Comparative efficacy and safety of radiofrequency ablation and microwave ablation in benign thyroid nodule treatment: a systematic review and meta-analysis.

OBJECTIVE: Ultrasound-guided thermal ablation, including radiofrequency ablation (RFA) and microwave ablation (MWA), has become one of the main options for treating benign thyroid nodules (BTNs). To assess the efficacy of thermal ablation of BTNs, we performed a systematic review and meta-analysis of relevant studies. MATERIALS AND METHODS: A comprehensive search of MEDLINE, EMBASE, and COCHRANE databases was performed up to September 25, 2023, to identify studies directly comparing RFA and MWA for pathologically proven BTNs and reporting clinical outcomes and complications. Data extraction and quality assessment were independently performed by two radiologists according to PRISMA guidelines. The analysis yielded the serial volume reduction ratios (VRRs) of ablated nodules for up to 12 months, symptom and cosmetic scores, and complications. RESULTS: This analysis included nine studies with 1305 BTNs treated by RFA and 1276 by MWA. VRRs at 1 month, 3 months, and 6 months were similar between RFA and MWA, but RFA showed a significantly higher VRR (83.3%) than MWA (76.9%) at 12 months (p = 0.02). Complication rates showed no significant difference between the two methods. Symptom and cosmetic scores significantly decreased after ablation, without a significant difference between the methods. Subgroup analysis indicated a significantly higher VRR at 12 months for RFA than for MWA for less experienced investigators (≤ 10 years), but no significant difference for more experienced investigators (> 10 years). CONCLUSION: RFA and MWA are both effective and safe methods for treating BTNs. RFA showed a higher VRR at 12 months and seems more suitable for less experienced investigators. CLINICAL RELEVANCE STATEMENT: RFA and MWA are both effective and safe treatments for BTNs, with RFA showing a higher VRR at 12 months. Both methods offer minimally invasive and reliable treatment for thyroid nodules. KEY POINTS: The most effective thermal ablation technique for BTNs remains undetermined. RFA showed a higher VRR at 12 months than MWA. Both techniques are effective for treating thyroid nodules; RFA offers greater benefits, particularly for less experienced investigators.

Effectiveness of microvascular flow imaging for radiofrequency ablation in recurrent thyroid cancer: comparison with power Doppler imaging.

OBJECTIVES: To compare microvascular flow imaging (MVFI) and power Doppler ultrasonography imaging (PDUS) for detecting intratumoral vascularity in recurrent thyroid cancer both before and after radiofrequency ablation (RFA). METHODS: This retrospective study included 80 patients (age, 57 ± 12 years; 54 women) with 110 recurrent tumors who underwent RFA between January 2021 and June 2023. A total of 151 PDUS and MVFI image sets were analyzed (85 pre-RFA, 66 post-RFA). Two readers assessed vascularity on the images using a four-point scale with a 2-week interval between PDUS and MVFI to estimate inter-reader agreement. Intra-reader agreement was determined by reinterpreting images in reverse order (MVFI-PDUS) after a 1-month gap. Additionally, diagnostic performance for identifying viable tumors after RFA was assessed in 44 lesions using thyroid-protocol CT as a reference standard. RESULTS: MVFI demonstrated higher vascular grades than PDUS, both before (reader 1: 3.04 ± 1.15 vs. 1.93 ± 1.07, p < 0.001; reader 2: 3.20 ± 0.96 vs. 2.12 ± 1.07, p < 0.001) and after RFA (reader 1: 2.44 ± 1.28 vs. 1.67 ± 1.06, p < 0.001; reader 2: 2.62 ± 1.23 vs. 1.83 ± 0.99, p < 0.001). Inter-reader agreement was substantial (κ = 0.743) and intra-reader agreement was almost perfect (κ = 0.840). MVFI showed higher sensitivity (81.5%-88.9%) and accuracy (84.1%-86.4%) than PDUS (sensitivity: 51.9%, p < 0.01; accuracy: 63.6-70.5%, p < 0.04), without sacrificing specificity. CONCLUSION: MVFI was superior to PDUS for assessing intratumoral vascularity and showed good inter- and intra-reader agreement, highlighting its clinical value for assessing pre-RFA vascularity and accurately identifying post-RFA viable tumors in recurrent thyroid cancer. CLINICAL RELEVANCE STATEMENT: Microvascular flow imaging (MVFI) is superior to power-Doppler US for assessing intratumoral vascularity; therefore, MVFI can be a valuable tool for assessing vascularity before radiofrequency ablation (RFA) and for identifying viable tumors after RFA in patients with recurrent thyroid cancer. KEY POINTS: The value of microvascular flow imaging (MVFI) for evaluating intratumoral vascularity is unexplored. MVFI demonstrated higher vascular grades than power Doppler US before and after ablation. Microvascular flow imaging showed higher sensitivity and accuracy than power Doppler US without sacrificing specificity.

Enhancement on CT for preoperative diagnosis of metastatic lymph nodes in thyroid cancer: a comparison across experience levels.

