Interobserver agreement of various thyroid imaging reporting and data systems

The value of ACR, European, Korean, and ATA ultrasound risk stratification systems combined with RAS mutations for detecting thyroid carcinoma in cytologically indeterminate and suspicious for malignancy thyroid nodules

PURPOSE

The aim of this study was to evaluate the diagnostic value of four commonly utilized ultrasound (US) RSSs, namely, the American College of Radiology [ACR], European [EU], Korean [K] TI-RADSs and American Thyroid Association [ATA] US-based RSS criteria, in combination with activating point mutations of the RAS genes (NRAS, HRAS, and KRAS) for detection of thyroid carcinoma in cytologically indeterminate and suspicious for malignancy thyroid nodules.

METHODS

We retrospectively analyzed cytologically indeterminate and suspicious for malignancy thyroid nodules which underwent US, molecular testing and surgery between September 1, 2018, and December 31, 2023. Receiver operating characteristic (ROC) curves were generated, and the area under the curve (AUC, 95% confidence interval [CI]) was calculated.

RESULTS

A total of 100 cytologically indeterminate and 24 suspicious for malignancy thyroid nodules were analyzed. Compared to the four US-based RSSs alone, the diagnostic value of the four US-based RSSs combined with RAS mutations did not significantly improved (cytologically indeterminate, AUC [95% CI] 0.6 [0.5-0.7] and 0.6 [0.5-0.7], respectively, p = 0.70; cytologically suspicious for malignancy, AUC [95% CI] 0.7 [0.5-0.9] and 0.8 [0.6-0.9], respectively, p = 0.23).

CONCLUSIONS

The diagnostic value of the four main US-based RSSs (ACR, EU, K, and ATA) was not improved in conjunction with the evaluation of RAS mutations for preoperative risk stratification of cytologically indeterminate thyroid nodules.

CLINICAL RELEVANCE STATEMENT

In cytologically indeterminate nodules categorized according to US-based RSSs, isolated RAS positivity does not reliably distinguish between benignity and malignancy.

Evaluating diagnostic accuracy and agreement of TI-RADS scoring in thyroid nodules: A comparative analysis between sonographers and radiologists

OBJECTIVE

The Thyroid Imaging Reporting and Data System (TI-RADS) is an essential tool for assessing thyroid nodules, primarily used by radiologists. This study aimed to compare the agreement of TI-RADS scores between sonographers and radiologists and to assess the diagnostic performance of these scores against histological findings in suspicious thyroid nodules.

METHODS

In a retrospective analysis, 168 patients with suspicious thyroid nodules classified as TR3 and above by the radiologists were included. Both sonographers and radiologists independently assigned the American College of Radiologists (ACR) TI-RADS scores, which were then compared for inter-reader agreement using Cohen's Kappa statistic. The scores were also evaluated for diagnostic performance against histological results based on the Bethesda system.

RESULTS

The study revealed a moderate overall agreement between sonographers and radiologists in TI-RADS scoring (κ = 0.504; 95% CI: 0.409-0.599), with poor agreement noted specifically for nodule margin scores (κ = 0.102; 95% CI: -1.430-0.301). In terms of diagnostic performance against histological outcomes, sonographers' TI-RADS scores showed a sensitivity of 100% and a specificity of 44.6%, while radiologists' scores showed a sensitivity of 100% but a lower specificity of 29.3%.

CONCLUSION

The findings indicate moderate agreement in TI-RADS scoring between sonographers and radiologists, with reproducibility challenges especially in scoring nodule margins. The marginally superior diagnostic performance of sonographers' scores suggests potential efficiency benefits in involving sonographers in preliminary assessments. Future research should aim to encompass a wider range of TI-RADS categories and focus on minimizing scoring variability to enhance the system's clinical utility.

Interobserver Agreement in Ultrasound Risk Stratification Systems for Thyroid Nodules on Static Images Versus Cine-Loop Video Sequences

PURPOSE

To evaluate the impact of video sequences (cine-loops) on the interobserver agreement (IOA) using risk stratification systems (RSSs) for thyroid nodules (TNs).

METHODS

Twenty TNs were randomly selected from a large database and evaluated by twelve experienced observers using five different RSSs (Kwak-, ACR-, EU-, Korean-TIRADS, ATA Guidelines). In the first step, the evaluation was conducted based on static ultrasound (US) images in two planes ("static"). Six months later, these cases were reevaluated by the same observers using video sequences in two planes ("cine-loops"). Fleiss' kappa (κ) was calculated for the IOA analyses.

RESULTS

IOA on static was moderate with κ values of 0.46, 0.42, 0.40, 0.45, and 0.38 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively, while the IOA on cine-loops was fair with κ values of 0.41, 0.38, 0.37, 0.36, and 0.34 for the Kwak-, ACR-, EU-, Korean-TIRADS, and ATA Guidelines, respectively. The overall IOA was superior in static images versus cine-loops (p = 0.024). Among other findings, the subgroup analyses (related to age, gender, US certificates, number of thyroid US per week, and RSSs experience) particularly showed that the experience of the observers in using RSSs had a significant influence on the IOA.

CONCLUSIONS

The overall IOA (all twelve observers and all five RSSs) was superior on static US images in comparison to cine-loops. Furthermore, the overall IOA of the five US features revealed superior κ values of the static images over cine-loops. However, this impact was significantly lower when the observers were highly experienced in the use of US RSSs of TNs.

