Image-Guided Thyroid Ablation: Proposal for Standardization of Terminology and Reporting Criteria

Thyroid nodule rupture after thermal ablation for benign thyroid nodules: incidence, risk factors, and clinical management

BACKGROUND

Thyroid nodule rupture (TNR) is a rare and severe complication after thermal ablation (TA), mostly from benign thyroid nodules (BTN).

OBJECTIVE

To summarize the incidence of TNR after TA and analyze the causes and prevention strategies.

MATERIALS AND METHODS

This retrospective study enrolled 3971 patients who underwent TA for BTN from January 2014 to March 2024. The incidence, causes, and risk factors of TNR were analyzed. Propensity score matching (PSM) controlled for confounding factors. Multivariate regression identified risk factors for TNR. ROC curves determined the optimal cutoff value for the maximum diameter (MD) for TNR.

RESULTS

TNR occurred in 8 cases [0.2% (8/3971)]. The mean time from TA to TNR was 29.6 ± 13.0 days (range, 20-60 days). After PSM, MD was larger in the TNR group than in the non-TNR group [mean 4.1 ± 1.6 cm vs. mean 1.8 ± 1.2 cm; p < 0.001]. The optimal cutoff value of MD for TNR was 2.75 cm. After PSM, the incidence of pressure on the ablation zone was significantly higher in the TNR group than in the non-TNR group [100% (8/8) vs. 0 (0/32); p < 0.001], which has been suspected as a case of TNR. Antibiotic drugs, aspiration, or incision drainage could successfully manage all TNR cases.

CONCLUSION

TNR could be encountered in case of pressure on the BTN after TA. Protecting the ablation site from pressure might be crucial in preventing TNR, especially within two months. TNR is more likely to occur if the MD of BTN exceeds 2.75 cm under pressure. Observation, antibiotics, and aspiration could successfully manage all TNR cases.

Comparison of US-guided thermal ablation and surgery for papillary thyroid cancer: a systematic review and meta-analysis

OBJECTIVE

We conducted the systematic review and meta-analysis to comprehensively compare ablation and surgery in terms of effectiveness, safety and multiple factors affecting life quality of patients with papillary thyroid cancer (PTC).

METHODS

PubMed, Embase, Scopus, Web of Science and EBSCO were searched for relevant studies published between January 1980 and September 2023. Two reviewers independently extracted data according to the PRISMA recommendations and assessed the quality of each study with the Cochrane Risk of Bias Tool. Pooled analyses were performed using random or fixed-effects models, as appropriate.

RESULTS

A total of 4829 patients with PTC from 19 eligible studies were included. Through the meta-analysis, similar tumor progression (OR: 1.07; 95% CI 0.78, 1.48; p = 0.66) and recurrence-free survival (OR: 0.86; 95% CI, 0.55, 1.34; p = 0.50) were found between the patients undergoing ablation and those undergoing surgery. More strikingly, the lower risk of major complications (OR: 0.31; 95% CI 0.24, 0.41; p < 0.001), the shorter hospital stay (MD = 3.67 d; 95% CI, -4.89, -2.44; p < 0.001), the abbreviated procedure time (MD: -66.33 min, 95% CI, -77.08, -55.59; p < 0.001), the less intraoperative blood loss (MD: -27.43 ml, 95% CI, -34.60, -20.27; p < 0.001) and the lower treatment cost (MD: -860.42 USD, 95% CI, -1008.03, -712.81; p < 0.001) were noticed in ablation techniques compared to surgical operation. Thermal ablation has shown multiple advantages by virtue of its percutaneous puncture compared with surgical resection.

CONCLUSION

As an effective, safe, minimally invasive and economical modality, thermal ablation might be a promising alternative to existing PTC management options.

Clinical outcomes of microwave ablation for solitary T1N0M0 papillary thyroid carcinoma: a more than 5-year follow-up study

OBJECTIVES

This study aimed to evaluate the long-term efficacy and safety of microwave ablation (MWA) for solitary T1N0M0 papillary thyroid carcinoma (PTC) and compare them between T1a and T1b disease.

MATERIALS AND METHODS

This retrospective study included 136 patients with solitary T1N0M0 PTC who were treated with MWA and followed up for more than 5 years. Outcomes were compared between patients with T1a and T1b disease. The primary outcomes were disease progression and disease-free survival (DFS). The secondary outcomes included the volume reduction rate (VRR), the rate of complete disappearance, and complications.

RESULTS

During a mean follow-up period of 70.6 ± 10.5 months, the overall disease progression rate was 5.88%. The incidences of lymph node metastases (LNMs) and new tumors were 2.21% and 5.15%, respectively. No patient was diagnosed with local recurrence, distant metastasis, or death due to PTC. There were no significant differences between the T1a and T1b groups in terms of disease progression (3.81% vs 12.90%, p = 0.15), LNMs (1.90% vs 3.23%, p = 0.54), or new tumors (2.86% vs 12.90%, p = 0.08). The 5-year DFS rate was 94.85%, the VRR was 99.7% ± 2.0%, and 97.79% of the tumors disappeared. Hoarseness occurred in five patients (3.68%).

CONCLUSION

MWA is a long-term effective and safe option for patients with solitary T1N0M0 PTC, providing a minimally invasive alternative for those who refuse surgery or active surveillance.

KEY POINTS

Question MWA, as a minimally invasive alternative for treating PTC, lacks comparison with surgical resection and active surveillance. Findings MWA resulted in overall disease progression in 5.88% of patients with solitary T1N0M0 PTC over more than 5 years of follow-up. Clinical relevance MWA is a safe, effective, and minimally invasive treatment for solitary T1N0M0 PTC, with high DFS rates and low complication rates, benefiting patients seeking alternatives to surgery or active surveillance.

Microwave ablation for benign thyroid nodules with cosmetic problems and related factors for post-ablative complete relief: a two-center retrospective study

PURPOSE

To investigate the efficacy of ultrasound (US)-guided percutaneous MWA for benign thyroid nodules with cosmetic problems and identify related factors contributing to post-ablative complete relief (CR).

METHODS

This retrospective study reviewed the efficacy of MWA in treating thyroid nodules in patients with cosmetic problems who underwent MWA from January 2021 to May 2023. Patients were followed up at 1, 3, and 6 months after MWA. Pre-treatment clinical characteristics, conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) features were analyzed to explore their correlation with cosmetic improvement, defined as a cosmetic score of 1 or 2 at the 6-month follow-up. Univariable and multivariable regression analyses were carried out to identify variables associated with CR, and the related nomogram was established. Calibration curve and decision curve analysis were used to evaluate the nomogram performance.

RESULTS

118 patients with 118 nodules were included in the study. During the 1-, 3- and 6-month follow-up, the mean volume reduction ratios (VRR) were 2%, 36% and 73%, respectively. 22.0% (26/118), 57.6% (68/118), and 89.8% (106/118) patients achieved CR of cosmetic problems at 1, 3, and 6 months after MWA. In multivariable analysis, three variables (i.e., non-hashimoto's thyroiditis [HT] [OR: 90.036, P = 0.001], nodule location not close to danger triangle area [OR: 66.812, P = 0.003], early hyperenhancement on CEUS [OR: 0.035, P = 0.024]) were found to be closely associated with CR of cosmetic problems at 6 months after MWA. A nomogram model was constructed, and its accuracy was well validated (i.e., C-index = 0.914).

CONCLUSION

MWA was effective and safe for treating benign thyroid nodules with cosmetic problems. Non-HT, nodule location not close to danger triangle area, and early hyperenhancement on CEUS were associated with CR of cosmetic problems after MWA.

The preliminary multicenter retrospective study on the efficacy and safety of thermal ablation for follicular thyroid neoplasms ≤ 3 cm

OBJECTIVES

To evaluate the efficacy and safety of thermal ablation (TA) for follicular thyroid neoplasms (FTN) ≤ 3 cm.

METHODS

This retrospective multicenter study enrolled 161 patients (131 females; mean age, 46 ± 15 years [range, 11-86]) who underwent TA for FTN ≤ 3 cm between January 2014 and October 2023 from eight centers in China. The median follow-up time was 12 months (IQR, 12-24 months). Based on the maximum diameter (MD) of the nodule, patients were divided into two groups: Group 1 (MD ≤ 2 cm) and Group 2 (2 < MD ≤ 3 cm). Post-ablation assessments encompassed evaluations of tumor size and volume changes, technical success rate, tumor disappearance, disease progression, complications, and risk factors associated with recurrent laryngeal nerve (RLN) injury.

RESULTS

All patients underwent complete ablation in a single session. The technical success rate was 100%. The mean volume reduction rate (VRR) of the ablation zone at 12 months was 78.11%. The VRR at 12 months was higher in Group 1 than that in Group 2 (Median VRR, 93.8% vs. 82.8%; P = 0.019). The complete tumor disappearance rate was 15.5% (25/161). Smaller tumors have a higher tumor disappearance rate (Group 1 vs Group 2 = 27.6% vs. 4.7%; P < 0.001). The disease progression rate was 2.5% (4/161), with no significant difference between Group 1 and Group 2 (P = 0.535). The complication rate was 3.1% (5/161), with no significant difference between Group 1 and Group 2 (P = 0.899). No risk factors were identified for RLN injury.

CONCLUSIONS

Thermal ablation is an effective and safe treatment option for patients with FTN ≤ 3 cm.

Radiofrequency Ablation of Benign Thyroid Nodules: 10-Year Follow-Up Results From a Single Center

OBJECTIVE

The long-term efficacy of radiofrequency ablation (RFA) for the treatment of benign thyroid nodules remains unclear. We aimed to evaluate the long-term efficacy, emphasizing single-session RFA, and identify the factors associated with cases requiring additional RFA sessions to achieve a comparable volume reduction rates (VRR).

MATERIALS AND METHODS

We retrospectively evaluated benign thyroid nodules treated with RFA between 2008 and 2018. Treatment efficacy at the 5- and 10-year follow-ups was analyzed. Additionally, subgroup analysis comparing technique efficacy, such as the final VRR, between the single- and multi-session RFA groups was performed. Continuous variables were analyzed using the two-sample t-test or Mann-Whitney U test, and categorical variables were analyzed using the Chi-square or Fisher's exact test.

RESULTS

A total of 267 nodules from 237 patients (age: 46.3 ± 15.0 years; female: 210/237 [88.6%]) were included. Of these, 60 were analyzed for the 5-year follow-up (mean follow-up duration ± standard deviation: 5.8 ± 0.4 years) and 29 for the 10-year follow-up (10.9 ± 0.9 years). Single-session RFA showed a median VRR of 95.7% (5th year) and 98.8% (10th year), while multi-session RFA showed comparable median VRRs of 97.4% (5th year) and 96.9% (10th year). The vascularity type, demographic factors, nodular components, and locations did not significantly differ between the single-session and multi-session RFA groups. However, nodules with pre-RFA volume <10 mL were more prevalent in the single-session RFA group than in the multi-session RFA group (5th year: 64.3% [18/28] vs. 34.4% [11/32], P = 0.040; 10th year: 75.0% [12/16] vs. 23.1% [3/13], P = 0.016).

