Ultrasound characterization for thyroid nodules with indeterminate cytology: inter-observer agreement and impact of combining pattern-based and scoring-based classifications in risk stratification

Assessment of the risk of malignancy in Bethesda III thyroid nodules: a comprehensive review

The increasing prevalence of thyroid cancer emphasizes the need for a thorough assessment of risk of malignancy in Bethesda III nodules. Various methods ranging commercial platforms of molecular genetic testing (including Afirma® GEC, Afirma® GSC, ThyroSeq® V3, RosettaGX®, ThyGeNEXT®/ThyraMIR®, ThyroidPRINT®) to radionuclide scans and ultrasonography have been investigated to provide a more nuanced comprehension of risk estimation. The integration of molecular studies and imaging techniques into clinical practice may provide clinicians with improved and personalized risk assessment. This integrated approach we feel may enable clinicians to carefully tailor interventions, thereby minimizing the likelihood of unnecessary thyroid surgeries and overall crafting the optimal treatment. By aligning with the evolving landscape of personalized healthcare, this comprehensive strategy ensures a patient-centric approach to thyroid nodule and thyroid cancer management.

Clinical value of molecular markers as diagnostic and prognostic tools to guide treatment of thyroid cancer

OBJECTIVE

Advances in our understanding of the molecular biology of thyroid tumours is being rapidly translated into their clinical management. This review summarizes the current use of molecular testing in thyroid tumours, focusing on their usefulness as diagnostic and prognostic tools to guide treatment with consideration of present limitations.

DESIGN

Considerations about molecular testing applications for the diagnosis and treatment of thyroid tumours are divided into four sections/roles: (1) evaluating cytologically indeterminate thyroid nodules; (2) guiding extent of surgery in indeterminate thyroid nodules; (3) completing histological characterization of thyroid tumours and (4) identifying actionable mutations in advanced progressive thyroid cancers.

RESULTS

Genomic testing can improve the presurgical malignancy risk assessment in indeterminate thyroid nodules. However, a prior in-depth analysis of institutional quality and outcomes of sonographical, cytological and histological characterization of thyroid tumours is necessary. Presently, it remains uncertain whether knowing the molecular profile of a cytologically indeterminate thyroid nodule might be advantageous to modify the extent of initial surgery. Molecular characterization of thyroid tumours can be a valuable adjunct to morphological diagnosis in some challenging cases, such as in low-risk follicular cell-derived neoplasms, or rare tumours. Finally, as selective kinase inhibitors are available, molecular testing in locally advanced/metastatic progressive thyroid cancers should also be integrated into the institutional clinical management pathway to improve outcomes and limit toxicity.

CONCLUSIONS

Molecular testing needs to be implemented into the local evidence-based clinical management thyroid nodule/cancer pathways to improve its diagnostic and prognostic value and to optimize cost-effectiveness.

Ultrasound imaging in thyroid nodule diagnosis, therapy, and follow-up: Current status and future trends

Ultrasound, the primary imaging modality in thyroid nodule management, suffers from drawbacks including: high inter- and intra-observer variability, limited field-of-view and limited functional imaging. Developments in ultrasound technologies are taking place to overcome these limitations, including three-dimensional-Doppler, -elastography, -nodule characteristics-extraction, and novel machine-learning algorithms. For thyroid ablative treatments and biopsies, perioperative use of three-dimensional ultrasound opens a new field of research. This review provides an overview of the current and future applications of ultrasound, and discusses the potential of new developments and trends that may improve the diagnosis, therapy, and follow-up of thyroid nodules.

Clinician Agreement on the Classification of Thyroid Nodules Ultrasound Features: A Survey of 2 Endocrine Societies

CONTEXT

Thyroid nodule risk stratification allows clinicians to standardize the evaluation of thyroid cancer risk according to ultrasound features.

OBJECTIVE

To evaluate interrater agreement among clinicians assessing thyroid nodules ultrasound features and thyroid cancer risk categories.

DESIGN, SETTING, AND PARTICIPANTS

We surveyed Endocrine Society and Latin American Thyroid Society members to assess their interpretation of composition, echogenicity, shape, margins, and presence of echogenic foci of 10 thyroid nodule cases. The risk category for thyroid cancer was calculated following the American College of Radiology-Thyroid Imaging Reporting & Data System (ACR-TIRADS) framework from individual responses.