Multiparametric ultrasound evaluation of thyroid nodules

Thyroid nodules are common incidental findings. Most of them are benign, but many unnecessary fine-needle aspiration procedures, core biopsies, and even thyroidectomies or non-invasive treatments have been performed. To improve thyroid nodule characterization, the use of multiparametric ultrasound evaluation has been encouraged by most experts and several societies. In particular, US elastography for assessing tissue stiffness and CEUS for providing insight into vascularization contribute to improved characterization. Moreover, the application of AI, particularly machine learning and deep learning, enhances diagnostic accuracy. Furthermore, AI-based computer-aided diagnosis (CAD) systems, integrated into the diagnostic process, aid in risk stratification and minimize unnecessary interventions. Despite these advancements, challenges persist, including the need for standardized TIRADS, the role of US elastography in routine practice, and the integration of AI into clinical protocols. However, the integration of clinical information, laboratory information, and multiparametric ultrasound features remains crucial for minimizing unnecessary interventions and guiding appropriate treatments. In conclusion, ultrasound plays a pivotal role in thyroid nodule management. Open questions regarding TIRADS selection, consistent use of US elastography, and the role of AI-based techniques underscore the need for ongoing research. Nonetheless, a comprehensive approach combining clinical, laboratory, and ultrasound data is recommended to minimize unnecessary interventions and treatments.

Diagnosing and management of thyroid nodules and goiter - current perspectives

Due to the frequent diagnosis of benign thyroid nodules, it is necessary to deviate from the traditional paradigm based on frequent surgical treatment. This article highlights the evolution of diagnosis and treatment in recent years, beginning from standardization of ultrasound assessment of nodules and cytology results to minimally invasive techniques to reduce the size of symptomatic thyroid nodules. These achievements reduce the number of surgeries, enable more individualized care for patients with benign thyroid disease, reduce long-term complications, and promote cost-effectiveness within healthcare systems. Furthermore, although the use of minimally invasive techniques significantly decreases thyroid nodule volume, the thyroid nodule usually does not disappear and the challenges in this field are discussed (the efficacy of thermal ablation, a variable part of thyroid nodules that remains viable after thermal ablation, some of the nodules treated with thermal ablation may require a second treatment over time and the efficacy of thermal ablation in nodules with different phenotypes). However, although surgery still represents the "gold standard" for establishing the final histopathologic diagnosis, it is associated with lifelong thyroid hormone substitution need and serious complications in rare cases. Therefore, it should represent the ultima ratio only after a detailed diagnostic procedure. In the future, artificial intelligence-assisted programs for the evaluation and management of nodules are expected.

Training on contrast-enhanced ultrasound LI-RADS classification for resident radiologists: a retrospective comparison of performance after training

OBJECTIVES

To evaluate the effects and benefits of training radiology residents on contrast-enhanced ultrasound (CEUS) according to the Liver Imaging Reporting and Data System (LI-RADS).

METHODS

In total, 234 patients at high risk of hepatocellular carcinoma (HCC) who underwent CEUS were enrolled, including 27 lesions in the education set and 207 lesions in the test sets (a-d). Forty-five radiology residents and 4 radiology experts involved in CEUS LI-RADS training individually reviewed the test sets before, immediately after, and 3-months after training. The consistency with kappa values of the description of CEUS features, the classification of focal liver lesions (FLLs), and the diagnostic performance were evaluated.

RESULTS

The level of agreement between the radiology experts and residents improved after training (all p < 0.05), while there were no significant differences between the post-training and 3-months post-training results (all p > 0.05). The sensitivity, specificity, positive predictive value, and area under the curve (AUC) based on the CEUS LI-RADS classification of the radiology experts in the diagnosis of HCC were 62.9%, 96.4%, 96.3%, and 0.796, respectively. The diagnostic performance of the radiology residents significantly improved after training (all p < 0.05). Misunderstanding of definitions and subjective interpretation of images were the main reasons for disagreement with multiple responses.

CONCLUSION

Dedicated CEUS LI-RADS training improved the performance of radiology residents in diagnosing FLLs and their agreement with radiology experts on CEUS features. Images and videos to explain typical features of the training were essential to improve agreement between the radiology experts and residents.

CRITICAL RELEVANCE STATEMENT

Agreement on lesion descriptors between radiology experts and residents can improve with training.

KEY POINTS

The diagnostic performance of less experienced radiologists for diagnosing HCC could be improved by training. Images and videos to explain typical features during training were essential. Agreement on lesion descriptors between radiology experts and residents improved after training.

Thyroid Nodule Characterization: Overview and State of the Art of Diagnosis with Recent Developments, from Imaging to Molecular Diagnosis and Artificial Intelligence

Ultrasound (US) is the primary tool for evaluating patients with thyroid nodules, and the risk of malignancy assessed is based on US features. These features help determine which patients require fine-needle aspiration (FNA) biopsy. Classification systems for US features have been developed to facilitate efficient interpretation, reporting, and communication of thyroid US findings. These systems have been validated by numerous studies and are reviewed in this article. Additionally, this overview provides a comprehensive description of the clinical and laboratory evaluation of patients with thyroid nodules, various imaging modalities, grayscale US features, color Doppler US, contrast-enhanced US (CEUS), US elastography, FNA biopsy assessment, and the recent introduction of molecular testing. The potential of artificial intelligence in thyroid US is also discussed.

A Multi-View Deep Learning Model for Thyroid Nodules Detection and Characterization in Ultrasound Imaging

Thyroid Ultrasound (US) is the primary method to evaluate thyroid nodules. Deep learning (DL) has been playing a significant role in evaluating thyroid cancer. We propose a DL-based pipeline to detect and classify thyroid nodules into benign or malignant groups relying on two views of US imaging. Transverse and longitudinal US images of thyroid nodules from 983 patients were collected retrospectively. Eighty-one cases were held out as a testing set, and the rest of the data were used in five-fold cross-validation (CV). Two You Look Only Once (YOLO) v5 models were trained to detect nodules and classify them. For each view, five models were developed during the CV, which was ensembled by using non-max suppression (NMS) to boost their collective generalizability. An extreme gradient boosting (XGBoost) model was trained on the outputs of the ensembled models for both views to yield a final prediction of malignancy for each nodule. The test set was evaluated by an expert radiologist using the American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS). The ensemble models for each view achieved a mAP0.5 of 0.797 (transverse) and 0.716 (longitudinal). The whole pipeline reached an AUROC of 0.84 (CI 95%: 0.75-0.91) with sensitivity and specificity of 84% and 63%, respectively, while the ACR-TIRADS evaluation of the same set had a sensitivity of 76% and specificity of 34% (p-value = 0.003). Our proposed work demonstrated the potential possibility of a deep learning model to achieve diagnostic performance for thyroid nodule evaluation.