CONCLUSION

Single-session RFA may be sufficient for achieving adequate volume reduction during long-term follow-up for small-volume benign thyroid nodules. A high VRR was maintained regardless of the nodular component, location, demographic factors, or vascularity type. However, large-volume nodules may require multiple RFA sessions to achieve a comparable VRR.

Radiofrequency Ablation of Low-Risk Papillary Thyroid Microcarcinoma: A Retrospective Cohort Study Including Patients with More than 10 Years of Follow-up

Background: The longest reported follow-up for thermal ablation of papillary thyroid microcarcinoma (PTMC) is 5 years. We evaluated the long-term efficacy and safety of radiofrequency ablation (RFA) in patients with low-risk PTMC with clinical follow-up of more than 10 years. Methods: In this retrospective cohort study, we included patients with low-risk PTMC who had more than 10 years of follow-up after ultrasound (US)-guided RFA (performed between May 2008 and December 2013). Sixty-five consecutive patients with 71 low-risk PTMCs who were unsuitable for surgery or declined surgery were included. Before RFA, all patients underwent US and thyroid computerized tomography. Repeat RFA for staged ablation was performed when the first RFA did not secure sufficient safety margins because of the tumor closely abutting the recurrent laryngeal nerve. Follow-up US imaging was performed at 1 week, 3 months, 6 months, every 6 months until 2 years, and then annually afterward. Primary outcomes were the respective cumulative rates of disease progression (defined by local tumor progression, lymph node, or distant metastasis), newly developed thyroid cancer, and conversion surgery. Secondary outcomes were serial volume reduction rate (VRR), complete disappearance rate of ablated PTMC, and adverse events associated with procedures. Results: Of 65 patients included in the study, 60 had unifocal and 5 had multifocal PTMCs. The mean number of RFA sessions per tumor was 1.2, and the median follow-up duration was 151 months (interquartile ranges, 131-157). Twenty percent (13/65) of patients required repeat RFA. There were no cases of disease progression. Five patients (5/65, 7.7%) developed a new papillary thyroid cancer (four treated with RFA and one with lobectomy). At 24 months, the mean VRR was 100%, and this was maintained throughout the final follow-up. The complete tumor disappearance rates after one or more RFA treatments were 40.8% (29/71), 74.6% (53/71), and 100% (71/71) at 6, 12, and 24 months, respectively. One major (subclinical hypothyroidism) and three minor adverse events occurred. Conclusions: In our experience, RFA of low-risk PTMC is effective and safe. During more than 10 years of follow-up, we observed no incident local tumor progression nor metastases, but 7.7% of patients developed a new papillary thyroid cancer.

Comparative outcomes of ultrasound-guided radiofrequency ablation vs. microwave ablation for patients with T1N0M0 papillary thyroid carcinoma: a retrospective cohort study

OBJECTIVE

To compare the clinical outcomes between radiofrequency ablation (RFA) and microwave ablation (MWA) for the treatment of T1N0M0 papillary thyroid carcinoma (PTC) in a large cohort.

MATERIALS AND METHODS

This retrospective study included 1111 patients with solitary T1N0M0 PTC treated with RFA (n = 894) or MWA (n = 215) by experienced physicians. A propensity score matching was used to compare disease progression, including lymph node metastases (LNM), recurrent tumors and persistent tumors, recurrence-free survival (RFS), volume reduction ratio (VRR), and complications between the RFA and MWA groups. The subgroup outcomes of T1a and T1b tumors treated with RFA and MWA were also compared.

RESULTS

During a mean follow-up period of 41.7 ± 12.6 months, the overall incidence rates of disease progression, LNM, recurrent tumors, and persistent tumors were 2.1%, 0.7%, 1.2%, and 0.2%, respectively. Eight patients (0.7%) experienced transient voice change and recovered within 3 months. After 1:1 matching, there were no significant differences in disease progression (3.3% vs. 3.7%, p = 0.793), LNM (1.4% vs. 1.9%, p = 1.000), recurrent tumor (1.4% vs. 1.9%, p = 1.000), persistent tumors (0.5% vs. 0%, p = 0.317), RFS rates (96.7% vs. 96.3%, p = 0.821), VRR (99.3 ± 3.0% vs. 98.3 ± 8.5%, p = 0.865), tumor disappearance rate (87.9% vs. 81.4%, p = 0.061) and complications (1.4% vs. 1.9%, p = 1.000) between the RFA and MWA groups. For T1a and T1b tumors, clinical outcomes were comparable between RFA and MWA.

CONCLUSIONS

RFA and MWA did not show significant differences in clinical outcomes for T1N0M0 PTC. The choice between RFA and MWA could depend on physician expertise and resources of local center resources. A qualified and experienced physician with extensive knowledge of the modalities is recommended when thermal ablation is performed.

KEY POINTS

Question With radiofrequency ablation (RFA) and microwave ablation (MWA) used worldwide for T1N0M0 papillary thyroid carcinoma (PTC), is one of them superior to the others? Findings There were no significant differences in disease progression, recurrence-free survival, volume reduction ratio, tumor disappearance, or complications between techniques for solitary T1N0M0 papillary thyroid carcinoma. Clinical relevance The choice between RFA and MWA could depend on physician expertise and resources of the local center resources. A qualified and experienced physician with extensive knowledge of the modalities is recommended when thermal ablation is performed.

Multicenter study of thermal ablation versus partial thyroidectomy for paratracheal papillary thyroid microcarcinoma

OBJECTIVE

To compare the clinical outcomes of patients with unifocal paratracheal papillary thyroid microcarcinoma (PTMC) after thermal ablation (TA) vs. partial thyroidectomy (PT).

MATERIALS AND METHODS

This retrospective multicenter study included 436 patients with unifocal, clinical N0 paratracheal PTMC who underwent TA (210 patients) or PT (236 patients) between June 2014 and December 2020. The propensity score matching method was used to mitigate confounding factors between the two groups. Disease progression, progression-free survival (PFS), complications, and treatment variables were compared. Adjusted Cox regression models were utilized to assess the impact of treatment on disease progression.

RESULTS

After matching, a comparable incidence of disease progression (3.3% vs. 2.2%, p = 0.79) and comparable 5-year PFS rates (97.0% vs. 97.4%, p = 0.75) were observed between the TA and PT groups. Adjusted Cox regression models showed no significant correlation between TA and disease progression. TA was associated with shorter hospitalization (0 vs. 6.0 days), less estimated blood loss (0 vs. 15.0 mL), shorter incision length (0.3 vs. 6.0 cm), and lower costs ($1748.3 vs. $2898.0) compared with PT (all p < 0.001). The complication rate was 1.1% after TA and 3.3% after PT (p = 0.28), with permanent complications were exclusively observed in the PT group.

CONCLUSION

The mid-term incidence of disease progression and PFS rates were similar between TA and PT in patients with unifocal paratracheal PTMC. TA might represent a promising alternative treatment to PT for eligible patients with paratracheal PTMC.

KEY POINTS

Question Is thermal ablation a viable alternative treatment to partial thyroidectomy for treating paratracheal papillary thyroid microcarcinoma? Findings Comparable incidence of disease progression and 5-year progression-free survival rates were observed between thermal ablation and partial thyroidectomy. Clinical relevance Thermal ablation, as a minimally invasive procedure, provides a promising alternative to partial thyroidectomy, with comparable clinical outcomes for patients with paratracheal papillary thyroid microcarcinoma.

Radiofrequency Ablation for Recurrent Thyroid Cancers: 2025 Korean Society of Thyroid Radiology Guideline

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Long-term clinical outcomes of thermal ablation for benign thyroid nodules and unresolved issues: a comprehensive systematic review

Thermal ablation is widely accepted as an effective and safe method for treating benign thyroid nodules. Many studies reporting short-term results have consistently demonstrated the efficacy and safety of thermal ablation. However, as the clinical application of thermal ablation grows and follow-up periods extend, long-term clinical outcomes of thermal ablation have revealed several issues, including regrowth and diagnosis of malignancy in ablated lesions. In this systematic review, we analyze the long-term clinical outcomes of thyroid thermal ablation, focusing on regrowth, delayed surgery, and the potential for malignancy after thermal ablation and propose solutions to address these unresolved issues and enhance the management of benign thyroid nodules through thermal ablation.

Diagnosing and management of thyroid nodules and goiter - current perspectives

Due to the frequent diagnosis of benign thyroid nodules, it is necessary to deviate from the traditional paradigm based on frequent surgical treatment. This article highlights the evolution of diagnosis and treatment in recent years, beginning from standardization of ultrasound assessment of nodules and cytology results to minimally invasive techniques to reduce the size of symptomatic thyroid nodules. These achievements reduce the number of surgeries, enable more individualized care for patients with benign thyroid disease, reduce long-term complications, and promote cost-effectiveness within healthcare systems. Furthermore, although the use of minimally invasive techniques significantly decreases thyroid nodule volume, the thyroid nodule usually does not disappear and the challenges in this field are discussed (the efficacy of thermal ablation, a variable part of thyroid nodules that remains viable after thermal ablation, some of the nodules treated with thermal ablation may require a second treatment over time and the efficacy of thermal ablation in nodules with different phenotypes). However, although surgery still represents the "gold standard" for establishing the final histopathologic diagnosis, it is associated with lifelong thyroid hormone substitution need and serious complications in rare cases. Therefore, it should represent the ultima ratio only after a detailed diagnostic procedure. In the future, artificial intelligence-assisted programs for the evaluation and management of nodules are expected.

Radiofrequency Ablation for Solitary Autonomously Functioning Thyroid Nodules: Multicenter Study from Latin America

Background: Autonomously functioning thyroid nodules (AFTNs) represent ∼5% of all thyroid nodules and often necessitate definitive treatments such as surgery or radioiodine (131I), both of which have inherent risks. Radiofrequency ablation (RFA) has emerged as an effective and safe therapeutic option for managing AFTNs. This study aims to assess the effectiveness and safety of RFA for solitary AFTNs in various countries across Latin America. Methods: This retrospective, observational, multicenter cohort study included patients with a solitary AFTN that was histologically confirmed as benign and treated with a single session of RFA. The study included an analysis of patient demographics, sonographic characteristics of the nodules, thyroid profile assessment at each follow-up visit, evaluation of clinical symptoms to determine the achievement of a euthyroid state, and the measurement of nodule volume reduction. In addition, a bivariate analysis was conducted to identify associations between these variables and the resolution of hyperthyroidism. Results: Our study enrolled 81 patients with a solitary, benign AFTN. The volume reduction ratio (VRR) consistently increased over the follow-up period, with medians of -50%, -74.9%, -78.4%, and -90.2% at 1, 3, 6, and 12 months, respectively. The rate of resolution of hyperthyroidism was 93.8% (76/81). Following the RFA procedure, 58.02% of patients (47/81) normalized their thyrotropin levels within 1 month of follow-up, and by 3 months, an additional 33.3% had achieved normalization (27/81). Notably, a baseline volume ≥10, 20, or 30 mL did not affect the achievement of clinical success. In bivariate analyses, a VRR ≥50% at the 6-month follow-up was associated with the resolution of hyperthyroidism. Overall complications occurred in 6.2% of patients (5/81), including 1.2% (1/81) of a major complication (transient Horner syndrome), 3.7% cases of transient dysphonia (3/81), and 1.2% (1/81) of hypothyroidism requiring low-dose levothyroxine replacement. Conclusions: The results of this multicenter study suggest that RFA is a promising treatment option for patients with solitary AFTN, regardless of their baseline characteristics, including volume, age, or composition. The clinical success of the intervention may be related to the VRR at 6 months.

