENTS

Demographic data of the patients, TFTs, Tg, thyroid autoantibodies and thyroid volume of the nodules were recorded before the procedure and follow-up. Any differences in serum thyroid hormone levels were investigated in pre-, post- and 6-month follow-up periods before and after MWA.

RESULTS

The difference between all thyroid hormone levels at pre MWA and 24 h after MWA was statistically significant (p < .001). FT3 (4.62) pmol/L and FT4 (10.81) pmol/L median levels increased significantly (p < .001), while thyrotropin (TSH) levels decreased at 24 h after MWA (p < .001). Thyroid antibodies levels were not statistically different at 6-month (p > .05), whereas Tg levels decreased (p < .001) compared to pre MWA.

CONCLUSIONS

While no significant effect was observed at 6 month, the effect of MWA on thyroid function tests was prominent at 24 h.

The efficacy and safety of microwave ablation versus lobectomy for the treatment of benign thyroid nodules greater than 4 cm

PURPOSE

To evaluate the safety and effectiveness of microwave ablation (MWA) versus lobectomy for the treatment of benign thyroid nodules > 4 cm.

METHODS

We retrospectively analyzed the data of 48 patients who underwent MWA and 53 patients who underwent lobectomy to treat benign thyroid nodules > 4 cm. The patients were followed up for 12 months. The volume reduction ratio (VRR) was calculated. The operation time, incision length, hospitalization time, complications, thyroid function, symptoms, and cosmetic improvement were analyzed and compared between the two groups.

RESULTS

During the 12-month follow-up, the mean nodule volume in the MWA group was reduced from 36.1 ± 23.1 to 4.0 ± 4.1 ml, and the mean VRR of the nodules was 90 ± 5% in the MWA group, which was comparable with that in the surgery group. No significant postoperative change in thyroid function was observed in the MWA group. Compared with the surgery group, the incidence of complications and postoperative pain in the MWA group were lower, the operation time, incision length, and hospitalization time in the MWA group were shorter, and satisfaction with the esthetic results in the MWA group was greater.

CONCLUSION

MWA is safe and effective for the treatment of benign thyroid nodules > 4 cm. Moreover, MWA is associated with a faster recovery, fewer complications, better protection of thyroid function, and superior esthetic results relative to thyroid lobectomy.

A Propensity Score Matching Study Between Microwave Ablation and Radiofrequency Ablation in Terms of Safety and Efficacy for Benign Thyroid Nodules Treatment

BACKGROUND

Large benign thyroid nodules often lead to cosmetic problems and compression on trachea. Thermal ablation is an effective method for benign thyroid nodules treatment. Among all the thermal ablation techniques, microwave and radiofrequency are frequently used energy sources. However, treatment outcomes of the two ablation types have not been compared in detail. Therefore, we conducted this study aiming for comparing the safety and efficacy of the two ablation techniques in benign thyroid nodules treatment.

METHODS

Information was retrospectively collected from patients with benign thyroid nodules, who received radiofrequency ablation or microwave ablation between January 1, 2018, and December 31, 2019, in a main hospital in South China. Patients were divided into microwave ablation group and radiofrequency ablation group according to the techniques applied. A propensity score matching was performed to balance the baseline indexes between the two groups. We also recorded and analyzed the operative variables including operative duration, intraoperative blood loss, hospitalization time, and overall costs. Postoperative quality of life, volume reduction rates, and complication rates were routinely evaluated during the follow-up by asking patients to fulfil questionnaires at the 1^st, 3^rd, 6^th, 12^th, and 18^th postoperative month.

RESULTS

A total of 943 patients receiving microwave ablation or radiofrequency ablation in the years of 2018 and 2019 met our inclusion criteria. After 1:1 propensity score matching, 289 pairs of patients were matched. There was no significant difference between the two groups in operative duration, intraoperative blood loss, hospitalization time, overall cost, quality of life scores, complication rates or volume reduction rates.

CONCLUSION

There was no significant difference between microwave and radiofrequency ablation in terms of safety and efficacy. Both of the two techniques` are ideal therapeutic methods in benign thyroid nodules treatment.

REGISTRATION NUMBER

ChiCTR2000034764.