Interobserver variability in thyroid ultrasound

PURPOSE

Ultrasound evaluation of thyroid nodules is the preferred technique, but it is dependent on operator interpretation, leading to inter-observer variability. The current study aimed to determine the inter-physician consensus on nodular characteristics, risk categorization in the classification systems, and the need for fine needle aspiration puncture.

METHODS

Four endocrinologists from the same center blindly evaluated 100 ultrasound images of thyroid nodules from 100 different patients. The following ultrasound features were evaluated: composition, echogenicity, margins, calcifications, and microcalcifications. Nodules were also classified according to ATA, EU-TIRADS, K-TIRADS, and ACR-TIRADS classifications. Krippendorff's alpha test was used to assess interobserver agreement.

RESULTS

The interobserver agreement for ultrasound features was: Krippendorff's coefficient 0.80 (0.71-0.89) for composition, 0.59 (0.47-0.72) for echogenicity, 0.73 (0.57-0.88) for margins, 0.55 (0.40-0.69) for calcifications, and 0.50 (0.34-0.67) for microcalcifications. The concordance for the classification systems was 0.7 (0.61-0.80) for ATA, 0.63 (0.54-0.73) for EU-TIRADS, 0.64 (0.55-0.73) for K-TIRADS, and 0.68 (0.60-0.77) for K-TIRADS. The concordance in the indication of fine needle aspiration puncture (FNA) was 0.86 (0.71-1), 0.80 (0.71-0.88), 0.77 0.67-0.87), and 0.73 (0.64-0.83) for systems previously described respectively.

CONCLUSIONS

Interobserver agreement was acceptable for the identification of nodules requiring cytologic study using various classification systems. However, limited concordance was observed in risk stratification and many ultrasonographic characteristics of the nodules.

The American Thyroid Association risk classification of papillary thyroid cancer according to presurgery cytology

OBJECTIVE

To compare the American Thyroid Association (ATA) risk staging of histologically proven papillary thyroid cancer (PTC) in patients who received a presurgery cytologic result of either indeterminate thyroid nodules (ITNs, Bethesda III/IV) or suspicious for malignancy/malignant (TIR 4/5, Bethesda V/VI).

METHODS

Clinical, ultrasonographic, cytological data from patients with histologically diagnosed PTC were retrospectively collected.

RESULTS

Patients were stratified according to the preoperative fine-needle aspiration cytology into 2 groups: 51 ITNs (TIR3A/3B) and 118 suspicious/malignant (TIR 4/5). Male/female ratio, age, and presurgery TSH level were similar between the 2 groups. At ultrasound, TIR 4/5 nodules were significantly more frequently hypoechoic (P = .037), with irregular margins (P = .041), and with microcalcifications (P = .020) and were more frequently classified as high-risk according to the European Thyroid Imaging and Reporting Data System (EU-TIRADS; P = .021). At histology, the follicular PTC subtype was significantly more prevalent among ITNs while classical PTC subtype was more frequent in TIR 4/5 group (P = .002). In TIR 4/5 group, a higher rate of focal vascular invasion (P < .001) and neck lymph node metastasis (P = .028) was observed. Intermediate-risk category according to ATA was significantly more frequent in TIR 4/5 group while low-risk category was more frequently found among ITNs (P = .021), with a higher number of patients receiving radioiodine in TIR 4/5 group (P = .002). At multivariate logistic regression, having a TIR 4/5 cytology was associated with a significant risk of having a higher ATA risk classification as compared to ITN (OR 4.6 [95% CI 1.523-14.007], P = .007), independently from presurgery findings (nodule size at ultrasound, sex, age, and EU-TIRADS score).

CONCLUSIONS

Papillary thyroid cancers recorded among ITNs are likely less aggressive and are generally assessed as at lower risk according to ATA classification.

[Standardized acquisition and documentation of cine loops on conventional thyroid ultrasound]

Ultrasound is the basic imaging method for the assessment of the thyroid gland. Due to the high prevalence of structural disease, the examination procedure is used very frequently in Germany, in many cases in the context of follow-up. The assessment of thyroid pathologies and their dynamics is subjected to relevant inter- and intraobserver variability. Findings that were not identified during live ultrasound cannot be assessed retrospectively. Applying an SOP for the acquisition and documentation of standardized video sequences of ultrasound images (so-called cine loops), allows for a secondary retrospective evaluation of the thyroid gland, taking into account previously acquired images analogous to other cross-sectional imaging methods such as CT or MRI. The cine loops can be acquired by non-physician personnel, stored to the local PACS and used for educational and research purposes.

Learnability of Thyroid Nodule Assessment on Ultrasonography: Using a Big Data Set

OBJECTIVE

The aims of the work described here were to evaluate the learnability of thyroid nodule assessment on ultrasonography (US) using a big data set of US images and to evaluate the diagnostic utilities of artificial intelligence computer-aided diagnosis (AI-CAD) used by readers with varying experience to differentiate benign and malignant thyroid nodules.

METHODS

Six college freshmen independently studied the "learning set" composed of images of 13,560 thyroid nodules, and their diagnostic performance was evaluated after their daily learning sessions using the "test set" composed of images of 282 thyroid nodules. The diagnostic performance of two residents and an experienced radiologist was evaluated using the same "test set." After an initial diagnosis, all readers once again evaluated the "test set" with the assistance of AI-CAD.

