Investigating the optimal maximum diameter of benign thyroid nodules for thermal ablation on the basis of complete disappearance rate.

OBJECTIVE: Thermal ablation (TA) is a safe and effective treatment for benign thyroid nodules (BTNs). However, there has been no consensus on the optimal maximum diameter (MD) of BTNs for TA. This study aimed to identify the optimal MD of BTNs for TA based on complete disappearance rate after TA. MATERIALS AND METHODS: This retrospective study included 639 BTNs treated with TA from June 2014 to January 2022. The complete disappearance rate of BTNs after TA was summarized, related influencing factors were explored, and the optimal MD of BTNs for TA was identified. RESULTS: At the final follow-up (median: 40 months, range: 24-95 months), the overall volume reduction rate was 95.4 ± 9.0%, and 50.5% of the BTNs (323/639) completely disappeared. The MD was significantly negatively correlated with complete disappearance (odds ratio 0.89, 95% confidence interval 0.87-0.92; p < 0.001). Calcification, comet-tail artifacts, multilocular cysts, and composition of BTNs, as well as diabetes were negatively correlated with complete disappearance. Restricted cubic spline indicated that an MD of 25.0 mm was the optimal threshold of BTNs for TA, which was confirmed by subgroup logistic regression analysis. Compared with BTNs with MD ≤ 25.0 mm, those with MD > 25.0 mm had a greater complication rate (6.5% vs. 2.4%, p = 0.012). CONCLUSIONS: The MD of BTNs was negatively correlated with complete disappearance after TA; an MD > 25.0 mm indicated a reduced likelihood of complete disappearance compared with an MD ≤ 25.0 mm. An MD of 25.0 mm is an appropriate threshold of BTNs for TA on the basis of complete disappearance rate.

Efficacy and safety of microwave ablation for treatment of follicular thyroid neoplasms: a preliminary study.

OBJECTIVE: To assess the feasibility, efficacy, and safety of microwave ablation in treating follicular thyroid neoplasms and suspicious follicular thyroid neoplasms. METHODS: In this retrospective study, the data of patients treated with microwave ablation for follicular neoplasms from December 2016 to January 2024 were summarized. The changes in nodule size, volume, technical success rate, disease progression, complete tumor resolution, thyroid function, and complications post-ablation were evaluated. RESULTS: Seventy-four patients (15 men, 59 women; mean age 46.3 ± 15.2 years) with follicular neoplasms were included. Over a median follow-up of 13 months, complete ablation was achieved, giving a 100% technical success rate. At the first month post-ablation, the maximum diameter of nodules showed no significant change (p = 0.287). From the third month, both maximum diameter and volume significantly decreased (p < 0.005 for all). Volume reduction rates remained stable at one and three months (p = 0.389 and 0.06, respectively) but increased significantly thereafter (p < 0.005 for all). By 24 months, the median maximum diameter had reduced from 2.3 cm to 0 cm, achieving a median volume reduction rate of 100%. Nodules disappeared completely in 20.3% (15/74). Local recurrence was noted in 2.7% of cases (2/74), with no metastasis or neoplasm-related deaths reported. Thyroid function remained unchanged post-treatment (p > 0.05). The complication and side effect rates were 8.1% and 4.1%, respectively. CONCLUSIONS: Initial findings suggest microwave ablation is an effective and safe treatment for follicular neoplasms, with low incidences of disease progression and complications, while maintaining thyroid function.

Efficacy of percutaneous microwave ablation guided by contrast-enhanced and two-dimensional ultrasound for in hepatic alveolar echinococcosis in difficult/dangerous locations.