OBJECTIVES: To investigate the diagnostic performance and interobserver agreement of quantitative CT parameters indicating strong lymph node (LN) enhancement in differentiated thyroid cancer (DTC), comparing them with qualitative analysis by radiologists of varying experience. MATERIALS AND METHODS: This study included 463 LNs from 399 patients with DTC. Three radiologists independently analyzed strong LN enhancement on CT. Qualitative analysis of strong enhancement was defined as LN cortex showing greater enhancement than adjacent muscles on the arterial phase. Quantitative analysis included the mean attenuation value (MAV) of LN on arterial phase (LNA) and venous phase (LNV), LNA normalized to the common carotid artery (NAVCCA), internal jugular vein (NAVIJV), and sternocleidomastoid muscle (NAVSCM), attenuation difference [AD; (LNA - MAVSCM)], and relative washout ratio [((LNA - LNV)/LNA) × 100]. The interobserver agreement and diagnostic performance of the quantitative and qualitative analyses were evaluated. RESULTS: Interobserver agreement was excellent for all quantitative CT parameters (ICC, 0.83-0.94) and substantial for qualitative assessment (κ = 0.61). All CT parameters except for LNV showed good diagnostic performance for metastatic LNs (AUC, 0.81-0.85). NAVCCA (0.85, 95% CI: 0.8-0.9) and AD (0.85, 95% CI: 0.81-0.89) had the highest AUCs. All quantitative parameters except for NAVIJV had significantly higher AUCs than qualitative assessments by inexperienced radiologists, with no significant difference from assessments by an experienced radiologist. CONCLUSION: Quantitative assessment of LN enhancement on arterial phase CT showed higher interobserver agreement and AUC values than qualitative analysis by inexperienced radiologists, supporting the need for a standardized quantitative CT parameter-based model for determining strong LN enhancement. CLINICAL RELEVANCE STATEMENT: When assessing strong LN enhancement in DTC, quantitative CT parameters indicating strong enhancement can improve interobserver agreement, regardless of experience level. Therefore, the development of a standardized diagnostic model based on quantitative CT parameters might be necessary. KEY POINTS: Accurate preoperative assessment of LN metastasis in thyroid cancer is crucial. Quantitative CT parameters indicating strong LN enhancement demonstrated excellent interobserver agreement and good diagnostic performance. Quantitative assessment of contrast enhancement offers a more objective model for the identification of metastatic LNs.

International Expert Consensus on US Lexicon for Thyroid Nodules.

Multiple US-based systems for risk stratification of thyroid nodules are in use worldwide. Unfortunately, the malignancy probability assigned to a nodule varies, and terms and definitions are not consistent, leading to confusion and making it challenging to compare study results and craft revisions. Consistent application of these systems is further hampered by interobserver variability in identifying the sonographic features on which they are founded. In 2018, an international multidisciplinary group of 19 physicians with expertise in thyroid sonography (termed the International Thyroid Nodule Ultrasound Working Group) was convened with the goal of developing an international system, tentatively called the International Thyroid Imaging Reporting and Data System, or I-TIRADS, in two phases: (phase I) creation of a lexicon and atlas of US descriptors of thyroid nodules and (phase II) development of a system that estimates the malignancy risk of a thyroid nodule. This article presents the methods and results of phase I. The purpose herein is to show what has been accomplished thus far, as well as generate interest in and support for this effort in the global thyroid community.

Limitations of fine-needle aspiration and core needle biopsies in the diagnosis of tall cell variant of papillary thyroid carcinoma.

BACKGROUND: The tall cell variant papillary thyroid carcinoma (TCV-PTC) shows aggressive behaviour. Thus far, the diagnosis of TCV-PTC can only be confirmed using the postoperative specimen. This study aims to evaluate whether fine-needle aspiration (FNA) or core needle biopsy (CNB) could diagnose TCV-PTC preoperatively. METHODS: This is a retrospective cohort study. We included adult patients diagnosed with TCV-PTC or PTC with tall cell features (TCF) at final surgical pathology between January 2015 and December 2018. Preoperative histology was reviewed for six cytomorphologic features suggesting TCV-PTC in FNA or the percentage of tall cells in the CNB specimen. The postoperative pathology was also reviewed to confirm the percentage of tall cells. RESULTS: A total of 119 patients were included in this study; 35 (29%) patients with PTC with TCF served as controls. The most frequent cytomorphological feature in FNA samples of TCV-PTC was tall columnar cells, including single tombstone-like cells (70%). Among 43 TCV-PTC evaluated by FNA, 3 FNA (7%) revealed the absence of any of the six cytomorphologic features suggesting TCV-PTC. When we defined 30% of tall cells in CNB specimens as a cutoff suggesting TCV-PTC, only 16 (41%) TCV-PTCs could be preoperatively detected, and 3 (7%) TCV-PTCs did not have any tall cells. The proportion of tall cells was not associated with the postoperative percentage of tall cells. CONCLUSION: Both cytomorphologic features in FNA and the percentage of tall cells in CNB present limitations for use as accurate preoperative diagnostic tools of TCV-PTC.