Preliminary Report Examining Efficacy and Safety of Radiofrequency Ablation for the Treatment of Skin-Involving Recurrent Thyroid Cancer

Background: This study assessed the efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treatment of skin-involving recurrent thyroid cancer. Methods: In this retrospective case series study, 43 patients (mean age: 67.9 ± 14.4 years; 31 females) with skin-involving recurrent thyroid cancer were treated with RFA for a total of 50 tumors between May 2008 and March 2023. The location of the tumor was classified into epidermis, dermis, or hypodermis on the basis of the involved skin layer. After RFA, the technique efficacy (absence of detectable vasculature and volume reduction at 12 months), clinical success (resolution of symptoms or cosmetic problems), volume reduction ratio (VRR), complete disappearance of tumor, and complications were assessed. Results: Of the 50 recurrent tumors, 9 involved the epidermis, 10 involved the dermis, and 31 involved the hypodermis. A total of 88 RFA sessions (mean, 1.8; range: 1-6) were performed. The technique efficacy at 1 year was 72% (36/50 [confidence interval or CI: 59.6-84.4%]). At the last follow-up (median [interquartile range]: 2.7 [1.1-4.5] years), the clinical success rate was 86% (44/50), the complete disappearance rate 54% (27/50), and the mean VRR 77.3% ± 44.2%. In a subgroup analysis comparing epidermis/dermis vs. hypodermis, there was no statistical difference in technique efficacy (57.9% [11/19] vs. 80.6% [25/31], p = 0.085), clinical success rate (78.9% [15/19] vs. 90.3% [28/31], p = 0.265), complete disappearance rate (42.1% [8/19] vs. 51.6% [16/31], p = 0.541), or mean VRR (65.5% vs. 84.6%, p = 0.141). Skin burns were observed in 4.9% per treatment session (2/41 [CI: 0-11.3%]) of epidermis/dermis-involving tumor procedures and none of the hypodermal tumor procedures. No patients experienced life-threatening or major complications. Conclusions: RFA might serve as a promising approach for managing skin-involving recurrent thyroid cancer, with no major complications reported in this preliminary study. Recurrent tumors involving the epidermis/dermis may pose a higher risk of skin burns than tumors involving the hypodermis. Early intervention with RFA before the tumor extends to the epidermis/dermis may thus be preferable.

Impact of thyrotropin levels on outcomes in T1N0M0 papillary thyroid cancer after microwave ablation

OBJECTIVE

To evaluate the impact of thyroid-stimulating hormone (TSH) levels on tumor progression and survival in patients with uni- and multifocal T1N0M0 papillary thyroid cancer (PTC) treated with microwave ablation (MWA).

METHODS

This retrospective study analyzed the records of 525 patients with uni- and multifocal T1N0M0 PTC who underwent MWA from January 2015 to December 2022. Patients were stratified into uni-focal (U-PTC) and multifocal (M-PTC) groups and further categorized based on post-ablation TSH levels into low (≤1 mU/L), medium (1-2 mU/L), and high (>2 mU/L) subgroups. The tumor progression rates and progression-free survival were assessed.

RESULTS

In U-PTC patients, lower TSH levels were significantly associated with higher tumor progression rates (10.1%) compared to those in the medium (2.9%) and high (2.1%) TSH groups (p = .009). Conversely, in M-PTC patients, tumor progression rates did not vary significantly across TSH levels. Progression-free survival rates in U-PTC patients were notably lower at the 5-year mark in the low TSH group (85.7%) compared to the medium TSH group (96.5%, p = .046). However, progression-free survival rates in M-PTC patients showed convergence across all TSH levels by the 5-year follow-up.

CONCLUSION

Maintaining TSH levels within the normal range post-ablation may be appropriate for managing T1N0M0 PTC treated with MWA, but randomized controlled trials are needed to confirm optimal TSH targets and their impact on outcomes.

The Influence of Impedance on the Efficacy of Radiofrequency Ablation for Benign Thyroid Nodules

OBJECTIVE

Radiofrequency ablation (RFA) uses the heat generated by a high-frequency alternating electric current, and according to Ohm's and Joule's law, the delivered current is inversely proportional to the circuit impedance. The primary objective of this study was to investigate whether tissue impedance during radiofrequency ablation (RFA) for benign thyroid nodules is related to the degree of volume reduction.

METHODS

This observational study included consecutive patients treated with RFA for benign thyroid nodules from February 2020 to August 2023. Technical effectiveness was defined as a volume reduction percentage (VRP) >75% at 6 months after the treatment. Multivariate logistic regression analyses were performed to identify the potential role of clinical factors and changes in tissue impedance on technique effectiveness.

RESULTS

Totally 72 patients were included with 73 benign thyroid nodules. Maximal impedance peaks reached <18 times, and mean procedural impedance ≤300 Ω were significantly associated with a volume decrease of >75% at bivariate analysis. These cutoff points were exploratory, as no existing literature suggests these variables are related to the degree of volume reduction. After adjusting for age, volume, and composition, significant associations were found for mean electrical impedance in the multivariate analysis (OR = 4.86 [confidence interval [CI] 1.29-18.26], p = 0.019). The energy adjusted by volume (delivered energy) was not associated with a VRP >75% (p = 0.7746).

CONCLUSIONS

This study suggests that a mean procedural impedance

LEVEL OF EVIDENCE

3 Laryngoscope, 134:5231-5238, 2024.

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Key Words

• benign thyroid nodule
• impedance
• minimally invasive techniques
• radiofrequency ablation
• thermal ablation

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MESH Headings

• Humans
• Thyroid Nodule/surgery
• Female
• Electric Impedance
• Male
• Radiofrequency Ablation/methods
• Middle Aged
• Treatment Outcome
• Adult
• Aged

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Affiliation(s)

Juan Pablo Dueñas Division of Endocrine Surgery, Integral Endocrine Surgery Clinic, Medellin, Colombia
Nathalia Buitrago-Gómez Department of Endocrinology, Universidad Pontificia Bolivariana, Medellin, Colombia
José Hugo Arias-Botero Medicine, CES University, Medellín, Colombia
Gregory Randolph Otolaryngology Head and Neck Surgery, Claire and John Bertucci Endowed Chair in Thyroid Surgical Oncology, Harvard Medical School, Chief Thyroid/Parathyroid Endocrine Surgical Division, Dept Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Member Endocrine Surgical Service, Massachusetts General Hospital, President American Academy of Otolaryngology Head and Neck Surgery 2016-17, American Head and Neck Society, Administration Division Chair, International Thyroid Oncology Group (ITOG) President, American College of Surgeons Otolaryngology Governor, Boston, Massachusetts, U.S.A
Marika Russell Division of Thyroid and Parathyroid Endocrine Surgery, Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, U.S.A
Amr Abdelhamid Ahmed Division of Thyroid and Parathyroid Endocrine Surgery, Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, U.S.A
Roberto Valcavi Division of Endocrinology, The Endocrine & Thyroid Clinic (ETC), Reggio Emilia, Italy
Carlos Simón Duque Head and Neck Surgeon, Intermedica, Medellin, Colombia
Ralph P Tufano FPG Thyroid and Parathyroid Center, Sarasota Memorial Health Care System, Sarasota, Florida, U.S.A

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Exploring Radiofrequency Ablation for T1 Papillary Thyroid Cancer in the United States: Mayo Clinic Experience

OBJECTIVE

To report the efficacy, safety, and feasibility of radiofrequency ablation (RFA) for T1 papillary thyroid carcinoma (PTC) in a large referral center in the United States.

PATIENTS AND METHODS

We conducted a retrospective study of 8 patients who underwent RFA for T1 PTC at Mayo Clinic in Rochester Minnesota, between July 1, 2020, and February 28, 2023. The RFA technique and the type of anesthesia are described. Thyroid function, changes in ablated zone, and adverse events were analyzed for up to 24 months after the procedure.

RESULTS

Of the 8 patients included in the study, 7 were female and 1 was male with a mean ± SD age of 53±16.4 years. Thyroid status was unaffected in 7 of the 8 patients. The median duration of RFA was 6 minutes (range, 2 to 14.5 minutes) with energy delivered at between 25 and 45 W. The mean ± SD volume of small PTCs was 0.3±0.2 mL, and the mean largest diameter was 9.5±3.3 mm (range, 6 to 15 mm). The mean ± SD ablated volume at 3 to 6 months was larger than the target lesion (0.8±0.7 mL), with a reduction in mean ± SD ablated volume of 0.4±0.4 mL at 7 to 12 months and 0.1±0.06 mL at 13 to 18 months. The ablated zone almost disappeared at 19 to 24 months (0.04±0.04 mL). There were no major adverse events during or after the RFA procedure.

CONCLUSION

This is the first reported series of T1 PTC treated with RFA in the United States. Early postablation imaging revealed that the ablated region was larger than the target lesions, followed by a serial decrease in size. Therefore, RFA at centers with such expertise appears to be a safe and effective treatment for small PTCs. Further studies are needed to evaluate its long-term efficacy and the risk of recurrence.

Efficacy and safety of laser ablation and microwave ablation to treat papillary thyroid microcarcinoma: A retrospective study

OBJECTIVE

To retrospectively analyze the efficacy and safety of laser ablation (LA) and microwave ablation (MWA) in the treatment of papillary thyroid microcarcinoma (PTMC).

METHODS

This was a retrospective study of 103 patients (109 nodules) who underwent thermal ablation for PTMC between October 2019 and March 2023; 61 underwent LA and 48 underwent MWA. The mean patients' age was 43.50 ± 12.42 years. After ablation, changes in tumor size at different time points, local recurrence, new lesions, lymph node metastasis, and complications were evaluated and recorded. The feasibility, success rate, and safety of LA and MWA were analyzed.

RESULTS

Complete absence of enhancement on contrast-enhanced ultrasonography was observed in all target tumors after ablation. At the last follow-up, the mean volume of the PTMC nodules decreased from 0.09 ± 0.09 to 0.03 ± 0.03 ml (LA group) and from 0.11 ± 0.10 to 0.06 ± 0.08 ml (MWA group) (both, P < 0.05). There was no significant difference in volume change between the groups (P (groups): 0.520; P (groups over time): 0.423), indicating similar efficacy between the groups. There was also no significant difference in the volume reduction rate between the groups during follow-up, except for at 3 months (P = 0.023). The complication rates did not differ between the LA group (8.2 %) and MWA group (6.3 %) (P > 0.05).

CONCLUSION

During the short-term follow-up, ultrasound-guided LA and MWA were effective and safe for PTMC, and there were no significant differences in treatment outcomes between the methods.

Outcomes of Radiofrequency Ablation for Autonomously Functioning Thyroid Adenomas-Mayo Clinic Experience

Background

Autonomously functioning thyroid nodules (AFTNs) constitute 5% to 7% of thyroid nodules and represent the second most common cause of hyperthyroidism following Graves' disease. Currently, radioactive iodine (RAI) and surgery are the standard treatment options, and both incur a risk of postprocedural hypothyroidism and other surgery and radiation-related complications.

