Prospective Validation of ATA and ETA Sonographic Pattern Risk of Thyroid Nodules Selected for FNAC

Risk Stratification of Thyroid Nodules: From Ultrasound Features to TIRADS

Simple Summary

Thyroid nodules are a frequent clinical issue. Their incidence has increased mainly due to the widespread use of neck ultrasound scans. Most thyroid nodules are asymptomatic, incidentally discovered, and benign at cytology. Thyroid ultrasound is the most sensitive diagnostic tool to evaluate patients with nodular thyroid disease. It is therefore important to use the ultrasound features to select nodules that require a fine-needle aspiration cytology.

Abstract

Thyroid nodules are common in iodine deficient areas, in females, and in patients undergoing neck irradiation. High-resolution ultrasonography (US) is important for detecting and evaluating thyroid nodules. US is used to determine the size and features of thyroid nodules, as well as the presence of neck lymph node metastasis. It also facilitates guided fine-needle aspiration (US-FNA). The most consistent US malignancy features of thyroid nodules are spiculated margins, microcalcifications, a taller-than-wide shape, and marked hypoechogenicity. Increased nodular vascularization is not identified as a predictor of malignancy. Thyroid elastosonography (USE) is also used to characterize thyroid nodules. In fact, a low elasticity of nodules at USE has been related to a higher risk of malignancy. According to their US features, thyroid nodules can be stratified into three categories: low-, intermediate-, and high-risk nodules. US-FNA is suggested for intermediate and high-risk nodules.

Macrocalcifications Do Not Alter Malignancy Risk Within the American Thyroid Association Sonographic Pattern System When Present in Non-High Suspicion Thyroid Nodules

Background: The American Thyroid Association Sonographic Pattern System (ATASPS) depicts five levels of suspicion for malignancy based on the sonographic appearance of a thyroid nodule. However, 3-37% of nodules are non-classifiable when the combination of grayscale findings is not depicted by the ATASPS. The only calcifications included in the ATASPS are in solid hypoechoic high suspicion (HS) nodules and include both microcalcifications and peripheral interrupted calcifications with soft tissue extrusion. Non-hypoechoic nodules with these and other calcification patterns, which we defined as non-high suspicion calcifications (NHSC), are not classifiable by ATASPS. We assessed the effect of assigning an ATASPS risk level to nodules with NHSC based on analysis of their other grayscale features. Methods: A retrospective review of 728 consecutively biopsied nodules was performed. Nodules were classified by ATASPS as HS, intermediate suspicion (IS), low suspicion (LS), or very low suspicion (VLS); other nodules with patterns not described by ATASPS were non-classifiable (NC). If NC was due to NHSC, the nodule was assigned an ATASPS by analysis of grayscale features alone. Cytology and pathology results were correlated with assigned ATASPS level. Results: A NC pattern was observed in 144 of the 728 nodules (20%). Of these, 101/144 (70%) had NHSC and the assigned ATASPS was IS (n = 18), LS (n = 62) and VLS (n = 21). The distribution of cytology diagnoses within this group was similar to classifiable nodules (IS p = 0.13, LS p = 0.55, VLS p = 0.44). The majority of NHSC (n = 92, 91%) were macrocalcifications (large central or linear dystrophic calcifications); however, 9 LS pattern nodules had punctate echogenic foci, possibly representing microcalcifcations, with an estimated cancer prevalence of 19% (vs. 10% for total LS group, p = 0.24). The remaining NC nodules (43/144, 30%) included solid nodules with heterogeneous echogenicity (n = 30) or presence of a complete circumferential rim calcification, limiting further sonographic assessment (n = 13). Malignancy was identified in 11 out of 43 (26%) of these [9/30 (30%) heterogeneous solid and 2/13 (15%) with complete rim calcifications]. Conclusions: Macrocalcifications accounted for the majority of NHSC and these did not alter the expected ATASPS malignancy risk based on grayscale features.

