2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The value of ACR, European, Korean, and ATA ultrasound risk stratification systems combined with RAS mutations for detecting thyroid carcinoma in cytologically indeterminate and suspicious for malignancy thyroid nodules

PURPOSE

The aim of this study was to evaluate the diagnostic value of four commonly utilized ultrasound (US) RSSs, namely, the American College of Radiology [ACR], European [EU], Korean [K] TI-RADSs and American Thyroid Association [ATA] US-based RSS criteria, in combination with activating point mutations of the RAS genes (NRAS, HRAS, and KRAS) for detection of thyroid carcinoma in cytologically indeterminate and suspicious for malignancy thyroid nodules.

METHODS

We retrospectively analyzed cytologically indeterminate and suspicious for malignancy thyroid nodules which underwent US, molecular testing and surgery between September 1, 2018, and December 31, 2023. Receiver operating characteristic (ROC) curves were generated, and the area under the curve (AUC, 95% confidence interval [CI]) was calculated.

RESULTS

A total of 100 cytologically indeterminate and 24 suspicious for malignancy thyroid nodules were analyzed. Compared to the four US-based RSSs alone, the diagnostic value of the four US-based RSSs combined with RAS mutations did not significantly improved (cytologically indeterminate, AUC [95% CI] 0.6 [0.5-0.7] and 0.6 [0.5-0.7], respectively, p = 0.70; cytologically suspicious for malignancy, AUC [95% CI] 0.7 [0.5-0.9] and 0.8 [0.6-0.9], respectively, p = 0.23).

CONCLUSIONS

The diagnostic value of the four main US-based RSSs (ACR, EU, K, and ATA) was not improved in conjunction with the evaluation of RAS mutations for preoperative risk stratification of cytologically indeterminate thyroid nodules.

CLINICAL RELEVANCE STATEMENT

In cytologically indeterminate nodules categorized according to US-based RSSs, isolated RAS positivity does not reliably distinguish between benignity and malignancy.

Meaning of ACR-TIRADS recommendation in favor of follow-up rather than FNAC in thyroid nodules

Thyroid Imaging Reporting and Data Systems (TIRADSs) have been largely diffused for their high accuracy in risk stratification of thyroid nodules (TNs) and their selection for fine-needle aspiration cytology (FNAC). The most popular TIRADSs are ACR-, EU-, and K-TIRADS, with some discrepancies each other. One major difference is that ACR-TIRADS includes a recommendation in favor of follow-up in TNs having a major diameter insufficient to indicate FNAC. The present study aimed to explore prevalence and significance of this recommendation. EU- and K-TIRADS were used as comparator. A retrospective series of thyroidectomies was searched according to a pre-defined protocol. The study period was 2019-2023. Preoperative ultrasound images were reviewed by radiologists blinded of clinical data. Matching of TIRADS and histology was performed later. Histology was the gold standard. The study series included 39 TNs classified as category 3, 4, or 5 and assessed for follow-up according to ACR-TIRADS. The overall cancer frequency was 25.6%, being 13% in category 3, 20% in category 4, and 83.3% in category 5. The category assessment according to ACR-, EU-, and K-TIRADS was not significantly different. EU-TIRADS indicated FNAC in 10 TNs of which two cancers and eight benign lesions. K-TIRADS recommended FNAC in 32 TNs of which seven cancers and 25 benign lesions. TNs assessed for follow-up according to ACR-TIRADS are cancer in one-fourth of cases. EU- and, especially, K-TIRADS allow us to select for FNAC cancers, with the burden of non-negligible frequency of unnecessary FNACs.

Tumor Growth Kinetics Based on Initial Tumor Volume Doubling Time in Active Surveillance of Low-Risk Papillary Thyroid Carcinoma

BACKGROUND

During active surveillance (AS) of low-risk papillary thyroid carcinomas (PTCs), the majority remain stable, while some exhibit either increase or decrease in tumor diameter or tumor volume (TV). We aimed to evaluate the clinical outcomes and relevant parameters influencing tumor growth kinetics of low-risk PTCs.

METHODS

This retrospective cohort study evaluated clinical parameters of 402 patients with low-risk PTC sized <2 cm, with a follow-up duration over 3 years. Changes in maximum tumor diameter, TV, and initial TV doubling time (i-TVDT) calculated within 3-year were assessed. A significant change in TV was defined as a change of 75% or more.

RESULTS

Of the 402 patients with low-risk PTC, 93.3% (375/402) were diagnosed with papillary thyroid microcarcinoma. During a median follow-up of 5 years, 3.4% (14/402) of patients developed new cervical lymph node (LN) metastasis, and 8.2% (33/402) experienced maximal diameter increase of ≥3 mm. The i-TVDT of <5 years emerged as an independent risk factor for both maximal diameter growth and new LN metastasis (p<0.001 and p=0.04, respectively). Based on TV changes and i-TVDT during AS, we identified four statistically significant tumor kinetic patterns (p<0.001): Stable (±75% change in TV), Rapid growth (TV increase >75% and i- TVDT <5 years), Slow growth (TV increase >75% and i-TVDT ≥5 years), and Shrinkage (TV decrease >75%). Most of the PTCs remained stable (67.7%), but 17.2% were rapidly growing, with a median onset of growth of 2.0 years. Slowly growing PTCs, comprising 10.9%, grew at a median of 4.3 years. A minority, 4.2%, exhibited shrinkage. In total, 115 (28.6%) patients underwent delayed surgery >12 months after initiating AS. The reasons for delayed surgery included patient preference (51/115, 44.3%), disease progression (31/115, 27.0%), and suspected disease progression, which was referred to as tumor growth not meeting the criteria of an increase of ≥3 mm in maximal tumor diameter (17/115, 14.8%).

CONCLUSION

An i-TVDT of <5 years serve as an important prognostic indicator for disease progression, including tumor growth and new LN metastasis. The four tumor kinetic patterns based on TV changes and i-TVDT assist in guiding personalized decisions early in AS.

The Comparison of Efficacy and Safety between Radiofrequency Ablation Alone and Ethanol Ablation Followed by Radiofrequency Ablation in the Treatment of Mixed Cystic and Solid Thyroid Nodule

Purpose

To compare the efficacy and safety of radiofrequency ablation (RFA) and ethanol ablation (EA) followed by RFA in treating mixed cystic and solid thyroid nodules.

Materials and Methods

We included 243 nodules from 243 patients who underwent RFA for mixed cystic and solid benign nodules. The nodules were divided into two groups (RFA alone and EA + RFA). We evaluated volume reduction rate (VRR), therapeutic success rate, improvement in symptomatic and cosmetic issues, complications, and adverse effects.

Results

The RFA group included 204 patients, and the EA + RFA group included 39 patients. The long-term success rates in the RFA only and EA + RFA groups were 90.2% and 97.4%, respectively. The mean VRR at the last follow-up in the RFA and EA + RFA groups were 81.6% and 87.2%, respectively. Therapeutic results were similar in both groups at the last follow-up. Cosmetic and symptomatic problems markedly improved in both groups. No major complications were observed.

Conclusion

Both RFA alone and EA + RA are safe and effective methods for treating mixed cystic and solid thyroid nodules, although EA + RFA is slightly more effective.

Undercover active surveillance of small highly suspicious thyroid nodules without fine needle aspiration

PURPOSE

Active surveillance (AS) is an alternative treatment approach for small, low-risk papillary thyroid microcarcinoma (PTMC). This study aimed to assess the clinical outcomes of small, highly suspicious nodules lacking initial cytological confirmation.

METHODS

This study included 112 patients with highly suspicious nodules measuring ≤ 10 mm who underwent serial ultrasound at Asan Medical Center, Korea, between 2010 and 2023.

RESULTS

The median participant age was 51.9 years, and 74.1% were female. The median maximal tumor diameter and tumor volume (TV) were 4.5 (interquartile range [IQR] 3.7-5.2, range 2.2-9.3) mm and 25.2 (IQR 13.1-49.2) mm3, respectively. During a median follow-up period of 4.8 years, four (3.6%) patients showed a ≥ 3 mm increase in maximal diameter, and two (1.8%) developed new lymph node (LN) metastasis. Disease progression was associated with a TV doubling time (TVDT) of < 5 years and a ≥ 75% increase in TV (p = 0.017 and p < 0.005, respectively). Furthermore, 34.8% of patients underwent fine needle aspiration (FNA), primarily at their own request, yielding 46.2%, 5.1%, 41.0%, and 12.8 % malignant, benign, indeterminate, and non-diagnostic results, respectively. Of 18 patients with PTMC, 8 (44.4%) underwent surgery and 10 continued AS, with no LN metastasis during AS and no postoperative recurrence.

