Risk of malignancy in 1502 solid thyroid nodules >1 cm using the new ultrasonographic classification of the American Thyroid Association

A comprehensive comparative assessment of eight risk stratification systems for thyroid nodules in the elderly population

Objective

This study aims to investigate the diagnostic value of eight risk stratification systems (RSSs) for thyroid nodules in the elderly and explore the reasons in comparison with a younger group.

Methods

Cases of thyroid nodules that underwent ultrasound examination with thyroidectomy or fine-needle aspiration (FNA) at our hospital between August 2013 and March 2023 were collected. The patients were categorized into two groups: an elderly group (aged ≥60) and a younger group (aged <60). Eight RSSs were applied to evaluate these nodules respectively.

Results

The malignant rate in the elderly group was significantly lower than that in the younger group (28.2% vs. 49.6%, P=0.000). There were statistically significant differences in nodule diameter, multiplicity, composition, echogenicity, orientation, margin, and echogenic foci between the elderly and younger groups (P<0.05). Among the eight RSSs evaluated in elderly adults, the artificial intelligence-based Thyroid Imaging Reporting and Data System (AI TIRADS) demonstrated the highest overall diagnostic efficacy, but with relatively high unnecessary FNA rate (UFR) and missed cancer rate (MCR) of 55.0% and 51.3%, respectively. By modifying the size thresholds, the new AI TI-RADS achieved the lowest UFR and MCR while maintaining nearly the lowest FNA rate (FNAR) among all the RSSs (P=0.172, 0.162, compared to the ACR and original AI, respectively, but P<0.05 compared to the other six RSSs).

Conclusion

Among the eight RSS systems, AI demonstrated higher diagnostic efficacy in the elderly population. However, the size thresholds for FNA needed to be adjusted.

The value of ultrasonography for the indication of fine-needle aspiration in autonomous thyroid nodules

BACKGROUND

The risk of malignancy in autonomous thyroid nodules is considered to be very low in adults and fine-needle aspiration (FNA) is not recommended in these cases; however, some studies contest this. Just as ultrasonography (US) has been used to select nonautonomous nodules with initial benign cytology that deserve FNA repetition, this method may also be useful to select autonomous nodules that are candidates for FNA.

METHODS

In this prospective study, FNA was obtained in 48 adults patients with autonomous solitary nodules >1 cm with suspicious US features (at least two of the following findings: hypoechogenicity, microcalcification, irregular margins, taller than wider shape, predominantly or exclusively central vascularization).

RESULTS

Cytology was benign in 28 patients (58.3%). Six patients (12.5%) had nondiagnostic cytology and histology revealed benign nodules in these cases. Cytology was indeterminate in nine other patients (18.5%). Of these, seven were adenomas and two were follicular carcinomas on histology. Finally, cytology suspicious for malignancy or malignant cytology was detected in five patients (10.4%), all of them confirmed histologically to be papillary carcinomas (the follicular variant in three). Thus, the frequency of malignancy was 14.6% (two follicular carcinomas and five papillary carcinomas), 8.3% in nodules with two suspicious findings vs 33.3% in nodules with ≥3 suspicious findings (P = .055).

CONCLUSION

The results suggest that the presence of ultrasonographic findings suspicious for malignancy in autonomous thyroid nodules >1 cm is a criterion for the indication of FNA.

Sonographic Risk Stratification Systems for Thyroid Nodules as Rule-Out Tests in Older Adults

Ultrasonographic risk-stratification systems (RSS), including various Thyroid Imaging Reporting and Data Systems (TIRADS), were proposed to improve reporting and reduce the number of fine-needle aspiration biopsies. However, age might be a confounder since some suspicious ultrasonographic features lack specificity in elderly patients. We aimed to investigate whether the diagnostic performance of the RSS varied between age groups. All patients consecutively referred for thyroid biopsy between November 1, 2015, and March 10, 2020, were included. The malignancy risk of each nodule was estimated according to five RSS: the American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi guidelines, the American College of Radiology (ACR) TIRADS, the American Thyroid Association guidelines, the European TIRADS, and the Korean TIRADS. Overall, 818 nodules (57 malignant) were evaluated. The malignancy rate was higher in patients ≤ 65 years (8.1%) than in patients > 65 years (3.8%; p = 0.02). All RSS confirmed a significant discriminative performance in both age groups, with a negative predictive value of 100% in patients > 65 years, although specificity was lower in older patients. The ACR TIRADS was the best performing in both age groups. RSS could avoid a sizable number of biopsies when applied as rule-out tests in elderly patients.