RESULTS

Diagnostic performance of almost all students increased after the learning program. Although the mean areas under the receiver operating characteristic curves (AUROCs) of residents and the experienced radiologist were significantly higher than those of students, the AUROCs of five of the six students did not differ significantly compared with that of the one resident. With the assistance of AI-CAD, sensitivity significantly increased in three students, specificity in one student, accuracy in four students and AUROC in four students. Diagnostic performance of the two residents and the experienced radiologist was better with the assistance of AI-CAD.

CONCLUSION

A self-learning method using a big data set of US images has potential as an ancillary tool alongside traditional training methods. With the assistance of AI-CAD, the diagnostic performance of readers with varying experience in thyroid imaging could be further improved.

Optimal Cutoff Values of the Contact Angle of Tumor on Sonography System for Predicting Extrathyroidal Extension of Papillary Thyroid Carcinoma by Tumor Location

Background

Extrathyroidal extension (ETE) significantly affects the treatment strategy for thyroid cancer. We present a new method to predict ETE of papillary thyroid carcinoma (PTC).

methods

We enrolled 1 481 patients with PTCs. The ETE was classified into minimal and gross ETE. Using the novel "contact angle of the tumor on sonography" (CATS) system, we calculated optimal cutoffs for predicting ETE according to tumor location and compared the diagnostic performance to that of previous methods.

Results

The optimal cutoff angles for predicting anterior minimal and gross ETE were 41.5° and 49.4°, respectively, while those for posterior ETE were 39.8° and 54.6°, respectively. The optimal cutoff angle predicting tracheal ETE was 88.0°. The diagnostic performance was comparable to that of previous methods.

Conclusion

The CATS method for predicting ETE is a valuable alternative.

2023 European Thyroid Association Clinical Practice Guidelines for thyroid nodule management

With the widespread use of sensitive imaging techniques, which include neck visualization, a conspicuous number of thyroid nodules emerge and demand attention. Most lesions are benign, asymptomatic, and do not warrant treatment. In the case of cancer diagnosis, most are small, intrathyroidal and indolent neoplasms that can safely be managed conservatively. There is a pronounced need for more cost-effective, risk-adapted approaches to the management of this highly prevalent condition, taking the wishes of the patient into consideration. Thus, the present guidelines aim at providing a clinical practice guide for the initial workup and the subsequent management of adult individuals harboring thyroid nodules. Importantly, these guidelines are not intended to cover the management of thyroid malignancy. The manuscript and the specific recommendations were developed by reconciling the best available research evidence with the knowledge and clinical experience of the panelists and updating aspects of a number of previous European Thyroid Association guidelines.

Diagnostic performance of ultrasound risk stratification systems on thyroid nodules cytologically classified as indeterminate: a systematic review and meta-analysis

PURPOSE

Ultrasound (US) risk stratification systems (RSSs) are increasingly being utilized for the optimal management of thyroid nodules, including those with indeterminate cytology. The goal of this study was to evaluate the category-based diagnostic performance of US RSSs in identifying malignancy in indeterminate nodules.

METHODS

This systematic review and meta-analysis was registered on PROSPERO (CRD42021266195). PubMed, EMBASE, and Web of Science were searched through December 1, 2022. Original articles reporting data on the performance of US RSSs for indeterminate nodules were included. The numbers of nodules classified as true negative, true positive, false negative, and false positive were extracted.

RESULTS

Thirty-three studies evaluating 7,225 indeterminate thyroid nodules were included. The diagnostic accuracy was quantitatively synthesized using a Bayesian bivariate model based on the integrated nested Laplace approximation in R. For the intermediate- to high-risk category, the sensitivity levels of the American College of Radiology, the American Thyroid Association, the European Thyroid Association, the Korean Thyroid Association/Korean Society of Thyroid Radiology, and Kwak et al. were found to be 0.80, 0.72, 0.76, 0.96, and 0.97, respectively. The corresponding specificity measurements were 0.36, 0.50, 0.49, 0.28, and 0.17. Furthermore, for the high-risk category, the sensitivity values were 0.40, 0.46, 0.55, 0.47, and 0.10, while the specificity levels were 0.91, 0.90, 0.71, 0.91, and 0.99, respectively.

CONCLUSION

The overall diagnostic performance of the US RSSs was moderate in the differentiation of indeterminate nodules.

Thyroid Nodule Detection and Region Estimation in Ultrasound Images: A Comparison between Physicians and an Automated Decision Support System Approach

BACKGROUND

Thyroid nodules are very common. In most cases, they are benign, but they can be malignant in a low percentage of cases. The accurate assessment of these nodules is critical to choosing the next diagnostic steps and potential treatment. Ultrasound (US) imaging, the primary modality for assessing these nodules, can lack objectivity due to varying expertise among physicians. This leads to observer variability, potentially affecting patient outcomes.

PURPOSE

This study aims to assess the potential of a Decision Support System (DSS) in reducing these variabilities for thyroid nodule detection and region estimation using US images, particularly in lesser experienced physicians.

METHODS

Three physicians with varying levels of experience evaluated thyroid nodules on US images, focusing on nodule detection and estimating cystic and solid regions. The outcomes were compared to those obtained from a DSS for comparison. Metrics such as classification match percentage and variance percentage were used to quantify differences.

RESULTS

Notable disparities exist between physician evaluations and the DSS assessments: the overall classification match percentage was just 19.2%. Individually, Physicians 1, 2, and 3 had match percentages of 57.6%, 42.3%, and 46.1% with the DSS, respectively. Variances in assessments highlight the subjectivity and observer variability based on physician experience levels.

CONCLUSIONS

The evident variability among physician evaluations underscores the need for supplementary decision-making tools. Given its consistency, the CAD offers potential as a reliable "second opinion" tool, minimizing human-induced variabilities in the critical diagnostic process of thyroid nodules using US images. Future integration of such systems could bolster diagnostic precision and improve patient outcomes.