CONCLUSION

Small, highly suspicious nodules had a low disease progression rate during AS without FNA. Disease progression was associated with a TVDT of < 5 years and a ≥ 75% increase in TV. FNA can be performed more conservatively than it currently is in patients with highly suspicious nodules measuring ≤ 10 mm.

Malignancy Risk of Follicular Neoplasm (Bethesda IV) With Variable Cutoffs of Tumor Size: A Systemic Review and Meta-Analysis

CONTEXT

The decision on diagnostic lobectomy for follicular neoplasms (FN) is challenging.

OBJECTIVE

This meta-analysis investigates whether an appropriate size cutoff exists for recommending surgery for thyroid nodules diagnosed as FN by fine needle aspiration.

METHODS

The Ovid-Medline, EMBASE, Cochrane, and KoreaMed databases were searched for studies reporting the malignancy rate of FN/suspicious for FN (FN/SFN) according to tumor size, using search terms "fine needle aspiration," "follicular neoplasm," "lobectomy," "surgery," and "thyroidectomy."

RESULTS

Fourteen observational studies comprising 2016 FN/SFN nodules with postsurgical pathologic reports were included, and 2 studies included malignancy rates with various tumor sizes. The pooled malignancy risk of FN/SFN nodules according to size was: odds ratio (OR) 2.29 (95% CI, 1.68-3.11) with cutoff of 4 cm (9 studies), OR 2.39 (95% CI, 1.45-3.95) with cutoff of 3 cm (3 studies), and OR 1.81 (95% CI, 0.94-3.50) with cutoff of 2 cm (5 studies). However, tumors ≥2 cm also showed a higher risk (OR 2.43; 95% CI, 1.54-3.82) based on the leave-one-out meta-analysis after removal of 1 influence study. When each cutoff size was evaluated by summary receiver operating characteristic (sROC) curves, the cutoff of 4 cm showed the highest summary area under the curve (sAUC, 0.645) compared to other cutoffs (sAUC, 0.58 with 2 cm, and 0.62 with 3 cm), although there was no significant difference.

CONCLUSION

Although the risk of malignancy increases with increasing tumor size, the risk remains significant at all tumor sizes and no cutoff limit can be recommended as a decision-making parameter for diagnostic surgery in Bethesda IV thyroid nodules.

Reappraising the role of thyroid scintigraphy in the era of TIRADS: A clinically-oriented viewpoint

Thyroid nodules (TNs) are a common entity, with the majority being benign. Therefore, employing an accurate rule-out strategy in clinical practice is essential. In the thyroid field, the current era is significantly marked by the worldwide diffusion of ultrasound (US)-based malignancy risk stratification systems of TN, usually reported as Thyroid Imaging Reporting And Data System (TIRADS). With the advent of US (and later TIRADS), the role of thyroid scintigraphy (TS) in clinical practice has gradually diminished. The authors of the present paper believe that the role of TS should be reappraised, also considering its essential role in detecting autonomously functioning thyroid nodules and its limited contribution to detecting thyroid cancers. Thus, this document aims to furnish endocrinologists, radiologists, surgeons, and nuclear medicine physicians with practical information to appropriately use TS.

The Diagnostic Role of Repeated Biopsy of Thyroid Nodules with Atypia of Undetermined Significance with Architectural Atypia on Core-Needle Biopsy

BACKGRUOUND

We aimed to evaluate the utility of repeat biopsy of thyroid nodules classified as atypia of undetermined significance with architectural atypia (IIIB) on core-needle biopsy (CNB).

METHODS

This retrospective study evaluated patients with thyroid nodules categorized as IIIB on CNB between 2013 and 2015. Demographic characteristics, subsequent biopsy results, and ultrasound (US) images were evaluated. The malignancy rates of nodules according to number of CNBs and the number of IIIB diagnoses was compared. Demographic and US features were evaluated to determine factors predictive of malignancy.

RESULTS

Of 1,003 IIIB nodules on CNB, the final diagnosis was determined for 328 (32.7%) nodules, with 121 of them confirmed as malignant, resulting in a malignancy rate of 36.9% (95% confidence interval, 31.7% to 42.1%). Repeat CNB was performed in 248 nodules (24.7%), with 75 (30.2%), 131 (52.8%), 13 (5.2%), 26 (10.5%), one (0.4%), and two (0.8%) reclassified into categories II, IIIB, IIIA, IV, V, and VI, respectively. Malignancy rates were not significantly affected by the number of CNBs (P=0.291) or the number of IIIB diagnoses (P=0.473). None of the nodules confirmed as category II on repeat CNB was malignant. US features significantly associated with malignancy (P<0.003) included solid composition, irregular margins, microcalcifications, and high suspicion on the US risk stratification system.

CONCLUSION

Repeat biopsy of nodules diagnosed with IIIB on CNB did not increase the detection of malignancy but can potentially reduce unnecessary surgery. Repeat biopsy should be performed selectively, with US features guiding the choice between repeat biopsy and diagnostic surgery.

Cost-Utility Analysis of Early Detection with Ultrasonography of Differentiated Thyroid Cancer: A Retrospective Study on a Korean Population

BACKGRUOUND

There is debate about ultrasonography screening for thyroid cancer and its cost-effectiveness. This study aimed to evaluate the cost-effectiveness of early screening (ES) versus symptomatic detection (SD) for differentiated thyroid cancer (DTC) in Korea.

METHODS

A Markov decision analysis model was constructed to compare the cost-effectiveness of ES and SD. The model considered direct medical costs, health outcomes, and different diagnostic and treatment pathways. Input data were derived from literature and Korean population studies. Incremental cost-effectiveness ratio (ICER) was calculated. Willingness-to-pay (WTP) threshold was set at USD 100,000 or 20,000 per quality-adjusted life year (QALY) gained. Sensitivity analyses were conducted to address uncertainties of the model's variables.

RESULTS

In a base case scenario with 50 years of follow-up, ES was found to be cost-effective compared to SD, with an ICER of $2,852 per QALY. With WTP set at $100,000, in the case with follow-up less than 10 years, the SD was cost-effective. Sensitivity analysis showed that variables such as lobectomy probability, age, mortality, and utility scores significantly influenced the ICER. Despite variations in costs and other factors, all ICER values remained below the WTP threshold.

CONCLUSION

Findings of this study indicate that ES is a cost-effective strategy for DTC screening in the Korean medical system. Early detection and subsequent lobectomy contribute to the cost-effectiveness of ES, while SD at an advanced stage makes ES more cost-effective. Expected follow-up duration should be considered to determine an optimal strategy for DTC screening.

Analysis of risk factors for lateral lymph node metastasis in T1 stage papillary thyroid carcinoma: a retrospective cohort study

Background

The occurrence of cervical lymph node metastasis in T1 stage papillary thyroid carcinoma (PTC) is frequently observed. Notably, lateral lymph node metastasis (LLNM) emerges as a critical risk factor adversely affecting prognostic outcomes in PTC. The primary aim of this investigation was to delineate the risk factors associated with LLNM in the initial stages of PTC.

Methods

This retrospective analysis encompassed 3,332 patients diagnosed with T1 stage PTC without evident LLNM at the time of diagnosis. These individuals underwent primary surgical intervention at West China Hospital, Sichuan University between June 2017 and February 2023. The cohort was divided into two groups: patients manifesting LLNM and those without metastasis at the time of surgery. Additionally, T1 stage PTC patients were subdivided into T1a and T1b categories. Factors influencing LLNM were scrutinized through both univariate and multivariate analyses.

Results

The incidence of LLNM was observed in 6.2% of the cohort (206 out of 3,332 patients). Univariate analysis revealed significant correlations between LLNM and male gender (P<0.001), tumor localization in the upper lobe (P<0.001), maximal volume of the primary tumor (P<0.001), largest tumor diameter (P<0.001), multifocality (P<0.001), and bilaterality (P<0.001), with the exception of age (P=0.788) and duration of active surveillance (AS) (P=0.978). Multivariate logistic regression analysis identified male gender (P<0.001), upper lobe tumor location (P<0.001), maximal primary tumor volume (P<0.001), and multifocality (P<0.001) as independent predictors of LLNM. However, age categories (≤55, >55 years), maximum tumor diameter, bilaterality, and surveillance duration did not exhibit a significant impact. Comparative analyses between T1a and T1b subgroups showed congruent univariate results but revealed differences in multivariate outcomes. In the T1a subgroup, gender, tumor location, and multifocality (all P<0.05) were associated with elevated LLNM risk. Conversely, in the T1b subgroup, tumor location, dimensions, and multifocality (all P<0.05) were significant predictors of LLNM risk, whereas gender (P=0.097) exerted a marginal influence.