Diagnostic performance rates of the ACR-TIRADS and EU-TIRADS based on histopathological evidence

PURPOSE

In this study, we aimed to assess the effectiveness of malignancy stratification algorithms of the American College of Radiology (ACR) and European Thyroid Association (ETA) in the delineation of thyroid nodules using a database of nodules that were unequivocally diagnosed by means of histopathological examination and meticulously matched with the imaged nodules.

METHODS

A total of 165 patients having 251 thyroid nodules with histopathologically proven definitive diagnoses during a 5-year period were included in this study. All patients had preoperatively undergone ultrasonography (US) examination, and US characteristics of the thyroid nodules were retrospectively analyzed and assigned in compliance with the thyroid imaging reporting and data system categories recommended by the ACR (ACR-TIRADS) and ETA (EU-TIRADS). The diagnostic effectiveness in the delineation of thyroid nodules and unnecessary fine-needle aspiration (FNAB) rates were evaluated.

RESULTS

Overall, 189 nodules (75.30%) were diagnosed as benign, while 62 nodules (24.70%) were reported to be malignant based on histopathological assessment. Sensitivity and specificity rates were 71% and 75% for ACR-TIRADS and 73% and 80% for EU-TIRADS. The area under the curve values were 0.78 and 0.80 for ACR-TIRADS and EU-TIRADS, respectively. The unnecessary FNAB rates were 61% for ACR-TIRADS and 64% for EU-TIRADS as per the recommended criteria of each algorithm.

CONCLUSION

The diagnostic performance of both malignancy stratification systems was signified to be moderate and sufficient in a cohort of nodules with definite histopathological diagnosis. In light of our results, we demonstrated the strengths and weaknesses of the ACR- and EU-TIRADS for physicians who should be familiar with them for optimal management of thyroid nodules.

Validation of American Thyroid Association Ultrasound Risk-Adapted Approach for Repeating Cytology in Benign Thyroid Nodules

Background: The 2015 American Thyroid Association (ATA) ultrasound (US) risk stratification system is used to identify thyroid nodules in which fine-needle aspiration cytology (FNAC) should be performed. In addition, this system is used to plan the long-term follow-up of patients with cytological benign thyroid nodules. The aim of our study was to evaluate the ATA US risk-adapted approach for repeating cytology in a large retrospective cohort of consecutive benign nodules with a second FNAC repeated after a median follow-up of 3.8 years (range 1.0-14.2 years). Methods: We retrospectively evaluated 1010 thyroid nodules, with an initial benign cytological diagnosis, that underwent at least one repeat FNAC during the follow-up. Results: The rate of missed cancer in the whole cohort of thyroid nodules was 1.0%, and it increased along by the US risk class (0.8% in very low/low-risk, 1.2% in intermediate-risk, and 3.1% in high-risk nodules). The 2015 ATA US risk stratification system showed a very high accuracy in selecting nodules that did not require a second FNAC (negative predictive value = 99.1%). In addition, the rate of missed cancer significantly increased along with the increase in the US risk class in nodules that showed an enlarged volume (0.4% in the low-risk class and 6.4% in the high-risk class, p = 0.005), while it was very low and not associated with the US features in the subgroup of thyroid nodules that did not grow during the follow-up (p = 0.96). Conclusions: Our results confirm the accuracy of the ATA recommendations in selecting benign nodules for FNAC repetition during the follow-up. An additional cytological evaluation maybe avoided in benign thyroid nodules with low-risk US features, regardless of the evidence of growth during the follow-up. While the utility of the routine repeat FNAC in all benign nodules with high-risk US features remains to be defined, based on our results, repetition of FNAC seems to be indicated in nodules with evidence of growth during the follow-up.

Evaluation of the Diagnostic Performance of EU-TIRADS in Discriminating Benign from Malignant Thyroid Nodules: A Prospective Study in One Referral Center

BACKGROUND

Several thyroid societies have endorsed ultrasound (US) malignancy risk stratification systems for thyroid nodules and the recently released European Thyroid Imaging Reporting and Data System (EU-TIRADS) needs large prospective studies for validation.

OBJECTIVE

The purpose of our study was to evaluate the performance of EU-TIRADS in identifying thyroid nodules for fine-needle aspiration biopsy (FNAB) and its ability to reduce the number of unnecessary biopsies.