Diagnostic performance of the 2021 Korean thyroid imaging reporting and data system in pediatric thyroid nodules.

OBJECTIVES: To evaluate the diagnostic performance of 2021 K-TIRADS biopsy criteria for detecting malignant thyroid nodules in a pediatric population, making comparisons with 2016 K-TIRADS. METHODS: This retrospective study included pediatric patients with histopathologically confirmed diagnoses. The diagnostic performance of 2021 K-TIRADS was compared with that of 2016 K-TIRADS. Simulation studies were performed by changing biopsy cut-off sizes for K-TIRADS 5 to 1.0 cm (K-TIRADS5-1.0cm) and 0.5 cm (K-TIRADS5-0.5cm), and for K-TIRADS 4 to 1.0 cm (K-TIRADS4-1.0cm) and 1.0-1.5 cm (K-TIRADS4-1.0~1.5cm). Subgroup analysis was performed in small (< 1.5 cm) and large nodules (≥ 1.5 cm). RESULTS: Two hundred seventy-seven thyroid nodules (54.9% malignant) from 221 pediatric patients were analyzed. All simulated 2021 K-TIRADS showed higher accuracy than 2016 K-TIRADS. Compared with 2021 K-TIRADS5-1.0cm, 2021 K-TIRADS5-0.5cm showed lower specificity (51.6% vs. 47.9%; p = 0.004) but higher sensitivity (77.2% vs. 90.3%; p < 0.001) and accuracy (62.7% vs. 68.9%; p < 0.001). Compared with 2021 K-TIRADS4-1.0cm, 2021 K-TIRADS4-1.0~1.5cm showed higher specificity (44.9% vs. 47.9%; p = 0.018) without significant difference in other diagnostic measures. Compared with 2016 K-TIRADS, 2021 K-TIRADS (biopsy cut-offs, 0.5 cm for K-TIRADS 5; 1.0-1.5 cm for K-TIRADS 4) showed higher sensitivity (34.0% vs. 67.3%; p < 0.001) while maintaining specificity (89.4% vs. 88.2%; p = 0.790) in small nodules, and higher specificity (5.9% vs. 25.4%; p < 0.001) while maintaining sensitivity (100% vs. 98.7%; p = 0.132) in large nodules. CONCLUSIONS: In pediatric patients, 2021 K-TIRADS showed superior diagnostic accuracy to 2016 K-TIRADS, especially with a biopsy cut-off of 0.5 cm for K-TIRADS 5 and 1.0-1.5 cm for K-TIRADS 4. KEY POINTS: • All simulated 2021 K-TIRADS showed higher accuracy than 2016 K-TIRADS. • 2021 K-TIRADS with cut-off size for K-TIRADS 5 of 0.5 cm showed lower specificity but higher sensitivity and accuracy than that of 1.0 cm. • Compared with 2016 K-TIRADS, 2021 K-TIRADS (biopsy cut-offs, 0.5 cm for K-TIRADS 5; 1.0-1.5 cm for K-TIRADS 4) showed higher sensitivity while maintaining specificity in small nodules, and higher specificity while maintaining sensitivity in large nodules.

Diagnostic Performance of Five Adult-based US Risk Stratification Systems in Pediatric Thyroid Nodules.

Background The validation of adult-based US risk stratification systems (RSSs) in the discrimination of malignant thyroid nodules in a pediatric population remains lacking. Purpose To estimate and compare the diagnostic performance of pediatric US RSSs based on five adult-based RSSs in the discrimination of malignant thyroid nodules in a pediatric sample. Materials and methods Pediatric patients (age ≤18 years) with histopathologically confirmed US-detected thyroid nodules at a tertiary referral hospital between January 2000 and April 2020 were analyzed retrospectively. The diagnostic performance of US-based fine-needle aspiration biopsy (FNAB) criteria in thyroid cancer detection was estimated. The following sensitivity analyses were performed: (a) scenario 1: nodules smaller than 1 cm, with the highest category additionally biopsied; (b) scenario 2, application of American College of Radiology Thyroid Imaging Reporting and Data System nodule size cutoffs to other RSSs; (c) scenario 3, scenarios 1 and 2 together. Generalized estimating equations (GEEs) were used for estimation. Results A total of 277 thyroid nodules in 221 pediatric patients (median age, 16 years [interquartile range {IQR}, 13-17]; 172 female; 152 of 277 patients [55%] malignant) were analyzed. The GEE-estimated sensitivity and specificity ranged from 70% to 78% (104 to 119 of 152 patients, based on each reader's interpretation) and from 42% to 78% (49 of 124 patients to 103 of 125 patients). In scenario 1, the missed malignancy rate was reduced from 32%-38% (41 of 134 patients to 34 of 83 patients) to 15%-21% (eight of 59 patients to 28 of 127 patients). In scenario 2, the unnecessary biopsy rate was reduced from 35%-39% (60 of 176 patients to 68 of 175 patients) to 20%-34% (18 of 109 patients to 62 of 179 patients). The highest accuracy was noted in scenario 3 (range, 71%-81%; 199 of 277 patients to 216 of 262 patients). Conclusion The diagnostic performances of the fine-needle aspiration biopsy criteria of five adult-based risk stratification systems were acceptable in the pediatric population and were improved by applying the American College of Radiology Thyroid Imaging Reporting and Data System size cutoff for nodules 1 cm or larger and allowing biopsy of the highest category nodules smaller than 1 cm. © RSNA, 2022 Online supplemental material is available for this article.