Methods

This work aimed at assessing the efficacy of radiofrequency ablation (RFA) as an alternative treatment option for resolving hyperthyroidism and the nodule volume rate reduction (VRR) and its associated adverse events.

Results

A total of 22 patients underwent RFA for a solitary AFTN. Seventy-two percent (n = 16) had subclinical hyperthyroidism, 9% (n = 2) had overt hyperthyroidism, and 18% (n = 4) were biochemically euthyroid on antithyroid medication. Average pretreatment TSH was 0.41 mIU/L (SD = 0.98) and free T4 1.29 ng/dL (SD = 0.33). Following a single RFA session, hyperthyroidism resolved in 90.9% (n = 20) and average VRR (61.13%) was achieved within 3 to 6 months following the ablation. Except for 1 nodule, none of the nodules grew during the follow-up period (16.5 months). Two patients (9%) developed transient tachycardia requiring short-term beta-blocker therapy, and 2 developed mild hypothyroidism requiring levothyroxine therapy. Two patients developed recurrent hyperthyroidism and elected to undergo lobectomy and repeat RFA respectively. No serious adverse effects were noted in this cohort.

Conclusion

RAI and/or surgery represent the standard of care for toxic adenomas, but RFA shows excellent efficacy and safety profile. Therefore, at centers with RFA expertise, it should be considered an alternative treatment strategy, avoiding radiation and surgery-related complications.

Ultrasound-guided ablation for T1N0M0 papillary thyroid carcinoma adjacent and non-adjacent danger triangle area: a retrospective comparative study

OBJECTIVES

To compare the safety and efficacy of ultrasound-guided radiofrequency ablation (RFA) in the treatment of T1N0M0 papillary thyroid carcinoma (PTC) with adjacent and non-adjacent danger triangle area (DTA).

MATERIALS AND METHODS

This retrospective study involved collecting clinical data of all T1N0M0 PTC patients who underwent RFA between January 2018 and December 2020 at the hospital. A total of 211 patients were enrolled in the study (mean age 43.25 ± 12.30 years, male-to-female ratio = 1:3). Among them, 91 had adjacent DTA involvement, while 120 had non-adjacent DTA involvement. Comparisons were made between the two groups patients regarding tumor volume changes, technical success rates, tumor disappearance, disease progression, complications.

RESULTS

In both groups, the technical success rate was 100%, with a median follow-up period of 30 months. The rates of complete tumor disappearance were 78% (71/91) and 74.2% (89/120) for the adjacent and non-adjacent DTA(p = .517). Disease progression rates were 2.2% (2/91) and 1.7% (2/120) (p > .99), Complication rates were 3.3%(3/91) in the adjacent DTA group and 1.7% (2/120) in the non-adjacent DTA group (p = .654). At 6th month after ablation, the volume reduction rate (VRR) in the non-adjacent DTA group (42.3%) was higher than in the adjacent DTA group (37.3%) (p = .002). However, no significant differences were observed in VRR between the two groups at 1, 3, 12, 18, 24, 30, and 36 months (p > .05).

CONCLUSION

In the treatment of T1N0M0 PTC, the complication rates and short-term efficacy of RFA in adjacent to the DTA did not differ from those of non-adjacent DTA.

Efficacy of echolaser smart interface-guided laser ablation in volume reduction of symptomatic benign thyroid nodules

Background

The management of benign symptomatic thyroid nodules until recent years has been limited to surgery, radioactive iodine treatment, or surveillance which is associated with the burden of morbidity of complications or symptom non-relief as well as cost. Laser ablation has emerged as a minimally invasive alternative, this uses laser energy to thermally ablate nodule tissue, leading to volume reduction and symptom relief. Long-term treatment response data is growing but remains limited in the United States. Our study aims to quantify the effectiveness of laser ablation in reducing the volume of thyroid nodules over a 12 to 18-month period.

Materials and methods

Retrospective review of data was conducted for 63 adults with cytologically benign, solid symptomatic thyroid nodules ranging from 1.333 cm3 to 103.794 cm3 in volume. Ultrasound-guided laser thermal ablation was performed on all nodules using EchoLaser X4 Smart Interface device with 1064 nm diode laser to deliver total ablation energy (joules), calculated per device guidelines. Serial sonographic volume measurements were conducted 1 month, 3 -6 months, 6 - 12 months, and 12 to 18 months post-ablation intervals.

Results

Study cohort was comprised of 63 thyroid nodules. reduction in nodule volume increased progressively over time, with median reductions of 46.05% [STD 21.8] at 1 month, 60.33% [STD 20.1] at 3-6 months, 68.69% [STD 18.8] at 6-12 months, and 64.04% [STD 19.27] at 12-18 months. A total of 62, 56, 42, and 17 nodules had available data for analysis at these respective intervals.

Conclusion

This study demonstrated a marked progressive reduction of thyroid nodule volume following ablation. The treatment appears to be consistently effective in reducing symptoms across a wide range of nodule sizes, although the degree of volume reduction varies. The results of our study underscore the potential of laser ablation as a viable treatment option for thyroid nodules, with a sustained reduction in nodule volume observed over an extended post-procedure period.

Efficacy of microwave ablation in the treatment of large benign thyroid nodules: a multi-center study

OBJECTIVE

To evaluate the efficacy, safety, and improvement of symptoms by ultrasound-guided microwave ablation (MWA) for patients with large benign thyroid nodules (BTNs).

METHODS

Eighty-seven patients with 87 BTNs (≥ 4 cm) treated with MWA between April 2015 and March 2021 were enrolled in this retrospective multicenter study, with clinical and ultrasound examinations performed at the 1st, 3rd, 6th, and 12th months. A multivariable linear mixed effects model was employed to explore the alterations in volume and volume reduction ratio (VRR), as well as the potential factors associated with VRR.

RESULTS

The mean age of the 87 patients was 45.69 ± 14.21 years (range 18-76 years), and the ratio of men to women was 1:4.8. The mean volumes were much decreased at the 12th month after ablation compared to the initial volumes (p < .001). The mean VRR was 76.09% at the 12th month. The technique efficacy (VRR > 50%) was 90.80% at the 12th month. A multivariate analysis revealed that VRR was related to the initial volume (p = .015), annular flow (p = .010), and nodule composition (p = .024). The mean symptomatic score decreased from 4.40 ± 0.28 to 0.26 ± 0.06 at the 12th month (p < .001). At the same time, the mean cosmetic score decreased from 3.22 ± 0.10 to 1.31 ± 0.08 (p < .001).

CONCLUSION

MWA could serve as a safe and effective therapy for large BTNs, significantly reducing the volume of BTNs and significantly improving compressive symptoms and appearance problems.

CLINICAL RELEVANCE STATEMENT

Microwave ablation could serve as a safe and effective therapy for large benign thyroid nodules, leading to significant volume reduction and satisfied symptom and cosmetic alleviation period.

KEY POINTS

• This multicenter study investigated the feasibility and safety of microwave ablation for large benign thyroid nodules. • After ablation, the nodule volume was significantly reduced, and patients' symptoms and appearance problems were significantly improved. • Microwave ablation is feasible for large benign thyroid nodules and has been a supplement treatment.

Laser ablation for spongiform thyroid nodules: identifying baseline nodule volume and energy to be delivered for successful treatment

BACKGROUND

Laser ablation (LA) is a minimally invasive treatment. It has been widely used since the early 2000s to induce volume reduction of symptomatic benign thyroid nodules. Up to 40% of laser-treated nodules have been reported to achieve a volume reduction of <50% (technique inefficacy) at 12 months and tend to regrow over time.

OBJECTIVE

This study aimed to assess the optimal baseline volume and energy to be delivered to minimize technique inefficacy.

METHODS

This was a retrospective study. Data were collected, including baseline volume, energy delivered, and 12-month volume reduction ratio (VRR) of spongiform nodules (EU-TIRADS 2) treated with LA between 2010 and 2020. Based on these data, the optimal baseline volume and energy to be delivered were calculated to maximize the rate of nodules with technique efficacy (VRR ≥ 50% at 12-month follow-up).

RESULTS

A total of 205 patients with spongiform nodules were included in this study. The energy delivered was positively associated with VRR. However, no association was observed between baseline volume and VRR. Delivering energy ≥500 J/mL to nodules with a mean baseline volume of 11.4 ± 4 mL resulted in technique efficacy in 83% of cases.

CONCLUSION

Treating spongiform nodules with a baseline volume of ≤15 mL and delivering energy ≥500 J/mL are key factors for achieving a relevant rate of technique efficacy.

Microwave versus Radiofrequency Ablation in Treating Predominantly Solid Benign Thyroid Nodules: A Randomized Controlled Trial

Background Current guidelines recommend radiofrequency ablation (RFA) as the first-line treatment for benign thyroid nodules. Purpose To compare the efficacy and safety of microwave ablation (MWA) and RFA for the treatment of predominantly solid benign thyroid nodules. Materials and Methods This prospective, randomized, open-label, multicenter study was conducted from August 2019 to February 2023. Participants with nonfunctioning, predominantly solid benign thyroid nodules from five institutions were randomly assigned with a 1:1 ratio to receive MWA or RFA treatment. Participants were followed up for at least 2 years. Primary outcomes were 6-month and 2-year volume reduction rate (VRR) of nodules after ablation. Secondary outcomes included VRR change over time, complications, and technique efficacy (defined as volumetric reduction ≥ 50% of the initial nodule volume). Continuous variables and categorical variables were compared using the t test and the χ2 test or Fisher exact test, respectively. Results This study included 76 participants in the MWA group (mean age, 46 years ± 12 [SD]; 58 female participants) and 76 in the RFA group (mean age, 50 years ± 13; 56 female participants). MWA was noninferior to RFA in terms of 6-month (mean difference, -5.6%; P = .01) and 2-year (-2.4%; P < .001) VRR after ablation. Comparing MWA and RFA, no evidence of a difference was observed for VRR change over time (mean difference from mixed-effects analysis, 6.9% [95% CI: -0.5, 13.9]; P = .73) or technique efficacy (91% vs 86%; P = .40). The most common major complication was voice change, which occurred in 6.6% of participants in the MWA group and 1.3% of participants in the RFA group (P = .21). Conclusion MWA and RFA showed comparable efficacy for treating participants with predominantly solid benign thyroid nodules. However, a larger sample size is needed to demonstrate that safety is comparable between the procedures. ClinicalTrials.gov Identifier: NCT04046354 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by McGahan in this issue.

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.

Adjustable-tip needles versus fixed-tip needles in radiofrequency ablation of symptomatic benign thyroid nodules: a single-center Italian experience

PURPOSE

In this retrospective, observational study we aim to compare the outcomes of the RFA treatment of benign thyroid nodules, carried out respectively with the standard fixed-needle approach (FTN) and the adjustable-tip needle technique (ATN), considered a more tailored, quicker and easier technical approach.

METHODS

We enrolled 36 patients who underwent RFA treatment of symptomatic, benign, thyroid nodule, 18 with the ATN and 18 with the FTN approach, respectively. Data about absolute volume reduction, volume reduction rate (VRR) and success rate (defined as VRR ≥ 50%), after 1, 3 and 6 months of follow-up were compared.