Real-Time Ultrasonography and the Evaluation of Static Images Yield Different Results in the Assessment of EU-TIRADS Categories

The studies on the effectiveness of various TIRADS in the diagnostics of thyroid nodules differ in the method of ultrasound image assessment: real time (rtUS) vs. static ultrasonography (stUS). The aim of the study was to evaluate the impact of those two methods on the categorization of nodules in EU-TIRADS. Three experienced raters assessed 842 nodules in routine rtUS and reassessed with the use of sUS. Reproducibility of the assessment of malignancy risk features and categorization of nodules with EU-TIRADS was estimated with Krippendorff's alpha coefficient (Kα). The reproducibility of EU-TIRADS categories on sUS in relation to rtUS was in range 70.9-76.5% for all raters (Kα: 0.60-0.68) with the highest reproducibility for category 3 (80.0-86.5%) and the lowest for category 5 (48.7-77.8%). There was a total disagreement of the identification of microcalcifications on sUS in relation to rtUS, a strongly variable reproducibility of marked hypoechogenicity (12.5-84.6%, Kα: 0.14-0.48) and a tendency toward more frequent identification of the non-oval shape on sUS. The percentage of agreement for each pair of raters in assigning the EU-TIRADS category on sUS was in the range 71.6-72.3% (Kα: 0.60-0.62). The method of sonographic image evaluation influences the nodule's feature assessment and, eventually, the categorization within EU-TIRADS.

A Reappraisal of Suspicious Sonographic Features of Thyroid Nodules: Shape Is Not an Independent Predictor of Malignancy

CONTEXT

For the correct clinical application of the sonographic risk-stratification systems, the definition of independent risk features that are foundational to each system is crucial.

OBJECTIVE

The aim of this study was to identify the gray-scale sonographic features independently associated with malignancy, and to compare different definitions.

METHODS

This prospective, diagnostic accuracy study took place in a single thyroid nodule referral center. All patients consecutively referred to our center for fine-needle aspiration cytology of a thyroid nodule between November 1, 2015 and March 30, 2020, were enrolled before cytology. Each nodule was examined by 2 experienced clinicians to record the sonographic features on a rating form. Histologic (when available) or cytologic diagnosis was used as the reference standard. For each single sonographic feature and definition, the sensitivity, specificity, positive and negative predictive values, and diagnostic odds ratios (DOR) were calculated. The significant predictors were then included in a multivariable regression model.

RESULTS

The final study cohort consisted of 903 nodules in 852 patients. A total of 76 nodules (8.4%) were malignant. Six features were independent predictors of malignancy: suspicious lymph node (DOR 16.23), extrathyroidal extension (DOR 6.60), irregular or infiltrative margins (DOR 7.13), marked hypoechogenicity (DOR 3.16), solid composition (DOR 3.61), and punctate hyperechoic foci (including microcalcifications and indeterminate foci; DOI 2.69). Taller-than-wide shape was not confirmed as an independent predictor.

CONCLUSION

We identified the key suspicious features of thyroid nodules and provided a simplified definition of some debated ones. Malignancy rate increases with number of features.

Preoperative prediction of extrathyroidal extension: radiomics signature based on multimodal ultrasound to papillary thyroid carcinoma

BACKGROUND

There is a recognized need for additional approaches to improve the accuracy of extrathyroidal extension (ETE) diagnosis in papillary thyroid carcinoma (PTC) before surgery. Up to now, multimodal ultrasound has been widely applied in disease diagnosis. We investigated the value of radiomic features extracted from multimodal ultrasound in the preoperative prediction of ETE.

METHODS

We retrospectively pathologically confirmed PTC lesions in 235 patients from January 2019 to April 2022 in our hospital, including 45 ETE lesions and 205 non-ETE lesions. MaZda software was employed to obtain radiomics parameters in multimodal sonography. The most valuable radiomics features were selected by the Fisher coefficient, mutual information, probability of classification error and average correlation coefficient methods (F + MI + PA) in combination with the least absolute shrinkage and selection operator (LASSO) method. Finally, the multimodal model was developed by incorporating the clinical records and radiomics features through fivefold cross-validation with a linear support vector machine algorithm. The predictive performance was evaluated by sensitivity, specificity, accuracy, F1 scores and the area under the receiver operating characteristic curve (AUC) in the training and test sets.

RESULTS

A total of 5972 radiomics features were extracted from multimodal sonography, and the 13 most valuable radiomics features were selected from the training set using the F + MI + PA method combined with LASSO regression. The multimodal prediction model yielded AUCs of 0.911 (95% CI 0.866-0.957) and 0.716 (95% CI 0.522-0.910) in the cross-validation and test sets, respectively. The multimodal model and radiomics model showed good discrimination between ETE and non-ETE lesions.

CONCLUSION

Radiomics features based on multimodal ultrasonography could play a promising role in detecting ETE before surgery.

The Size of a Thyroid Nodule with ACR TI-RADS Does Not Provide a Better Prediction of the Nature of the Nodule: A Single-Center Retrospective Real-Life Observational Study

We investigated if thyroid nodule size has a predictive value of malignancy on a par with composition, echogenicity, shape, margin, and echogenic foci, and what would be the consequence of observing the rule of the American College of Radiology (ACR) to perform a fine-needle aspiration biopsy (FNAB). We conducted a retrospective real-life observational study on 86 patients who underwent surgery after a standardized diagnostic protocol. We divided the TR3, TR4, and TR5 classes into sub-classes according to the size threshold indicating FNAB (a: up to the threshold for no FNAB; b: over the threshold for FNAB suggested). We computed sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) for the different sub-classes and Youden's index (Y) for the different possible cutoffs. Each sub-class showed the following PPV (0.67, 0.68, 0.70, 0.78, 0.72), NPV (0.56, 0.54, 0.51, 0.52, 0.59), and Y (0.20, 0.20, 0.22, 0.31, 0.30). In this real-life series, we did not find a significant difference in prediction of malignancy between the sub-categories according to the size threshold. All nodules have a pre-evaluation likelihood of being malignant, and the impact and utility of size thresholds may be less clear than suggested by the ACR TIRADS guidelines in patients undergoing standardized thyroid work up.