Background: Ultrasound-guided microwave ablation (MWA) has become a popular method for treating malignant liver tumors. However, few studies have investigated its use in the treatment of hepatoalveolar echinococcosis (HAE). This study aimed to explore the effectiveness and safety of contrast-enhanced ultrasound combined with two-dimensional ultrasound-guided MWA for the treatment of HAE in difficult/dangerous locations. Methods: Data from 81 patients, who were diagnosed with hepatic alveolar hydatid disease in difficult/dangerous locations between January 2018 and January 2023, and underwent contrast-enhanced ultrasonography combined with two-dimensional ultrasound-guided MWA, were analyzed. After undergoing MWA, patients were followed up to determine whether the lesions recurred and to evaluate the therapeutic effect of MWA. Preoperatively, individualized strategies were designed for lesions in different locations, and different auxiliary ablation technologies were used for contrast-enhanced ultrasound combined with two-dimensional ultrasound-guided MWA to achieve complete inactivation of lesions in difficult/dangerous locations. Results: MWA was performed on 89 HAE lesions in 81 patients. The median diameter of the lesions was 2.86 cm (interquartile range [IQR] 2.36-3.49 cm). The complete ablation rate after surgery was 100%, with a recurrence rate of 11.11%, and median follow-up of 24 months (IQR 12-48 months). The incidence of minor complications was 14.81%; no serious complications or deaths occurred. Compared with before surgery, TB, DB, alanine aminotransferase, and aspartate aminotransferase levels increased (p < 0.001), albumin platelets and activated partial thromboplastin time decreased (p < 0.05), with no statistical difference in prothrombin time (p > 0.05). Conclusion: MWA may be a safe and effective method for treating HAE in difficult/dangerous locations, and may represent a new and alternative option for this patient population.

Risk factors for recurrent laryngeal nerve injury in microwave ablation of thyroid nodules: A multicenter study.

BACKGROUND AND PURPOSE: This study aimed to investigate the risk factors for recurrent laryngeal nerve (RLN) injury after microwave ablation (MWA) of thyroid nodules and to identify factors influencing the recovery time of post-procedure hoarseness. MATERIALS AND METHODS: We retrospectively analyzed data from patients who underwent MWA for thyroid nodules at five hospitals between November 2018 and July 2022. Patients were divided into malignant and benign nodule groups. Variables analyzed included nodule size and location, the shortest distance from nodules to the thyroid capsule and tracheoesophageal groove (TEG-D), and ablation parameters. Univariate and multivariate analyses were performed to identify risk factors. Kaplan-Meier and Cox analyses were used to evaluate the recovery time of hoarseness after MWA. RESULTS: The study included 1,216 patients (mean age 44 ± 12 [SD] years; 901 women) with 602 malignant nodules and 614 benign nodules. The posterior capsule distance (PCD) and TEG-D were identified as independent influencing factors for hoarseness in all patients (P = 0.014, OR = 0.068; P < 0.001, OR = 0.005; AUC = 0.869). TEG-D was a significant risk factor for hoarseness, with safe thresholds identified at 4.9 mm for malignant nodules and 2.2 mm for benign nodules. Among patients who developed hoarseness, those in the close-distance group (TEG-D≤2 mm) had a longer recovery time compared to the distant-distance group. TEG-D was an independent factor influencing recovery time (P = 0.008, HR = 11.204). CONCLUSION: Clinicians should consider several factors, particularly TEG-D and PCD, when assessing the risk of RLN injury before MWA. TEG-D was a vital independent factor influencing recovery time. SUMMARY: Clinicians should pay attention to several influencing factors for RLN injury before MWA and TEG-D was an independent influencing factor for recovery time of hoarseness after MWA.

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.

Influence of maximum diameter on fine-needle aspiration biopsy outcomes in ACR TI-RADS 5 thyroid nodules.

Introduction: Fine needle aspiration (FNA) biopsy is a widely accepted method for diagnosing thyroid nodules. However, the influence of maximum diameter (MD) of ACR TIRADS 5 (TR5) thyroid nodules on the FNA outcomes remains debated. This study examined the influence of MD on the FNA outcomes and investigated the optimal MD threshold for FNA in TR5 nodules. Methods: We conducted a retrospective analysis of 280 TR5 thyroid nodules from 226 patients who underwent FNA from January to June 2022 in our department. Probably malignant (PM) group was defined as Bethesda V in cytopathology with confirmed BRAF V600E mutation or Bethesda VI, the other cytopathology outcomes were defined as probably benign (PB) group. We examined factors influencing malignant cytopathology outcomes and determined the optimal MD threshold for FNA in TR5 nodules using logistic regression and restricted cubic spline (RCS) analysis. Results: Among these nodules, 58.2% (163/280) had PM outcomes. The PM group had a significantly larger MD than the PB group [6.5mm (range 5.0-8.4) vs. 5.3mm (range 4.0-7.0), p < 0.001]. In multivariate logistic regression fully adjusted for confounders, MD was significantly associated with PM outcomes [odds ratio 1.16, 95%CI 1.05-1.31; p = 0.042]. The highest quartile of MD had a greater likelihood of PM outcomes compared to the lowest quartile [odds ratio 4.71, 95% CI 1.97-11.69, p = 0.001]. The RCS analysis identified 6.2 mm as the optimal MD threshold for FNA in TR5 nodules. Conclusion: MD significantly affects the probability of malignant outcomes in FNA of TR5 thyroid nodules. A MD threshold of ≥6.2mm is suggested for FNA in these nodules.