Risk factors for metastasis in indeterminate lymph nodes in preoperative patients with thyroid cancer.

OBJECTIVES: To investigate the relevance of clinical and sonographic features as indicators of metastasis in indeterminate lymph node (LN), to determine possible indications for fine-needle aspiration (FNA). METHODS: Consecutive patients who underwent US-guided FNA for sonographic indeterminate LNs from differentiated thyroid carcinoma between January 2014 and December 2018 were retrospectively reviewed. Indeterminate LNs were defined as LNs which had neither an echogenic hilum nor hilar vascularity in the absence of any suspicious finding in accordance with the Korean Society of Thyroid Radiology (KSThR) guidelines. Univariate and multivariate logistic regression analyses were performed to identify significant risk factors related to malignancy of indeterminate LNs. RESULTS: Of the 236 LNs in 212 patients enrolled in this study, 67 LNs (28.3%) were metastatic. The multivariate logistic regression analysis showed that the long diameter of LNs has a negative association with metastasis in indeterminate LNs and the sonographic features of extrathyroidal extension (ETE) and nonparallel orientation of the primary tumor are associated with metastasis in indeterminate LNs. The sensitivity and positive predictive value were increased when FNA was performed for LNs with primary tumors showing ETE or nonparallel orientation than when FNA was performed for LNs larger than 5 mm (59.7% and 40.4% vs. 11.94% and 15.69%). CONCLUSIONS: The size of LNs has a negative association with metastasis in indeterminate LNs. Performing FNA for indeterminate LNs in patients whose primary tumor shows ETE or a nonparallel orientation can improve the diagnostic performance and decrease the rate of unnecessary FNA. KEY POINTS: • The size of lymph nodes was negatively related to the risk of metastasis in indeterminate lymph nodes. • Extrathyroidal extension and a nonparallel orientation of the primary tumor were suggested as sonographic features predicting metastasis in indeterminate lymph nodes. • The routine practice of FNA for large indeterminate lymph nodes detected during preoperative evaluation of thyroid cancer should be discouraged.

Ethanol ablation for the treatment of thyroglossal duct cysts: follow-up results for longer than 2 years.

OBJECTIVES: To evaluate the long-term efficacy and safety of ethanol ablation (EA) for the treatment of thyroglossal duct cysts (TGDCs). METHODS: This retrospective study included 81 consecutive patients diagnosed with and treated for symptomatic TGDCs at two institutions between Jan 2008 and Oct 2018. Preprocedural evaluation included US assessment with calculation of the TGDC volume. EA was performed under US guidance using 99% ethanol. Post-treatment follow-up was scheduled within 3 months, 6 months, and then annually. Immediate success was defined as a volume reduction ratio (VRR; ratio of the volume difference after EA to the initial TGDC volume) > 50% within 3 months. Long-term success was defined as VRR > 50% or resolution or improvement of cosmetic problems and symptoms without recurrence at last follow-up. RESULTS: Seventy-seven patients underwent EA, and outcomes were assessed in 68 patients with available follow-up data. The immediate success rate of the first EA was 81% (55/68), with a mean VRR within 3 months of 73% ± 31%. One patient (1.5%, 1/68) developed wound inflammation after the first EA. Forty-two patients were followed up for longer than 2 years. For the median follow-up of 69 months (range, 24-131 months), the long-term success rate was 83% (35/42), with a mean VRR at last follow-up of 81% ± 35%. No patients developed malignancy from the ablated TGDCs. CONCLUSIONS: EA for treatment of TGDCs achieved acceptable rates of immediate and long-term efficacy with a low complication rate, and can be considered as a first-line treatment for the management of TGDCs. KEY POINTS: • The immediate success rate of EA for the treatment of TGDCs was 81% (55/68), with a mean VRR within 3 months of 73% ± 31%. • For the median follow-up of 69 months (range, 24-131 months), the long-term success rate was 83% (35/42), with a mean VRR at last follow-up of 81% ± 35%. • No patients developed malignancy from the ablated TGDCs but one patient (1.5%, 1/68) developed wound inflammation after the first EA.

Sonographic assessment of minor extrathyroidal extension of papillary thyroid microcarcinoma involving the posterior thyroid capsule.