Considerable interobserver variation calls for unambiguous definitions of thyroid nodule ultrasound characteristics

Objective

Thyroid nodule ultrasound characteristics are used as an indication for fine-needle aspiration cytology, usually as the basis for Thyroid Imaging Reporting and Data System (TIRADS) score calculation. Few studies on interobserver variation are available, all of which are based on analysis of preselected still ultrasound images and often lack surgical confirmation.

Methods

After the blinded online evaluation of video recordings of the ultrasound examinations of 47 consecutive malignant and 76 consecutive benign thyroid lesions, 7 experts from 7 thyroid centers answered 17 TIRADS-related questions. Surgical histology was the reference standard. Interobserver variations of each ultrasound characteristic were compared using Gwet's AC1 inter-rater coefficients; higher values mean better concordance, the maximum being 1.0.

Results

On a scale from 0.0 to 1.0, the Gwet's AC1 values were 0.34, 0.53, 0.72, and 0.79 for the four most important features in decision-making, i.e. irregular margins, microcalcifications, echogenicity, and extrathyroidal extension, respectively. The concordance in the discrimination between mildly/moderately and very hypoechogenic nodules was 0.17. The smaller the nodule size the better the agreement in echogenicity, and the larger the nodule size the better the agreement on the presence of microcalcifications. Extrathyroidal extension was correctly identified in just 45.8% of the cases.

Conclusions

Examination of video recordings, closely simulating the real-world situation, revealed substantial interobserver variation in the interpretation of each of the four most important ultrasound characteristics. In view of the importance for the management of thyroid nodules, unambiguous and widely accepted definitions of each nodule characteristic are warranted, although it remains to be investigated whether this diminishes observer variation.

A prospective comparison of ACR-TIRADS and EU-TIRADS in thyroid nodule assessment for FNA-US

OBJECTIVE

Prospective data on the accuracy of ultrasound (US) classification systems in thyroid nodules are still scarce. The aim of this study is to compare the accuracy of the American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS) and European (EU)-TIRADS classification systems.

DESIGN AND PATIENTS

Consecutive patients with one or more thyroid nodule(s) who underwent fine-needle aspiration (FNA) under ultrasonographic guidance (FNA-US) were prospectively evaluated.

MEASUREMENTS

Clinical evaluation and US data were collected. The reference standard used for this study was FNA-US cytology and histopathological diagnosis.

RESULTS

A total of 186 thyroid nodules in 166 patients were evaluated, resulting in 168 nodules from 149 patients with conclusive benign or malignant results. Sensitivity, specificity, negative predictive value (NPV) and false negative (FN) were 100.0%, 28.7%, 100.0% and 0.0%, respectively, for ACR-TIRADS; and 90.0%, 19.1%, 96.8% and 9.1% (n = 1), respectively, for EU-TIRADS. The number of unnecessary FNA-US indicated by ACR-TIRADS was lower than EU-TIRADS (71.3% vs. 80.9%, p = .017), and the number of possibly avoided FNA-US was higher (26.7% vs. 17.8%). Using the same threshold of ACR-TIRADS to indicate FNA-US in EU-TIRADS 3 nodules (2.5 cm), there was an improvement in specificity (30.6%) and avoided FNA-US (28.6%). The best performance of both systems was demonstrated when FNA-US would be indicated only in highly suspicious nodules and/or in the presence of lymphadenopathy, with 85.7% and 89.3% of possibly avoided FNA-US for ACR-TIRADS and EU-TIRADS, respectively, without increasing FN.

CONCLUSION

Both systems presented high sensitivity, but low specificity in selecting nodules for FNA-US. The use of nodular size for FNA-US selection is questioned.

Inter-Rater Reliability of Thyroid Ultrasound Risk Criteria: A Systematic Review and Meta-Analysis

OBJECTIVE

The most commonly employed diagnostic criteria for identifying thyroid nodules include Thyroid Imaging and Reporting Data System (TI-RADS) and American Thyroid Association (ATA) guidelines. The purpose of this systematic review and meta-analysis is to determine the inter-rater reliability of thyroid ultrasound criteria.

METHODS

We performed a library search of MEDLINE (Ovid), EMBASE (Ovid), and Web of Science for full-text articles published from January 2005 to June 2022. We included full-text primary research articles that used TI-RADS and/or ATA guidelines to evaluate thyroid nodules in adults. These included studies must have calculated inter-rater reliability using any validated metric. The Quality Appraisal for Reliability Studies (QAREL) was used to assess study quality. We planned for a random-effects meta-analysis, in addition to covariate and publication bias analyses. This study was performed in accordance with Preferred Reporting Items for a Systematic Review and Meta-analysis guidelines and registered prior to conduction (International prospective register of systematic reviews-PROSPERO: CRD42021275072).

RESULTS

Of the 951 articles identified via the database search, 35 met eligibility criteria. All studies were observational. The most commonly utilized criteria were ACR Thyroid Imaging and Reporting Data System (TI-RADS) and/or ATA criteria, while the majority of studies employed Κ statistics. For ACR TI-RADS, the pooled Κ was 0.51 (95% confidence interval [CI]: 0.42, 0.57; n = 7) while for ATA, the pooled Κ was 0.52 (95% CI: 0.37, 0.67; n = 3). Due to the small number of studies, covariate or publication bias analyses were not performed.

CONCLUSION

Ultrasound criteria demonstrate moderate inter-rater reliability, but these findings are impacted by poor study quality and a lack of standardization. Laryngoscope, 133:485-493, 2023.

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.