Conclusions

The investigation highlights several key risk factors for LLNM in T1 stage PTC patients, including gender, upper lobe tumor location, larger tumor size, and multifocality. Conversely, prolonged AS and younger age did not significantly elevate LLNM risk, suggesting the viability of AS as a strategic option in selected cases.

Associations of Combined Exposure to Metabolic and Inflammatory Indicators with Thyroid Nodules in Adults: A Nested Case-Control Study

Objective

To explore associations of combined exposure to metabolic/inflammatory indicators with thyroid nodules.

Methods

We reviewed personal data for health screenings from 2020 to 2021. A propensity score matching method was used to match 931 adults recently diagnosed with thyroid nodules in a 1 : 4 ratio based on age and gender. Conditional logistic regression and Bayesian kernel machine regression (BKMR) were used to explore the associations of single metabolic/inflammatory indicators and the mixture with thyroid nodules, respectively.

Results

In the adjusted models, five indicators (ORQ4 vs. Q1: 1.30, 95% CI: 1.07-1.58 for fasting blood glucose; ORQ4 vs. Q1: 1.30, 95% CI: 1.08-1.57 for systolic blood pressure; ORQ4 vs. Q1: 1.26, 95% CI: 1.04-1.53 for diastolic blood pressure; ORQ4 vs. Q1: 1.23, 95% CI: 1.02-1.48 for white blood cell; ORQ4 vs. Q1: 1.28, 95% CI: 1.07-1.55 for neutrophil) were positively associated with the risk of thyroid nodules, while high-density lipoproteins (ORQ3 vs. Q1: 0.75, 95% CI: 0.61-0.91) were negatively associated with the risk of thyroid nodules. Univariate exposure-response functions from BKMR models showed similar results. Moreover, the metabolic and inflammatory mixture exhibited a significant positive association with thyroid nodules in a dose-response pattern, with systolic blood pressure being the greatest contributor within the mixture (conditional posterior inclusion probability of 0.82). No interaction effects were found among the five indicators. These associations were more prominent in males, participants with higher age (≥40 years old), and individuals with abnormal body mass index status.

Conclusions

Levels of the metabolic and inflammatory mixture have a linear dose-response relationship with the risk of developing thyroid nodules, with systolic blood pressure levels being the most important contributor.

Sonographic characteristics of diffuse sclerosing variant of papillary thyroid carcinoma with histopathological correlation: a preliminary study

BACKGROUND

Diffuse sclerosing variant of papillary thyroid carcinoma (DSVPTC) is a rare but high invasive subtype of papillary thyroid carcinoma, which mandates an aggressive clinical strategy. Few studies have focused on the sonographic characteristics of DSVPTC and the role of ultrasound in diagnosis and treatment of this variant remains unknown. This study aimed to identify and understand DSVPTC more accurately under ultrasound in correlation with pathology.

METHODS

The ultrasound characteristics and histopathologic sections of 10 lesions in 10 DSVPTC patients who underwent thyroid surgery at our center between 2014 and 2020 were reviewed and compared with 184 lesions in 168 classic variant of papillary thyroid carcinoma (cPTC) patients.

RESULTS

6 DSVPTC cases (60%) showed the "snowstorm" pattern on sonogram and 4 cases (40%) presented hypoechoic solid nodules only. Vague borders (100.0% vs. 18.5%, P = 0.019) and abundant microcalcifications (66.7% vs. 10.9%, P = 0.037) were more common in DSVPTC nodules than in cPTC nodules, corresponding to the infiltrating boundaries and numerous psammoma bodies under the microscope respectively. Most of the DSVPTC cases had a heterogeneous background (80%) and suspicious metastatic cervical lymph nodes (80%) on sonograms. All DSVPTC cases had histopathological metastatic cervical lymph nodes.

CONCLUSION

The sonographic "snowstorm" pattern indicated DSVPTC with whole-lobe occupation. Hypoechoic solid nodules with vague borders and abundant microcalcifications on sonogram suggested DSVPTC lesion with an ongoing invasion. Regardless of which of the two sonograms was shown, the corresponding DSVPTC lesions were aggressive and required the same attention from the surgeons.

Comparison of ultrasound risk stratification systems for pediatric thyroid nodules

Background

There is currently insufficient data to validate adult-based US risk stratification systems (RSSs) for the identification of malignant thyroid nodules in a pediatric population.

Methods

From October 2016 and May 2023, 173 thyroid nodules of pediatric patients (age ≤ 18 years) with definitive pathology results and ultrasound (US) examination within 1 month before surgery or fine-needle aspiration (FNA) biopsy in our institution were enrolled in this study. The clinical and US characteristics of these nodules were retrospectively reviewed and categorized according to the ACR-TIRADS, C-TIRADS, and ATA guidelines. The diagnostic performance of US-based FNA criteria (original and simulating) of the three guidelines in thyroid cancer detection was estimated.

Results

The three RSSs had similar AUC according to the categories(0.849-0.852, all P > 0.05). When combined with the original FNA criteria of the three RSSs to manage the nodules, the FNA rate of ACR-TIRADS and C-TIRADS were significantly less than ATA guidelines (53.18% vs. 64.63%, P < 0.05, and 52.60% vs. 64.63%, P < 0.05). The missed malignancy rate (MMR) and unnecessary FNA rate (UFR) of ATA guidelines (50.00%, 35.85%) was highest among the three RSSs, followed by the C-TIRADS (37.80%, 19.57%) and the ACR-TIRADS (37.04%, 19.57%). When nodules < 1 cm with the highest category in each RSS biopsied, that is when using the simulating FNA thresholds, the MMR was reduced overall (all P < 0.001), without a change in the UFR (all P > 0.05). All the three RSSs showed a substantial improvement in accuracy and malignant detection rate (all P < 0.05).

Conclusion

The ACR-TIRADS, C-TIRADS, and ATA guidelines showed high missed malignancy rates when using their original recommended FNA criteria. When nodules < 1 cm with the highest category in each RSS biopsied, the missed malignancy rate of each RSS was decreased. Decreasing the FNA thresholds for highly suspicious malignant nodules may therefore be an effective means of managing malignant thyroid nodules in pediatric patients.

Malignancy risk stratification and subcategorization of K-TIRADS intermediate suspicion thyroid nodules: a retrospective multicenter study

PURPOSE

This study aimed to develop the ultrasonography (US) criteria for risk stratification of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) 4 nodules, and to evaluate the diagnostic yield of a modified biopsy criterion in a multicenter cohort.

METHODS

In total, 1,542 K-TIRADS 4 nodules (≥1 cm) were included in the study. US criteria for the subcategorization of K-TIRADS 4 nodules were developed based on high-risk US features. The diagnostic yields and false referral rates of biopsy criterion 1 (size cut-off of 1 cm), biopsy criterion 2 (size cut-off of 1.5 cm), and modified biopsy criterion 3 (size cut-off of 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A) were evaluated.

RESULTS

The five high-risk US features (solid composition, marked hypoechogenicity, macrocalcification, punctate echogenic foci, and irregular margin) independently increased the malignancy risk of the K-TIRADS 4 nodules (P<0.001). The K-TIRADS 4 nodules could be subcategorized into higher- and lower-risk subcategories according to the number of high-risk US features: K-TIRADS 4B (≥2 US features) and K-TIRADS 4A (≤1 US feature). The modified biopsy criterion increased the diagnostic yield by 7.8% compared with criterion 2 and reduced the false referral rate by 15.3% compared with criterion 1 (P<0.001).

CONCLUSION

The K-TIRADS 4 nodules were subcategorized as K-TIRADS 4B and K-TIRADS 4A based on high-risk US features. The modified biopsy criterion 3 showed a similar diagnostic yield and reduced false referral rate compared to criterion 1.

Malignancy risk of indeterminate lymph node at the central compartment in patients with thyroid cancer and concomitant sonographic thyroiditis

BACKGROUND

To evaluate the malignancy risk of sonographic (US) indeterminate lymph node (LN)s at the central compartment in thyroid cancer patients with US-thyroiditis (ST).