OBJECTIVES: This study aimed to determine sonographic features and clinical significance of minor extrathyroidal extension (ETE) to the posterior thyroid capsule in papillary thyroid microcarcinoma (PTMC) patients. METHODS: We retrospectively reviewed the records of 506 PTMC patients consisting of 151 patients with minor ETE and 355 patients without ETE. Significant clinicoradiologic features associated with ETE were identified by logistic regression analyses. The diagnostic performance of sonographic features, including the presence of capsular abutment, capsular abutment degree (< 25%, 25-50%, ≥ 50%), and protrusion, were assessed for the diagnosis of posterior minor ETE. Interobserver agreement was calculated. RESULTS: PTMC patients with posterior minor ETE were more likely to have lymphovascular invasion and lateral neck lymph node metastasis (OR = 2.636, 95%CI: 1.754, 3.963 and OR = 2.897, 95%CI: 1.069, 7.848). Regarding the diagnostic performance, the capsular abutment yielded the highest sensitivity (81.5%), followed by ≥ 25% abutment, protrusion, and ≥ 50% abutment (57.0%, 21.9%, and 4.6%, respectively), with similar levels of diagnostic accuracy (71.3-75.1%). The specificity was highest for the sonographic feature of ≥ 50% abutment (99.7%), followed by protrusion, ≥ 25% abutment, and capsular abutment (97.8%, 82.0%, and 68.7%, respectively). Abutment assessment had a moderate interobserver agreement (K = 0.705), and abutment degree and protrusion assessment had a fair and slight interobserver agreement (K = 0.553 and 0.287). CONCLUSIONS: Sonographic features of posterior capsular abutment are sensitive and reliable for diagnosis of posterior minor ETE and are associated with lymphovascular invasion and lateral neck lymph node metastasis in PTMC patients. The assessment of posterior minor ETE is important for considering candidates for active surveillance among PTMC patients. KEY POINTS: • PTMC patients with posterior minor ETE were more likely to have lymphovascular invasion and lateral neck lymph node metastasis. • Sonographic features of posterior capsular abutment are sensitive and reliable for the diagnosis of posterior minor ETE. • The assessment of posterior minor ETE is important for considering candidates for active surveillance among PTMC patients.

Thermal Ablation for the Management of Papillary Thyroid Microcarcinoma in the Era of Active Surveillance and Hemithyroidectomy.

PURPOSE OF REVIEW: Thermal ablation presents a therapeutic option other than active surveillance and immediate surgery for patients with low-risk papillary thyroid microcarcinomas (PTMC). Here, we have reviewed the current oncologic outcome of thermal ablation in PTMC cases and compared it with active surveillance and surgery. RECENT FINDINGS: Thermal ablation in PTMC cases revealed no tumor progression for pooled 5-year follow-up data. This oncologic outcome of thermal ablation was comparable to that of immediate surgery with less morbidity. Additionally, no patient who underwent thermal ablation received delayed surgery during the follow-up period due to anxiety. However, active surveillance has indicated that a substantial proportion (range, 8-32%) of patients underwent surgery mainly due to anxiety. In a subset of PTMC patients who are high-risk surgical candidates or who refuse surgery, especially those who have failed or are reluctant to pursue active surveillance, thermal ablation can be a good option.

Thyroid-dedicated internally-cooled wet electrode for benign thyroid nodules: experimental and clinical study.

BACKGROUND: To assess the effects of radiofrequency ablation (RFA) using an internally-cooled wet (ICW) electrode in ex vivo bovine liver and evaluate the feasibility of the ICW electrode for benign thyroid nodules. METHODS: We developed an 18-gauge ICW electrode with a microhole at the distal tip for tissue infusion of chilled (0 - 4 °C) isotonic saline (rate = 1.5 ml/min). RFA using ICW and IC electrodes were performed in bovine livers (40 pairs, 1-cm active tip, 50 W, 1-min). We compared the morphological characteristics of ablation zones and presence of carbonization. Twenty patients with benign thyroid nodules larger than 5 ml were prospectively enrolled in a clinical study and underwent ultrasound-guided RFA with ICW electrodes. Ultrasound examinations, laboratory data, and symptom and cosmetic scores were evaluated preprocedure and 1 and 6 months after the procedure. RESULTS: In the ex vivo study, the ICW achieved significantly larger ablation zones than the IC (p<.001). In the clinical study, ICW electrodes were tolerable in all patients. At last follow-up, nodule volume had decreased from 15.6 ± 12.1 ml to 4.1 ± 4.3 ml (p<.001), and the mean volume reduction ratio (VRR) was 73.3 ± 13.7% at 6.0 months follow-up. Cosmetic and symptom scores were reduced from 3.52 ± 1.03 to 2.65 ± 0.88 and 3.10 ± 2.17 to 0.85 ± 0.99 (both p<.001), respectively. After RFA, thyroid function was well preserved in all patients, and mean thyroglobulin level decreased from 36.6 ± 52.1 ng/ml to 26.9 ± 62.2 ng/ml. One patient experienced a temporary voice change that recovered within a week. CONCLUSIONS: We developed a thyroid-dedicated ICW electrode that we showed to be feasible and effective in patients with benign thyroid nodules.

Residual, regrowth, and new growth of radiofrequency ablation for benign thyroid nodules of different volumes: two-year follow-up results.