MAIN OUTCOMES AND MEASURES

We used descriptive statistics and Gwet's agreement coefficient (AC1) to assess the primary outcome of interrater agreement for ACR-TIRADS risk category. As secondary outcomes, the interrater agreement for individual features and a subgroup analysis of interrater agreement for the ACR-TIRADS category were performed (ultrasound reporting system, type of practice, and number of monthly appraisals).

RESULTS

A total of 144 participants were included, mostly endocrinologists. There was moderate level of agreement for the absence of echogenic foci (AC1 0.53, 95% CI 0.24-0.81) and composition (AC1 0.54, 95% CI 0.36-0.71). The agreement for margins (AC1 0.24, 95% CI 0.15-0.33), echogenicity (AC1 0.34, 95% CI 0.22-0.46), and shape assessment (AC1 0.42, 95% CI 0.13-0.70) was lower. The overall agreement for ACR-TIRADS assessment was AC1 0.29, (95% CI 0.13-0.45). The AC1 of ACR-TIRADS among subgroups was similar.

CONCLUSIONS

This study found high variation of judgments about ACR-TIRADS risk category and individual features, which poses a potential challenge for the widescale implementation of thyroid nodule risk stratification.

Computer-Analyzed Ultrasound Predictors of the Treatment Efficacy of Radiofrequency Ablation for Benign Thyroid Nodules

AIM

Radiofrequency ablation (RFA) is a relatively safe and efficient alternative to surgery for patients with benign thyroid nodules. We investigated predictive factors associated with volume reduction using digital imaging analysis.

METHODS

In this retrospective study, a prospectively maintained database containing the data of patients who received treatment from April 2019 to March 2020 was analyzed. Computerized analysis for quantitative measurement of echogenicity, heterogeneity, and the proportion of cystic components was performed on ultrasonographic images. The volume reduction rate (VRR) was calculated during follow-up. Treatment efficacy was defined as a volume reduction greater than 50% of baseline volume.

RESULTS

The median volume of 58 benign thyroid nodules before RFA was 22.7 mL. Of 53 nodules with sufficient follow-up, the median VRR was 46.4%, 61.5%, 63.4%, and 67.4% at 1, 3, 6, and 12 months, respectively. Overall, at one-year follow-up, treatment efficacy was achieved in 39 (74%) nodules. In a multivariate regression analysis, the proportion of cystic components and RFA treatment time were independently associated with treatment efficacy. A subgroup analysis focusing on solid nodules indicated a negative correlation between echogenicity and VRR.

CONCLUSIONS

The proportion of cystic components in thyroid nodules is the main predictor of RFA treatment efficacy. In solid nodules, higher echogenicity is associated with a lower volume reduction.

Inter-Reader Agreement of ATA Sonographic Risk in Thyroid Nodules with Bethesda Category III Indeterminate Cytology

Background: Substantial inter-observer variation has been documented in the recognition and description of specific sonographic features as well as for ATA sonographic risk (ASR). This raises the question if the risk stratification proposed by the ATA guidelines is reproducible and applicable for nodules with indeterminate cytology. The aim of the study was to determine the inter-reader agreement (IRR) among radiologists using the 2015 ASR stratification in indeterminate thyroid nodules. Methods: Three board certified radiologists who were blinded to clinical data and to each other, interpreted the ultrasound findings of 179 nodules that had Bethesda III cytology. The nodules were classified into high suspicion (HS), intermediate (IS), low (LS), very low (VLS). Echogenicity, composition, shape taller than wide, vascularity, type of margins, presence and type of calcifications were also described. Results: The majority consensus revealed that 28%, 27%, 39% and 5% were described as high, intermediate, low and very low ASR, respectively. The inter-reader agreement was near perfect (k 0.82 CI 95% (0.77–0.87)). Nodules were paired into a higher risk (HS + IS) and lower risk (LS + VLS) categories with substantial agreement (k 0.7) in both categories. Conclusion: A near perfect agreement among readers was observed when stratifying indeterminate cytology nodules for ASR.

Ultrasound-guided fine needle aspiration cytology and ultrasound examination of thyroid nodules in the UAE: A comparison

Background

Thyroid nodules are a common clinical finding and most are benign, however, 5–15% can be malignant. There is limited regional data describing the accuracy of ultrasound-guided fine needle aspiration (FNA) cytological examination compared to ultrasound examination of thyroid in patients who have undergone thyroid surgery.

Methods

A retrospective analysis of ultrasonographic (US) reports, FNA cytology reports and histopathology reports of 161 thyroid nodules presented at the endocrine center at Tawam hospital in Al Ain city, the United Arab Emirates during the period 2011–2019 was performed. US reports and images with FNA cytopathology reports and slides were reviewed by an independent radiologist and pathologist.