METHODS

Among the central compartments of suspicious, indeterminate, and probably benign LN US categories, the malignancy rates were compared between ST and non-US-thyroiditis (non-ST) groups. Those of indeterminate category were compared with suspicious and probably benign categories.

RESULTS

At 531 central compartments from 349 patients, the malignancy rate was lower in ST group (34.4% [44/128]) than non-ST group (43.4% [175/403]), although statistically not significant (p = 0.08). The malignancy rate of indeterminate category in ST group (35.7% [5/14]) was lower than non-ST group (71.9% [23/32]) (p = 0.047). Within ST group, the malignancy rate of indeterminate category (35.7% [5/14]) did not differ from probably benign category (29.1% [30/103]) (p = 0.756), but was lower than suspicious category (81.8% [9/11]) (p = 0.042).

CONCLUSIONS

The malignancy risk of US indeterminate LNs at the central compartment in thyroid cancer patients with US thyroiditis was lower than that in patients without US thyroiditis.

A Narrative Review of the 2023 Korean Thyroid Association Management Guideline for Patients with Thyroid Nodules

The 2023 Korean Thyroid Association (KTA) Management Guideline for Patients with Thyroid Nodules constitute an update of the 2016 KTA guideline for thyroid nodules and cancers that focuses specifically on nodules. The 2023 guideline aim to offer updated guidance based on new evidence that reflects the changes in clinical practice since the 2016 KTA guideline. To update the 2023 guideline, a comprehensive literature search was conducted from January 2022 to May 2022. The literature search included studies, reviews, and other evidence involving human subjects that were published in English in MEDLINE (PubMed), Embase, and other relevant databases. Additional significant clinical trials and research studies published up to April 2023 were also reviewed. The limitations of the current evidence are discussed, and suggestions for areas in need of further research are identified. The purpose of this review is to provide a summary of the 2023 KTA guideline for the management of thyroid nodules released in May 2023 and to give a balanced insight with comparison of recent guidelines from other societies.

Correct and Incorrect Recommendations for or against Fine Needle Biopsies of Hypofunctioning Thyroid Nodules: Performance of Different Ultrasound-based Risk Stratification Systems

PURPOSE

 To evaluate the recommendations for or against fine needle biopsy (FNB) of hypofunctioning thyroid nodules (TNs) using of five different Ultrasound (US) -based risk stratification systems (RSSs).

METHODS

 German multicenter study with 563 TNs (≥ 10 mm) in 534 patients who underwent thyroid US and surgery. All TNs were evaluated with ACR TI-RADS, EU-TIRADS, ATA, K-TIRADS 2016 and modified K-TIRADS 2021. A correct recommendation was defined as: malignant TN with recommendation for FNB (appropriate) or benign TN without recommendation for FNB (avoided). An incorrect recommendation was defined as: malignant TN without recommendation for FNB (missed) or benign TN with recommendation for FNB (unnecessary).

RESULTS

 ACR TI-RADS demonstrated the highest rate of correct (42.3 %) and lowest rate of incorrect recommendations (57.7 %). The other RRSs showed similar results for correct (26.5 %-35.7 %) and incorrect (64.3 %-73.5 %) recommendations. ACR TI-RADS demonstrated the lowest rate of unnecessary (73.4 %) and the highest rate of appropriate (26.6 %) FNB recommendation. For other RSSs, the rates of unnecessary and appropriate FNB were between 75.2 %-77.1 % and 22.9 %-24.8 %. The lowest rate of missed FNB (14.7 %) and the highest rate of avoided FNB (85.3 %) was found for ACR TI-RADS. For the other RSSs, the rates of missed and avoided FNB were between 17.8 %-26.9 % and 73.1 %-82.2 %. When the size cutoff was disregarded, an increase of correct recommendations and a decrease of incorrect recommendations was observed for all RSSs.

CONCLUSION

 The RSSs vary in their ability to correctly recommend for or against FNB. An understanding of the impact of nodule size cutoffs seems necessary for the future of TIRADS.

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.

Artificial Intelligence Model Assisting Thyroid Nodule Diagnosis and Management: A Multicenter Diagnostic Study

CONTEXT

It is not clear how to integrate artificial intelligence (AI)-based models into diagnostic workflows.

OBJECTIVE

To develop and validate a deep-learning-based AI model (AI-Thyroid) for thyroid cancer diagnosis, and to explore how this improves diagnostic performance.

METHODS

The system was trained using 19 711 images of 6163 patients in a tertiary hospital (Ajou University Medical Center; AUMC). It was validated using 11 185 images of 4820 patients in 24 hospitals (test set 1) and 4490 images of 2367 patients in AUMC (test set 2). The clinical implications were determined by comparing the findings of six physicians with different levels of experience (group 1: 4 trainees, and group 2: 2 faculty radiologists) before and after AI-Thyroid assistance.

RESULTS

The area under the receiver operating characteristic (AUROC) curve of AI-Thyroid was 0.939. The AUROC, sensitivity, and specificity were 0.922, 87.0%, and 81.5% for test set 1 and 0.938, 89.9%, and 81.6% for test set 2. The AUROCs of AI-Thyroid did not differ significantly according to the prevalence of malignancies (>15.0% vs ≤15.0%, P = .226). In the simulated scenario, AI-Thyroid assistance changed the AUROC, sensitivity, and specificity from 0.854 to 0.945, from 84.2% to 92.7%, and from 72.9% to 86.6% (all P < .001) in group 1, and from 0.914 to 0.939 (P = .022), from 78.6% to 85.5% (P = .053) and from 91.9% to 92.5% (P = .683) in group 2. The interobserver agreement improved from moderate to substantial in both groups.

CONCLUSION

AI-Thyroid can improve diagnostic performance and interobserver agreement in thyroid cancer diagnosis, especially in less-experienced physicians.

Thyroid Imaging Reporting and Data Systems: Applicability of the "Taller than Wide" Criterium in Primary/Secondary Care Units and the Role of Thyroid Scintigraphy

BACKGROUND

To examine the applicability of the "taller than wide" (ttw) criterium for risk assessment of thyroid nodules (TNs) in primary/secondary care units and the role of thyroid scintigraphy therein.

METHODS

German bicenter study performed in a setting of primary/secondary care. Patient recruitment and analysis in center A was conducted in a prospective manner. In center B, patient data were retrieved from a database that was originally generated by prospective data collection. TNs were assessed by ultrasound and thyroid scans, mostly fine needle biopsy and occasionally surgery and others. In center A, only patients who presented for the first time were included. The inclusion criterion was any TN ≥ 10 mm that had at least the following two sonographic risk features: solidity and a ttw shape. In center B, consecutive patients who had at least ttw and hypofunctioning nodules ≥ 10 mm were retrieved from the above-mentioned database. The risk of malignancy was determined according to a mixed reference standard and compared with literature data.

RESULTS

In center A, 223 patients with 259 TNs were included into the study. For further analysis, 200 nodules with a reference standard were available. The overall malignancy rate was 2.5% (upper limit of the 95% CI: 5.1%). After the exclusion of scintigraphically hyperfunctioning nodules, the malignancy rate increased slightly to 2.8% (upper limit of the 95% CI: 5.7%). Malignant nodules exhibited sonographic risk features additional to solidity and ttw shape more often than benign ones. In addition to the exclusion of hyperfunctioning nodules, when considering only nodules without additional US risk features, i.e., exclusively solid and ttw-nodules, the malignancy rate decreased to 0.9% (upper limit 95% CI: 3.7%). In center B, from 58 patients, 58 ttw and hypofunctioning TNs on thyroid scans with a reference standard were available. Malignant nodules from center B were always solid and hypoechoic. The overall malignancy rate of hypofunctioning and ttw nodules was 21%, with the lower limit of the 95% CI (one-sided) being 12%.

CONCLUSIONS

In primary/secondary care units, the lowest TIRADS categories for indicating FNB, e.g., applying one out of five sonographic risk features, may not be appropriate owing to the much lower a priori malignancy risk in TNs compared to tertiary/quaternary care units. Even the combination of two sonographic risk features, "solidity" and "ttw", may only be appropriate in a limited fashion. In contrast, the preselection of TNs according to hypofunctioning findings on thyroid scans clearly warranted FNB, even when applying only one sonographic risk criterion ("ttw"). For this reason, thyroid scans in TNs may not only be indicated to rule out hyperfunctioning nodules from FNB but also to rule in hypofunctioning ones.

Diagnostic value of qualitative and quantitative parameters of contrast-enhanced ultrasound for differentiating differentiated thyroid carcinomas from benign nodules

Objective

To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) of qualitative and quantitative parameters for differentiating differentiated thyroid cancers from benign nodules.