Diagnostic Value of Six Thyroid Imaging Reporting and Data Systems (TIRADS) in Cytologically Equivocal Thyroid Nodules

The aim was to compare the usefulness of selected thyroid sonographic risk-stratification systems in the diagnostics of nodules with indeterminate/suspicious cytology or unequivocal cytology in a population with a history of iodine deficiency. The diagnostic efficacy of ACR-TIRADS (the American College of Radiology Thyroid Imaging Reporting and Data Systems), EU-TIRADS (European Thyroid Association TIRADS), Korean-TIRADS, Kwak-TIRADS, AACE/ACE-AME-guidelines (American Association of Clinical Endocrinologists/ American College of Endocrinology-Associazione Medici Endocrinologi guidelines) and ATA-guidelines (American Thyroid Association guidelines) was evaluated in 1000 nodules with determined histopathological diagnosis: 329 FLUS/AUS (10.6% cancers), 167 SFN/SHT (11.6% cancers), 44 SM (77.3% cancers), 298 BL (benign lesions), 162 MN (malignant neoplasms). The percentage of PTC (papillary thyroid carcinoma) among cancers was higher in Bethesda MN (86.4%) and SM (suspicion of malignancy) nodules (91.2%) than in FLUS/AUS (57.1%, p < 0.005) and SFN/SHT (suspicion of follicular neoplasm/ suspicion of Hürthle cell tumor) nodules (36.8%, p < 0.001). TIRADS efficacy was higher for MN (AUC: 0.827-0.874) and SM nodules (AUC: 0.775-0.851) than for FLUS/AUS (AUC: 0.655-0.701) or SFN/SHT nodules (AUC: 0.593-0.621). FLUS/AUS (follicular lesion of undetermined significance/ atypia of undetermined significance) nodules assigned to a high risk TIRADS category had malignancy risk of 25%. In the SFN/SHT subgroup none TIRADS category changed nodule's malignancy risk. EU-TIRADS and AACE/ACE-AME-guidelines would allow diagnosing the highest number of PTC, FTC (follicular thyroid carcinoma), HTC (Hürthle cell carcinoma), MTC (medullary thyroid carcinoma). The highest OR value was for Kwak-TIRADS (12.6) and Korean-TIRADS (12.0). Conclusions: TIRADS efficacy depends on the incidence of PTC among cancers. All evaluated TIRADS facilitate the selection of FLUS/AUS nodules for the surgical treatment but these systems are not efficient in the management of SFN/SHT nodules.

Performance of Five Ultrasound Risk Stratification Systems in Selecting Thyroid Nodules for FNA

CONTEXT

Ultrasound (US) risk stratification systems (RSSs) have been developed to reduce the number of unnecessary fine-needle aspiration procedures (FNA) in patients with thyroid nodules.

OBJECTIVE

We conducted a systematic review and meta-analysis evaluating the ability of the 5 most common US RSSs for the appropriate selection of thyroid nodules for FNA.

DATA SOURCES

This systematic review and meta-analysis was registered on PROSPERO (CRD42019131771). PubMed, CENTRAL, Scopus, and Web of Science were searched until March 2019.

STUDY SELECTION

Original articles reporting data on the performance of AACE/ACE/AME, ACR TI-RADS, ATA, EU-TIRADS, and K-TIRADS were included.

DATA EXTRACTION

The number of nodules classified as true negative, true positive, false negative, and false positive was extracted. Summary operating points were estimated using a random-effects model. Interobserver agreement was also assessed.

DATA SYNTHESIS

Twelve studies evaluating 18 750 thyroid nodules were included. Participants were adult outpatients with thyroid nodules submitted to either FNA or core-needle biopsy or surgery and with available US images. The final diagnosis for malignant nodules was generally based on histology, while cytology was used for benign nodules. Diagnostic odds ratio (DOR) ranged from 2.2 to 4.9. A head-to-head comparison showed a higher relative DOR for ACR-TIRADS versus ATA (P = .002) or K-TIRADS (P = .002), due to a higher relative likelihood ratio for positive results.

CONCLUSIONS

The present meta-analysis found a higher performance of ACR TI-RADS in selecting thyroid nodules for FNA. However, the comparison across the most common US RSSs was limited by the data available. Further studies are needed to confirm this finding.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

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.

Reducing the Number of Unnecessary Thyroid Biopsies While Improving Diagnostic Accuracy: Toward the "Right" TIRADS

CONTEXT

The prevalence of thyroid nodules in the general population is increasingly high, and at least half of those biopsied prove to be benign. Sonographic risk-stratification systems are being proposed as "rule-out" tests that can identify nodules that do not require fine-needle aspiration (FNA) cytology.

OBJECTIVE

To comparatively assess the performances of five internationally endorsed sonographic classification systems [those of the American Thyroid Association, the American Association of Clinical Endocrinologists, the American College of Radiology (ACR), the European Thyroid Association, and the Korean Society of Thyroid Radiology] in identifying nodules whose FNAs can be safely deferred and to estimate their negative predictive values (NPVs).

DESIGN

Prospective study of thyroid nodules referred for FNA.

SETTING

Single academic referral center.

PATIENTS

Four hundred seventy-seven patients (358 females, 75.2%); mean (SD) age, 55.9 (13.9) years.

