Vital volume increase versus clinical evaluation as the indication of additional radiofrequency ablation for benign thyroid nodule: a single center retrospective study

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

A New Perspective for Predicting the Therapeutic Success of RFA in Solid BTNs: Quantitative Initial RFA Ratio by Contrast-Enhanced Ultrasound

OBJECTIVE

The short-term therapeutic success of radiofrequency ablation (RFA) in solid benign thyroid nodules is of great concern. The aim of this study was to investigate a new method, initial radiofrequency ablative ratio (IRAR) using contrast-enhanced ultrasound (CEUS), for predicting therapeutic success of RFA in solid benign thyroid nodules (BTNs) immediately and effectively after RFA.

METHODS

A total of 813 nodules in 776 patients with benign thyroid nodules were treated with RFA from January 2014 to August 2018, among which 120 patients (M:F=41:79) with 120 solid BTNs (small: ≤10ml, n=57; medium: 10-30ml, n=42; large: >30ml, n=21) were enrolled in our study according to the inclusion criteria. The IRAR was defined as the ablative volume ratio immediately after RFA displayed by CEUS. The therapeutic success was evaluated at the 6-month follow-up. The relationship between the IRAR and volume reduction ratio (VRR) at 6-month was analyzed. The marginal regrowth of solid BTNs was also examined by CEUS at the 6 and 12 months of follow-up.

RESULTS

In medium and large nodules, the IRAR was significantly and positively correlated with VRR (r= 0.69, P < 0.001) at 6 months after RFA. There was a tendency to achieve therapeutic success (50% VRR: 55/63, 87.3%) when the IRAR exceeded 75%, and marginal regrowth was also relatively slow within 12 months after a single session treatment. No significant correlation between IRAR and VRR of small nodules was found. In conclusion, IRAR is significantly and positively correlated with VRR, which may indicate therapeutic success when it exceeds 75%.

CONCLUSIONS

CEUS can be used to accurately quantify the IRAR, which is positively correlated with the VRR. Moreover, the IRAR may be used as a parameter to predict the short-term therapeutic success of RFA in solid BTNs.

Contrast-enhanced ultrasound is a reliable and reproducible assessment of necrotic ablated volume after radiofrequency ablation for benign thyroid nodules: a retrospective study

PURPOSE

To investigate the intra- and inter-observer reliability and agreement of contrast-enhanced ultrasound (CEUS) in measuring ablated volume (Va) after radiofrequency ablation (RFA) for benign thyroid nodules.

MATERIALS

This retrospective study evaluated 65 patients with 74 benign thyroid nodules who underwent RFA. Patients were followed up at 1, 3, 6, and 12 months and every 12 months thereafter. Two independent observers measured the Va using CEUS during the same follow-up visit. The intra- and inter-observer reliability was assessed using intraclass correlation coefficient (ICC) with 95% confidence interval. The Bland-Altman analysis was used to evaluate the inter-observer agreement, which was expressed as a mean difference with 95% limit of agreement (LOA).

RESULTS

No significant difference was found in Va measurements by the two observers with a mean follow-up time of 41.17 ± 16.80 months (all p > 0.05). The intra- and inter-observer reliability were both excellent (ICC >0.90) at each follow-up period. The 95% LOA became wider over the follow-up period. The smallest 95% LOA was found at 1 month with a LOA from 0.8117 to 1.122, and the largest 95% LOA was from 0.5694 to 1.343 at 36 months.

CONCLUSIONS

CEUS could provide a reliable and reproducible assessment of Va after RFA for benign thyroid nodules. In clinical post-ablation follow-up, the irregular morphology of ablated area and the variation by different observers could not affect the assessment of Va by CEUS.