Method

A total of 290 thyroid nodules that were pathologically confirmed were enrolled in this study. The univariate analysis was performed for the clinical characteristics and CEUS qualitative and quantitative parameters of the inside and peripheral zone of nodules, including age, gender, nodule size, intensity of enhancement, homogeneity, wash-in and wash-out patterns, margin after CEUS, ring enhancement, peak intensity, sharpness, time to peak(TP), and area under the curve(AUC), and the meaningful indicators in the single-factor analysis were further included in multivariate logistic regression analysis.

Results

Multivariate analysis showed that there were significant differences in age (p=0.031), nodule size (p<0.001), heterogeneous enhancement (p<0.001), hypo-enhancement (p=0.001), unclear margin after CEUS(p=0.007), inside peak (p<0.001), and outside sharpness(p<0.001) between benign and malignant nodules. However, there were no significant differences in gender, ring enhancement, wash-in, wash-out, outside TP, outside AUC between benign and malignant thyroid nodules (P>0.05, for all).

Conclusion

CEUS might be useful in the differential diagnosis of differentiated thyroid cancers and benign nodules, which could provide a certain basis for clinical treatment.

Radiofrequency ablation for thyroid nodules in Ecuador: a cross-sectional study

OBJECTIVES

To describe the demographic characteristics and clinical outcomes following the first cohort of patients with Bening Thyroid Nodule (BTN) and (Papillary Thyroid Microcarcinoma) (PTMC) treated with Radiofrequency Ablation (RFA)in Ecuador.

METHODS

Single-center, cross-sectional study. We included adults undergoing RFA for BTN and PTMC between July 2019 and May 2022. Descriptive statistics and the Wilcoxon signed-rank test were used to compare some pre- and post-intervention outcomes.

RESULTS

We included 44 patients with 36 BTNs and eight PTMCs. The median age was 45.80 years (IQR 16-79 years), and most patients had normal thyroid function (72.72%). The median follow-up time was 7.80 months (IQR1.0-34.0). Nodules were primarily solid (43.21%) or predominantly solid (56.81%). The pre-RFA median volume in the benign lesions group was 10.30 ml (IQR 1.86-18.97). After ablation, the 1-month, 3-month, 6-month, and 12-month median volumes were 6.90 (IQR 0.48-10.15; p < 0.01) mL, 5.72 (IQR 0.77-7.25; p = 0.045); 0.98 (IQR 0.25-3.64; p < 0.01), and 0.11 (IQR 0.07-11.26; p = 0.026), respectively. The volume rate reduction was 47.20%, 72.20%, 74.00%, and 96.20% at 1, 3, 6, and 12-month follow-ups, respectively. The pre-RFA median volume in the PTMC group was 0.25 ml (IQR 0.19-0.48). After ablation, the 1-month, 3-month, and 6-month mean volumes were 0.19 (range 0.12-0.31; p = 0.120) mL, 0.10 (IQR 0.05-0.15; p = 0.13), and 0.01 (IQR 0.005-0.04; p = 0.364), respectively.

CONCLUSIONS

In this first report from Ecuador, we found that RFA may be a feasible alternative for treating benign and malignant thyroid nodules in the short term. Long-term data are needed to evaluate oncologic outcomes in PTMC patients.

Utility of Six Ultrasound-Based Risk Stratification Systems in the Diagnosis of AUS/FLUS Thyroid Nodules

RATIONALE AND OBJECTIVES

To estimate the diagnostic performance of the currently used ultrasound (US)-based risk stratification systems (RSSs) (American Thyroid Association, American Association of Clinical Endocrinologists, American College of Endocrinology, and Association Medici Endocrinology Medical Guidelines for Clinical Practice for the Diagnosis and Management of Thyroid Nodules, European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules in Adults [EU-TIRADS], American College of Radiology Thyroid Imaging Reporting and Data System [ACR-TIRADS], Chinese Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules [C-TIRADS], and Thyroid Imaging Reporting and Data System Developed by Kwak et al [Kwak-TIRADS]) for atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) thyroid nodules.

MATERIALS AND METHODS

This retrospective study included 514 consecutive AUS/FLUS nodules in 481 patients with final diagnosis. The US characteristics were reviewed and classified using the categories defined by each RSS. The diagnostic performance was evaluated and compared using a generalized estimating equation method.

RESULTS

Of the 514 AUS/FLUS nodules, 148 (28.8%) were malignant and 366 (71.2%) were benign. The calculated malignancy rate increased from the low-risk to high-risk categories for all RSSs (all P < .001). Interobserver correlation for both US features and RSSs showed substantial to almost perfect agreement. The diagnostic efficacy of Kwak-TIRADS (AUC=0.808) and C-TIRADS (AUC=0.804) were similar (P = .721) and higher than those of other RSSs (all P < .05). The EU-TIRADS and Kwak-TIRADS exhibited similar sensitivity (86.5% vs 85.1%, P = .739) and were only higher than that of the C-TIRADS (all P < .05). The specificity of C-TIRADS and ACR-TIRADS were similar (78.1% vs 72.1%, P = .06) and were higher than those of other RSSs (all P < .05).

CONCLUSION

Currently used RSSs can provide risk stratification for AUS/FLUS nodules. Kwak-TIRADS and C-TIRADS have the highest diagnostic efficacy in identifying malignant AUS/FLUS nodules. A detailed knowledge of the benefits and shortcomings of the various RSSs is essential.

Association of Ultrasonography Features of Follicular Thyroid Carcinoma With Tumor Invasiveness and Prognosis Based on WHO Classification and TERT Promoter Mutation

OBJECTIVE

To investigate the association of ultrasound (US) features of follicular thyroid carcinoma (FTC) with tumor invasiveness and prognosis based on the World Health Organization (WHO) classification and telomerase reverse transcriptase (TERT) promoter mutations.

MATERIALS AND METHODS

This retrospective study included 54 surgically confirmed FTC patients with US images and TERT promoter mutations (41 females and 13 males; median age [interquartile range], 40 years [30-51 years]). The WHO classification consisted of minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTCs. Alternative classifications included Group 1 (MI-FTC and EA-FTC with wild type TERT), Group 2 (WI-FTC with wild type TERT), and Group 3 (EA-FTC and WI-FTC with mutant TERT). Each nodule was categorized according to the US patterns of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and American College of Radiology-TIRADS (ACR-TIRADS). The Jonckheere-Terpstra and Cochran-Armitage tests were used for statistical analysis.

RESULTS

Among 54 patients, 29 (53.7%) had MI-FTC, 16 (29.6%) had EA-FTC, and nine (16.7%) had WI-FTC. In both the classifications, lobulation, irregular margins, and final assessment categories showed significant differences (all Ps ≤ 0.04). Furthermore, the incidences of lobulation, irregular margin, and high suspicion category tended to increase with increasing tumor invasiveness and worse prognosis (all Ps for trend ≤ 0.006). In the WHO groups, hypoechogenicity differed significantly among the groups (P = 0.01) and tended to increase in proportion as tumor invasiveness increased (P for trend = 0.02). In the alternative group, punctate echogenic foci were associated with prognosis (P = 0.03, P for trend = 0.03).

CONCLUSION

Increasing tumor invasiveness and worsening prognosis in FTC based on the WHO classification and TERT promoter mutation results were positively correlated with US features that indicate malignant probability according to both K-TIRADS and ACR-TIRADS.

Diagnostic Performance of Thyroid Nodule Risk Stratification Systems: Comparison of ACR-TIRADS, EU-TIRADS, K-TIRADS, and ATA Guidelines

ABSTRACT

The purpose of this study was to compare the diagnostic performance of 4 different ultrasound-based risk scoring systems for thyroid nodules (TNs). This study consecutively included 256 patients (mean age: 43.98 ± 12.94 years, min-max: 18-89 years; 225 females, 31 males) with 266 TNs. Each nodule was evaluated and classified according to the American Thyroid Association (ATA), American College of Radiology (ACR), European Thyroid Association, and Korean Thyroid Imaging Reporting and Data System (ACR-TIRADS, EU-TIRADS, and K-TIRADS, respectively) before performing ultrasound-guided fine-needle aspiration biopsy. Pathological results were reported according to the Bethesda system. Outcomes of the 4 classification systems were compared with respect to Bethesda results. Twenty-eight (10.5%) nodules had malignant cytology results. Diagnostic performances of the scoring systems were comparable with similar area under the curve values according to the reference standards of category 5 of each scoring system. The sensitivity and specificity values of these guidelines were as follows: ACR-TIRADS, 60.7% and 95.4%; EU-TIRADS, 71.4% and 93.3%; ATA-2015, 71.4% and 93.3%; and K-TIRADS, 67.9% and 93.3%. The biopsy rate of malignant nodules was 57.1% for K-TIRADS and ATA, whereas this value was 46.4% for ACR and EU-TIRADS. ACR-TIRADS had the lowest unnecessary biopsy rate (141 of 238 benign nodules, 46%). The diagnostic performance of 4 risk stratification systems appears to be comparable, as shown by similar sensitivity, specificity, and area under the curve values. However, the ACR-TIRADS had slightly higher accuracy and necessitated fewer unnecessary biopsies for benign nodules.