MAIN OUTCOME MEASURES

Number of biopsies classified as unnecessary, false-negative rate (FNR), sensitivity, specificity, predictive values, and diagnostic ORs for each system.

RESULTS

Application of the systems' FNA criteria would have reduced the number of biopsies performed by 17.1% to 53.4%. The ACR Thyroid Imaging Reporting and Data System (TIRADS) allowed the largest reduction (268 of 502) with the lowest FNR (NPV, 97.8%; 95% CI, 95.2% to 99.2%). Except for the Korean Society of Thyroid Radiology TIRADS, all other systems exhibited significant discriminatory performance but produced significantly smaller reductions in the number of procedures.

CONCLUSIONS

Internationally endorsed sonographic risk stratification systems vary widely in their ability to reduce the number of unnecessary thyroid nodule FNAs. The ACR TIRADS outperformed the others, classifying more than half the biopsies as unnecessary with a FNR of 2.2%.

Sonographically Estimated Risks of Malignancy for Thyroid Nodules Computed with Five Standard Classification Systems: Changes over Time and Their Relation to Malignancy

BACKGROUND

Over 50% of newly diagnosed thyroid nodules are either cytologically benign or presumed to be benign on the basis of low-suspicion sonographic findings. The strategies used for their long-term surveillance are based mainly on the estimated residual risk of malignancy calculated with various ultrasonographic classification systems (e.g., Thyroid Image Reporting and Data Systems [TIRADS]). We conducted a longitudinal study to evaluate the temporal stability of the initial risk estimates computed with five widely used systems and to determine whether risk class increases during follow-up are indeed predictive of malignancy.

METHODS

We re-analyzed data prospectively collected at a single academic referral center on 232 patients (age: 54.1 ± 13.7 years) with 432 asymptomatic, sonographically or cytologically benign thyroid nodules at baseline (T0) and 122 new nodules that were present five years later (T5). At both time points, the sonographically estimated risk of malignancy was calculated as recommended by the American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi, the American College of Radiologists' TIRADS, the American Thyroid Association's 2015 practice guidelines, the European Thyroid Association's TIRADS (EU-TIRADS), and the TIRADS of the Korean Society of Thyroid Radiology (K-TIRADS).

RESULTS

For 57 to 127 (13.2-29.4%) of the original nodules, depending on the system used, the estimated malignancy risk increased over the 5-year interval. Of the nodules whose baseline risk had not warranted cytological assessment, very few (6.3-8.3%) met the criteria for cytology at the 5-year evaluation. Biopsy was indicated for only 4 to 8 (3.3-6.6%) of the new nodules based on T5 risk estimates. Despite these changes, none of the 232 patients was ever diagnosed with a cancer.

CONCLUSIONS

Ultrasound-based risk classes of presumably benign thyroid nodules remain fairly stable over time, and changes warranting biopsy are rare indeed. The appearance of new nodules is a frequent event, but very few (<5%) are classified as high risk, and only the 3-7% meet the criteria for cytological assessment. Collectively, these findings support the view that patients with presumably benign thyroid nodules can be safely followed with less intensive protocols.

Reliability of Thyroid Imaging Reporting and Data System (TI-RADS), and ultrasonographic classification of the American Thyroid Association (ATA) in differentiating benign from malignant thyroid nodules

OBJECTIVE

Ultrasonography (US) is the best diagnostic tool for initial assessment of thyroid nodule. Recently, data reporting systems for thyroid lesions, such as the Thyroid Imaging Reporting and Data System (TI-RADS) and American Thyroid Association (ATA), which stratifies the risk for malignancy, have demonstrated good performance in differentiating malignant thyroid nodules. The purpose of this study is to determine the reliability of both data reporting systems in predicting thyroid malignancy in a tertiary care hospital.

MATERIALS AND METHODS

We evaluated 195 thyroid nodules using modified TI-RADS and ATA risk stratification. The results were compared to the cyto-pathology analysis. Histopathological results were available for 45 cases after surgery, which is considered the golden standard for diagnosis of thyroid cancer.

RESULTS

When compared with cytological results, sensitivity, specificity, negative predictive value (NPV), and accuracy were 100, 61.1, 100, and 63%, respectively, for TI-RADS; and 100, 75, 100, and 76%, respectively, for ATA. When compared with histopathological results, sensitivity, specificity, NPV, and accuracy were 90, 51.4, 94.7, and 60% respectively, for TI-RADS; and 100, 60, 100, and 68%, respectively, for ATA. All patients with malignant nodules were classified in the categories 4 or 5 of TI-RADS and in the intermediate or high suspicion risk according to the ATA system.

CONCLUSION

Both TI-RADS and the ATA guidelines have high sensitivity and NPV for the diagnosis of thyroid carcinoma. These systems are feasible for clinical application, allowing to better select patients to undergo fine-needle aspiration biopsies.