Results

In total, 40 nodules were reported as benign by US examination, while very low suspicious, low suspicious, intermediate suspicious and highly suspicious categories were reported in 21, 41, 14 and 45 nodules respectively. In addition, 68 nodules were reported as benign (Bethesda category II), while atypical follicular cells of unknown significance (Bethesda category III), follicular neoplasm (Bethesda category IV), suspicious for malignancy (Bethesda category V), and malignant (Bethesda category VI) categories were reported in 33, 9, 24 and 27 nodules respectively. The risk of malignancy for US benign nodules was 5%, while the risks of malignancy in very low suspicious, low suspicious, intermediate suspicious and highly suspicious nodules were 52%, 36%, 100% and 87%, respectively. The risk of malignancy for Bethesda category II was 3%, while the risks of malignancy in category III, IV, V and VI were 58%, 67%, 96% and 100%, respectively.

Conclusion

Thyroid FNA cytological examination and ultrasonography are key tools in predicting malignancy in thyroid nodules. Thyroid nodules with the diagnosis of Bethesda category III & IV run a high risk of malignancy thus more vigilance is required.

Molecular Determinants of Thyroid Nodules with Indeterminate Cytology and RAS Mutations

Background:RAS gene family mutations are the most prevalent in thyroid nodules with indeterminate cytology and are present in a wide spectrum of histological diagnoses. We evaluated differentially expressed genes and signaling pathways across the histological/clinical spectrum of RAS-mutant nodules to determine key molecular determinants associated with a high risk of malignancy. Methods: Sixty-one thyroid nodules with RAS mutations were identified. Based on the histological diagnosis and biological behavior, the nodules were grouped into five categories indicating their degree of malignancy: non-neoplastic appearance, benign neoplasm, indeterminate malignant potential, low-risk cancer, or high-risk cancer. Gene expression profiles of these nodules were determined using the NanoString PanCancer Pathways and IO 360 Panels, and Angiopoietin-2 level was determined by immunohistochemical staining. Results: The analysis of differentially expressed genes using the five categories as supervising parameters unearthed a significant correlation between the degree of malignancy and genes involved in cell cycle and apoptosis (BAX, CCNE2, CDKN2A, CDKN2B, CHEK1, E2F1, GSK3B, NFKB1, and PRKAR2A), PI3K pathway (CCNE2, CSF3, GSKB3, NFKB1, PPP2R2C, and SGK2), and stromal factors (ANGPT2 and DLL4). The expression of Angiopoietin-2 by immunohistochemistry also showed the same trend of increasing expression from non-neoplastic appearance to high-risk cancer (p < 0.0001). Conclusions: The gene expression analysis of RAS-mutant thyroid nodules suggests increasing upregulation of key oncogenic pathways depending on their degree of malignancy and supports the concept of a stepwise progression. The utility of ANGPT2 expression as a potential diagnostic biomarker warrants further evaluation.

Risk Stratification in Patients With Follicular Neoplasm on Cytology: Use of Quantitative Characteristics and Sonographic Patterns

OBJECTIVES

Differentiating thyroid nodules with a cytological diagnosis of follicular neoplasm remains an issue. The goal of this study was to determine whether ultrasonographic (US) findings obtained preoperatively from the computer-aided detection (CAD) system are sufficient to further stratify the risk of malignancy for this diagnostic cytological category.

METHODS

From September 2016 to September 2018 in our hospital, patients diagnosed with Bethesda category IV (follicular neoplasm or suspicion of follicular neoplasm) thyroid nodules and underwent surgical excisions were include in the study. Quantification and analysis of tumor features were performed using CAD software. The US findings of the region of interest, including index of composition, margin, echogenicity, texture, echogenic dots indicative of calcifications, tall and wide orientation, and margin were calculated into computerized values. The nodules were further classified into American Thyroid Association (ATA) and American College of Radiology Thyroid Imaging Reporting & Data System (TI-RADS) categories.

RESULTS

92 (10.1%) of 913 patients were diagnosed with Bethesda category IV thyroid nodules. In 65 patients, the histological type of the nodule was identified. The quantitative features between patients with benign and malignant conditions differed significantly. The presence of heterogeneous echotexture, blurred margins, or irregular margins was shown to have the highest diagnostic value. The risks of malignancy for nodules classified as having very low to intermediate suspicion ATA, non-ATA, and high suspicion ATA patterns were 9%, 35.7%, and 51.7%, respectively. Meanwhile, the risks of malignancy were 12.5%, 26.1%, and 53.8% for nodules classified as TIRADS 3, 4, and 5, respectively. When compared to human observers, among whom poor agreement was noticeable, the CAD software has shown a higher average accuracy.

