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

Evaluation and application of American College of Radiology Thyroid Imaging Reporting and Data System for improved malignancy detection in paediatric thyroid nodules

OBJECTIVE

The American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) is a widely used method for the management of adult thyroid nodules. However, its use in paediatric patients is controversial because adult fine needle aspiration biopsy (FNAB) recommendations may lead to delayed diagnoses of cancer in children. The objectives of this study were to evaluate the performance of TI-RADS in paediatric thyroid nodules and to tailor FNAB recommendations for children.

METHODS

Consecutive surgically resected paediatric thyroid nodules from two tertiary care centres between 2003 and 2021 were reviewed. Ultrasounds were blindly scored by radiologists according to TI-RADS. Management recommendations based on TI-RADS were evaluated. Various modelling methodologies were used to determine the optimal cutoff for FNAB in children.

RESULTS

Of the 96 patients, 79 (82%) were female and the median age at surgery was 16.1 years. Fifty (52%) nodules were malignant on surgical pathology. The area under the receiver operating characteristic curve of TI-RADS for predicting malignancy was 0.78. Adult TI-RADS recommendations would have resulted in 4% of cancerous nodules being lost to follow-up. Modifications to TI-RADS (FNAB of all TR3 nodules ≥1.5 cm, FNAB of TR4 and TR5 nodules ≥0.5 cm, surveillance of nodules ≥1 cm, consider surgery for nodules >4 cm) reduced this missed malignancy rate to 0%.

CONCLUSIONS

TI-RADS can risk-stratify paediatric thyroid nodules. However, the system requires modifications to reduce the missed malignancy rate in paediatric thyroid nodules. Our data suggest that lower size thresholds for FNAB are warranted in children.

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.

Evolving approaches in paediatric thyroid cytopathology: A review

The guidelines for the workup of thyroid nodules have been established in adult populations and secondarily applied to paediatric populations. In particular, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) is commonly applied to both adult and paediatric thyroid nodules. However, as paediatric nodules have distinct molecular drivers and behavioural trajectories, there is renewed interest in diagnostic and management strategies that are paediatric specific. Here, we review key differences between paediatric and adult thyroid cancer and recent literature evaluating the use of TBSRTC in paediatric populations.

Modification of size cutoff for biopsy based on the American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) for thyroid nodules in patients younger than 19 years

OBJECTIVES

To modify the size cutoff for biopsy for thyroid nodules in patients < 19 years based on the American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) and evaluate the performance of the new criteria in two referral centers.

METHODS

Patients < 19 years with cytopathologic or surgical pathology results were retrospectively identified from two centers from May 2005 to August 2022. Patients from one center were classified as the training cohort, and those from the other center were classified as the validation cohort. The diagnostic performance, unnecessary biopsy rates, and missed malignancy rates of the TI-RADS guideline, and the new criteria (≥ 35 mm for TR3 and no threshold for TR5) were compared.

RESULTS

A total of 236 nodules from 204 patients in the training cohort and 225 nodules from 190 patients in the validation cohort were analyzed. The area under the receiver operating characteristic curve of the new criteria in identifying thyroid malignant nodules was higher (0.809 vs. 0.681, p < 0.001; 0.819 vs. 0.683, p < 0.001), and the unnecessary biopsy rates (45.0% vs. 56.8%; 42.2% vs. 56.8%) and missed malignancy rates (5.7% vs. 18.6%; 9.2% vs. 21.5%) were lower than that of the TI-RADS guideline in the training cohort and validation cohort, respectively.

CONCLUSIONS

The new criteria (≥ 35 mm for TR3 and no threshold for TR5) for biopsy based on the TI-RADS may help improve the diagnostic performance and reduce unnecessary biopsy rates and missed malignancy rates for thyroid nodules in patients < 19 years.

CLINICAL RELEVANCE STATEMENT

The study developed and validated the new criteria (≥ 35 mm for TR3 and no threshold for TR5) to indicate FNA based on the ACR TI-RADS of thyroid nodules in patients younger than 19 years.