Differences in the dielectric properties of various benign and malignant thyroid nodules

PURPOSE

This experiment was conducted to investigate the dielectric properties of different types of thyroid nodules. Our goal was to find a simple and fast method to detect thyroid diseases at different stages from the dielectric properties of thyroid nodules.

METHODS

We used the open-ended coaxial line method to measure the dielectric permittivities of thyroid tissues from 155 patients at frequencies ranging from 1 to 4000 MHz. Tissues that were investigated included normal thyroid tissue and benign and malignant thyroid nodules (nodular goiter, follicular adenoma, papillary carcinoma, and follicular carcinoma), as determined from pathological reports. Differences in dielectric properties were measured between each nodule and the surrounding 1 cm of tissue.

RESULTS

The analysis results revealed that the dielectric permittivity and conductivity values were positively correlated with the degree of malignancy of the nodule (normal < benign < malignant; all differences P < 0.05). This was more obvious at frequencies within 20~70 MHz, following the order normal tissue < nodular goiter < follicular adenoma < papillary carcinoma < follicular carcinoma. A significant difference (P < 0.05) in dielectric permittivity and conductivity was found when comparing these nodules with the surrounding 1 cm of tissue.

CONCLUSIONS

Normal, benign, and malignant nodules were successfully distinguished from one another, and dielectric permittivity was found to be a more sensitive parameter than conductivity. In particular, different disease types can be distinguished at a stimulation frequency of 20~70 MHz, which shows that dielectric properties have application prospects for the detection and diagnosis of cancer. At the same time, the dielectric parameter differences between the surrounding 1 cm of tissue and the diseased nodule can distinguish the tumor and its surrounding tissues in real time during surgery to determine the tumor boundary.

Microwave Ablation of Visible Benign Thyroid Nodules with Different Internal Characteristics: A Comparative Study with Follow-up Results

PURPOSE

To investigate the effects of microwave ablation (MWA) on visible benign thyroid nodules (BTN) with different internal characteristics.

MATERIALS & METHODS

A total of 51 cases with 53 visible BTN were treated by ultrasound-guided percutaneous MWA. The 53 nodules were classified into three categories according to the internal characteristics, which were simple solid, mainly solid and mainly cystic nodules. Ultrasound examinations were performed to evaluate the volume shrinkage rations during follow-up. The thyroid functions and the cervical cosmetic scores were evaluated. The complications were observed during and after ablation.

RESULTS

A total of 53 symptomatic BTN were treated by MWA completely. The average volume of the nodules was 11.68 ± 10.16 ml, the volume reduction rates (VRR) at 1st, 3rd, 6th, 12th, and 18th months after ablation were 0.29 ± 0.27, 0.46 ± 0.25, 0.67 ± 0.19, 0.83 ± 0.10, and 0.92 ± 0.10, respectively. The VRR was significantly different among the three categories of lesions (p < 0.05). The symptoms of all patients were improved. Thyroid function indicators were fluctuated in normal range. There were no serious complications during and after the procedure.

CONCLUSION

MWA of visible BTN is safe and effective, and the short-time ablation effect is significantly different due to the internal characteristics of the nodule.

Comparison of ultrasound-guided thermal ablation and conventional thyroidectomy for benign thyroid nodules: a systematic review and meta-analysis

Objective: To compare the safety and efficacy of ultrasound-guided thermal ablation and conventional thyroidectomy for benign thyroid nodules (TNs) by performing a systematic review and meta-analysis.Methods: We searched PubMed, Embase, Web of Science and Cochrane Library databases for clinical trials from the date of their inception to 1 April 2019. Two investigators independently examined the trials to select qualified studies, extracted relevant information and assessed the risk of bias according to the Cochrane Collaboration checklist (Oxford, UK). The primary study outcomes were safety (hoarseness, hypothyroidism and postoperative pain) and efficacy (symptom improvement, postoperative cosmetic effects and hospitalization time). This study is registered with PROSPERO (CRD42019125643).Results: Seven studies involving 1289 patients were included. The results demonstrated that the incidences of hoarseness [odds ratio (OR) 0.33, 95% confidence interval (95% CI) (0.14, 0.79)], hypothyroidism [risk difference (RD) -0.31, 95% CI (-0.34, -0.28)] and postoperative pain [OR 0.35, 95% CI (0.25, 0.49)] were lower, and the hospitalization time was shorter [standard mean difference (SMD) -4.01, 95% CI (-4.22, -3.81)], in the thermal ablation group than in the conventional thyroidectomy group, and postoperative cosmetic effects were better [relative risk (RR) ratio 1.12, 95% CI (1.01, 1.24)] (p < 0.05). For symptom improvement, the difference was not statistically significant.Conclusions: This study shows that for benign TNs, ultrasound-guided thermal ablation may have potential advantages in terms of safety, cosmetic effects and shorter hospitalization time compared with conventional thyroidectomy, while symptom improvement is the same.