INTRODUCTION: Radiofrequency ablation (RFA) is recognized as an effective technique for the treatment of benign thyroid nodules (BTNs), although the long-term results are limited. This study aimed to evaluate the residual vital volume increase, regrowth, and new growth over a 2-year period after RFA among different nodule volume groups. SUBJECTS AND METHODS: This retrospective study evaluated 135 patients with 153 BTNs who underwent ultrasound guided RFA. The BTNs were categorized into small (<10 mL), medium (10-30 mL), and large (>30 mL) according to the initial volume of BTNs prior to ablation. The volume changes of each nodule were analyzed at 1, 3, 6, 12 and 24 months after RFA. New growth was defined as the growth in volume not found in the early follow-up on ultrasonography. RESULTS: The initial ablation ratio of all BTNs was 99.67%. The mean volume reduction ratio (VRR) of BTNs was 85.53% after 2-year follow-up. The small nodule group showed a lower VRR compared to the other two groups at the 1-month follow-up, and there was no difference of VRR at the subsequent follow-ups. The incidence of residual vital volume increase was 4.58%. The overall incidence of regrowth was 3.92% and the mean timing of regrowth was 16.71 months. New growth occurred in 18.95% of patients. No further treatment was required in the majority of cases. CONCLUSION: RFA achieved a clinically relevant volume reduction in different sizes of single BTNs which persisted for at least 2 years, thereby preventing the need for retreatment.

Comparison Between Familial and Sporadic Non-medullary Thyroid Carcinoma: A Retrospective Individual Risk Factor-Matched Cohort Study.

BACKGROUND: This study aimed to compare clinicopathologic features and outcomes between patients with familial non-medullary thyroid carcinoma (FNMTC) and patients with sporadic non-medullary thyroid carcinoma (SNMTC) after performing individual risk factor-matching. Additionally, the study evaluated a dynamic risk stratification (DRS) system to validate its usefulness for familial-type thyroid carcinoma. METHODS: After individual risk factor-matching, 286 patients remained in the FNMTC group, and 858 patients were assigned to the SNMTC group consisting of papillary thyroid carcinoma (PTC). The prognostic outcomes were compared between the two groups in a matched cohort. RESULTS: During the mean follow-up period of 142 months, recurrences were experienced by 64 patients in the sporadic group (7.5%) and 29 patients in the familial group (10.1%). In the multivariate analysis, the independent risk factors for recurrence were primary tumor size (p = 0.033), gross extrathyroidal extension (p = 0.001), and lymph node metastasis (p < 0.001). The independent risk factors did not include family history alone (p = 1.101) or the number of affected family members (p = 0.122 for 2 members and p = 0.625 for ≥ 3 members). In this matched-cohort study, the DRS system was well adjusted in the FNMTC and SNMTC groups. Moreover, the proportion of DRS categories and the recurrence rate in each DRS category were similar between the familial and sporadic groups. CONCLUSIONS: Family history did not present a statistically significant association with a poor prognosis for PTC patients. With a family history of PTC alone, less aggressive treatment could be considered. In this matched cohort, DRS was adjusted well and could be useful in predicting prognosis, even for PTC patients with a family history of PTC.

Efficacy and safety of thermal ablation for autonomously functioning thyroid nodules: a systematic review and meta-analysis.

BACKGROUND: Although thermal ablation has been regarded as an alternative treatment option for autonomously functioning thyroid nodules (AFTNs), the efficacy of this treatment in patients with AFTNs has not yet been systematically evaluated. In this systematic review and meta-analysis, we aimed to evaluate the efficacy and safety of thermal ablation in the treatment of AFTN, and identify the factors affecting the effectiveness of the treatment. METHODS: Ovid-MEDLINE and Embase databases were searched for studies reporting the efficacy and safety of thermal ablation for patients with AFTN published up until January 6, 2020. Data extraction and quality assessment were performed by two radiologists according to PRISMA guidelines. The primary and secondary outcomes were to yield the pooled proportions of thyroid-stimulating hormone (TSH) normalization and pooled estimates of volume reduction rate (VRR), respectively. Subgroup analyses were performed to identify factors affecting the treatment efficacy. RESULTS: This systematic review identified 411 AFTNs treated by thermal ablation in 391 patients in 14 studies. TSH normalization was achieved in 71.2% of patients and the volume reduction rate was 69.4% at a mean follow-up period of 12.8 months. No patients experienced hypothyroidism or a life-threatening complication during follow-up. Subgroup analyses according to nodule volume did not find a significant difference in TSH normalization (p = 0.54) or VRR (p = 0.94). CONCLUSIONS: Thermal ablation is an effective and safe treatment method for patients with AFTNs. The nodule volume did not affect the efficacy of thermal ablation, and this result should be considered in future thermal ablation guidelines. KEY POINTS: • Thermal ablation has good efficacy and safety in the treatment of autonomously functioning thyroid nodule. • The efficacy of thermal ablation was not affected by nodule volume.

Diagnostic performance of adult-based ATA and ACR-TIRADS ultrasound risk stratification systems in pediatric thyroid nodules: a systematic review and meta-analysis.