METHODS

This was a single-center prospective study. From August 2017 to September 2018, 783 consecutive patients with 1,000 thyroid nodules underwent US examination and US-guided FNAB. A total of 741 patients (median age 50 years; range, 15-87 years; 649 females, 92 males) with 942 nodules (median largest diameter 14 mm; range, 4-96 mm) met the following inclusion criteria: (1) nodules with benign or malignant cytology - categories II and VI of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC); (2) nodules with non-diagnostic and indeterminate cytology (BSRTC I, BSRTC III, and BSRTC IV), or suspicious for malignancy (BSRTC V), if postoperative histology was present; (3) nodules classified as BSRTC I and BSRTC III with a repeat FNAB and conclusive cytology.

RESULTS

Of 942 nodules, 839 (89.1%) were benign and 103 (10.9%) were malignant. Nodules were classified as follows: EU-TIRADS 2 - 4.8%, EU-TIRADS 3 - 37.4%, EU-TIRADS 4 - 25.2%, and EU-TIRADS 5 - 32.6%. The malignancy rate in categories 2 to 5 was 0, 0, 3.8, and 30.6%, respectively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of EU-TIRADS with a cut-off set at category 5 were 91.3, 74.6, 30.6, 98.6, and 76.4%, respectively. Diagnostic performance other than sensitivity and NPV was superior in nodules ≥10 mm. FNAB number would be reduced by 53.4% if FNAB criteria were strictly applied. When the indication for FNAB was applied as test positivity, the estimated sensitivity, specificity, PPV, and NPV of EU-TIRADS were 69.9, 56.3, 16.4, and 93.8%, respectively.

CONCLUSION

EU-TIRADS provides effective malignancy risk stratification that can guide the selection of thyroid nodules for biopsy. The application of the guidelines criteria for FNAB in the clinical practice might reduce significantly the number of unnecessary FNAB.

Comparison of Diagnostic Performance of Five Different Ultrasound TI-RADS Classification Guidelines for Thyroid Nodules

Objectives

We aimed to evaluate and compare the diagnostic performance of five ultrasound thyroid imaging reporting and data system (TI-RADS) classification guidelines for thyroid nodules through a review and meta-analysis.

Methods

We searched for relevant studies before February 2020 in PubMed. Then we pooled the sensitivity, specificity, likelihood ratios, diagnostic odds ratios, and area under the summary receiver operating characteristic curves. And the diagnostic odds ratios were used to compare the performance.

Results

We totally included 19 studies with 4,696 lesions in this research. The pooled sensitivity of American College of Radiology (ACR) guidelines, American Thyroid Association (ATA) guidelines, TI-RADS proposed by Kwak (Kwak TI-RADS), Korean Thyroid Association/Korean Society of Thyroid Radiology (KTA/KSThR) guidelines for malignancy risk and European Thyroid Association (ETA) guidelines is between 0.84 and 0.94. The pooled specificity is 0.68, 0.44, 0.62, 0.47, and 0.61, respectively. And the RDOR is 1.57 (ACR vs ATA), 1.37 (ACR vs ETA), 1.80 (ACR vs Kawk), 1.74 (ARC vs KTA).

Conclusions

The results suggest that five classification guidelines are all effective methods for differential diagnosis of benign and malignant thyroid nodules and ACR guideline is a better choice.

Systems of Risk Stratification of Malignancy by Ultrasound of Thyroid Nodules

Thyroid nodules (TN) are more frequently identified with the use of thyroid ultrasonography, and they have a low risk of malignancy. Ultrasonographic features have been established that increase the probability of being faced with thyroid carcinoma; however, individually, these characteristics do not perform adequately in the diagnosis of malignancy, limiting their usefulness when indicating cytological studies by means of fine-needle aspiration (FNC). This situation motivated the development of risk stratification systems for thyroid nodules, which unified their ultrasound characteristics, with the aim of establishing risk categories, standardizing the preparation of reports, and providing the clinician with useful tools to define the surveillance option or form invasive studies.