Neural monitoring during ultrasound-guided radiofrequency ablation of thyroid nodules

BACKGROUND

Intraoperative neurological monitoring is important in locating and assessing nerves during surgery. This study aimed to investigate the feasibility of neural monitoring during ultrasound-guided radiofrequency ablation (RFA) of thyroid nodules.

METHODS

From February 2019 to August 2019, 16 patients (age, 42.8 ± 15.9 years; range, 17-74 years) with benign thyroid nodules who underwent ultrasound-guided RFA with neural monitoring in Zhongshan Hospital, Xiamen University, were included. A neuromonitoring system stimulated the vagus nerve to obtain electromyographic (EMG) signals and predict the function of recurrent laryngeal nerves (RLNs) during RFA. The hydrodissection technique was used to protect the RLN area. Thyroid nodules were treated with the moving-shot technique. The EMG signal value results were recorded and analyzed. All patients underwent laryngoscopic investigation 1 day after the procedure.

RESULTS

Twenty vagus nerves were stimulated preprocedure and postprocedure, and the EMG signals were successfully recorded (100%). The mean initial (before ablation) and final (final ablation) vagus nerve amplitudes were 612.7 ± 130.4 μV (range, 455-882 μV) and 592.7 ± 127.3 μV (range, 410-817 μV), respectively. Based on the EMG signals, all 20 RLNs were judged to be in good condition, consistent with the postprocedure laryngoscopic results. The maximum lesion size and volume at 6 months after RFA were significantly lesser than those at baseline (p < 0.05). The volume reduction rate was 68.5% ± 21.5% (range, 13.0-97.3%). Cosmetic and symptom scores were significantly lower than those at baseline. No complications from neural monitoring occurred.

CONCLUSIONS

Neural monitoring during ultrasound-guided RFA of thyroid nodules is feasible to predict RLN function.

Thermal Ablation of Benign Thyroid Nodules and Papillary Thyroid Microcarcinoma

Due to the increasing rates of physical examination and application of advanced ultrasound machines, incidences of benign thyroid nodules (BTNs) and papillary thyroid microcarcinoma (PTMC) were dramatically up-regulated in recent years. Thermal ablation (TA) has been widely used and regarded as a safe and effective method to eliminate or reduce BTNs and recurrent low-risk PTMC. However, conclusions using TA to treat primary PTMC are controversial. Recently, several long-term and prospective studies on TA treatment of BTNs and primary PTMC have been reported. Here, we review current literatures and progress on TA treatment of BTNs and PTMC and underline the way to get the best treatment outcomes, providing a comprehensive insight into the research progresses in this field.

A pilot study of the shapes of ablation lesions in the canine prostate by laser, radiofrequency and microwave and their clinical significance