RESULTS

Our study suggested no substantial difference between the approaches, up to 6 months of follow-up, both in terms of absolute reduction (p = 0.27) and VRR (p = 0.14). These results were confirmed when the success rates, both in terms of 50%-reduction (p = 0.12) and absolute reduction (p = 0.42), was considered. Only at the 6-month evaluation, the FTN procedure showed a better success rate, yet without statistical significance (88.9% vs. 61.1%, p = 0.12). No difference emerged both in terms of patients' satisfaction and safety.

CONCLUSION

Our small experience suggested no substantial difference between ATN and FTN, in terms of outcomes. On the other hand, ATN was considered to be more straightforward and could consequently allow for a shorter operator learning curve.

A prognostic model for thermal ablation of benign thyroid nodules based on interpretable machine learning

Introduction

The detection rate of benign thyroid nodules is increasing every year, with some affected patients experiencing symptoms. Ultrasound-guided thermal ablation can reduce the volume of nodules to alleviate symptoms. As the degree and speed of lesion absorption vary greatly between individuals, an effective model to predict curative effect after ablation is lacking. This study aims to predict the efficacy of ultrasound-guided thermal ablation for benign thyroid nodules using machine learning and explain the characteristics affecting the nodule volume reduction ratio (VRR).

Design

Prospective study.

Patients

The clinical and ultrasonic characteristics of patients who underwent ultrasound-guided thermal ablation of benign thyroid nodules at our hospital between January 2020 and January 2023 were recorded.

Measurements

Six machine learning models (logistic regression, support vector machine, decision tree, random forest, eXtreme Gradient Boosting [XGBoost], and Light Gradient Boosting Machine [LGBM]) were constructed to predict efficacy; the effectiveness of each model was evaluated, and the optimal model selected. SHapley Additive exPlanations (SHAP) was used to visualize the decision process of the optimal model and analyze the characteristics affecting the VRR.

Results

In total, 518 benign thyroid nodules were included: 356 in the satisfactory group (VRR ≥70% 1 year after operation) and 162 in the unsatisfactory group. The optimal XGBoost model predicted satisfactory efficacy with 78.9% accuracy, 88.8% precision, 79.8% recall rate, an F1 value of 0.84 F1, and an area under the curve of 0.86. The top five characteristics that affected VRRs were the proportion of solid components < 20%, initial nodule volume, blood flow score, peripheral blood flow pattern, and proportion of solid components 50-80%.

Conclusions

The models, based on interpretable machine learning, predicted the VRR after thermal ablation for benign thyroid nodules, which provided a reference for preoperative treatment decisions.

Microwave ablation for lymph node metastasis in thyroid cancer: the impact of lymph node diameter

Objectives

To explore the impact of lymph node diameter on the efficacy and safety of ultrasound-guided microwave ablation (MWA) in the treatment of cervical metastatic lymph nodes (CMLNs) from thyroid cancer.

Methods

A total of 32 patients with 58 CMLNs from thyroid cancer underwent ultrasound-guided MWA and were included in the retrospective study. Patients were divided into three groups based on the mean largest diameter of the CMLNs: Group A (diameter ≤10mm), Group B (10mm < diameter ≤20mm), and Group C (diameter >20mm). The research involved comparing changes in cervical metastatic lymph nodes and serum thyroglobulin (sTg) levels, as well as the incidence of complications, before and after microwave ablation across three groups of patients.

Results

The technical success rate of this study was 100% (32/32), and they showed no major complications. Compared with measurements taken before MWA, the mean largest diameter and volume of CMLNs, as well as the sTg level, showed significant reductions (p <0.05) at the last follow-up in all three patient groups. Group A and B exhibited higher lymph node volume reduction rates and complete disappearance rates compared to Group C. However, the recurrence rate in the three groups were in the following order: Group C > Group B > Group A. The occurrence rate of mild complications was Group A > Group C > Group B.

Conclusion

MWA is a safe and effective method for treating CMLNs, with advantages for localized nodes but limitations for larger ones. Careful consideration and personalized plans are advised, based on comprehensive evidence assessment.

Efficacy and Safety of Thermal Ablation for Solitary Low-Risk T2N0M0 Papillary Thyroid Carcinoma

OBJECTIVE

To evaluate the efficacy and safety of thermal ablation in treating solitary low-risk T2N0M0 papillary thyroid cancer (PTC) and compare the outcomes of microwave ablation (MWA) and radiofrequency ablation (RFA).

MATERIALS AND METHODS

This retrospective, single center study involved 34 patients (age: 40.0 ± 13.9 years; 28 female) who had low-risk T2N0M0 PTC with a maximum diameter >2 cm and ≤4 cm and underwent MWA (n = 15) or RFA (n = 19) from November 2016 to April 2023. The primary outcomes were the cumulative rate of disease progression and delayed surgery rates. In contrast, the secondary outcomes included changes in tumor size, cumulative rate of complete tumor disappearance, and complication rates.

RESULTS

The median follow-up period was 18.0 months (interquartile range [IQR]: 9.0-40.0 months). At 12 months, the median volume reduction rate of the ablation zone was 74.2% (IQR: 53.7%-86.0%). Disease progression was noted in two patients within 1 year, including one patient with local tumor progression post-RFA and one with a new tumor post-MWA, resulting in a constant cumulative disease progression rate of 8.8% (95% confidence interval [CI]: 0%-19.8%) throughout the remaining follow-up period. Both patients were subsequently treated with additional ablation and did not require surgery. The cumulative rates of complete tumor disappearance at 1, 3, and 5 years were 4.0% (95% CI: 0%-11.4%), 26.8% (95% CI: 2.7%-44.9%), and 51.2% (95% CI: 0%-79.1%), respectively. No significant differences were observed in the disease progression (P = 0.829) or complete tumor disappearance (P = 0.633) rates between the MWA and RFA groups. Complications occurred in 14.7% (5/34) of patients presenting with transient hoarseness. RFA had a higher but not statistically significant complication rate than MWA did (21.1% [4/19] vs. 6.7% [1/15]; P = 0.355).

CONCLUSION

Both MWA and RFA demonstrated promising short-term outcomes in terms of efficacy and safety in treating solitary low-risk T2N0M0 PTC, with no significant differences.

Radiofrequency Ablation for the Treatment of Benign Thyroid Nodules: 10-Year Experience

Background: Longer follow-up after radiofrequency ablation (RFA) of benign thyroid nodules is needed to understand regrowth and other causes of delayed surgery and long-term complications. Methods: This retrospective study included consecutive patients treated with RFA for symptomatic benign nonfunctioning thyroid nodules between March 2007 and December 2010. RFA was performed according to the standard protocol. We followed up patients at 1, 6, and 12 months, then yearly, until August 2022, and calculated the volume reduction ratio (VRR) at each follow-up. We assessed the incidence of regrowth according to three published criteria, delayed surgery, and complications. The Kaplan-Meier method was used to evaluate the cumulative incidence of regrowth, and univariable and multivariable Cox regression analyses were performed to identify risk factors for regrowth. Results: This study included 421 patients (mean age, 47 ± 13 years; 372 women) with 456 nodules (mean volume, 21 ± 23 mL). The median follow-up period was 90 months (interquartile range, 24-143 months). The mean VRR was 81% at 2 years, 90% at 5 years, and 94% at ≥10 years. Overall regrowth was noted in 12% (53/456) of nodules and was treated with repeat RFA (n = 33) or surgery (n = 4) or left under observation (n = 16). Thyroid nodules with ≥20 mL initial volume had significantly higher risk of regrowth compared with nodules with <10 mL initial volume (hazard ratio, 2.315 [95% confidence interval, 1.183-4.530]; p = 0.014 on multivariable Cox regression analysis). Delayed surgery was performed in 6% (26/421) of patients because of regrowth and/or persistent symptoms (n = 4) or newly detected thyroid tumors (n = 22), one benign and 21 malignant. The overall complication rate was 2.4% (10/421), with no procedure-related deaths or long-term complications. Conclusion: RFA is safe and effective for treating benign thyroid nodules, with a high VRR at long-term follow-up. Regular follow-up after initial success is warranted because of the possibility of regrowth of ablated nodules and the need for delayed surgery in some patients.

Long-term comparison of image-guided thermal ablation vs. lobectomy for solitary papillary thyroid microcarcinoma: a multi-center retrospective cohort study

BACKGROUND

Image-guided thermal ablation has been applied in patients with papillary thyroid microcarcinoma (PTMC) who refuse surgery or active surveillance. However, evidence to support ablation is limited by single-center designs and a lack of long-term data. The purpose of this study was to compare long-term outcomes between ablation and lobectomy for patients with solitary PTMC.

MATERIALS AND METHODS

This multi-center retrospective study included 1021 consecutive patients with solitary PTMC who underwent ablation ( n =444) or lobectomy ( n =577) at the four university-affiliated hospitals. The primary outcomes were disease progression [lymph node metastasis (LNM), recurrent tumors, persistent tumors and distant metastasis] and disease-free survival (DFS). Secondary outcomes were complications, hospitalization, procedure time, estimated blood loss and cost. The two groups were compared using propensity score matching.

RESULTS

After matching, no significant differences were observed in disease progression (4.7% vs. 3.4%, P =0.307), LNM (1.6% vs. 1.6%, P =1.000), recurrent tumors (2.9% vs. 1.8%, P =0.269), persistent tumors(0.2% vs. 0%, P =0.317) and DFS (95.5% vs. 97.1%, P =0.246) between the ablation and lobectomy groups during the median follow-up of 96.5 months. The ablation group had significantly lower complication rates (0.7% vs. 5.2%, P <0.001), shorter post-treatment hospitalization {median [interquartile range (IQR)], 0 vs. 4.0 [3.0] days, P <0.001}, shorter procedure time [8.5 (2.8) vs. 90.0 (43.8) min, P <0.001], reduced estimated blood loss [0 vs. 20.0 (10.0) ml, P <0.001], and lower cost [$1873.2 (254.0) vs. $2292.9 (797.8), P <0.001] than the lobectomy group.

CONCLUSIONS

This study revealed comparable disease progression and survival outcomes between ablation and lobectomy for solitary PTMC. Imaged-guided thermal ablation could be effective and safe alternatives to lobectomy for properly selected patients with PTMC.

Radiofrequency ablation for capsular-located versus noncapsular-located papillary thyroid microcarcinoma: a propensity score matching study of 1095 patients

OBJECTIVES

To assess the safety and efficacy of radiofrequency ablation (RFA) for capsular-located papillary thyroid microcarcinoma (PTMC) in a large cohort and to compare its outcomes with those of noncapsular-located PTMC.

METHODS

We retrospectively reviewed patients who underwent RFA for solitary capsular-located and noncapsular-located low-risk PTMC (n = 1095) from June 2014 to October 2020. To balance confounding variables between capsular and noncapsular groups, we employed the 1:1 propensity score matching approach. We evaluated and compared tumor changes, disease progression, and complications in both groups. Furthermore, we analyzed the association between capsular location and disease progression using multivariable Cox regression.

