Diagnostic Performance of ACR TI-RADS and ATA Guidelines in the Prediction of Thyroid Malignancy: A Prospective Single Tertiary Center Study and Literature Review

AIM

This study sought to compare two common risk stratification systems in terms of their diagnostic performance for the evaluation of thyroid malignancy.

METHODS

The American College of Radiology (ACR) Thyroid Imaging, Reporting and Data System (TI-RADS) and the American Thyroid Association (ATA) guidelines were compared among 571 thyroid nodules with definitive fine needle aspiration (FNA) cytology or postoperative histopathology. Ultrasound characteristics such as composition, echogenicity, shape, margin, size, and vascularity were assessed for each thyroid nodule. Diagnostic performance measures were determined and compared through receiver operating characteristic (ROC) curves, and decision curve analysis (DCA).

RESULTS

Of 571 nodules, 65 (11.4%) were malignant. The AUC, sensitivity, specificity, positive predictive value, and negative predictive value were 0.691, 49.2%, 84.9%, 29.6%, and 92.8% for ATA guideline, and 0.776, 72.3%, 79.2%, 30.9%, and 95.7%, for ACR TI-RADS, respectively. ACR TI-RADS was more sensitive (p = 0.003), while the ATA guideline was more specific (p < 0.001). DCA demonstrated that the ACR TI-RADS provided a greater net benefit than the ATA guideline. In addition, the net reduction in unnecessary biopsies is higher for ACR TI-RADS than ATA guidelines. The total number of indicated biopsies and unnecessary FNA rates were lower in ACR TI-RADS compared to ATA guideline (293 vs. 527 and 80.2 vs. 87.8). ACR TI-RADS presented no biopsy indication in seven malignant nodules (all categorized as TR2), whereas ATA guideline missed one. Hypoechogenicity was the most significant predictor of malignancy (OR = 8.34, 95% CI: 3.75-19.45), followed by a taller-than-wide shape (OR = 6.73, 95% CI: 3.07-14.77).

CONCLUSIONS

Our findings suggest that each system has particular advantages in the evaluation of thyroid nodules. ACR TI-RADS reduces unnecessary FNA rates, however, malignant nodules categorized as TR2 might be missed using this system. Further evaluation of this group of nodules using Doppler and other ultrasound modalities is recommended.

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.

Trends in Thyroid Surgery and Guideline-Concordant Care in the United States, 2007-2018

Background: The American Thyroid Association (ATA) published the 2015 Management Guidelines for patients with thyroid nodules and differentiated thyroid cancer, recommending a shift to less aggressive diagnostic, surgical, and postoperative treatment strategies. At the same time and perhaps related to the new guidelines, there has been a shift to outpatient thyroid surgery. The aim of the current study was to assess physician adherence to these recommendations by identifying and quantifying temporal trends in the rates and indications for thyroid procedures in the inpatient and outpatient settings. Methods: Using the IBM^® MarketScan^® Commercial database, we identified employer-insured patients in the United States who underwent outpatient and inpatient thyroid surgery from 2007 to 2018. Thyroid surgery was classified as total thyroidectomy (TT), thyroid lobectomy (TL), or a completion thyroidectomy. The surgical indication diagnosis was also determined and classified as either benign or malignant thyroid disease. We compared outpatient and inpatient trends in surgery between benign and malignant thyroid disease both before and after the release of the 2015 ATA guidelines. Results: A total of 220,088 patients who underwent thyroid surgery were included in the analysis. Approximately 80% of TLs were performed in the outpatient setting versus 70% of TTs. Longitudinal analysis showed a statistically significant changepoint for TT proportion occurring in November 2015. The proportion of TT as compared with TL decreased from 80% in September 2015 to 39% by December 2018. For thyroid cancer, there is an increasing trend in performing TL over TT, increasing from 17% in 2015 to 28% by the end of 2018. Conclusions: There was a significant changepoint occurring in November 2015 in the operative and management trends for benign and malignant thyroid disease.