To explore the shape characteristics of ablation lesions created via laser ablation (LA), radiofrequency ablation (RFA) and microwave ablation (MWA) in canine prostates and the clinical significance of these characteristics, six adult male beagles were randomly assigned to the LA, RFA, and MWA groups. These ablations were performed with common parameters applied in clinical practice (LA, 3 W/1200 J; RFA and MWA, 30 W/120 s). One ablation lesion was created in each lobe of the prostate via the ablation technique, resulting in a total of twelve ablation lesions. Transrectal ultrasound (TRUS) was used as guidance during puncture and to monitor changes in the ablation lesions. Finally, the ablation efficacy was assessed using transrectal contrast-enhanced ultrasonography (CEUS), and the transverse diameter (TRD), anteroposterior diameter (APD) and longitudinal diameter (LD) of each ablation lesion were measured. The volume (V) and the ratio (R) value were calculated. R reflects the shape characteristic of the ablation lesion (the R value close to 1.0 indicates a more spherical shape). The R values of the ablation lesions were 0.89 ± 0.02, 0.72 ± 0.01, and 0.65 ± 0.03 for RFA, MWA and LA, respectively, and they were significantly different (P = 0.027). The volumes of the ablation lesions were 2.17 ± 0.10 ml, 1.51 ± 0.20 ml, and 0.79 ± 0.07 ml for MWA, LA and RFA, respectively, and they were also significantly different (P = 0.001). The three abovementioned thermal ablation techniques with common parameters in clinical practice can be used for ablation in the prostate. The shapes and volumes of the ablation lesions of the three techniques were varied: The RFA-created lesions had the lowest volumes and were more spherical in shape, demonstrating that RFA could be used for the treatment of relatively small lesions or tumours adjacent to vital organs. The MWA lesions had the largest size with a spherical shape, which could be advantageous for the ablation of tumours with relatively large sizes. The sizes of the ablation lesions created via LA were between those of RFA and MWA but presented more oval in shape, suggesting that this method is highly appropriate for the ablation of benign prostatic hyperplasia (BPH).

Non-Surgical and Non-Radioiodine Techniques for Ablation of Benign Thyroid Nodules: Consensus Statement and Recommendation

Thyroid nodules and cysts are frequently diagnosed in Germany with a prevalence of about 20% in young adults reaching up to 70% in older adults. Surgery is the standard treatment of symptomatic nodules, nodules with suspicion of malignancy and thyroid cancer. Radioiodine treatment is applied for autonomously functioning nodules. During the last years new non-surgical and non-radioiodine techniques have been introduced to treat thyroid nodules. These techniques include ethanol/polidocanol treatment, radiofrequency, microwave, and laser ablation, and high frequency ultrasound ablation. A significant reduction in nodule size could be documented for these techniques in several studies, but long-term outcome data are missing. Until now, there is no general consensus regarding the appropriate indications for these methods. For this reason, the Thyroid Section (German Society for Endocrinology), the Thyroid Working Committee (German Society for Nuclear Medicine), and the German Association of Endocrine Surgeons (CAEK) for the German Society of General and Visceral Surgery (DGAV) reviewed the respective literature, discussed the pro and cons and developed a consensus statement and recommendation to help physicians and patients in their decision making.

A Novel Strategy for Single-Session Ultrasound-Guided Radiofrequency Ablation of Large Benign Thyroid Nodules: A Pilot Cohort Study

Background: Ultrasound-guided radiofrequency ablation (RFA) of thyroid nodules (TNs) is a minimally invasive procedure that has been widely used to induce volume reduction in symptomatic solid benign TNs. The goal of this study was to investigate a novel therapeutic approach for single-session ablation of large thyroid nodules (LTNs, vol > 20 ml). Methods: We performed a pilot cohort study of 21 patients with symptomatic solid benign LTNs (vol > 20 ml), who accepted ultrasound-guided RFA treatment between September 2018 and November 2019. RFA was performed using an 18-gauge internally cooled electrode with ultrasonographic guidance in a single session combined with intraoperative hydrodissection and immediate contrast-enhanced ultrasound (CEUS) to optimize safety and efficacy. Nodule volume was evaluated before ablation and at 1, 3, and 6 months after initial ablation, and all patients were asked to assess the cosmetic score (from 1 to 4) and symptom score (from 0 to 10) before ablation and at every follow-up after ablation. Results: At the 6 month follow-up, there was significant nodule volume reduction, from 27.49 ml ± 7.9 (standard deviation) to 3.82 ml ± 5.02 (p = 0.001). Cosmetic signs (p = 0.001) and pressure symptoms (p = 0.001) were significantly improved. All patients underwent RFA without any major complications, and very few patients developed a change in voice (2/21). However, the changes subsided within 1 month. Almost half of the patients received an additional RFA (11/21) treatment to achieve complete ablation on the intraoperative immediate CEUS evaluation. Conclusion: RFA is effective for treating LTNs (vol > 20 ml) and controlling clinical symptoms with a low complication rate. Patients were satisfied with cosmetic sign and pressure symptom improvement. The intraoperative hydrodissection and immediate CEUS represent a novel therapeutic approach for single-session ablation of LTNs.