Impact of Additional Preoperative Computed Tomography Imaging on Staging, Surgery, and Postsurgical Survival in Patients With Papillary Thyroid Carcinoma

OBJECTIVE

We investigated the impacts of computed tomography (CT) added to ultrasound (US) for preoperative evaluation of patients with papillary thyroid carcinoma (PTC) on staging, surgical extent, and postsurgical survival.

MATERIALS AND METHODS

Consecutive patients who underwent surgery for PTC between January 2015 and December 2015 were retrospectively identified. Of them, 584 had undergone preoperative additional thyroid CT imaging (CT + US group), and 859 had not (US group). Inverse probability of treatment weighting (IPTW) and propensity score matching (PSM) were used to adjust for 14 variables and balance the two groups. Changes in nodal staging and surgical extent caused by CT were recorded. The recurrence-free survival and distant metastasis-free survival after surgery were compared between the two groups.

RESULTS

In the CT + US group, discordant nodal staging results between CT and US were observed in 94 of 584 patients (16.1%). Of them, CT accurately diagnosed nodal staging in 54 patients (57.4%), while the US provided incorrect nodal staging. Ten patients (1.7%) had a change in the extent of surgery based on CT findings. Postsurgical recurrence developed in 3.6% (31 of 859) of the CT + US group and 2.9% (17 of 584) of the US group during the median follow-up of 59 months. After adjustment using IPTW (580 vs. 861 patients), the CT + US group showed significantly higher recurrence-free survival rates than the US group (hazard ratio [HR], 0.52 [95% confidence interval {CI}, 0.29-0.96]; P = 0.037). PSM analysis (535 patients in each group) showed similar HR without statistical significance (HR, 0.60 [95% CI, 0.31-1.17]; P = 0.134). For distant metastasis-free survival, HRs after IPTW and PSM were 0.75 (95% CI, 0.17-3.36; P = 0.71) and 0.87 (95% CI, 0.20-3.80; P = 0.851), respectively.

CONCLUSION

The addition of CT imaging for preoperative evaluation changed nodal staging and surgical extent and might improve recurrence-free survival in patients with PTC.

Effects of iodine status on thyroid volume and goiter in children living in an iodine-replete area

Objective

Adequate iodine intake is essential for growing children, and thyroid volume (Tvol) is considered as an indicator of iodine status. We investigated Tvol and goiter using ultrasonography (US) and their association with iodine status in 228 6-year-old children living in Korea.

Methods

Iodine status was assessed using urine iodine concentration (UIC) and categorized as deficient (<100 μg/L), adequate (100-299 μg/L), mild excess (300-499 μg/L), moderate excess (500-999 μg/L), and severe excess (≥1000 μg/L). Tvol was measured using US, and a goiter on the US (goiter-US) was defined as Tvol greater than 97th percentile value by age- and body surface area (BSA)-specific international references.

Results

The median Tvol was 2.4 mL, larger than the international reference value (1.6 mL). The age- and BSA-specific goiter-US rates were 25.9% (n = 59) and 34.6% (n = 79), respectively. The prevalence of excess iodine was 73.7% (n = 168). As iodine status increased from adequate to severe excess, the goiter-US rate significantly increased (P for trend <0.05). The moderate and severe iodine excess groups showed higher risk of goiter-US (adjusted odds ratio (aOR) = 3.1 (95% CI: 1.1-9.2) and aOR = 3.1 (95% CI: 1.2-8.3), respectively; age-specific criteria) than the iodine-adequate group.

Conclusions

Excess iodine was prevalent in Korean children, and their Tvol was higher than the international reference values. Goiter rate was associated with iodine excess, which significantly increased in the moderate and severe iodine excess groups. Further studies are warranted to define optimal iodine intake in children.

Deep learning approaches for differentiating thyroid nodules with calcification: a two-center study

BACKGROUND

Calcification is a common phenomenon in both benign and malignant thyroid nodules. However, the clinical significance of calcification remains unclear. Therefore, we explored a more objective method for distinguishing between benign and malignant thyroid calcified nodules.

METHODS

This retrospective study, conducted at two centers, involved a total of 631 thyroid nodules, all of which were pathologically confirmed. Ultrasound image sets were employed for analysis. The primary evaluation index was the area under the receiver-operator characteristic curve (AUROC). We compared the diagnostic performance of deep learning (DL) methods with that of radiologists and determined whether DL could enhance the diagnostic capabilities of radiologists.

RESULTS

The Xception classification model exhibited the highest performance, achieving an AUROC of up to 0.970, followed by the DenseNet169 model, which attained an AUROC of up to 0.959. Notably, both DL models outperformed radiologists (P < 0.05). The success of the Xception model can be attributed to its incorporation of deep separable convolution, which effectively reduces the model's parameter count. This feature enables the model to capture features more effectively during the feature extraction process, resulting in superior performance, particularly when dealing with limited data.

CONCLUSIONS

This study conclusively demonstrated that DL outperformed radiologists in differentiating between benign and malignant calcified thyroid nodules. Additionally, the diagnostic capabilities of radiologists could be enhanced with the aid of DL.

Markedly hypoechoic: a new definition improves the diagnostic performance of thyroid ultrasound

OBJECTIVES

To determine the contribution of a modified definition of markedly hypoechoic in the differential diagnosis of thyroid nodules.

METHODS

A total of 1031 thyroid nodules were included in this retrospective multicenter study. All of the nodules were examined with US before surgery. The US features of the nodules were evaluated, in particular, the classical markedly hypoechoic and modified markedly hypoechoic (decreased or similar echogenicity relative to the adjacent strap muscles). The sensitivity, specificity, and AUC of classical/modified markedly hypoechoic and the corresponding ACR-TIRADS, EU-TIRADS, and C-TIRADS categories were calculated and compared. The inter- and intraobserver variability in the evaluation of the main US features of the nodules was assessed.

RESULTS

There were 264 malignant nodules and 767 benign nodules. Compared with classical markedly hypoechoic as a diagnostic criterion for malignancy, using modified markedly hypoechoic as the criterion resulted in a significant increase in sensitivity (28.03% vs. 63.26%) and AUC (0.598 vs. 0.741), despite a significant decrease in specificity (91.53% vs. 84.88%) (p < 0.001 for all). Compared to the AUC of the C-TIRADS with the classical markedly hypoechoic, the AUC of the C-TIRADS with the modified markedly hypoechoic increased from 0.878 to 0.888 (p = 0.01); however, the AUCs of the ACR-TIRADS and EU-TIRADS did not change significantly (p > 0.05 for both). There was substantial interobserver agreement (κ = 0.624) and perfect intraobserver agreement (κ = 0.828) for the modified markedly hypoechoic.

CONCLUSION

The modified definition of markedly hypoechoic resulted in a significantly improved diagnostic efficacy in determining malignant thyroid nodules and may improve the diagnostic performance of the C-TIRADS.

CLINICAL RELEVANCE STATEMENT

Our study found that, compared with the original definition, modified markedly hypoechoic significantly improved the diagnostic performance in differentiating malignant from benign thyroid nodules and the predictive efficacy of the risk stratification systems.

KEY POINTS

• Compared with the classical markedly hypoechoic as a diagnostic criterion for malignancy, the modified markedly hypoechoic resulted in a significant increase in sensitivity and AUC. • The C-TIRADS with the modified markedly hypoechoic achieved higher AUC and specificity than that with the classical markedly hypoechoic (p = 0.01 and  < 0.001, respectively).