RESULTS

During a mean follow-up time of 29.86 ± 16.14 months and 29.73 ± 15.69 months, no substantial difference was observed between capsular and noncapsular groups in the latest volume (0.83 ± 3.66 mm3 vs. 0.85 ± 3.67 mm3, p = 0.44) and volume reduction ratio (99.29 ± 4.04% vs. 99.43 ± 3.03%, p = 0.43), and cumulative disappearance rate (87.87% vs. 86.07%, p = 0.31). In addition, no significant differences were observed in complication incidence (1.35% vs. 1.12%, p = 0.76) and progression-free survival (p = 0.53). Based on adjusted multivariate Cox proportional hazard analysis, the association between capsular location and disease progression was nonsignificant (all p > 0.05).

CONCLUSION

This study demonstrates that the short-term outcomes of RFA for capsular-located PTMCs are comparable to those of noncapsular-located PTMCs. These findings indicate that RFA may be a viable and effective alternative for eligible patients with solitary capsular-located PTMC.

CLINICAL RELEVANCE STATEMENT

Radiofrequency ablation may serve as a safe and effective alternative treatment method for eligible patients with capsular-located and noncapsular-located papillary thyroid microcarcinoma.

KEY POINTS

• The safety and efficacy of radiofrequency ablation for capsular-located and noncapsular-located papillary thyroid microcarcinomas were comparable. • Disease progression did not differ significantly between capsular-located and noncapsular-located papillary thyroid microcarcinomas. • The incidence of complications for capsular-located papillary thyroid microcarcinoma was low.

A 6-year single-center prospective follow-up study of the efficacy of radiofrequency ablation for thyroid nodules

Background

Radiofrequency ablation (RFA) is an alternative modality for thyroid nodules (TNs) and many studies have also confirmed its favorable efficacy and safety. The scope of RFA increases in clinical practice and the aim of our study was to evaluate the efficacy of RFA.

Methods

We conducted a prospective study to evaluate the efficacy of RFA for thyroid nodules between January 2017 and December 2022 at our institution. We assessed the change in nodal volume, volume reduction ratio (VRR), technique effective (TE) rate, complete ablation (CA) rate, and nodal regrowth rate and time after RFA.

Results

We performed RFA for 1703 patients with TNs between January 2017 and December 2022, of which a total of 970 eligible patients were enrolled in the study. The preoperative volume of TNs was 6.23 ± 8.11ml, with 821 benign and 149 malignant nodules. The post-RFA TE and adjusted TE rate were 80% and 88.8%, respectively. CA was achieved in 145 (14.9%) patients with a mean time of 18.32± 12.98 months; nodal regrowth occurred in 15 (1.5%) patients with a mean time of 29.80 ± 12.47 months. TNs volume and VRR changed significantly at years 1 and 2 after RFA and stabilized after 5 years. A serious postoperative adverse event occurred in one patient with cervical sympathetic chain injury resulting in Horner's syndrome. A transient or permanent damage of the recurrent laryngeal nerve could not be evaluated due to the lack of postoperative laryngoscopy, and this is a significant limitation of the study.

Conclusion

The expanded RFA indications were also effective for TNs, with no significant change in long-term efficacy.

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.

Safety and efficacy of microwave ablation for symptomatic benign thyroid nodules in children

OBJECTIVE

To evaluate the efficacy and safety of microwave ablation (MWA) for the treatment of symptomatic benign thyroid nodules in children.

METHODS

A retrospective study of MWA for the treatment of 34 symptomatic benign thyroid nodules in 25 children was conducted. Volume reduction ratio (VRR), technique efficacy, symptom score, cosmetic score, and thyroid function were used to evaluate the efficacy of the technique. The associated complications and side effects were recorded.

RESULTS

The participants were followed for at least 6 months (median 12 months, range 6-48 months). After MWA treatment, the volumes of the targeted nodules decreased gradually (median volume 5.86 mL before MWA and 0.34 mL at the final follow-up assessment), the VRR achieved was up to 85.03% at the final follow-up assessment, and the technical efficacy at this time was 91.2%. The subjective and objective nodule-related symptoms were also ameliorated. The circulating hormone concentrations reflecting thyroid function remained within their normal ranges in all the participants after one month of follow-up. The procedure had no major complications.

CONCLUSIONS

MWA seems to be an effective and safe technique for the treatment of symptomatic benign thyroid nodules in pediatric patients.

CLINICAL RELEVANCE STATEMENT

Microwave ablation is a safe and effective method to treat symptomatic benign thyroid nodules in pediatric patients. This treatment may be selected if the patient or parents are not suitable or refuse to undergo surgery.

KEY POINTS

• Microwave ablation is effective in reducing the volume of benign thyroid nodules and ameliorating nodule-related symptoms in pediatric patients. • Microwave ablation is a safe method in children, with low complications. • Microwave ablation does not affect the circulating thyroid hormone concentrations of children.

Comparison of safety, efficacy, and patient satisfaction with thermal ablation versus endoscopic thyroidectomy for benign thyroid nodules in a propensity-matched cohort

BACKGROUND

Thyroid nodules (TNs) often require intervention due to symptomatic or cosmetic concerns. Radiofrequency ablation (RFA) has shown promise as a treatment option, offering potential advantages without neck scars. Recently, the scarless treatment alternative of transoral endoscopic thyroidectomy vestibular approach (TOETVA) has emerged. When surgery can be performed in a scarless manner, it remains unclear whether ablation is still the preferred treatment choice. This study aims to compare the safety, efficacy, and patient satisfaction of RFA and TOETVA.

STUDY DESIGN

A retrospective data analysis was conducted on patients treated with RFA or TOETVA for unilateral benign TNs between December 2016 and September 2021. Propensity score matching was employed to create comparable groups. Various clinicopathologic parameters, treatment outcomes, and costs were assessed.

RESULTS

Of the 2814 nonfunctional thyroid nodules treated during this period, 642 were benign and unilateral. A total of 121 and 100 patients underwent thermal ablation and transoral endoscopic thyroidectomy, respectively. After matching, 84 patients were selected for each group. Both RFA and TOETVA demonstrated low complication rates, with unique complications associated with each procedure. Treatment time (30.8±13.6 vs. 120.7±36.5 min, P <0.0001) was shorter in the RFA group. Patient satisfaction (significant improvement: 89.3% vs. 61.9%, P <0.0001) and cosmetic results (cosmetic score 1-2: 100.0% vs. 54.76%, P <0.0001) favored TOETVA. RFA was found to be less costly for a single treatment, but the cost of retreatment should be considered. The histological diagnoses post-TOETVA revealed malignancies in 9 out of 84 cases, underscoring the significance of follow-up assessments.

CONCLUSION

Scarless procedures, RFA and TOETVA, are effective for treating unilateral benign TNs, each with unique advantages and drawbacks. While RFA is cheaper for a single treatment, TOETVA offers superior cosmetic results and patient satisfaction. Further research is needed to evaluate long-term safety and cost-effectiveness. It is crucial to remain vigilant about the possibility of malignancy despite benign cytology pre-treatment.

Microwave Ablation versus Surgical Resection for US-detected Multifocal T1N0M0 Papillary Thyroid Carcinoma: A 10-Center Study

Background Microwave ablation (MWA) is currently under preliminary investigation for the treatment of multifocal papillary thyroid carcinoma (PTC) and has shown promising treatment efficacy. Compared with surgical resection (SR), MWA is minimally invasive and could preserve thyroid function. However, a comparative analysis between MWA and SR is warranted to draw definitive conclusions. Purpose To compare MWA and SR for preoperative US-detected T1N0M0 multifocal PTC in terms of overall and 1-, 3-, and 5-year progression-free survival rates and complication rates. Materials and Methods In this retrospective study, 775 patients with preoperative US-detected T1N0M0 multifocal PTC treated with MWA or SR across 10 centers between May 2015 and December 2021 were included. Propensity score matching (PSM) was performed for patients in the MWA and SR groups, followed by comparisons between the two groups. The primary outcomes were overall and 1-, 3-, and 5-year progression-free survival (PFS) rates and complication rates. Results After PSM, 229 patients (median age, 44 years [IQR 36.5-50.5 years]; 179 female) in the MWA group and 453 patients (median age, 45 years [IQR 37-53 years]; 367 female) in the SR group were observed for a median of 20 months (range, 12-74 months) and 26 months (range, 12-64 months), respectively. MWA resulted in less blood loss, shorter incision length, and shorter procedure and hospitalization durations (all P < .001). There was no evidence of differences in overall and 1-, 3-, or 5-year PFS rates (all P > .05) between MWA and SR (5-year rate, 77.2% vs 83.1%; P = .36) groups. Permanent hoarseness (2.2%, P = .05) and hypoparathyroidism (4.0%, P = .005) were encountered only in the SR group. Conclusion There was no evidence of a significant difference in PFS rates between MWA and SR for US-detected multifocal T1N0M0 PTC, and MWA resulted in fewer complications. Therefore, MWA is a feasible option for selected patients with multifocal T1N0M0 PTC. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Georgiades in this issue.

Can Ethanol Ablation Achieve Durable Control of Neck Nodal Recurrences in Adults With Stage I Papillary Thyroid Cancer?

Objective

Results of ethanol ablation (EA) for controlling neck nodal metastases (NNM) in adult patients with papillary thyroid carcinoma (APTC) beyond 6 months have rarely been reported. We now describe outcome results in controlling 71 NNM in 40 node-positive stage I APTC patients followed for 66 to 269 months.

Methods

All 40 patients were managed with bilateral thyroidectomy and radioiodine therapy and followed with neck ultrasound (US) for >48 months after EA. Cumulative radioiodine doses ranged from 30 to 550 mCi; pre-EA 27 patients (67%) had 36 additional neck surgeries. Cytologic diagnosis of PTC in 71 NNM selected for EA was confirmed by US-guided biopsy. EA technique and follow-up protocol were as previously described.

Results

The 40 patients had 1 to 4 NNM; 67/71 NNM (94%) received 2 to 4 ethanol injections (total median volume 0.8 cc). All ablated 71 NNM shrank (mean volume reduction of 93%); nodal hypervascularity was eliminated. Thirty-eight NNM (54%) with initial volumes of 12-1404 mm3 (median 164) disappeared on neck sonography. Thirty-three hypovascular foci from ablated NNM (pre-EA volume range 31-636 mm3; median 147) were still identifiable with volume reductions of 45% to 97% observed (median 81%). There were no complications and no postprocedure hoarseness. Final results were considered to be ideal or near ideal in 55% and satisfactory in 45%. There was no evidence of tumor regrowth after EA.

Conclusion

Our results demonstrate that for patients with American Joint Committee on Cancer stage I APTC, who do not wish further surgery or radioiodine, and are uncomfortable with active surveillance, EA can achieve durable control of recurrent NNM.