Ultrasound-Guided Percutaneous Microwave Ablation for Substernal Goiter: Initial Experience

OBJECTIVES

To preliminarily evaluate the safety, effectiveness, and feasibility of microwave ablation (MWA) for substernal goiter (SSG) in select patients and to provide a relevant treatment reference for further studies.

METHODS

From April 2017 to December 2017, 10 patients with SSG were treated by MWA. All patients were followed for at least 3 months to observe the therapeutic effects and complications. Therapeutic effects were assessed at follow-up for the relief of patients' symptoms, resolution of the cosmetic grade, and volume reduction rate (VRR) of SSG. Possibly related factors for the 3-month VRR of the nodules were analyzed.

RESULTS

The study included 9 female patients and 1 male patient with a mean age ± SD of 56.8 ± 10.1 years (range, 34-70 years). The mean volume of the nodules was 52.9 ± 27.9 mL (range, 23.7-122.6 mL). The nodule volume was significantly reduced at the 3-month follow-up (17.5 ± 9.5 mL; P < .05). The mean 3-month VRR of the index nodule was 66.7% ± 7.1%. A higher ablated portion-to-nodule ratio 1 day after MWA predicted a higher 3-month VRR (Spearman r = 0.646; P = .044). The mean symptom score (from 4.5 ± 1.7 to 1.5 ± 1.0; P = .005) and cosmetic grade (from 3.3 ± 0.5 to 2.2 ± 0.4; P = .004) declined significantly 3 months after the procedure. No complications or unexpected side effects were observed.

CONCLUSIONS

Our preliminary results support the effectiveness and safety of MWA for local control of SSG. This technology can be applied in select patients with SSG who are ineligible for surgery.

Value of monopolar and bipolar radiofrequency ablation for the treatment of benign thyroid nodules

Only a few thyroid nodules are perceived as functional or optically disturbing. If there is a need for action, surgical intervention is the long-term standard by which thermoablative procedures (radiofrequency-, laser-, microwave ablation, high intensity focused ultrasound) must be measured against in terms of safety, effectiveness and patient satisfaction. Prior to intervention assessment of the dignity of the nodule by ultrasound-guided fine needle aspiration is essential for cold and warm nodules, as is the confirmation of an inconspicuous cervical lymph node status. The short-term treatment results of these newer interventions in terms of nodule volume reduction and symptomatic improvement are promising and the general complication rate of the procedures is low. Since functional thyroid parenchyma is preserved, maintaining normal thyroid status is the rule. The procedure is usually performed on an outpatient basis, under local anesthesia and monitoring. The subsequent convalescence is usually very short. Most studies are available on monopolar radiofrequency ablation. Several professional societies have defined indications for radiofrequency ablation (RFA), but these need to be further refined based on practical experience and literature. An acceptable long-term recurrence rate still has to be proven for practically all thermoablative methods, for monopolar RFA limited long-term data are encouraging so far. The recurrence rate as well as patient satisfaction will provide the basis for a meaningful overall cost-benefit analysis in the future.

Comparison of stress response following microwave ablation and surgical resection of benign thyroid nodules

PURPOSE

To compare the effects and safety of using microwave ablation (MWA) and surgical resection for the treatment of benign thyroid nodules (BTNs) under ultrasonic guidance and investigate the effects of this treatment on stress response.

METHODS

Patients with BTNs were divided into the MWA and operation groups (72 cases each). Interleukin (IL)-6, IL-8, serum tumor necrosis factor (TNF-α), and hydrostatic visual analog scale (VAS) prior to the operation, at 6 h, 24 h, and 72 h post-operation were compared between the two groups. Operation times, hospitalization times, hospitalization expenses, and postoperative complications in the two groups were also compared. All patients underwent routine ultrasound and thyroid function testing at 3 and 6 months post-operation for assessment of nodule changes and thyroid hormone levels.