KEY POINTS

•The AUC of the new criteria (≥ 35 mm for TR3 and no threshold for TR5) in identifying thyroid malignant nodules was higher than that of the TI-RADS guideline (0.809 vs. 0.681) in patients < 19 years. •The unnecessary biopsy rates and missed malignancy rates of the new criteria (≥ 35 mm for TR3 and no threshold for TR5) in identifying thyroid malignant nodules were lower than that of the TI-RADS guideline in patients < 19 years (45.0% vs. 56.8% and 5.7% vs. 18.6%, respectively).

Performance of ACR TI-RADS and the Bethesda System in Predicting Risk of Malignancy in Thyroid Nodules at a Large Children's Hospital and a Comprehensive Review of the Pediatric Literature

While thyroid nodules are less common in children than in adults, they are more frequently malignant. However, pediatric data are scarce regarding the performance characteristics of imaging and cytopathology classification systems validated to predict the risk of malignancy (ROM) in adults and select those patients who require fine-needle aspiration (FNA) and possibly surgical resection. We retrospectively reviewed the electronic medical records of all patients 18 years of age or younger who underwent thyroid FNA at our institution from 1 July 2015 to 31 May 2022. Based on surgical follow-up from 74 of the 208 FNA cases, we determined the ROM for the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) ultrasound risk stratification system and The Bethesda System for Reporting Thyroid Cytopathology and added our results to those of pediatric cohorts from other institutions already published in the literature. We found the following ROMs for 1458 cases using ACR TI-RADS (TR): TR1. Benign: 2.2%, TR2. Not Suspicious: 9.3%, TR3. Mildly Suspicious: 16.6%, TR4. Moderately Suspicious: 27.0%, and TR5. Highly Suspicious 76.5%; and for 5911 cases using the Bethesda system: Bethesda I. Unsatisfactory: 16.8%, Bethesda II. Benign: 7.2%, Bethesda III: Atypia of Undetermined Significance: 29.6%, Bethesda IV. Follicular Neoplasm: 42.3%, Bethesda V. Suspicious for Malignancy: 90.8%, and Bethesda VI. Malignant: 98.8%. We conclude that ACR TI-RADS levels imply higher ROMs for the pediatric population than the corresponding suggested ROMs for adults, and, in order to avoid missing malignancies, we should consider modifying or altogether abandoning size cutoffs for recommending FNA in children and adolescents whose thyroid glands are smaller than those of adults. The Bethesda categories also imply higher ROMs for pediatric patients compared to adults.

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

Purpose

Ultrasound (US) is the first choice in the detection of thyroid nodules in pediatric and adult patients. The purpose of this study was to evaluate the diagnostic performance of adult-based US risk stratification systems (RSSs) when applied to the pediatric population.

Methods

Medline, Embase, and Cochrane Library (CENTRAL) were searched up to 5 March 2023 for studies about the diagnostic performance of adult-based US RSS in pediatric patients. The pooled sensitivity, specificity, positive likelihood ratio (LR), negative LR, and diagnostic odds ratio (DOR) were calculated. The summary receiver operating characteristic (SROC) curves and area under the curve (AUC) were also analyzed.

Results

The sensitivity was highest in American College of Radiology-Thyroid Imaging Reporting and Data System (ACR-TIRADS) category 4-5 and American Thyroid Association RSS high-intermediate risk (ATA), which was 0.84 [0.79, 0.88] and 0.84 [0.75, 0.90], respectively. The specificity was highest in ACR-TIRADS category 5 and Europe-TIRADS (EU-TIRADS) category 5, which was 0.93 [0.83, 0.97] and 0.93 [0.88, 0.98], respectively. The ACR-TIRADS, ATA, and EU-TIRADS showed moderate diagnostic performance in pediatric thyroid nodule patients. For Korea-TIRADS (K-TRADS) category 5, the summary sensitivity and specificity with a 95% CI were 0.64 [0.40, 0.83] and 0.84 [0.38, 0.99], respectively.