The combination of ATA classification and FNA results can improve the diagnostic efficiency of malignant thyroid nodules

PURPOSE

To determine the diagnostic efficiency of the ATA classification and ultrasound-guided fine-needle aspiration (FNA) results in identifying the risk factors of malignancy, we analyzed the thyroid nodules of patients who underwent thyroidectomy and compared preoperative ATA classifications with FNA results.

METHODS

We retrospectively analyzed 274 nodules of 196 patients who underwent ultrasonography, FNA and thyroidectomy. Histopathological findings of thyroid nodules were considered as the Au standard in the analysis of the diagnostic efficiency of the ATA classification and FNA results. Univariate analysis and binary multivariate logistic regression analysis were applied to identify the ultrasound features associated with malignancy.

RESULTS

The overall malignancy rate of 274 nodules was 41.6%. The areas under the ROC curves (AUCs) for the ATA classification and FNA results were 0.88 and 0.878, respectively (P < 0.001). The sensitivity and specificity of the ATA classification were 86 and 86.9%, whereas those of FNA results were 68.5 and 91.4%, respectively. The specificity (98.7%) and sensitivity (94.3%) increased after the combined use of the ATA classification and FNA results. Taller-than-wide shape, microcalcifications, hypoechogenicity and irregular margins were independent risk factors for malignancy. Microcalcifications had the highest OR (7.58), and taller-than-wide shape had the highest specificity in BSRTC I, II, III and IV cytology.

CONCLUSION

The diagnostic efficiency of the ATA classification and FNA results in identifying malignant nodules was high, and the use of both criteria improved the diagnostic accuracy. Taller-than-wide shape, microcalcifications, hypoechogenicity and irregular margins were independent risk factors for malignancy.

ACR TI-RADS: An advance in the management of thyroid nodules or Pandora's box of surveillance?

Numerous sets of guidelines have been proposed regarding ultrasound of thyroid nodules. None has been universally accepted. American College of Radiology-Thyroid Imaging, Reporting and Data System (ACR-TIRADS) has been promoted as an improvement to existing guidelines such as the 2015 revised American Thyroid Association (ATA) guidelines. This commentary compares and contrasts these two guidelines. Adoption of TI-RADS is likely to result in large-scale, costly surveillance without clear benefit. Replacement of 2015 revised ATA guidelines by TI-RADS is not justified. The shortcomings that exist in the ATA guidelines can be addressed as described in this commentary.

Diagnostic performance of 2015 American Thyroid Association guidelines and inter-observer variability in assigning risk category

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Risk of malignancy at 75–90% in the high suspicion sonographic pattern of the 2015 ATA guidelines may have been over estimated.

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The 2015 ATA guidelines show moderate inter-observer agreement for assigning a final risk category.

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The study highlights certain sonographic features which are not included in any ATA risk categories leading to inter-observer variability.

Objective

To determine the interobserver variability of the 2015 American Thyroid Association (ATA) thyroid guidelines and to evaluate the diagnostic accuracy of the guidelines in detecting thyroid cancer.

Materials and methods

Sonographic patterns of 189 thyroid lesions were retrospectively analyzed by two radiologists according to the 2015 guidelines. The risk of malignancy was calculated for each pattern and compared with the published expected risk of malignancy.

Results

The observed risk of malignancy for very low suspicion, low suspicion, intermediate suspicion and high suspicion patterns were 2%, 12.7%, 26.3% and 29.8% respectively. Interobserver agreement for final category assignment was moderate (κ 0.518).

Conclusion

The estimated risk of malignancy in the high suspicion pattern of the 2015 ATA thyroid biopsy guidelines appears to be less than stated. However, this needs further validation in a larger cohort study.

High suspicion US pattern on the ATA guidelines, not cytologic diagnosis, may be a predicting marker of lymph node metastasis in patients with classical papillary thyroid carcinoma

BACKGROUND

To evaluate the utility of ultrasound (US) patterns based on the 2015 American Thyroid Association (ATA) guidelines and cytologic diagnosis of the Bethesda System for Reporting Thyroid Cytopathology as predicting markers for lymph node metastasis (LNM) in classical papillary thyroid carcinoma (PTC).