Contralateral Low-to-Intermediate Suspicion Nodule Is Not a Contraindication for Lobectomy in Patients with Papillary Thyroid Carcinoma

Background: The optimal extent of surgery for unilateral papillary thyroid carcinoma (PTC) with contralateral nodules remains unclear. This study evaluated the long-term outcomes in a large cohort of patients with unilateral PTC and contralateral low-to-intermediate suspicious nodules who underwent lobectomy. Methods: This retrospective cohort study included patients with unilateral PTC who underwent lobectomy between January 2016 and December 2017 at Asan Medical Center in Korea. Patients were divided into two groups, those with and without contralateral nodules at the time of lobectomy: the Present group and the Absent group. All contralateral nodules observed at the time of surgery and during follow-up were evaluated. Results: The study cohort consisted of 1761 patients (1879 nodules), including 700 (39.8%) with and 1061 (60.2%) without contralateral nodules. The median size of the contralateral nodules was 0.5 cm. After a median follow-up of 59 months, the median growth of the contralateral nodules in the Present group was 0.1 cm (range, -3.4 to 4.7 cm). Of the contralateral nodules present at the time of lobectomy, 54.7% remained unchanged, decreased in size, or disappeared; whereas 14.8% increased ≥0.3 cm. Of the 700 patients with contralateral nodules, 20 (2.9%) were diagnosed with contralateral PTC. The 5-year contralateral PTC disease-free survival rates in patients with and without contralateral nodules were 98.2% and 99.3% (p = 0.003), respectively, whereas the 5-year recurrence-free survival rates did not differ significantly in these two groups. Of the 39 patients who underwent completion thyroidectomy, 2 (5.1%) experienced permanent hypocalcemia. Conclusions: Lobectomy may be a safe and feasible initial treatment option for patients with unilateral low-risk PTC and contralateral low-to-intermediate suspicious nodules.

Validation of CT-Based Risk Stratification System for Lymph Node Metastasis in Patients With Thyroid Cancer

OBJECTIVE

To evaluate the computed tomography (CT) features for diagnosing metastatic cervical lymph nodes (LNs) in patients with differentiated thyroid cancer (DTC) and validate the CT-based risk stratification system suggested by the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) guidelines.

MATERIALS AND METHODS

A total of 463 LNs from 399 patients with DTC who underwent preoperative CT staging and ultrasound-guided fine-needle aspiration were included. The following CT features for each LN were evaluated: absence of hilum, cystic changes, calcification, strong enhancement, and heterogeneous enhancement. Multivariable logistic regression analysis was performed to identify independent CT features associated with metastatic LNs, and their diagnostic performances were evaluated. LNs were classified into probably benign, indeterminate, and suspicious categories according to the K-TIRADS and the modified LN classification proposed in our study. The diagnostic performance of both classification systems was compared using the exact McNemar and Kosinski tests.

RESULTS

The absence of hilum (odds ratio [OR], 4.859; 95% confidence interval [CI], 1.593-14.823; P = 0.005), strong enhancement (OR, 28.755; 95% CI, 12.719-65.007; P < 0.001), and cystic changes (OR, 46.157; 95% CI, 5.07-420.234; P = 0.001) were independently associated with metastatic LNs. All LNs showing calcification were diagnosed as metastases. Heterogeneous enhancement did not show a significant independent association with metastatic LNs. Strong enhancement, calcification, and cystic changes showed moderate to high specificity (70.1%-100%) and positive predictive value (PPV) (91.8%-100%). The absence of the hilum showed high sensitivity (97.8%) but low specificity (34.0%). The modified LN classification, which excluded heterogeneous enhancement from the K-TIRADS, demonstrated higher specificity (70.1% vs. 62.9%, P = 0.016) and PPV (92.5% vs. 90.9%, P = 0.011) than the K-TIRADS.

CONCLUSION

Excluding heterogeneous enhancement as a suspicious feature resulted in a higher specificity and PPV for diagnosing metastatic LNs than the K-TIRADS. Our research results may provide a basis for revising the LN classification in future guidelines.

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.

Immune response and mesenchymal transition of papillary thyroid carcinoma reflected in ultrasonography features assessed by radiologists and deep learning

INTRODUCTION

Ultrasonography (US) features of papillary thyroid cancers (PTCs) are used to select nodules for biopsy due to their association with tumor behavior. However, the molecular biological mechanisms that lead to the characteristic US features of PTCs are largely unknown.

OBJECTIVES

This study aimed to investigate the molecular biological mechanisms behind US features assessed by radiologists and three convolutional neural networks (CNN) through transcriptome analysis.

METHODS

Transcriptome data from 273 PTC tissue samples were generated and differentially expressed genes (DEGs) were identified according to US feature. Pathway enrichment analyses were also conducted by gene set enrichment analysis (GSEA) and ClusterProfiler according to assessments made by radiologists and three CNNs - CNN1 (ResNet50), CNN2 (ResNet101) and CNN3 (VGG16). Signature gene scores for PTCs were calculated by single-sample GSEA (ssGSEA).

RESULTS

Individual suspicious US features consistently suggested an upregulation of genes related to immune response and epithelial-mesenchymal transition (EMT). Likewise, PTCs assessed as positive by radiologists and three CNNs showed the coordinate enrichment of similar gene sets with abundant immune and stromal components. However, PTCs assessed as positive by radiologists had the highest number of DEGs, and those assessed as positive by CNN3 had more diverse DEGs and gene sets compared to CNN1 or CNN2. The percentage of PTCs assessed as positive or negative concordantly by radiologists and three CNNs was 85.6% (231/273) and 7.1% (3/273), respectively.

CONCLUSION

US features assessed by radiologists and CNNs revealed molecular biologic features and tumor microenvironment in PTCs.

Comparison of Diagnostic Values of ACR TI-RADS versus C-TIRADS Scoring and Classification Systems for the Elderly Thyroid Cancers

Purpose

To compare the diagnostic value of the Thyroid Imaging Reporting and Data System (TI-RADS) of the American College of Radiology (ACR) versus the Chinese Thyroid Imaging Reporting and Data System (C-TIRADS) scoring and classification system for elderly thyroid cancers.

Patients and Methods

A total of 512 nodules from 465 patients aged ≥60 with surgical pathology-proven thyroid nodules were enrolled in our study. The ultrasound features of thyroid nodules were independently evaluated by the ACR TI-RADS and C-TIRADS classification systems, and the receiver operating characteristic curve (ROC) was plotted. The optimal cut-off values of the ACR TI-RADS and C-TIRADS scoring and classification systems for diagnosing elderly thyroid nodules were estimated, and the diagnostic efficacy was analyzed.

Results

The ACR TI-RADS and C-TIRADS scores and classifications of thyroid cancers were both higher than benign nodules (both P < 0.05). The area under the curve (AUC) of ACR TI-RADS and C-TIRADS scoring and classification systems were 0.861, 0.897, 0.879, and 0.900, respectively, and the AUC of the scoring system was greater than the classification system for both criteria. When the Youden index was the highest, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the ACR TI-RADS scoring and classification systems were consistent, ie, they were 89.66%, 41.70%, 89.93%, and 59.00%, respectively; the sensitivity, specificity, PPV, and NPV of the C-TIRADS scoring and classification systems were also consistent, ie, they were 88.71%, 44.26%, 90.23%, 59.69%, respectively. The diagnostic efficacy between the two systems was not statistically significant.

Conclusion

ACR TI-RADS and C-TIRADS systems had relatively high diagnostic efficacy for elderly thyroid cancer. The diagnostic efficiency of the scoring systems of ACR TI-RADS and C-TIRADS were higher than the classification systems. In addition, the two systems had high clinical practical values, while there is still a significant risk of missed diagnosis.

[Application of Radiofrequency Ablation to Thyroid Cancer: Past, Present, and Future]

Thyroid cancer, characterized by high incidence rates, good prognosis, and frequent recurrence, is typically treated surgically. However, since the early 2000s, radiofrequency ablation, which is commonly utilized in liver, lung, and kidney cancers, is being performed for management of primary and recurrent thyroid cancers. Many studies have focused on inoperable cases of low-risk papillary microcarcinoma (≤ 1 cm) and some have investigated its role in larger lesions (up to 4 cm). Overall, these studies have reported positive results. Radiofrequency ablation for recurrent cancer has primarily been performed for locally recurrent cervical cancer, and this therapeutic approach has been attempted for treatment of distant metastases in lungs and bones, with encouraging outcomes. A growing global trend, particularly in South Korea, the United States, and Europe supports radiofrequency ablation for thyroid cancer. However, this therapy is currently not recognized as a treatment option recommended by universally accepted clinical guidelines such as those established by the National Comprehensive Cancer Network. Based on past efforts and future research, radiofrequency ablation is expected to play a key role in thyroid cancer treatment in the near future.