Conclusions

In conclusion, the ACR-TIRADS, ATA, and EU-TIRADS have moderate diagnostic performance in pediatric thyroid nodule patients. The diagnostic efficacy of the K-TIRADS was not as high as expected. However, the diagnostic performance of Kwak-TIRADS was uncertain because of the small sample size and small number of studies included. More studies are needed to evaluate these adult-based RSSs in pediatric patients with thyroid nodules. RSSs specific for pediatric thyroid nodules and thyroid malignancies were necessary.

Effect of the categorization method on the diagnostic performance of ultrasound risk stratification systems for thyroid nodules

Objective

To evaluate whether the categorization methods of risk stratification systems (RSSs) is a decisive factor that influenced the diagnostic performances and unnecessary FNA rates in order to choose optimal RSS for the management of thyroid nodules.

Methods

From July 2013 to January 2019, 2667 patients with 3944 thyroid nodules had undergone pathological diagnosis after thyroidectomy and/or US-guided FNA. US categories were assigned according to the six RSSs. The diagnostic performances and unnecessary FNA rates were calculated and compared according to the US-based final assessment categories and the unified size thresholds for biopsy proposed by ACR-TIRADS, respectively.

Results

A total of 1781 (45.2%) thyroid nodules were diagnosed as malignant after thyroidectomy or biopsy. Significantly lowest specificity and accuracy, along with the highest unnecessary FNA rates were seen in EU-TIRADS for both US categories (47.9%, 70.2%, and 39.4%, respectively, all P < 0.05) and indications for FNA (54.2%, 50.0%, and 55.4%, respectively, all P < 0.05). Diagnostic performances for US-based final assessment categories exhibited similar accuracy for AI-TIRADS, Kwak-TIRADS, C-TIRADS, and ATA guidelines (78.0%, 77.8%, 77.9%, and 76.3%, respectively, all P > 0.05), while the lowest unnecessary FNA rate was seen in C-TIRADS (30.9%) and without significant differences to that of AI-TIRADS, Kwak-TIRADS, and ATA guideline (31.5%, 31.7%, and 33.6%, respectively, all P > 0.05). Diagnostic performance for US-FNA indications showed similar accuracy for ACR-TIRADS, Kwak-TIRADS, C-TIRADS and ATA guidelines (58.0%, 59.7%, 58.7%, and 57.1%, respectively, all P > 0.05). The highest accuracy and lowest unnecessary FNA rate were seen in AI-TIRADS (61.9%, 38.6%) and without significant differences to that of Kwak-TIRADS(59.7%, 42.9%) and C-TIRADS 58.7%, 43.9%, all P > 0.05).

Conclusion

The different US categorization methods used by each RSS were not determinant influential factors in diagnostic performance and unnecessary FNA rate. For daily clinical practice, the score-based counting RSS was an optimal choice.

The feasibility of decreasing the thresholds for biopsy in Kwak and C TIRADSs

Objectives

To estimate the feasibility of decreasing the original thresholds for biopsy in the Kwak Thyroid Imaging Reporting and Data System (Kwak TIRADS) and Chinese Thyroid Imaging Reporting and Data System (C TIRADS).

Methods

This retrospective study included 3,201 thyroid nodules from 2,146 patients with a pathological diagnosis. We lowered the original fine-needle aspiration (FNA) thresholds with the TR4a-TR5 in Kwak and C TIRADSs and calculated the ratio of additional benign-to-malignant nodules being biopsied (RABM). If the RABM is less than 1, the decreased FNA thresholds could be accepted and used to the modified TIRADSs (modified C and Kwak TIRADSs). Then, we estimated and compared the diagnostic performance between the modified TIRADS and the original TIRADS to determine if the decreased thresholds could be an effective strategy.