The objective of this review is to compare the different systems developed by some scientific societies for the stratification of thyroid nodules, with respect to their predictive capacities for malignancy, their operational characteristics for diagnosis, and, to suggest recommendations for the implementation of these systems, placing emphasis on those with the best ability to reduce the performance of unnecessary invasive studies and to guide decision-making in the face of undetermined cytological results.

Influence of Care Pathway on Thyroid Nodule Surgery Relevance: A Historical Cohort Study

Background: Guidelines recommend using fine-needle aspiration cytology (FNAC) to guide thyroid nodule surgical indication. However, the extent to which these guidelines are followed remains unclear. This study aimed to analyze the quality of the preoperative care pathway and to evaluate whether compliance with the recommended care pathway influenced the relevance of surgical indications. Methods: Nationwide historical cohort study based on data from a sample (1/97th) of French health insurance beneficiaries. Evaluation of the care pathway of adult patients operated on between 2012 and 2015 during the year preceding thyroid nodule surgery. The pathway containing only FNAC was called “FNAC”, the pathway including an endocrinology consultation (ENDO) with FNAC was called “FNAC+ENDO”, whereas the no FNAC pathway was called “NO FNAC”. The main outcome was the malignant nature of the nodule. Results: Among the 1080 patients included in the study, “FNAC+ENDO” was found in 197 (18.2%), “FNAC” in 207 (19.2%), and “NO FNAC” in 676 (62.6%) patients. Cancer diagnosis was recorded in 72 (36.5%) “FNAC+ENDO” patients and 66 (31.9%) “FNAC” patients, against 119 (17.6%) “NO FNAC” patients. As compared to “NO FNAC”, the “FNAC+ENDO” care pathway was associated with thyroid cancer diagnosis (OR 2.67, 1.88–3.81), as was “FNAC” (OR 2.09, 1.46–2.98). Surgeries performed in university hospitals were also associated with thyroid cancer diagnosis (OR 1.61, 1.19–2.17). Increasing the year for surgery was associated with optimal care pathway (2015 vs. 2012, OR 1.52, 1.06–2.18). Conclusions: The recommended care pathway was associated with more relevant surgical indications. While clinical guidelines were insufficiently followed, compliance improved over the years.

A Multidisciplinary Head-to-Head Comparison of American College of Radiology Thyroid Imaging and Reporting Data System and American Thyroid Association Ultrasound Risk Stratification Systems

BACKGROUND

Ultrasound plays a critical role in evaluating thyroid nodules. We compared the performance of the two most popular ultrasound malignancy risk stratification systems, the 2015 American Thyroid Association (ATA) guidelines and the American College of Radiology Thyroid Imaging and Reporting Data System (ACR TI-RADS).

MATERIALS AND METHODS

We retrospectively identified 250 thyroid nodules that were surgically removed from 137 patients. Their ultrasound images were independently rated using both ATA and ACR TI-RADS by six raters with expertise in ultrasound interpretation. For each system, we generated a receiver operating characteristic curve and calculated the area under the curve (AUC).

RESULTS

Sixty-five (26%) nodules were malignant. There was "fair agreement" among raters for both ATA and ACR TI-RADS. Our observed malignancy risks for ATA and ACR TI-RADS categories were similar to expected risk thresholds with a few notable exceptions including the intermediate ATA risk category and the three highest risk categories for ACR TI-RADS. Biopsy of 226 of the 250 nodules would be indicated by ATA guidelines based on nodule size and mean ATA rating. One hundred forty-six nodules would be biopsied based on ACR TI-RADS. The sensitivity, specificity, and negative and positive predictive values were 92%, 10%, 79%, and 27%, respectively, for ATA and 74%, 47%, 84%, and 33%, respectively, for ACR TI-RADS. The AUC for ATA was 0.734 and for ACR TI-RADS was 0.718.

CONCLUSION

Although both systems demonstrated good diagnostic performance, ATA guidelines resulted in a greater number of thyroid biopsies and exhibited more consistent malignancy risk prediction for higher risk categories.