CONCLUSIONS

For patients with nodules diagnosed as Bethesda category IV, the software-based characterizations of US features, along with the associated ATA patterns and TIRADS system, were shown helpful in the risk stratification of malignancy.

Ultrasound findings of noninvasive follicular thyroid neoplasm with papillary-like nuclear features compared with those of follicular variant of papillary carcinoma and encapsulated papillary carcinoma: a single-institution study in Japan

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a new entity adopted by the newest World Health Organization classification. It is differentiated from follicular variant papillary thyroid carcinoma (FVPTC) and regarded as non-malignant disease. Here, we compared the ultrasound findings of NIFTP (n = 40) with those of FVPTC (n = 94) and encapsulated PTC (encap-PTC) (n = 157). The NIFTP group showed benign findings on ultrasound significantly more frequently than the FVPTC group based on the Japan Society of Ultrasonics in Medicine criteria: a regular shape (p < 0.001), well edge definition (p = 0.007), smooth character (p < 0.001), isoechoic and homogeneous internal echoes (p < 0.001), lack of punctate microcalcification (p = 0.027), and a regular marginal hypoechoic zone (p < 0.001). Compared to encap-PTC, NIFTP has a significantly higher incidence of benign findings: isoechoic and homogeneous internal echoes (p < 0.001), lack of punctate microcalcification (p < 0.001), and a regular marginal hypoechoic zone (p = 0.004). Based on the ultrasound classification (USC) system at Kuma Hospital, no cases were classified as malignant (USC ≥3.5), but 55.4% of the FVPTCs and 53.5% of the encap-PTCs were diagnosed as malignancy. However, on cytology, the incidence of NIFTP classified as Bethesda-V or -VI (PTC) was very high at 86.9%. All patients underwent surgical treatment, but none of the NIFTP patients showed postoperative recurrence. Although avoiding surgery might be difficult because of the high incidence of malignant cytology, overtreatment (including extensive surgery) for NIFTP can be avoided by paying close attention to the lack of malignant findings on ultrasound.

Ultrasound grading of thyroid nodules using the BTA U-scoring guidelines - Is there evidence of intra-and interobserver variability?

Introduction

U-score ultrasound classification (graded U1-U5) is widely used to grade thyroid nodules based on benign and malignant sonographic features. It is well established that ultrasound is an operator-dependent imaging modality and thus more susceptible to subjective variances between operators when using imaging-based scoring systems. We aimed to assess whether there is any intra- or interobserver variability when U-scoring thyroid nodules and whether previous thyroid ultrasound experience has an effect on this variability.

Methods

A total of 14 ultrasound operators were identified (five experienced thyroid operators, five with intermediate experience and four with no experience) and were asked to U-score images from 20 thyroid cases shown as a single projection, with and without Doppler flow. The cases were subsequently rescored by the 14 operators after six weeks. The first and second round U-scores for the three operator groups were then analysed using Fleiss' kappa to assess interobserver variability and Cochran's Q test to determine any intraobserver variability.

Results

We found no significant interobserver variability on combined assessment of all operators with fair agreement in round 1 (Fleiss' kappa = 0.30, p <0.0001) and slight agreement in round 2 (Fleiss' kappa = 0.19, p < 0.0001). Cochran's Q test revealed no significant intraobserver variability in all 14 operators between round 1 and round 2 (all p>0.05).

Conclusions

We found no statistically significant inter- or intraobserver variability in the U-scoring of thyroid nodules between all participants reinforcing the validity of this scoring method in clinical practice, allaying concerns regarding potential subjective biases in reporting.

American Thyroid Association Sonographic Risk and Afirma Gene Expression Classifier Alone and in Combination for the Diagnosis of Thyroid Nodules with Bethesda Category III Cytology