METHODS

A retrospective analysis of 657 patients with classical PTC who underwent ultrasound-guided fine-needle aspiration (US-FNA) and surgery were included in this study. The associations between LNM and the US features or the Bethesda System for Reporting Thyroid Cytopathology were evaluated.

RESULTS

Multivariate logistic regression analysis showed that the high suspicion US pattern was independently associated with LNM (odds ratio = 3.081; 95% confidence interval = 1.515-6.262; P = .002). And the Bethesda category was not significantly associated with LNM (P = .056).

CONCLUSIONS

The high suspicion US pattern of the 2015 ATA guidelines, not cytologic diagnosis, could be a predicting marker of LNM in patients with classical PTC.

Validation of American Thyroid Association Ultrasound Risk Assessment of Thyroid Nodules Selected for Ultrasound Fine-Needle Aspiration

OBJECTIVE

The aim of this study was to validate the American Thyroid Association (ATA) sonographic risk assessment of thyroid nodules.

METHODS

The ATA sonographic risk assessment was prospectively applied to 206 thyroid nodules selected for ultrasound-guided fine-needle aspiration (US-FNA), and analyzed with The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC), as well as surgical pathology for the subset undergoing surgical excision.

RESULTS

The analysis included 206 thyroid nodules averaging 2.4 cm (range 1-7 cm; standard error of the mean 0.07). Using the ATA US pattern risk assessment, nodules were classified as high (4%), intermediate (31%), low (38%), and very low (26%) risk of malignancy. Nodule size was inversely correlated with sonographic risk assessment, as lower risk nodules were larger on average (p < 0.0001). Malignancy rates determined by cytology/surgical pathology were high 100%, intermediate 11%, low 8%, and very low 2%, which were closely aligned with ATA malignancy risk estimates (high 70-90%, intermediate 10-20%, low 5-10%, and very low 3%). ATA US pattern risk assessment also appropriately predicted the proportion of nodules classified as malignant or suspicious for malignancy through TBSRTC classification-high (77%), intermediate (6%), low (1%), and very low 0%-as well as benign TBSRTC classification-high (0%), intermediate (47%), low (61%), and very low (70%) (p < 0.0001). Malignancy rates of surgically excised, cytologically indeterminate nodules followed ATA sonographic risk stratification (high 100%, intermediate 21%, low 17%, and very low 12%; p = 0.003).

CONCLUSION

This prospective study supports the new ATA sonographic pattern risk assessment for selection of thyroid nodules for US-FNA based upon TBSRTC and surgical pathology results. In the setting of indeterminate cytopathology, nodules categorized as atypia of undetermined significance/follicular lesion of undetermined significance with ATA high-risk sonographic patterns have a high likelihood of being malignant.

Incidental positive lymph nodes in patients with papillary thyroid cancer is independently associated with recurrent disease

BACKGROUND AND OBJECTIVES

Pathological examination occasionally reveals incidental central lymph nodes metastasis (iLNM) after thyroidectomy for patients with papillary thyroid cancer (PTC) who did not undergo compartment-orientated lymphadenectomy. We aimed to investigate the risk of recurrence for patients with iLNM.

METHODS

We conducted a retrospective review of all patients undergoing total thyroidectomy for PTC (January 2000 to January 2010). Patients with distant metastases, central- or lateral neck dissection and pre-operative suspicious lymph nodes (by ultrasound or clinical examination) were excluded. The association between iLNM and recurrent disease was investigated using Kaplan-Meier survival estimates and Cox proportional hazards analysis.

RESULTS

225/1000 patients had incidental nodes after total thyroidectomy for PTC. 183 were node-negative and 42 had iLNM. Mean age was 46 years and 201 (89%) were women. Mean number of resected nodes was 2.3. Disease recurred in 8/183 (4.4%) of patients with N0 versus 7/42 (17%) with iLNM. After adjusting for other factors, iLNM was independently associated with recurrent disease (hazard ratio = 4.01 [95% CI 1.21-13.3]).