Clinical Outcomes of Thermal Ablation Re-Treatment of Benign Thyroid Nodules: A Multicenter Study from the Italian Minimally Invasive Treatments of the Thyroid Group

Background: Thermal ablation (TA) is an established therapeutic option alternative to surgery in patients with solid benign thyroid nodules causing local symptoms. However, a variable part of thyroid nodules remain viable after these nonsurgical treatments, and as many as 15% of nodules treated with TA may require a second treatment over time. This study aimed to evaluate the outcomes of TA re-treatment on symptomatic benign thyroid nodules where the volume decreased by <50% after the first procedure ( = technique inefficacy). Methods: We performed a multicenter retrospective cohort study including patients who underwent re-treatment with TA for benign thyroid nodules, whose volume decreased by <50% after initial treatment. The primary aim was to evaluate volume and volume reduction ratio (VRR) over time and compare the 6- and 12-month VRR after first versus second treatment. The secondary aim was to identify protective or risk factors for technique inefficacy, regrowth, and further treatments, expressed as adjusted hazard ratios (HRs) and confidence interval [CI], after adjustment for sex, age, nodule volume, structure and function, nodule regrowth or symptom relapse, technique used and if the same technique was used for the first and second TA and time between them. Results: We included 135 patients. Re-treatment led to VRR of 50% and 52.2% after 6 and 12 months. VRR after re-treatment was greater than after first treatment in small and medium size nodules (<30 mL), while there were no differences for large nodules (>30 mL). After re-treatment technique inefficacy rate was 51.9%, regrowth rate was 12.6%, and further treatment rate was 15.6%. Radiofrequency ablation (RFA) was protective toward technique inefficacy (HR = 0.40 [CI 0.24-0.65]) and need of further treatments (HR = 0.30 [CI 0.12-0.76]). Large nodule volume (>30 mL) was associated with increased risk of re-treatment (HR = 4.52 [CI 1.38-14.82]). Conclusions: This is the first study evaluating the outcomes of re-treatment on symptomatic benign thyroid nodules with a VRR <50% after the initial TA treatment. Best results were seen in small and medium nodules (<30 mL) and after RFA. Prospective confirmatory studies are needed.

Ultrasound-guided radiofrequency ablation for the treatment of papillary thyroid carcinoma: a review of the current state and future perspectives

Papillary thyroid carcinoma (PTC) is a highly prevalent cancer that typically exhibits indolent behavior and is associated with a favorable prognosis. The treatment of choice is surgical intervention; however, this approach carries the risk of complications, including scarring and loss of thyroid function. Although active surveillance can mitigate the risk of PTC overtreatment, the possibility of tumor growth and metastasis can elicit anxiety among patients. Ultrasoundguided thermal ablation has emerged as a safe and effective alternative for individuals who are ineligible for or decline surgery. This article provides a review of the clinical research on radiofrequency ablation as a treatment for PTC, offering a thorough examination of its efficacy, safety, and future perspectives.

Complications of microwave ablation in patients with persistent/recurrent hyperparathyroidism after surgical or ablative treatment

OBJECTIVE

To evaluate the complications associated with microwave ablation (MWA) in treating persistent/recurrent hyperparathyroidism (HPT) post-surgical or ablative treatments.

MATERIALS AND METHODS

From January 2015 to December 2022, 87 persistent/recurrent HPT patients (primary HPT [PHPT]: secondary HPT [SHPT] = 13:74) who underwent MWA after surgical or ablative treatment were studied. Grouping was based on ablation order (initial vs. re-MWA), prior treatment (parathyroidectomy [PTX] vs. MWA), and etiology (PHPT vs. SHPT). The study focused on documenting and comparing treatment complications and analyzing major complication risk factors.

RESULT

Among the 87 patients, the overall complication rate was 17.6% (15/87), with major complications at 13.8% (12/87) and minor complications at 3.4% (3/87). Major complications included recurrent laryngeal nerve (RLN) palsy (12.6%) and Horner syndrome (1.1%), while minor complications were limited to hematoma (3.4%). Severe hypocalcemia noted in 21.6% of SHPT patients. No significant differences in major complication rates were observed between initial and re-MWA groups (10.7% vs. 13.8%, p = 0.455), PTX and MWA groups (12.5% vs. 15.4%, p = 0.770), or PHPT and SHPT groups (15.4% vs. 13.5%, p > 0.999). Risk factors for RLN palsy included ablation of superior and large parathyroid glands (>1.7 cm). All patients recovered spontaneously except for one with permanent RLN palsy in the PTX group (2.1%).

CONCLUSION

Complication rates for MWA post-surgical or ablative treatments were comparable to initial MWA rates. Most complications were transient, indicating MWA as a viable and safe treatment option for persistent/recurrent HPT patients.

Comparison of the Therapeutic Efficacy and Technical Outcomes between Conventional Fixed Electrodes and Adjustable Electrodes in the Radiofrequency Ablation of Benign Thyroid Nodules

OBJECTIVE

This study aimed to compare therapeutic efficacy and technical outcomes between adjustable electrode (AE) and conventional fixed electrode (FE) for radiofrequency ablation (RFA) of benign thyroid nodules.

MATERIALS AND METHODS

Between 2013 and 2021, RFA was performed on histologically proven benign thyroid nodules. For the AE method, AE length ≥ 1 cm with higher power and < 1 cm with lower power were utilized for ablating feeding vessels and nodules, especially those near anatomical structures, respectively. The therapeutic efficacy (volume reduction rate [VRR], complication rate, and regrowth rate) and technical outcomes (total energy delivery, ablated volume/energy, RFA time, and ablated volume/time) of FE and AE were compared. Continuous parameters were compared using a two-sample t-test or Mann-Whitney U test, and categorical parameters were compared using a chi-squared test or Fisher's exact test.

RESULTS

A total of 182 nodules (FE: 92 vs. AE: 90) in 173 patients (mean age ± standard deviation, 47.0 ± 14.7 years; female, 90.8% [157/173]; median follow-up, 726 days [interquartile range, 441-1075 days]) were analyzed. The therapeutic efficacy was comparable, whereas technical outcomes were more favorable for AE. Both electrodes demonstrated comparable overall median VRR (FE: 92.4% vs. AE: 84.9%, P = 0.240) without immediate major complications. Overall regrowth rates were comparable between the two groups (FE: 2.2% [2/90] vs. AE: 1.1% [1/90], P > 0.99). AE demonstrated a shorter median RFA time (FE: 811 vs. AE: 627 seconds, P = 0.009). Both delivered comparable median energy (FE: 42.8 vs. AE: 29.2 kJ, P = 0.069), but AE demonstrated higher median ablated volume/energy and median ablated volume/time (FE: 0.2 vs. AE: 0.3 cc/kJ, P < 0.001; and FE: 0.7 vs. AE: 1.0 cc/min, P < 0.001, respectively).

CONCLUSION

Therapeutic efficacy between FE and AE was comparable. AE demonstrated better technical outcomes than FE in terms of RFA time, ablated volume/energy, and ablated volume/time.

Comparison of the efficacy and safety of ultrasound-guided radiofrequency ablation and microwave ablation for the treatment of unifocal papillary thyroid microcarcinoma: a retrospective study

PURPOSE

This study aimed to compare the efficacy and safety of ultrasound-guided RFA and MWA in the treatment of unifocal PTMC.

METHODS

This retrospective study included 512 patients with 512 unifocal papillary thyroid microcarcinomas (PTMCs) who underwent RFA (n = 346) and MWA (n = 166) between January 2021 and December 2021. The volumes of the ablation areas were measured during follow-up, and the volume reduction rates were evaluated. The ablation duration, volume of hydrodissection, and ablation-related complications were also compared between the groups.

RESULTS

All lesions received complete ablation and no local or distant recurrences were observed in the two groups. A larger volume of isolation liquid was used for RFA than for MWA (p = 0.000). Hoarseness occurred in seven patients who underwent RFA (p = 0.102). At the 1-week follow-up, the mean volume of the areas ablated by RFA was smaller than that of the areas ablated by MWA (p = 0.049). During follow-ups at months 3, 9, 12, 15, and 18, the mean volumes of the ablated areas were larger in the RFA group than in the MWA group (all, p < 0.05). The mean volume of the ablated lesions increased slightly at the 1-week follow-up and then decreased at 1 month after ablation in both groups. The absorption curve of the ablated lesions in the RFA group was similar to that in the MWA group.

CONCLUSIONS

RFA and MWA are both efficient and safe methods for treating unifocal PTMC. They may be alternative techniques for patients who are not eligible or are unwilling to undergo surgery.

Radiofrequency ablation for papillary thyroid microcarcinoma with a trachea-adjacent versus trachea-distant location

OBJECTIVE

To evaluate the outcomes of radiofrequency ablation (RFA) for papillary thyroid microcarcinoma (PTMC) adjacent to the trachea and compare them with those of PTMC distant from the trachea.

METHODS

Patients who received RFA for solitary low-risk PTMC between June 2014 and July 2020 were reviewed and classified into adjacent and distant groups. To balance between-group confounders, the propensity score matching approach was employed. Volume, volume reduction ratio (VRR), tumor disappearance, complications, and disease progression were assessed and compared between the groups. Furthermore, factors affecting disease progression were evaluated.

RESULTS

A total of 122 and 470 patients were included in the adjacent and distant groups, respectively. Overall VRR was 99.5% ± 3.1 and cumulative tumor disappearance rate was 99.4% after a mean follow-up time of 40.1 months ± 16.2. Overall disease progression and complications incidence were 3.7% and 1.0%, respectively. No substantial differences were observed between the two groups in the latest volume (0.8 mm3 ± 4.1 vs. 0.9 mm3 ± 4.2, p = .77), VRR (99.7% ± 1.6 vs. 99.5% ± 2.7, p = .75), cumulative tumor disappearance rate (92.6% vs. 94.2%, p = .58), and incidence of disease progression (4.1% vs. 4.5%, p = .70) and complication (1.7% vs. 0.8%, p = .86) after 1:2 matching. Additionally, tracheal adjacency exhibited no association with disease progression in multivariate Cox regression analysis (p = .73).

CONCLUSION

For eligible patients with PTMC located adjacent to or distant from the trachea, RFA may offer a safe and effective alternative treatment method.

Long-Term Outcomes and Risk Factors of Radiofrequency Ablation for T1N0M0 Papillary Thyroid Carcinoma

Importance

Radiofrequency ablation (RFA) has gained increasing interest as a minimally invasive procedure to treat low-risk papillary thyroid carcinoma (PTC). Considering the indolent nature of this disease, studies in large populations with long follow-up would be invaluable to further substantiate the effectiveness of RFA.

Objective

To evaluate the long-term (58.5 months) outcomes of patients with T1N0M0 PTC who underwent RFA and investigate risk factors for local tumor progression (LTP).

Design, Setting, and Participants

This cohort study included 1613 patients aged 18 years or older with T1N0M0 PTC who underwent ultrasonography-guided RFA between January 2014 and December 2020 at the Chinese People's Liberation Army General Hospital in Beijing, China. Included in the analysis were patients with PTC (confirmed by biopsy) with a maximum diameter of 20 mm or less; no evidence of extrathyroidal extension (capsular disruption or involvement of perithyroidal tissue), lymph node metastasis, or distant metastasis on ultrasonography or computed tomography; and no evidence of an aggressive subtype of PTC on biopsy. Patients with PTC larger than 2 cm, less than 12 months of follow-up, or inadequate follow-up information were excluded. Data were analyzed in April 2023.

Main Outcomes and Measures

Long-term progression rate, disease-free survival, and complete tumor disappearance and their associations with patient and tumor characteristics. Disease-free survival was calculated using Kaplan-Meier analysis. Cox proportional hazards regression analyses were performed to assess risk factors for LTP and complete tumor disappearance.