The clinical significance of the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) category 5 thyroid nodules: Not as risky as we think?

BACKGROUND

Although the prevalence of thyroid nodules is high, few prove to be malignant. Based on sonographic features, the American College of Radiology Thyroid Imaging Reporting and Data System categorizes malignancy risk of thyroid nodules with associated management recommendations for each category level. Malignancy rates among nodules with a highly suspicious Thyroid Imaging Reporting and Data System category 5 warrant examination in the context of additional risk stratification tools, including cytopathology and molecular testing.

METHODS

All patients who underwent fine-needle aspiration biopsy for Thyroid Imaging Reporting and Data System category 5 nodules from January 2018 to September 2021 in a large integrated academic health system were reviewed. Using the Bethesda System for Reporting Thyroid Cytopathology, categories V and VI were set as malignant. Molecular testing (ThyroSeq version 3; Rye Brook, NY) yielding ≥50% risk of malignancy was deemed positive and correlated with surgical pathology.

RESULTS

A total of 496 Thyroid Imaging Reporting and Data System category 5 nodules were identified. On fine-needle aspiration cytopathology, 61 (12.3%) were malignant. The breakdown included Bethesda System for Reporting Thyroid Cytopathology I, 15 (3%); II, 362 (73%); III, 52 (10.5%); IV, 5 (1%); V, 6 (1.3%); and VI, 55 (11.1%). Of Bethesda System for Reporting Thyroid Cytopathology III/IV nodules with molecular testing (n = 53), 24.5% yielded positive results. In total, 42 (8.5%) nodules underwent surgical resection, most of which were Bethesda System for Reporting Thyroid Cytopathology VI (n = 26, 61.9%). Of excised nodules, 33 (78.6%) nodules were malignant, 6 (14.3%) benign, and 3 (7.1%) noninvasive follicular thyroid neoplasm with papillary-like nuclear features. All Thyroid Imaging Reporting and Data System category 5 nodules with malignant cytology (Bethesda System for Reporting Thyroid Cytopathology V/VI) that underwent surgery were malignant on histopathology. On average, the total Thyroid Imaging Reporting and Data System points were higher in malignant nodules compared with benign (9.3 vs 7.3; P = .015). Moreover, benign nodules more frequently received Thyroid Imaging Reporting and Data System points when the radiologist was unable to determine composition or echogenicity (33% vs 3% among malignant nodules; P = .01).

CONCLUSION

Thyroid Imaging Reporting and Data System category 5 designation in thyroid nodules is associated with a lower risk of malignancy than previously reported. Benign and malignant nodules with Thyroid Imaging Reporting and Data System category 5 designation have discrepancies in certain Thyroid Imaging Reporting and Data System characteristics and individual points assigned, which may offer an opportunity for quality improvement and standardization measures in ultrasound reporting practices.

Thyroid cytology: The reality before and after the introduction of ultrasound classification systems for thyroid nodules

BACKGROUND

Several ultrasound-based systems for classification of thyroid nodules are available. They allow for a better triage of the nodules that require cytological assessment, and lead to standardized recommendations. Our aim was to compare patients and nodules referred to fine-needle aspiration (FNA) before and after the introduction of these systems.

METHODS

A retrospective study comparing two cohorts of patients referred for FNA was performed (386 patients and 463 nodules in 2015; 220 patients and 263 nodules in 2021).

RESULTS

The sex distribution (89.1% vs 85.9% females, p=0.243), number of nodules referred to FNA per patient (median of 1), and the distribution of the Bethesda categories (p=0.082) was similar in both years. In 2021, patients were older (53.4±14.5 years vs 57.8±13.2 years, p<0.001) and nodules over one centimetre were larger (median 17.0mm vs 19.0mm, p=0.002), especially the ones categorized as Bethesda III (median size 11mm vs 23mm, p=0.043). In 2021, at least 23.1% of the nodules referred to FNA did not have any criteria, and 38.8% of the nodules were not categorized by any system.

CONCLUSION

This analysis draws attention to the importance of systematically applying ultrasound-based classification systems. It seems that, by not being focused mainly on size thresholds, they allow for longer surveillance periods, without aggravating the cytology results when FNA becomes indicated. Nevertheless, greater efforts are needed to ensure more standardized reports, and to increase adherence to the resulting recommendations to reduce clinical uncertainty, unnecessary FNA, and overtreatment.

Comparing ATA guidelines vs TI-RADS for evaluation of pediatric thyroid lesions

OBJECTIVE

To compare TI-RADS vs ATA guidelines for pediatric thyroid lesions based on ultrasound, in a retrospective study over 10 years. The primary outcome measure was sensitivity of both guidelines in diagnosing a thyroid malignancy on Fine Needle Aspiration (FNA) results.

METHODS

Retrospective data collection of all pediatric patients who had an FNA at the Primary Children's Hospital for thyroid lesions. Both guidelines were compared to determine which set of guidelines is most sensitive based on final outcome of pathology.

RESULTS

Seventy-seven patients were included in the study. All 77 underwent FNA as recommended by the ATA guidelines. 54.5% were benign, 22.1% were suspicious, and 23.4% were malignant lesions. Following the TI-RADS guidelines, 40.5% of these patients could have skipped the FNA. Using the ATA guidelines, all malignant lesions would have undergone FNA. However, using the TI-RADS guidelines, some patients with malignant lesions would have been ignored (5.6%) and some followed (22.2%) showing overall less sensitivity (75%).

CONCLUSIONS

The ATA ultrasound guidelines for evaluation of thyroid nodules in children are more sensitive in screening for well-differentiated thyroid malignancy. Increased sensitivity is due in part to the size constraint within the TIRADS system. All providers who evaluate thyroid nodules in children should use the ATA pediatric guidelines to avoid missing smaller malignancies in children.