OBJECTIVES: To evaluate the diagnostic performance of adult-based "American College of Radiology- Thyroid Imaging Reporting And Data System" (ACR-TIRADS) and "American Thyroid Association" (ATA) in the pediatric population. METHODS: MEDLINE/PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for articles investigating the diagnostic performance of each stratification system (ACR-TIRADS or ATA) and evaluated them according to three aspects: (a) the risk of malignancy in each category; (b) diagnostic performance using the classic indicators (sensitivity, specificity); and (c) diagnostic performance regarding fine needle aspiration/biopsy recommendation. In addition to pathologic diagnosis, we allowed imaging follow-up as the reference standard for benign nodules. RESULTS: Eight articles (1036 thyroid nodules) were included. For ACR-TIRADS, the pooled risk of malignancy in category was as follows: category 5 (59.3%); 4 (20.7%); 3 (11.0%); 2 (6.0%), and 1 (5.5%). For nodules of high suspicion of malignancy (category 4 or 5), the pooled sensitivity and specificity were 0.84 and 0.64. For ATA, the pooled risk of malignancy was as follows: category 5 (55.4%); 4 (34.2%); 3 (12.2%); and 2 (7.5%). For nodules of high suspicion of malignancy (category 4 or 5), the pooled sensitivity and specificity were 0.90 and 0.50. For category 5 nodules, the pooled specificity was significantly higher in ACR-TIRADS (p = 0.02). For ACR-TIRADS, the missed malignancy rate was 21.7% and the unnecessary biopsy rate was 62.7%. Information was not sufficient for this calculation with ATA. CONCLUSIONS: The diagnostic performance of ACR-TIRADS and ATA in the pediatric population was somewhat modest. Large studies are mandatory for further validation and future amendments. KEY POINTS: • The pooled sensitivity and specificity for highly suspicious nodules (category 4 or 5) for ACR-TIRADS were 0.84 and 0.64, and for ATA were 0.90 and 0.50, respectively. • When applying ACR-TIRADS for children, the pooled missed malignancy rate (21.7%) and unnecessary biopsy rates (62.7%) are still reasonably high. Insufficient information was available to perform these calculations for the ATA system. • Current risk stratification systems, especially ACR-TIRADS, require modification by focusing more on increasing the sensitivity and decreasing the missed malignancy rate. Lowering size cut-off for biopsy would be a reasonable option.

Efficacy of radiofrequency ablation for recurrent thyroid cancer invading the airways.

OBJECTIVES: To evaluate the efficacy of radiofrequency ablation (RFA) in patients with recurrent thyroid cancer invading the airways. METHODS: We reviewed patients who had undergone RFA for recurrent thyroid cancer in the central compartment after total thyroidectomy between January 2008 and December 2018. All tumors were classified according to their association with the laryngeal structure and trachea. The volume reduction rate (VRR) and complete disappearance rate were calculated, and their differences were determined relative to the association between the tumor and trachea. Complication rates associated with RFA were evaluated. RESULTS: The study population included 119 patients with 172 recurrent tumors. Mean VRR was 81.2% ± 55.7%, with 124 tumors (72.1%) completely disappearing after a mean follow-up of 47.9 ± 35.4 months. The complete disappearance rate of recurrent tumors not in contact with the trachea was highest, followed by tumors forming acute angles, right angles, and obtuse angles with the trachea, and tumors with intraluminal tracheal invasion (p value < 0.001). The overall complication rate was 21.4%. CONCLUSIONS: RFA is effective and safe for the local control of recurrent tumors in the central neck compartment after total thyroidectomy, even for tumors invading the airways, and may be considered an alternative to surgical resection. The inverse relationship between RFA efficacy and airway invasion suggests that early RFA may benefit patients with recurrent tumors in the central neck compartment. KEY POINTS: • RFA achieved a mean VRR of 81.2% ± 55.7% and complete disappearance of 124 tumors (72.1%) after a mean follow-up of 47.9 ± 35.4 months. • The complete disappearance rate of recurrent tumors not in contact with the trachea was the highest, followed by tumors forming acute angles, right angles, and obtuse angles with the trachea, and tumors with intraluminal tracheal invasion. • Stent-assisted RFA may be a good alternative for palliative treatment of recurrent tumors with intraluminal tracheal invasion.

Unnecessary thyroid nodule biopsy rates under four ultrasound risk stratification systems: a systematic review and meta-analysis.