Results

The study comprised 1613 patients (mean [SD] age, 43.3 [10.2] years; 1256 women [77.9%]) with 1834 T1N0M0 PTC tumors. During a mean follow-up of 58.5 months (range, 27 to 111 months), LTP was observed in 69 patients (4.3%), including 42 (2.6%) with tumor recurrence and 27 (1.7%) with tumor persistence. Cumulative disease-free survival rates at 1, 3, 5, and 8 years were 98.0%, 96.7%, 96.0%, and 95.7%, respectively. The overall complication rate was 2.0% (32 patients), with 6 (0.4%) major complications. Independent risk factors for LTP included subcapsular tumor location 2 mm or less from the capsule or trachea (hazard ratio [HR], 3.36; 95% CI, 2.02-5.59; P < .001) and multifocal tumors (HR, 2.27; 95% CI, 1.30-3.96; P = .004). Furthermore, 1376 patients (85.3%) showed complete tumor disappearance at follow-up ultrasonographic examination. Factors associated with complete tumor disappearance included age 40 years or less (HR, 0.78; 95% CI, 0.70-0.87; P < .001), stage T1a tumors (HR, 0.37; 95% CI, 0.31-0.45; P < .001), and unifocal tumors (HR, 0.50; 95% CI, 0.42-0.60; P < .001).

Conclusions and Relevance

In this cohort study, ultrasonography-guided RFA for T1N0M0 PTC had excellent long-term outcomes. Patients with unifocal T1N0M0 PTC and subcapsular tumor location more than 2 mm from the capsule or trachea may be the best candidates for RFA.

Radiofrequency ablation of benign thyroid nodules: A prospective, multi-institutional North American experience

BACKGROUND

Radiofrequency ablation for benign thyroid nodules aims to achieve a volume reduction rate of ≥50%. However, factors that predict treatment success have not been defined in a large-scale study.

METHODS

A prospective cohort study of biopsy-proven benign thyroid nodules treated with radiofrequency ablation at 3 institutions was performed. Patient demographics, nodule sonographic features, procedural data, and nodule volume reduction were evaluated. Binary logistic regression analysis was performed to identify features associated with treatment response.

RESULTS

A total of 620 nodules were analyzed. The pooled median volume reduction rate at 12 months was 70.9% (interquartile range 52.9-86.6). At 1 year follow-up, 78.4% of nodules reached treatment success with a volume reduction rate ≥50%. The overall complication rate was 3.2% and included temporary voice changes (n = 14), vasovagal episodes (n = 5), nodule rupture (n = 3), and lightheadedness (n = 2). No permanent voice changes occurred. Four patients developed postprocedural hypothyroidism. Large baseline nodule volume (>20 mL) was associated with a lower rate of successful volume reduction (odds ratio 0.60 [0.37-0.976]). Large nodules achieved treatment success by 12-month follow-up at a rate of 64.5%, compared with 81.4% for small nodules and 87.2% for medium nodules.

CONCLUSION

To our knowledge, this is the largest North American cohort of patients with benign thyroid nodules treated with radiofrequency ablation. Overall, radiofrequency ablation was an effective treatment option with a low risk of procedural complications. Large volume nodules (>20 mL) may be associated with a lower rate of successful reduction with radiofrequency ablation treatment.

Laser Ablation for Benign and Malignant Thyroid Nodules - A Mini-Literature Review

BACKGROUND

Thyroid nodules are a common disease in endocrine clinical practice. They are often benign, asymptomatic, and do not require any treatment. But, in a non-negligible proportion, they can cause local symptoms of compression or esthetic concerns. In the last two decades, the advent of laser ablation (LA) has become a valid alternative to surgery for these nodules. Moreover, LA has also been successfully used to treat small thyroid cancers and neck recurrence.

OBJECTIVE

This study aims to review and summarize the published literature regarding LA in the treatment of benign and malignant thyroid nodules.

METHODS

A comprehensive literature search on PubMed from 2000 to 2023 was carried out. The search terms included: thyroid, nodules, laser, cancer, lymph node metastasis, and autonomously functioning nodules. The most relevant investigations in the field were selected.

RESULTS

In the last two decades, a very remarkable number of papers consistently demonstrated that LA is able to durably shrink benign nodules on average by about 50%; better results are obtained in spongiform nodules with a volume less than 15 ml; 500 J/ml of tissue should be administered. LA may be a valid option to treat autonomously functioning nodules and papillary thyroid cancers especially if they are <10 mm, and with neck recurrence in patients already submitted to surgery. LA has also been demonstrated to be cost-effective compared to surgical treatment both in benign and malignant lesions, with similar outcomes.

CONCLUSION

Evidence demonstrated that LA is a valid alternative to surgery in benign and malignant thyroid lesions, but also to obtain a successful treatment, a careful selection of the lesion is mandatory.

Sonographic Evolution and Pathologic Findings of Papillary Thyroid Cancer After Radiofrequency Ablation: A Five-Year Retrospective Cohort Study

Background: The criteria for determining technical efficacy of thermal ablation for papillary thyroid carcinoma (PTC) are not clearly defined. We analyzed the involution process of the ablation zone with clear pathologic results on core-needle biopsy (CNB) to clarify the relationship between sonographic changes and pathologic findings. Methods: This retrospective cohort study included 382 patients with unifocal T1N0M0 PTC who underwent radiofrequency ablation (RFA) between May 2014 and August 2021. Patients with a single ablation zone biopsy (recommended at 3 or 6 months for T1a and 6 or 12 months for T1b) and regular neck ultrasound (US)/contrast-enhanced ultrasound imaging follow-up at 1, 3, 6, and 12 months and every 6-12 months thereafter after RFA were included. Patients also underwent yearly chest computed tomography. CNB was performed in the target lesion ablation zone's central, peripheral, and surrounding thyroid parenchyma to detect the presence of tumor cells. If the thyrotropin (TSH) was >2 mU/L, levothyroxine was prescribed with the intention of keeping the TSH 0.5-2 mU/L. Technical efficacy was defined as tumor disappearance by imaging follow-up together with the pathologically confirmed absence of tumor cells in the ablation zone. Results: During the mean follow-up period of 67.8 ± 18.2 months (22-110 months), the overall incidence of persistent disease and the technical efficacy rate were 3.9% (15/382; 2.9% of T1a, and 12.2% of T1b) and 96.1%, respectively. Tumor size (p = 0.03) and subcapsular location (p = 0.04) were risk factors associated with persistent disease. The technical success rate was 100%. Of the 367 ablation zones with benign CNB results, 336 (91.6%) showed tumor disappearance on US and no re-emergence of imaging-visible tumors during follow-up. Male sex (p = 0.006), age <40 years (p = 0.003), T1a tumor (p < 0.01), and energy per milliliter (p < 0.03) were significantly associated with tumor disappearance. Conclusions: US-guided RFA is an effective treatment for small low-risk PTC. Tumor disappearance on US after RFA may suggest an excellent prognosis and confirm complete ablation of the macroscopic tumor, but this sonographic finding is generally late and requires histological confirmation.

Efficacy and safety of ultrasound-guided radiofrequency, microwave and laser ablation for the treatment of T1N0M0 papillary thyroid carcinoma on a large scale: a systematic review and meta-analysis

BACKGROUND

To analyze the efficacy and safety of radiofrequency ablation (RFA), microwave ablation (MWA) and laser ablation (LA) in T1N0M0 papillary thyroid carcinoma (PTC) patients by evaluating data on several outcomes on a large scale.

MATERIALS AND METHODS

Literature searches were conducted in PUBMED, EMBASE and the Cochrane Library for studies of thermal ablation (TA) for treating T1N0M0 PTC. Data on the volume reduction rate (VRR) at the 12-month follow-up and final follow-up, complete disappearance rate, local recurrence rate, lymph node metastasis rate, and complication rate of RFA, MWA and LA were evaluated separately. RFA effects were compared between T1aN0M0 and T1bN0M0 patients.

RESULTS

A total of 36 eligible studies were included. RFA presented superior efficacy than MWA in 12-month VRR. At the final follow-up, the difference was slight in subgroups, showing a significant reduction. The complete disappearance rate of LA (93.00%) was higher than that of RFA (81.00%) and MWA (71.00%). Additionally, the local recurrence rate pooled proportions of MWA and RFA were both 2.00%, lower than that of the LA group (3.00%). There was no event of distant metastasis. The lymph node metastasis rates were similar, as RFA (1.00%) had the lowest. For minor complication rates, the pooled proportions of RFA (3.00%) were smaller than those of LA (6.00%) and MWA (13.00%). T1aN0M0 lesions presented with better outcomes than T1bN0M0 lesions.

CONCLUSION

RFA, MWA and LA were reliable in curing PTC, and RFA presented advantages in most outcomes. T1aN0M0 patients may experience fewer side effects than T1bN0M0 patients.

Efficacy and safety of microwave ablation for the treatment of multifocal versus unifocal T1N0M0 papillary thyroid carcinoma: a propensity-matched multicentre retrospective study

OBJECTIVES

Microwave ablation (MWA) has been widely used for unifocal papillary thyroid carcinoma (U-PTC) and has recently been preliminarily used in multifocal papillary thyroid carcinoma (M-PTC). However, the efficacy and safety of MWA for M-PTC have not been investigated in large samples. The aim of the present study was to evaluate the efficacy and safety of MWA for M-PTC and compare them with MWA for U-PTC.

MATERIALS AND METHODS

This retrospective multicentre study enrolled 504 patients (376 females) who underwent MWA for U-PTC (340 cases) or M-PTC (164 cases) from Jan 2015 to Dec 2020. The median age of the patients was 43 years (age range, 20-80 years). Propensity score matching (PSM) was used to balance the baseline characteristics between M-PTC group and U-PTC group. The tumour progression, tumour disappearance, and complication rates were compared between the two groups.

RESULTS

The complete ablation was achieved in all enrolled cases in one session. According to the statistical results, no significant differences were shown in tumour progression-free survival (p  = 0.29) or cumulative tumour progression rate (6.7% vs. 4.3%, p  = 0.33) between the M-PTC and U-PTC groups during the follow-up time. However, the tumour disappearance rate in the M-PTC group was lower in the U-PTC group (40.9% vs. 62.8%, p < 0.001), and tumour disappearance was slower in the M-PTC group (p < 0.001). The complication rate showed no significant difference (3.0% vs. 4.9%, p  = 0.571).

CONCLUSIONS

MWA is an effective and safe treatment for selected patients with M-PTC, and the prognosis is similar to that of U-PTC.

CLINICAL RELEVANCE STATEMENT

The present study provided evidence that compared with unifocal papillary thyroid cancer, microwave ablation could also treat multifocal T1N0M0 papillary thyroid cancer safely with similar clinical outcome, which could promote the application of minimally invasive treatment for papillary thyroid cancer.

KEY RESULTS

• Microwave ablation for multifocal and unifocal T1N0M0 papillary thyroid carcinoma had similar tumour progression rates after propensity score matching (6.7% vs. 4.3%, p = 0.33). • The tumour disappearance rate in the multifocal group was lower than that in the unifocal group (40.9% vs. 62.8%, p < 0.001), and tumour disappearance was slower in the multifocal group (p < 0.001). • Tumour size, number, and location were not risk factors for tumour progression in the multifocal papillary thyroid cancer group.