IMPLICATIONS FOR PRACTICE

With the rising incidence of thyroid nodules, the need for accurate detection of malignancy is important to avoid the overtreatment of benign nodules. Ultrasonography is one of the key tools for the evaluation of thyroid nodules, although the use of many different ultrasound risk stratification systems is a hindrance to clinical collaboration in everyday practice and the comparison of data in research. The first step toward the development of a universal thyroid nodule ultrasound malignancy risk stratification system is to better understand the strengths and weaknesses of the current systems in use.

A multicentre validation study for the EU-TIRADS using histological diagnosis as a gold standard

OBJECTIVE

Many systems for risk stratification of thyroid nodule with ultrasound (US) have been proposed and the EU-TIRADS issued by the ETA in 2017 was the last to have been published. The present study was undertaken to evaluate whether the malignancy risk of each category corresponded to the given range of the guidelines and assess the diagnostic value of EU-TIRADS in a multi-institutional trial with histology as gold standard.

DESIGN

Three institutions in Switzerland, France and United Kingdom shared this retrospective study. Enrolment period was 2013-2017. Included were patients who had undergone surgery with a detailed preoperative thyroid US.

METHODS

Cancer risk was calculated for each EU-TIRADS score. Predictivity tests were estimated. Nonparametric statistical analysis was used.

RESULTS

The final series included 1058 nodules of which 257 (24.3%) carcinomas. Nodules were classified as EU-TIRADS 2, 3, 4 and 5 in 6.7, 46.4, 26.2 and 20.7%, respectively. Cancer prevalence was 1.4, 3.5, 17 and 87.7% in classes 2-5, respectively (P < 0.0001). EU-TIRADS 5 had a significantly higher cancer rate than the other summed categories (7.7%; P < 0.0001) with OR 84.7. When EU-TIRADS 4 and 5 were combined, 93% sensitivity and 97% NPV were found and findings of the three institutions were quite similar. Using the recommended criteria for FNA negative predictive value was 90.9%.

CONCLUSIONS

The cancer rate was within or close to the given range described in the EU-TIRADS guidelines. The diagnostic value was satisfactory. The results were similar in the three institutions participating in the study.

Diagnostic performance of the American Thyroid Association ultrasound risk assessment of thyroid nodules in endocrinology (the ETIEN 3 study)

INTRODUCTION

No study has been published to date in Spain about the value of the American Thyroid Association (ATA) ultrasound risk assessment of thyroid nodules applied by endocrinologists.

OBJECTIVES

To assess the diagnostic performance of ATA thyroid nodule risk classification applied by endocrinologists with respect to histological results.

METHODS

A retrospective, observational study of 317 patients (mean age, 51.7±13.7 years; 83.3% women) with thyroid nodules (maximum diameter: 3.2±1.4cm) who underwent US-guided FNA in endocrinology between October 2015 and December 2018, were classified based on the ATA ultrasound risk assessment. Surgery was performed in all of them. Quality criteria of the ultrasound classification were assessed as compared to histological results.

RESULTS

Overall, 61.2% of nodules assessed were classified as benign (n=3) and very low (n=60) or low suspicion (n=131), 11.7% as intermediate suspicion (n=37), and 27.1% as high suspicion (n=86). Benign nodular disease was found in 260 patients, and thyroid cancer in 57 patients. There were 14 incidental papillary microcarcinomas. Classification of thyroid nodules as high suspicion showed a high diagnostic performance to identify malignant nodules (87.7% sensitivity, 86.2% specificity, negative predictive value 97.0%), improving sensitivity (93.0%) and reducing specificity (73.1%) when considering high and intermediate suspicion nodules as a risk for thyroid cancer.

CONCLUSIONS

Application by endocrinologists of the ATA ultrasound risk assessment of thyroid nodules shows a high diagnostic performance to identify malignant thyroid nodules before surgery.

