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

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.

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.

Advances in influence factors of ultrasound-guided percutaneous thermal ablations for benign thyroid nodules: A review

Ultrasound-guided percutaneous thermal ablation is a safe and effective minimally invasive treatment for benign thyroid nodules, which is now widely used in the world. Studies have found that some preoperative factors played an important role in the outcome of thermal ablation. This paper mainly reviews the various factors affecting the efficacy of ultrasound-guided percutaneous thermal ablation in the treatment of benign thyroid nodules to provide a variety of perspectives for the clinical and to promote the postoperative outcome of patients.

Sublethal thermal stress promotes migration and invasion of thyroid cancer cells

OBJECTIVE

Radiofrequency ablation is a viable option in the treatment of benign thyroid nodules. Some reports suggest that thermal ablation may also be safe for the management of low-risk thyroid cancer. In this study, we applied transient heat treatment to thyroid cancer cells to mimic clinical scenarios in which insufficient ablation leads to incomplete eradication of thyroid cancer.

METHODS

Differentiated thyroid cancer cell lines B-CPAP, TPC-1, and FTC-133 were subjected to heat treatment at different temperatures for 10 min. Effects on cell growth, clonogenicity, wound healing assay, and Transwell invasion were determined.

RESULTS

Heat treatment at 45°C or higher reduced cell growth, whereas viability of thyroid cancer cells was not changed after heat treatment at 37, 40, or 42°C. Heat treatment at 40°C increased the number of colony formations by 16% to 39%. Additionally, transient heat treatment at 40°C resulted in a 1.75-fold to 2.56-fold higher migratory activity than treatment at 37°C. Invasive capacity was increased after heat treatment, ranging from 115% to 126%. Expression of several epithelial-mesenchymal transition markers, including ZEB1, N-cadherin, and MMP2, was upregulated following heat treatment at 40°C.

CONCLUSION

We for the first time demonstrate that sublethal thermal stress may increase clonogenicity, migration, and invasion of thyroid cancer cells.

Effect of ultrasound parameters of benign thyroid nodules on radiofrequency ablation efficacy

BACKGROUND AND AIM

Ultrasound-guided radiofrequency ablation (RFA) is a minimally invasive therapy for thyroid nodules (TNs). Understanding the determinants of RFA efficacy can improve treatment and prognosis. This study aims to investigate the relationship between ultrasound parameters of benign TNs and the efficacy of RFA.

METHODS

A pretest-posttest interventional study was conducted in 2021 on 250 randomly sampled patients with benign TNs, receiving RFA. For this purpose, the volume reduction (VR) and the VR ratio (VRR) of the nodules were measured at the 1-, 3-, 6-, and 12-month follow-up periods after the RFA completion. The technical success rate (TSR) of this procedure was then categorized into four states, including low (VRR < 25%), moderate (VRR = 25-49%), high (VRR = 50-74%), and very high (VRR ≥ 75). Ordered logistic regression (OLR) was further utilized to investigate the effect of the ultrasound parameters of TNs on the TSR. The analyses were notably performed using Stata 14.2.

RESULTS

The VRR at the 1-, 3-, 6-, and 12-month follow-up periods were 38.7%, 53.6%, 59.3%, and 59.9%, respectively. The mean VR was also statistically significant at all follow-ups (p < 0.001). At the 1-, 3-, and 6-month follow-up periods, the VR of over 50% was observed in 28.2%, 52.1%, and 65.2% of the nodules, respectively. The odds ratios (ORs) of the RFA success were found to be 4.3 times higher for the nodules in the left lobe compared to the right lobe (OR: 4.31, p = 0.002), 6.3 times greater for isoechoic nodules compared to hyperechoic nodules (OR: 6.39, p < 0.001), 6.2 times higher for hyper-vascular nodules compared to hypo-vascular nodules (OR: 6.25, p = 0.005), and 2.3 times greater for mixed nodules compared to solid ones (OR: 2.37, p = 0.049).

CONCLUSION

The ultrasound parameters of TNs had a statistically significant effect on the efficacy of RFA. Small-sized, isoechoic, and hyper-vascular nodules, as well as those with mixed tissue, were observed to respond better to RFA, leading to a better prognosis in terms of VR after treatment.

Safety and Efficacy of Ultrasound-Guided Radiofrequency Ablation for Benign Nonfunctional Thyroid Nodules in Children: A Retrospective Study of 62 Patients with Over Four Years of Follow-Up

Background: Image-guided radiofrequency ablation (RFA) for benign nonfunctional thyroid nodules in adults has been shown to be effective and safe, but few trials address the use of RFA in children. Therefore, this study was designed to assess the efficacy and safety of RFA application to benign nonfunctional thyroid nodules in children. Methods: A retrospective study of RFA for 70 benign nonfunctional thyroid nodules in 62 children with four-year follow-up was conducted. Volume reduction ratio (VRR), technique efficacy, regrowth rate, symptom score, and cosmetic score were calculated to evaluate the efficacy. Complications and side effects were recorded. Logistic regression analysis was performed to identify risk factors, and subgroup analyses were performed. Results: Patients were followed up for at least four years (59.1 ± 10.5 months, range 48-85 months). After RFA treatment, the VRR and technique efficacy rates were highest at the first year^* (77.5% and 91.4%, respectively) but decreased by four years (55.1% and 81.4%, respectively). The symptom score decreased from 4.0 ± 2.1^* to 0.8 ± 1.6 (Z = -6.82, p < 0.001), and the cosmetic score decreased from 3.3 ± 0.7 to 1.3 ± 0.9 (Z = -7.0, p < 0.001).^* The nodule regrowth rate was 22.9%, of which 56.3% of cases represented loss of efficacy. In the cases of loss of efficacy, 66.7% had greater volume than their initial presentation. Patients who received a second RFA treatment due to loss of efficacy lost efficacy again. Bilateral nodules, low vascularity, and low cystic components were independent risk factors correlating with technique efficacy. Bilateral nodules correlated with low VRR, low efficacy rate, and high regrowth rate. Nodules with a higher proportion of cystic components had higher VRR. The overall complication rate was 4.8%. Conclusions: RFA was effective in reducing the volume of benign nonfunctional thyroid nodules in children, providing significant symptomatic relief with a good safety profile during short- and long-term follow-up. RFA is a good minimally invasive treatment modality for selected pediatric patients, and it may not be appropriate for the treatment of bilateral thyroid nodules in children.