CONCLUSIONS

Positive incidental lymph nodes are independently associated with recurrent disease in patients with PTC. These patients should therefore be monitored more carefully.

Thyroid Ultrasound-Guided Fine-Needle Aspiration Cytology Results: Observed Increase in Indeterminate Rate over the Past Decade

Objectives To evaluate changes in distribution of reported thyroid nodule fine-needle aspiration (FNA) cytopathology results since implementation of the Bethesda classification and revised 2015 American Thyroid Association (ATA) guidelines for selecting nodules for biopsy. Study Design Retrospective review. Setting Tertiary academic medical center. Subjects and Methods Evaluation of ultrasound (US)-guided thyroid FNA by a single surgeon using 2015 ATA nodule selection criteria and Bethesda reporting on 211 thyroid nodules in a 1-year period (2015). Comparison is made to an earlier sample wherein any nodule >1 cm underwent US FNA with cytology reported prior to Bethesda consensus (2006). Results The current cohort involved mostly women (79%); nodules ranged from 1 to 7 cm (mean ± SEM, 2.4 ± 0.07 cm). Mean ± SEM age was 53.5 ± 1.1 years. Bethesda reporting yielded 6% nondiagnostic, 57% benign, 3% malignant, and 34% indeterminate (27% atypia of undetermined significance [AUS]/follicular lesion of undetermined significance [FLUS], 4% follicular neoplasm [FN]/Hürthle neoplasm [HN], and 2% suspicious for malignancy [SFM]). The malignancy rate in indeterminate nodules was 26% (18% AUS/FLUS, 33% FN/HN, and 80% SFM). Age, sex, or nodule size did not correlate with indeterminate cytology. The comparator sample of 447 nodules had significantly different distribution, with 7% nondiagnostic, 80% benign, 5% malignant, and 8% indeterminate ( P < .00001). Conclusion We observed a significantly increased proportion of indeterminate cytology and corresponding decrease in benign nodules compared with an earlier sample, predominately from an increase in AUS/FLUS. Multiple factors are likely involved, including selection of sonographically suspicious nodules for biopsy based upon 2015 ATA guidelines coupled with cytopathological interpretation by a new generation of cytopathologists trained in the era of Bethesda reporting; further study is required to make a definitive conclusion.

Temporal analysis of thyroid cancer management in a Melbourne tertiary centre

BACKGROUND

The American Thyroid Association (ATA) management guidelines for thyroid cancer were revised in 2009. The aim of this study was to determine if management of thyroid cancer in our institution has changed in accordance with the introduction of the revised ATA guidelines (ATA²⁰⁰⁹ ), and to compare the characteristics and management of thyroid cancer in a Melbourne endocrine surgery unit over a 7-year period.

METHODS

All patients treated by the Monash University Endocrine Surgery Unit for thyroid cancer between 2007 and 2013 were divided into two groups - the pre-ATA²⁰⁰⁹ group (2007-2010) and the post-ATA²⁰⁰⁹ group (2011-2013). Comparisons were made of the demographics, cytology, pathology, surgical outcome and adjuvant therapy using t-test and chi-squared tests.

RESULTS

There were 333 patients in the pre-ATA²⁰⁰⁹ group and 342 patients in the post-ATA²⁰⁰⁹ group. Fewer non-diagnostic fine-needle aspiration cytology results were identified in the post-ATA²⁰⁰⁹ group (4% versus 0.9%; P = 0.01), while the rates of other fine-needle aspiration cytology categories were similar. There was a reduction in the use of radioactive iodine ablation in the post-ATA²⁰⁰⁹ group, both in the proportion of patients being treated (66% versus 48%; P < 0.001) and the dosages used (mean 96 mCi versus 80 mCi; P < 0.01), despite similar tumour size in both groups.

CONCLUSION

The key changes in practice thought to be attributable to the 2009 revised ATA guidelines were the reduction in the use and dosage of radioactive iodine in the management of differentiated thyroid cancer.