Results

A total of 1,474 (46.0%) thyroid nodules were diagnosed as malignant after thyroidectomy. The TR4c-TR5 in Kwak TIRADS and TR4b-TR5 in C TIRADS had a rational RABM (RABM < 1). The modified Kwak TIRADS had higher sensitivity, a positive predictive value, a negative predictive value, lower specificity, an unnecessary biopsy rate, and a missed malignancy rate compared with the original Kwak TIRADS (94.1% vs. 42.6%, 59.4% vs. 44.6%, 89.9% vs. 52.8%, 45.0% vs. 54.9%, 40.6% vs. 55.4%, and 10.1% vs. 47.1%, respectively, P < 0.05 for all). Similar trends were seen in the modified C TIRADS versus the original C TIRADS (95.1% vs. 38.7%, 61.7% vs. 47.8%, 92.3% vs. 55.0%, 49.7% vs. 64.0%, 38.3% vs. 52.2%, and 7.7% vs. 44.9%, respectively, P < 0.05 for all).

Conclusions

The biopsy of all nodules with TR4C-TR5 in the Kwak TIRADS and TR4B-TR5 in the C TIRADS might be an effective strategy. This paper contributes to the contradiction concerning whether to perform FNA for the nodules smaller than 10 mm.

[Clinical Application of the 2021 Korean Thyroid Imaging Reporting and Data System (K-TIRADS)]

In patients with thyroid nodules, ultrasonography (US) has been established as a primary diagnostic imaging method and is essential for treatment decision. The Korean Thyroid Imaging Reporting and Data System (K-TIRADS) is a pattern-based, US malignancy risk stratification system that can easily diagnose nodules during real-time ultrasound examinations. The 2021 K-TIRADS clarified the US criteria for nodule classification and revised the size thresholds for nodule biopsy, thereby reducing unnecessary biopsies for benign nodules while maintaining the appropriate sensitivity to detect malignant tumors in patients without feature of high risk thyroid cancer. Thyroid radiology practice has an important clinical role in the diagnosis and non-surgical treatment of patients with thyroid nodules, and should be performed according to standard practice guidelines for proper and effective clinical care.

The diagnostic efficacy and inappropriate biopsy rate of ACR TI-RADS and ATA guidelines for thyroid nodules in children and adolescents

BACKGROUND

This study is aimed at evaluating the diagnostic efficacy and unnecessary fine-needle aspiration (FNA) rate of ultrasound-based risk stratification for thyroid nodules in the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) and the American Thyroid Association (ATA) risk stratification systems.

METHODS

Children and adolescents with pathology confirmed thyroid nodules were retrospectively included in this study. A total of 217 thyroid nodules from multicenter of Union Medical College Hospital, China Japan Friendship Hospital and Civil Aviation Hospital were included, the diagnostic efficiency and unnecessary FNA rate were calculated according to ACR and ATA guidelines.

RESULTS

Among all thyroid nodules, 139 nodules were malignant, and 78 nodules were benign. Choosing ATA high suspicion and ACR TI-RADS TR5 as benign and malignant cut-off points, the area under the curve and sensitivity of ATA were higher than ACR (AUC: 0.887 vs 0.840, p=0.0037; sensitivity 81.3% vs 71.0%, P <0.049;specificity 96.2% vs 97.4%, p=1.000;specificity both 85.9%); choosing high/intermediate suspicion in ATA and ACR TR4/5 as benign and malignant cut-off points, the two guidelines demonstrated similar diagnostic efficacy (AUC:0.890 vs 0.897, p=0.6038, sensitivity 92.1% vs 93.5%, P =0.817;specificity both 85.9%, p=1.000). The inappropriate FNA rate of ACR guideline was relatively lower (ATA 42.9% vs ACR 27.2%, P <0.001). If ACR TI-RADS TR5 nodules less than 1.0cm were included in the FNA indication, the unnecessary biopsy rate would be further reduced to 17.9%.

CONCLUSION

This study indicated that both ATA and ACR TI-RADS risk stratification systems could provide a feasible differential diagnosis of benign and malignant thyroid nodules, while the ACR risk stratification system demonstrates a lower rate of inappropriate FNA rate. In addition, it was necessary to further study the minimum FNA threshold of thyroid nodules in Children and adolescents in order to reduce the missed biopsy rate of malignant nodules.