OBJECTIVES: To summarize and compare unnecessary biopsy rates and diagnostic performance in the examination of thyroid nodules according to four representative US-based risk stratification systems. METHODS: MEDLINE/PubMed and EMBASE databases were searched to identify original articles investigating unnecessary biopsy rates according to at least one of the following guidelines: ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS. The unnecessary biopsy rates for each risk stratification system were pooled using a random-effects model. Meta-regression analyses were performed to explore heterogeneity. Diagnostic odds ratios (DORs) for the appropriate selection of thyroid nodules for fine-needle aspiration were also pooled using a bivariate random-effects model. RESULTS: Eight articles including 13,092 thyroid nodules met the eligibility criteria and were included. The pooled unnecessary biopsy rates of ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS were 25% (95% CI, 22-29%), 51% (95% CI, 44-58%), 38% (95% CI, 16-66%), and 55% (95% CI, 42-67%), respectively. The pooled unnecessary biopsy rate of ACR-TIRADS was significantly lower than that of ATA (p < .001) and K-TIRADS (p < .001), and also lower than that of EU-TIRADS, but not reaching statistical significance (p = .087). The pooled DORs of ACR-TIRADS, ATA, and K-TIRADS were 5.9 (95% CI, 3.6-9.6), 6.3 (95% CI, 4.5-8.8), and 4.5 (95% CI, 1.7-11.6), respectively, with the differences not being statistically significant. CONCLUSIONS: ACR-TIRADS showed a lower unnecessary biopsy rate than the other risk stratification systems albeit DOR was comparable between ACR-TIRADS, ATA, and K-TIRADS. Future revisions of each system should be made by referring to ACR-TIRADS to reduce unnecessary biopsy rates. KEY POINTS: • The pooled unnecessary biopsy rates of ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS were 25% (95% CI, 22-29%), 51% (95% CI, 44-58%), 38% (95% CI, 16-66%), and 55% (95% CI, 42-67%), respectively. • The pooled unnecessary biopsy rate of ACR-TIRADS was significantly lower than that of ATA (p < .001) and K-TIRADS (p < .001). • The pooled DORs of ACR-TIRADS, ATA, and K-TIRADS were 5.9 (95% CI, 3.6-9.6), 6.3 (95% CI, 4.5-8.8), and 4.5 (95% CI, 1.7-11.6), respectively, with the differences not being statistically significant.

Five-year follow-up results of thermal ablation for low-risk papillary thyroid microcarcinomas: systematic review and meta-analysis.

OBJECTIVES: Confidence in long-term treatment results of thermal ablation for papillary thyroid microcarcinoma (PTMC) is required in comparison with active surveillance. The objective of this meta-analysis is to report 5-year follow-up results of thermal ablation for PTMC. METHODS: Ovid MEDLINE and EMBASE databases were searched through May 30, 2020, for studies reporting outcomes in patients with PTMC treated with thermal ablation and followed up for at least 5 years. Data were extracted and methodological quality was assessed independently by two radiologists according to the PRISMA guidelines. RESULTS: Three studies, involving 207 patients with 219 PTMCs, met the inclusion criteria through database searches. None of these patients experienced local tumor recurrence, lymph node metastasis, or distant metastasis or underwent delayed surgery during a mean pooled 67.8-month follow-up. Five new tumors appeared in the remaining thyroid gland of four patients, with four of these tumors successfully treated by repeat thermal ablation. The pooled mean major complication rate was 1.2%, with no patient experiencing life-threatening or delayed complications. CONCLUSIONS: Thermal ablation is an excellent local tumor control method in patients with low-risk PTMC, with low major complication rates at 5 years. KEY POINTS: • No local tumor recurrence, lymph node metastasis, or distant metastasis was noted by thermal ablation during follow-up of 5 years and none underwent delayed surgery. • The pooled mean major complication rate was 1.2%.

Chemical ablation using ethanol or OK-432 for the treatment of thyroglossal duct cysts: a systematic review and meta-analysis.

OBJECTIVES: To review the effectiveness and safety of chemical ablation using ethanol or OK-432 for the treatment of TGDCs (thyroglossal duct cysts). METHODS: MEDLINE and EMBASE databases were searched up to May 29, 2020, to identify studies reporting the safety and efficacy of chemical ablation using ethanol or OK-432 for the treatment of TGDCs. The search query consisted of synonyms of thyroglossal duct cysts and ethanol or OK-432 ablation. The pooled success and complication rates were calculated using the inverse variance method to calculate weights, and pooled proportions were determined using the DerSimonian-Laird random-effects method. RESULTS: Seven original articles including a total of 129 patients were included. The efficacy of chemical ablation was acceptable, with a pooled success rate of 70% (95% CI, 47-86%). The pooled success rate of ethanol ablation was superior to that of OK-432 ablation, although with equivocal statistical significance (84% vs. 51%, p = 0.055). Repeat ethanol ablation achieved a pooled success rate of 47% (95% CI, 24-71%). The chemical ablation procedures were safe, with a pooled major complication rate of 0.9% (95% CI, 0.1-5.8%). CONCLUSIONS: Chemical ablation using ethanol or OK-432 for the treatment of TGDCs had acceptable success and low complication rates, and repeat treatment after initial failure was also feasible. In addition, it is an inexpensive and simple procedure and could therefore be considered a first-line treatment for TGDCs. KEY POINTS: • The efficacy of chemical ablation using ethanol or OK-432 was acceptable, with a pooled success rate of 70% (95% CI, 47-86%). The pooled success rate of ethanol ablation was superior to that of OK-432 ablation, although with equivocal statistical significance (84% vs. 51%, p = 0.055). • Repeat ethanol ablation was also feasible, with a pooled success rate of 47% (95% CI, 24-71%). • The chemical ablation procedures were safe, with a pooled major complication rate of 0.9% (95% CI, 0.1-5.8%).