Nodular Thyroid Disease in the Era of Precision Medicine

Management of thyroid nodules in the era of precision medicine is continuously changing. Neck ultrasound plays a pivotal role in the diagnosis and several ultrasound stratification systems have been proposed in order to predict malignancy and help clinicians in therapeutic and follow-up decision. Ultrasound elastosonography is another powerful diagnostic technique and can be an added value to stratify the risk of malignancy of thyroid nodules. Moreover, the development of new techniques in the era of "Deep Learning," has led to a creation of machine-learning algorithms based on ultrasound examinations that showed similar accuracy to that obtained by expert radiologists. Despite new technologies in thyroid imaging, diagnostic surgery in 50-70% of patients with indeterminate cytology is still performed. Molecular tests can increase accuracy in diagnosis when performed on "indeterminate" nodules. However, the more updated tools that can be used to this purpose in order to "rule out" (Afirma GSC) or "rule in" (Thyroseq v3) malignancy, have a main limitation: the high costs. In the last years various image-guided procedures have been proposed as alternative and less invasive approaches to surgery for symptomatic thyroid nodules. These minimally invasive techniques (laser and radio-frequency ablation, high intensity focused ultrasound and percutaneous microwave ablation) results in nodule shrinkage and improvement of local symptoms, with a lower risk of complications and minor costs compared to surgery. Finally, ultrasound-guided ablation therapy was introduced with promising results as a feasible treatment for low-risk papillary thyroid microcarcinoma or cervical lymph node metastases.

Thyroid ultrasonography reporting: consensus of Italian Thyroid Association (AIT), Italian Society of Endocrinology (SIE), Italian Society of Ultrasonography in Medicine and Biology (SIUMB) and Ultrasound Chapter of Italian Society of Medical Radiology (SIRM)

Thyroid ultrasonography (US) is the gold standard for thyroid imaging and its widespread use is due to an optimal spatial resolution for superficial anatomic structures, a low cost and the lack of health risks. Thyroid US is a pivotal tool for the diagnosis and follow-up of autoimmune thyroid diseases, for assessing nodule size and echostructure and defining the risk of malignancy in thyroid nodules. The main limitation of US is the poor reproducibility, due to the variable experience of the operators and the different performance and settings of the equipments. Aim of this consensus statement is to standardize the report of thyroid US through the definition of common minimum requirements and a correct terminology. US patterns of autoimmune thyroid diseases are defined. US signs of malignancy in thyroid nodules are classified and scored in each nodule. We also propose a simplified nodule risk stratification, based on the predictive value of each US sign, classified and scored according to the strength of association with malignancy, but also to the estimated reproducibility among different operators.

Limitations of the 2015 ATA Guidelines for Prediction of Thyroid Cancer: A Review of 1947 Consecutive Aspirations

BACKGROUND

The 2015 American Thyroid Association (ATA) guidelines have been proposed to aid in the management of thyroid nodules by determining whether fine needle aspiration is indicated.

OBJECTIVE

To determine whether the ATA guidelines contribute to the overdiagnosis of thyroid cancer.

PATIENTS AND METHODS

This was a retrospective cohort study of ultrasound-imaged thyroid nodules (n = 1947) consecutively aspirated at a tertiary care center from 1 October 2009 to 22 February 2016. Nodules were retrospectively reviewed, assigned a 2015 ATA morphology, and placed into one of five 2015 ATA categories of risk (ATA-1, <1% risk of malignancy; ATA-2, <3% risk; ATA-3, 5% to 10% risk, ATA-4: 10% to 20% risk; ATA-5, >70% to 90% risk) by a reader who was blinded to cytology. ATA category was compared with cytopathology. The positive predictive value (PPV) of each ATA category was calculated with respect to cancer. Numbers needed to aspirate and Pearson correlations were calculated. Interrater agreement for ATA category across five readers was assessed.

RESULTS

The PPV for cancer increased by ATA category [category 1 to 5, respectively: 0% (0/14), 2% (4/249), 5% (36/733), 12% (104/850), 28% (28/101)]. The number needed to sample to detect one papillary cancer was 125 (ATA-2), 49 (ATA-3), 13 (ATA-4), and 5 (ATA-5). The overall interrater agreement for ATA score across all five readers was fair (intraclass correlation coefficient 0.460).

CONCLUSIONS

The 2015 ATA guidelines stratify risk for thyroid cancer; however, the stratification system is overly optimistic regarding cancer detection rates for the higher-risk nodules, and there is only fair interrater agreement.