RESULTS

Compared to the MWA group, the operation group had longer average operation times, longer hospital stays, a higher rate of neck pain after surgery, and a higher rate of fever (P < 0.05). Body temperature, as well as VAS, IL-6, IL-8, and TNF-α levels in the operation group were higher than those in the MWA group at 6 h, 24 h, and 72 h post-operation (P < 0.05). The levels of free thyroxine and free triiodothyronine in the operation group were lower than those in the MWA group (P < 0.05).

CONCLUSION

MWA is a safe and effective treatment for patients with BTNs. The effects of MWA are more tolerable than those of surgical resection and the physiological function of the thyroid is preserved, which has high clinical value.

Safety and efficiency of ultrasound-guided low power microwave ablation in the treatment of cervical metastatic lymph node from papillary thyroid carcinoma: a mean of 32 months follow-up study

PURPOSE

To evaluate the safety and efficiency of microwave ablation (MWA) with low power of 20 w, respectively, in the treatment of cervical metastatic lymph node (CMLN) from papillary thyroid carcinoma (PTC) with a mean of 32-month follow-up.

METHODS

Eleven patients in total with 24 cervical lymph nodes (LNs) diagnosed with CMLN from PTC underwent MWA at a power of 20 w. We recorded images of the LNs under ultrasound first before MWA and 1, 3, 6, 12, months after MWA, and then every 6 months, respectively. The volumes of the LNs were compared before MWA and at each follow-up point after MWA. The thyroglobulin (Tg) test was performed before MWA and 3 months after MWA.

RESULTS

All patients were successfully treated, and they showed no major complications. Before MWA, the mean volume of the LNs was 364.15 ± 306.89 mm³, which decreased to 234.10 ± 230.34 mm³, 107.51 ± 129.47 mm³, 20.88 ± 39.27 mm³, 3.38 ± 12.74 mm³, and completely disappeared at the follow-up point of 1, 3, 6, 12, and 18 months after MWA, respectively. The mean Tg was 11.81 ± 7.50 ng/ml, a data significantly decreased to 0.43 ± 0.11 ng/ml 3 months after MWA (P = 0.000). In the follow-up period, no recurrent lesions were found.

CONCLUSIONS

For the treatment of CMLN from PTC, low power MWA showed good safety and efficacy. MWA is likely to be a candidate for patients with high risks or who refuse reoperation.

Efficacy and safety of cooled and uncooled microwave ablation for the treatment of benign thyroid nodules: a systematic review and meta-analysis

PURPOSE

To evaluate the effectiveness and safety of microwave ablation (MWA), including cooled MWA (cMWA) and uncooled MWA (uMWA), for the treatment of benign thyroid nodules (BTNs).

METHODS

The databases of MEDLINE, EMBASE and Cochrane library were searched up to 3 Jun, 2018. In this meta-analysis, data of volume reduction rates (VRRs) at the 3-, 6- and 12-month follow-up, and complications are obtained to evaluate the effectiveness and safety of cMWA and uMWA for the treatment of BTNs.

RESULTS

Nine studies involving 1461 patients with 1845 BTNs were included. The pooled VRR at the 3-month follow-up after MWA therapy reached 54.3% (95% CI: 45.3-63.3%, I2 = 97.6%), 73.5% (95% CI: 66.7-80.3%, I2 = 94.9%) at the 6-month follow-up, and 88.6% (95% CI: 84.9-92.4%, I2 = 92.7%) at the 12-month follow-up. The pooled proportions of overall, major and minor complications were 52.4% (95% CI: 29.8-74.9%; I2 = 99.5%), 4.8% (95% CI: 2.7-7.0%; I2 = 55.9%) and 48.3% (95% CI: 31.2-65.4%; I2 = 99.7%). Both cMWA and uMWA achieved similar pooled VRR at the 3-month follow-up (58.4 vs 45.3%, P = 0.07) and pooled proportion of major complications (4.9 vs 5.0%, P = 0.49), while uMWA had higher pooled proportions of overall and minor complications than cMWA (97.8 vs 29.7%, P < 0.01; 97.8 vs 21.0%, P < 0.01), with more patients suffering pain and skin burn after uMWA (100 vs 5.5%, P < 0.01; 47.2 vs 0.2%, P < 0.01).

CONCLUSION

MWA is an effective treatment modality for BTNs. When considering the patient's comfort, cMWA would be a more preferable procedure with less complications.