Learning curve for radiofrequency ablation of benign thyroid nodules

Objective: To evaluate the effect of operator experience on the treatment outcomes of radiofrequency ablation (RFA) for benign thyroid nodules (BTN). Methods: Data from the 90 first RFA procedures of a single operator in treating benign thyroid nodules were prospectively collected and retrospectively analyzed. Patients were divided into 3 groups according to their chronological treatment rank: patients 1-30 (G1), 31-60 (G2) and 61-90 (G3). Clinical symptoms, volume reduction ratio (VRR), technique efficacy (TE) defined as a VRR > 50% and ablation ratio (AR) were compared between the three groups at 6 months follow-up. All complications and side effects were recorded. Results: No significant difference was observed in improvement of clinical symptoms after the RFA procedure between the three groups, with higher satisfaction however for pressure symptoms than for esthetic complaints (complete resolution 87.5% and 52.6%, respectively). In groups 1, 2 and 3, TE was 60%, 93.3%, 76.7%, VRR 54%, 65%, 60% and AR 13.1%, 34%, 34.6%, respectively. Thus, all ultrasound efficacy parameters (TE, VRR, AR) improved significantly between G1 and G2, with no difference between G2 and G3. Solely did AR improve in nodules ≤ 30 mL between G2 and G3 to reach a median value of 94.4% in G3 versus 57.1% in G2 and 13.7% in G1. Maximum values of TE and VRR (95.6% and 68%, respectively) were seen in nodules ≤ 30 mL in G2 at 6 months follow-up, with no improvement in G3 (84.2% and 63%, respectively). Both baseline volume and energy per volume were independently associated with VRR and AR. Three minor complications were recorded which all recovered totally after conservative treatment. Conclusion: There was a measurable learning curve in RFA for benign thyroid nodules regarding efficacy until 90 patients. VRR and AR can be used as proficiency markers. Only three transient complications occurred confirming the safety of the procedure.

Long-Term Results of Ultrasound-Guided Radiofrequency Ablation of Benign Thyroid Nodules: State of the Art and Future Perspectives-A Systematic Review

Background

Nearly 20 years after the first feasibility study, minimally invasive ultrasound (US)-guided therapeutic techniques are now considered as a safe and effective alternative to surgery for symptomatic benign thyroid nodules. Radiofrequency ablation (RFA) is one of the most widely used treatment in specialized thyroid centers but, due to the relatively recent introduction into clinical practice, there are limited long-term follow-up studies. Aim of our work was to review the outcomes of RFA on solid nonfunctioning and on autonomous thyroid nodules (AFTN) on a long-time period for assessing the results in term of efficacy, complications, and costs and to compare them to the current indications of RFA.

Methods

A systematic review was performed using EMBASE and Medline library data between 2008 and 2021. Seventeen studies evaluated RFA for the treatment of benign solid (nonfunctioning or autonomous) thyroid nodules, with an at least 18 months of follow-up. Data extraction and quality assessment were performed by two endocrinologist according to PRISMA guidelines. Anthropometric data, safety and efficacy parameters were collected.

Results

The majority of the studies was retrospective study and reported 933 nodules, mostly solid. Baseline volume ranged between 6.1 ± 9.6 and 36.3 ± 59.8 ml. Local analgesia was used and the time duration of the treatment was between 5 ± 2 and 22.1 ± 10.9 min. The volume reduction rate at 12 months ranged from 67% to 75% for the nodule treated with a single procedure and reached to 93.6 ± 9.7% for nodules treated with repeat ablations. The regrowth rate at 12 months ranged from 0% to 34%.

Conclusion

All the studies under examination consistently validated the long-term clinical efficacy and the substantial safety of RFA for the treatment of benign thyroid nodules. Thermal ablation, however, is an operator-dependent technique and should be performed in centers with specific expertise. The selection of the patients should be rigorous because the nodule size and the structural and functional characteristics influence the appropriateness and the outcomes of the treatment. Future perspectives as the treatment of micro-papillary thyroid cancer or cervical recurrence need further investigations.

A Nomogram to Predict Regrowth After Ultrasound-Guided Radiofrequency Ablation for Benign Thyroid Nodules

OBJECTIVE

To develop and validate a nomogram to predict regrowth for patients with benign thyroid nodules undergoing radiofrequency ablation (RFA).

METHODS

A total of 200 patients with 220 benign thyroid nodules who underwent RFA were included in this respective study. After RFA, patients were followed up at 1, 3, 6, and 12 months, and every 12 months thereafter. Regrowth was defined as an increase in nodule volume 50% over the previously recorded smallest volume. A nomogram was developed based on the variables identified by multivariate logistic regression and the model performance was evaluated by discrimination(concordance index) and calibration curves.

RESULTS

The incidence of regrowth was 13.64% (30/220) after a mean follow-up period of 27.43 ± 17.99 months. Multivariate logistic regression revealed initial volume (OR = 1.047, 95%CI 1.020-1.075), vascularity (OR = 2.037, 95%CI 1.218-3.404), and location close to critical structure (OR = 4.713, 95%CI 1.817-12.223) were independent factors associated with regrowth. The prognostic nomogram incorporating these three factors achieved good calibration and discriminatory abilities with a concordance index of 0.779 (95%CI 0.686-0.872).

CONCLUSIONS

A prognostic nomogram was successfully developed to predict nodule regrowth after RFA, which might guide physician in stratifying patients and provide precise guidance for individualized treatment protocols.