Validation of Ultrasound and Computed Tomography-Based Risk Stratification System and Biopsy Criteria for Cervical Lymph Nodes in Preoperative Patients With Thyroid Cancer

OBJECTIVE

This study aimed to validate the risk stratification system (RSS) and biopsy criteria for cervical lymph nodes (LNs) proposed by the Korean Society of Thyroid Radiology (KSThR).

MATERIALS AND METHODS

This retrospective study included a consecutive series of preoperative patients with thyroid cancer who underwent LN biopsy, ultrasound (US), and computed tomography (CT) between December 2006 and June 2015. LNs were categorized as probably benign, indeterminate, or suspicious according to the current US- and CT-based RSS and the size thresholds for cervical LN biopsy as suggested by the KSThR. The diagnostic performance and unnecessary biopsy rates were calculated.

RESULTS

A total of 277 LNs (53.1% metastatic) in 228 patients (mean age ± standard deviation, 47.4 years ± 14) were analyzed. In US, the malignancy risks were significantly different among the three categories (all P < 0.001); however, CT-detected probably benign and indeterminate LNs showed similarly low malignancy risks (P = 0.468). The combined US + CT criteria stratified the malignancy risks among the three categories (all P < 0.001) and reduced the proportion of indeterminate LNs (from 20.6% to 14.4%) and the malignancy risk in the indeterminate LNs (from 31.6% to 12.5%) compared with US alone. In all image-based classifications, nodal size did not affect the malignancy risks (short diameter [SD] ≤ 5 mm LNs vs. SD > 5 mm LNs, P ≥ 0.177). The criteria covering only suspicious LNs showed higher specificity and lower unnecessary biopsy rates than the current criteria, while maintaining sensitivity in all imaging modalities.

CONCLUSION

Integrative evaluation of US and CT helps in reducing the proportion of indeterminate LNs and the malignancy risk among them. Nodal size did not affect the malignancy risk of LNs, and the addition of indeterminate LNs to biopsy candidates did not have an advantage in detecting LN metastases in all imaging modalities.

Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation: Ultrasound Characteristics and Predictors for Cancer

OBJECTIVE

Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules, initially treated as benign, sometimes turns out to be malignancies. This study aimed to assess the ultrasound (US) characteristics of thyroid nodules initially treated as benign with RFA and later diagnosed as cancers, predictive factors for cancers masquerading as benign, and methods to avoid RFA in these cancers.

MATERIALS AND METHODS

We reviewed the medical records of 134 consecutive patients with 148 nodules who underwent RFA between February 2008 and November 2016 for the debulking of symptomatic thyroid nodules diagnosed as benign using US-guided biopsy. We investigated the pre-RFA characteristics of the thyroid nodules, changes at follow-up after RFA, and the final surgical pathology.

RESULTS

Nodule regrowth after RFA was observed in 36 (24.3%) of the 148 benign nodules. Twenty-two of the 36 nodules were surgically removed, and malignancies were confirmed in seven (19.4% of 36). Of the 22 nodules removed surgically, pre-RFA median volume (range) was significantly larger for malignant nodules than for benign nodules: 22.4 (13.9-84.5) vs. 13.4 (7.3-16.8) mL (P = 0.04). There was no significant difference in the regrowth interval between benign and malignant nodules (P = 0.49). The median volume reduction rate (range) at 12 months was significantly lower for malignant nodules than for benign nodules (51.4% [0-57.8] vs. 83.8% [47.9-89.6]) (P = 0.01). The pre-RFA benignity of all seven malignant nodules was confirmed using two US-guided fine-needle aspirations (FNAs), except for one nodule, which was confirmed using US-guided core-needle biopsy (CNB). Regrown malignant nodules were diagnosed as suspicious follicular neoplasms by CNB. Histological examination of the malignant nodules revealed follicular thyroid carcinomas, except for one follicular variant, a papillary thyroid carcinoma.

CONCLUSION

Symptomatic large benign thyroid nodules showing regrowth or suboptimal reduction after RFA may have malignant potential. The confirmation of these nodules is better with CNB than with FNA.

A Reappraisal of Suspicious Sonographic Features of Thyroid Nodules: Shape Is Not an Independent Predictor of Malignancy

CONTEXT

For the correct clinical application of the sonographic risk-stratification systems, the definition of independent risk features that are foundational to each system is crucial.

OBJECTIVE

The aim of this study was to identify the gray-scale sonographic features independently associated with malignancy, and to compare different definitions.

METHODS

This prospective, diagnostic accuracy study took place in a single thyroid nodule referral center. All patients consecutively referred to our center for fine-needle aspiration cytology of a thyroid nodule between November 1, 2015 and March 30, 2020, were enrolled before cytology. Each nodule was examined by 2 experienced clinicians to record the sonographic features on a rating form. Histologic (when available) or cytologic diagnosis was used as the reference standard. For each single sonographic feature and definition, the sensitivity, specificity, positive and negative predictive values, and diagnostic odds ratios (DOR) were calculated. The significant predictors were then included in a multivariable regression model.

RESULTS

The final study cohort consisted of 903 nodules in 852 patients. A total of 76 nodules (8.4%) were malignant. Six features were independent predictors of malignancy: suspicious lymph node (DOR 16.23), extrathyroidal extension (DOR 6.60), irregular or infiltrative margins (DOR 7.13), marked hypoechogenicity (DOR 3.16), solid composition (DOR 3.61), and punctate hyperechoic foci (including microcalcifications and indeterminate foci; DOI 2.69). Taller-than-wide shape was not confirmed as an independent predictor.

CONCLUSION

We identified the key suspicious features of thyroid nodules and provided a simplified definition of some debated ones. Malignancy rate increases with number of features.

Percutaneous Radiofrequency Ablation of Thyroid Carcinomas Ineligible for Surgery, in the Elderly

Thirty to 50% of differentiated thyroid carcinomas include papillary thyroid microcarcinomas (mPTC). Most of these tumors remain clinically silent, have a bright prognosis and a disease-specific mortality <1%. Surgery has been recommended as first line-treatment by current guidelines, the standard treatment being lobectomy. However, surgery has some drawbacks, including potential recurrent laryngeal nerve paralysis, hypothyroidism, hypoparathyroidism, in -patient basis hospital stay, lifelong medication, scarring of the neck, and general anesthesia related risks. Moreover, elderly patients who present severe comorbidities, could be ineligible for surgery, and others may refuse invasive surgery. Another option supported by the American Thyroid Association is active surveillance. This option can be considered as unattractive and difficult to accept by European patients, as there is a 2-6% risk of disease progression. Percutaneous image-guided thermal ablation has been successfully applied in the treatment of liver and lung tumors in the 1990s and 2000s; and has recently been proposed as an alternative to surgery in patients presenting with thyroid diseases. This minimally invasive treatment has similar efficacy, fewer complications, better quality of life and cosmetic outcomes than surgery. We report herein two cases of radiofrequency ablation of mPTC and T2 PTC in elderly patients who were ineligible for surgery.

Leveraging deep learning to identify calcification and colloid in thyroid nodules

Background

Both calcification and colloid in thyroid nodules are reflected as echogenic foci in ultrasound images. However, calcification and colloid have significantly different probabilities of malignancy. We explored the performance of a deep learning (DL) model in distinguishing the echogenic foci of thyroid nodules as calcification or colloid.

Methods

We conducted a retrospective study using ultrasound image sets. The DL model was trained and tested on 30,388 images of 1127 nodules. All nodules were pathologically confirmed. The area under the receiver-operator characteristic curve (AUC) was employed as the primary evaluation index.

Results

The YoloV5 (You Only Look Once Version 5) transfer learning model for thyroid nodules based on DL detection showed that the average sensitivity, specificity, and accuracy of distinguishing echogenic foci in the test 1 group (n = 192) was 78.41%, 91.36%, and 77.81%, respectively. The average sensitivity, specificity, and accuracy of the three radiologists were 51.14%, 82.58%, and 61.29%, respectively. The average sensitivity, specificity, and accuracy of distinguishing small echogenic foci in the test 2 group (n = 58) was 70.17%, 77.14%, and 73.33%, respectively. Correspondingly, the average sensitivity, specificity, and accuracy of the radiologists were 57.69%, 63.29%, and 59.38%.

Conclusions

The study demonstrated that DL performed far better than radiologists in distinguishing echogenic foci of thyroid nodules as calcifications or colloid.