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.

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.

A Preliminary Study on the Microwave Ablation of Multifocal Papillary Thyroid Microcarcinoma.

RATIONALE AND OBJECTIVES: To evaluate the feasibility, efficiency, and safety of microwave ablation (MWA) for multifocal papillary thyroid microcarcinoma (PTMC). METHODS: This was a retrospective study, and the data of patients who underwent MWA for multifocal PTMC from October 2016 to December 2021 were reviewed. After ablation, the changes in tumor size and volume, as well as the rates of technical success, tumor disappearance, disease progression, and complications, were assessed. According to the tumor location, the cases were further divided into a unilateral multifocal disease (UMD) subgroup and a bilateral multifocal disease (BMD) subgroup. Further analyses were carried out. RESULTS: There was a total of 94 cases enrolled in the present study, which included 24 males and 70 females. The median age was 40 years (22-66 years); the median follow-up time was 14 months (6-48 months). Complete ablation was achieved in all enrolled cases. Therefore, the technical success rate was 100%. Due to expanding ablation, the MD and volume of the ablation zone increased at the 1st and 3rd months after ablation and decreased from the 12th month after ablation (p < 0.05 for all). The total complete tumor disappearance rates were 45/94 (47.87%) overall, 40.625% (13/32) in the UMD subgroup and 51.61% (32/62) in the BMD subgroup (p = 0.312). The total disease progression rates were 4.26% (4/94) overall, 6.25% (2/32) in the UMD subgroup and 3.23% (2/62) in the BMD subgroup (p = 0.881). The overall complication rate was 4.26% (4/94). CONCLUSION: This preliminary study indicates that MWA is a safe and effective treatment for multifocal PTMC.

Ultrasound-guided microwave ablation versus surgery for solitary T1bN0M0 papillary thyroid carcinoma: a prospective multicenter study.

OBJECTIVE: Microwave ablation (MWA) has emerged as a minimally invasive technology for papillary thyroid microcarcinoma (PTMC), but it has not been widely applied to treat T1bN0M0 PTC with high-level evidence. This study was designed to compare the real-world efficacy and safety of MWA or surgery for treating T1bN0M0 PTC. METHODS: From December 2019 to April 2021, 123 continuous unifocal T1bN0M0 PTC patients without lymph node metastasis (LNM) or distant metastasis (DM) were included from 10 hospitals. Patients were allocated into the MWA or surgery group based on their willingness. The main outcomes were local tumour progression (LTP), new thyroid cancer, LNM, and DM. The secondary outcomes included changes in tumour size and volume, complications, and cosmetic results. Subgroup analyses were conducted to identify influencing factors. RESULTS: Fifty-two patients chose MWA, and 71 patients chose surgery. Patients had similar demographic information and tumour characteristics in the two groups. The follow-up durations after MWA and surgery were 10.6 ± 4.2 and 10.4 ± 3.4 months, respectively. The LNM rate was 5.8% in the MWA group and 1.4% in the surgery group (p = 0.177). No LTP, new thyroid cancer, or distant metastasis (DM) occurred in either group. Five (9.6%) of the 52 patients in the MWA group and 8 (11.3%) of the 71 patients in the surgery group had complications (p = 0.27). Better cosmetic results were found in the MWA group (p < 0.01). CONCLUSION: MWA achieved comparable short-term treatment efficacy with surgery. MWA might be an optional choice for surgery for low-risk T1bN0M0 PTC but concerns about LNM need to be studied further. CLINICAL RELEVANCE STATEMENT: MWA achieved comparable short-time treatment efficacy with surgery. MWA might be an optional choice for surgery for low-risk T1bN0M0 PTC. KEY POINTS: • MWA achieved comparable short-term treatment efficacy with surgery. MWA might be an optional choice for surgery for low-risk T1bN0M0 PTC but concerns about LNM need to be studied further. • The complication rate in the surgery group was higher than that in the MWA group without a significant difference. • There was no statistically significant difference in the LNM rate between the MWA and surgery groups.