Background: The Afirma gene expression classifier (GEC) has been used to aid in the diagnosis and management of thyroid nodules having Bethesda category III fine-needle aspiration cytologic diagnosis (B3 nodules). The American Thyroid Association sonographic risk stratification system for thyroid nodules (ATA-US) may stratify B3 nodules and aid in the decision to order a molecular test. The aim of this study was to assess the association between ATA-US and GEC as well as to determine their individual and combined diagnostic performances when applied to B3 nodules. Methods: A retrospective single-center study included B3 nodules that had undergone evaluation by GEC. Each ultrasound was reviewed by three radiologists, and nodules were classified using the 2015 ATA sonographic risk categories. Nodules were determined to be benign or malignant based on surgical pathology or minimum 11 months of follow-up. Positive predictive values (PPV) and negative predictive values (NPV) were calculated for GEC, ATA-US, and GEC across all ATA-US categories. Results: One hundred twenty-six B3 nodules with GEC results were included and deemed benign or malignant based on final pathology or follow-up. Prevalence of malignancy was 32%. The rate of malignancy was similar in the ATA-US high suspicion (HS) and intermediate suspicion (IS) categories at 42% and 38%, respectively; and lower in nodules with low suspicion sonography (LS) and very low suspicion sonography (VLS) at 23% and 11%, respectively. The PPV and NPV of ATA-US was calculated by designating HS or IS sonography as a "positive" test and the lower risk categories as "negative." ATA-US had a PPV of 40% and NPV of 79%. The GEC PPV was 40% and NPV was 83%. The PPV of GEC was 50% in nodules with HS or IS ATA-US and lower at 28% and 20%, respectively, in LS and VLS nodules. The NPV of GEC was 80% in HS, 77% in IS, 84% in LS, and 100% in VLS sonography categories. Conclusions: In B3 nodules, ATA-US and GEC have similar diagnostic performance. The PPV of GEC varies across ATA-US categories, while the NPV remains similar. These data support the need for future prospective studies.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: a problematic entity

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a borderline thyroid tumour formerly known as noninvasive encapsulated follicular variant of papillary thyroid carcinoma. The prevalence of NIFTP is estimated at 4.4-9.1% of all papillary thyroid carcinomas worldwide; however, the rate of occurrence of NIFTP is eight times lower in Asian countries than in Western Europe and America. At the molecular level, NIFTP is characterised by the lack of BRAF V600E and BRAF V600E-like mutations or other high-risk mutations (TERT, TP53), and a high rate of RAS mutations, which is similar to other follicular-pattern thyroid tumours. The diagnosis of NIFTP can only be made after histological examination of the entire tumour removed during surgery, and is based on strictly defined inclusion and exclusion criteria. Although the diagnosis is postoperative, the combination of certain findings of preoperative tests including ultrasonography, cytology, and molecular testing may raise suspicion of NIFTP. These tumours can be effectively treated by lobectomy, although total thyroidectomy remains an option for some patients. Radioactive iodine and thyroid stimulating hormone suppression therapy are not required. NIFTP has an extremely good prognosis, even when treated conservatively with lobectomy alone. Nevertheless, it cannot be considered as a benign lesion. The risk of adverse outcomes, including lymph node and distant metastases, is low but not negligible.

The Added Value of Operator's Judgement in Thyroid Nodule Ultrasound Classification Arising From Histologically Based Comparison of Different Risk Stratification Systems

Objective: Several ultrasound classifications for thyroid nodules were proposed but their accuracy is still debated, since mainly estimated on cytology and not on histology. The aim of this study was to test the diagnostic accuracy and the inter-classification agreement of AACE/ACE-AME, American Thyroid Association (ATA), British Thyroid Association (BTA), and Modena Ultrasound Thyroid Classification (MUT) that stratifies malignancy risk considering also the clinician subjective impression. Methods: A prospective study collecting thyroid nodule features at ultrasound and histological diagnosis was conducted. Ultrasound features were collected following a preformed checklist in candidates for surgery because of indeterminate, suspicious, or malignant cytology. All the nodules, besides the cytologically suspicious one, were blinded analyzed. MUT score was applied prospectively, and the others retrospectively. Sensitivity, specificity, diagnostic cut-off value, and accuracy of each classification were calculated. The overall agreement between classifications was tested by Bland-Altman, and agreement between single nodule analysis by different classifications by Weighted Cohen's Kappa. Results: In classifying a total of 457 nodules, MUT has the highest accuracy (AUC 0.808) and specificity (89%), followed by ATA and BTA, and finally by AACE/ACE-AME. ATA, BTA, and MUT are highly interchangeable. Considering agreement between single nodule analyses, ATA and BTA had the best (κ = 0.723); AACE/ACE-AME showed slight agreement with BTA (κ = 0.177) and MUT (κ = 0.183), and fair agreement with ATA (κ = 0.282); MUT had fair agreement with both ATA (κ = 0.291) and BTA (κ = 0.271). Conclusion: Classifications have an acceptable overall diagnostic accuracy, improved using a less rigid system that takes into consideration operator subjective impression.