Changes in thyroid nodule cytology rates after institutional implementation of the Thyroid Imaging Reporting and Data System

BACKGROUND

The American College of Radiology Thyroid Imaging Reporting and Data System for ultrasound classification of malignancy risk was developed to better triage thyroid nodules for fine-needle aspiration biopsy. To examine further, we compared thyroid cytologic classification rates in nodules before and after institutional Thyroid Imaging Reporting and Data System implementation.

METHODS

Cytology diagnoses by Bethesda criteria (categories I-VI) from January 2014 to October 2021 were retrieved; observed changes in yearly category frequency were analyzed by linear regression; and pooled cohorts of pre- (2014-2018) and post-Thyroid Imaging Reporting and Data System (2019-2021) cytology call rates were compared.

RESULTS

Overall, 7,413 cytologic specimens were included (range/year 715-1,444). From 2014 to 2021, the proportion of benign (Bethesda category II) diagnosis per year declined stepwise from 49.7% to 19.4%, and atypia of undetermined significance/follicular lesion of undetermined significance (Bethesda category III) increased sequentially from 21.3% to 51.5%. Between 2014 and 2021, Bethesda category III diagnosis increased on average by 4.8% per year (95% confidence internal, 3.29-5.54; P < .001) and Bethesda category II results decreased on average by 4.4% per year (95% confidence interval, 6.29-3.42; P < .001). When comparing pre- and post-Thyroid Imaging Reporting and Data System, the proportion of Bethesda category II cytology results decreased (43.1% vs 21%; P = .001) while Bethesda category III (28.3% vs 47.7%; P = .002) and Bethesda category V (1.1% vs 1.7%; P = .015) results increased.

CONCLUSION

After implementation of American College of Radiology Thyroid Imaging Reporting and Data System ultrasound criteria, we observed a 2.5-fold decline in the rate of benign cytology and an increase in the proportion of atypia of undetermined significance/follicular lesion of undetermined significance results.

The Prospective Implementation of the 2015 ATA Guidelines and Modified ATA Recurrence Risk Stratification System for Treatment of Differentiated Thyroid Cancer in a Canadian Tertiary Care Referral Setting

Objective: To present clinical outcomes of the prospective implementation of the 2015 American Thyroid Association (ATA) guidelines for the management of thyroid nodules and differentiated thyroid cancer (DTC) using the modified ATA recurrence risk (RR) stratification system. Methods: We prospectively analyzed 612 patients with DTC treated between April 2017 and December 2021 in Calgary, Alberta. Each patient was prospectively assigned a modified ATA RR and American Joint Committee Cancer 8th edition stage. Initial risk stratification and consideration of the 2015 ATA guidelines guided surgical management as well as the indication for and dose of radioiodine (RAI) and other adjuvant therapies. Patients were assessed for their response to treatment (RTT) at 2-years postoperatively. Results: There were 479 patients who had 2-year follow-up data and were included in the study. Of these patients, there were 253 (53%) low-, 129 (27%) intermediate-, and 97 (20%) high-RR patients. Of these, 227 patients (47%) underwent total thyroidectomy (TTX) plus RAI, 178 (37%) underwent TTX only, and 74 (16%) underwent lobectomy. The RTT at 2 years was excellent for 89% (66) of patients with lobectomy, 84% (149) for TTX only, and 53% (121) for TTX plus RAI. Among 253 patients who were deemed low RR, 85% (216) had excellent RTT, 13% (32) indeterminate RTT, 2% (4) biochemical incomplete RTT, and 1 patient had structural incomplete RTT. The intermediate RR group had the following RTT outcomes: 64% (83) excellent, 23% (30) indeterminate, 6% (7) biochemical incomplete, and 7% (9) structural incomplete. The high RR group had the worst RTT outcomes, with 38% (37) excellent, 19% (18) indeterminate, 10% (10) biochemical incomplete, and 33% (32) structural incomplete RTT. Conclusions: The 2015 ATA RR stratification system is useful for predicting disease status at 2-year post-treatment in patients with DTC. The 2015 ATA guidelines and modified ATA RR stratification treatment recommendations may reduce thyroid cancer overtreatment by including lobectomy as a definitive treatment option for low-risk thyroid cancers and selective use of RAI for intermediate and high-risk patients.

Interobserver variability in ultrasound assessment of thyroid nodules

The first diagnostic tool for thyroid disease management is ultrasound. Despite its importance, ultrasound is an extremely subjective procedure that requires a high level of performance skill. Few studies have assessed thyroid ultrasound performance and its effectiveness, particularly the variability between observers in the assessment of ultrasound images. This study evaluated the variability in ultrasound assessments and diagnoses of thyroid nodules between 2 radiologists. In this retrospective study, 75 thyroid nodules in 39 patients were reviewed by 2 experienced radiologists. The nodule composition, margin, shape, calcification, and vasculitis were determined using echogenicity. The study evaluation included these 5 assessments and the final diagnosis. Interobserver variation was determined using Cohen kappa statistics. The interobserver agreements in the interpretation of echogenicity, shape, and margin were fair (κ = 0.21-0.40), whereas there were substantial agreements for vascularity and calcification (κ = 0.62-0.78). The agreements between the observers for individual ultrasound features in this study were the highest for vascularity and the presence/absence of calcification. The interobserver reproducibility for thyroid nodule ultrasound reporting was adequate, but the diagnostic evaluation ability of the observers was inconsistent. The variability in the interpretation of sonographic features could influence the level of suspicion of thyroid malignancy. This study emphasizes the need for consistency in the training of sonographic interpretation of thyroid nodules, particularly for echogenicity, shape, and margin.

Advanced imaging and theranostics in thyroid cancer

PURPOSE OF REVIEW

Thyroid cancers are endocrine neoplasms with diverse gene expression and behavior, for which constantly evolving anatomic and functional imaging/theranostic agents have an essential role for diagnosis, staging, and treatment.

RECENT FINDINGS

To achieve definitive diagnosis, neck ultrasound and associated risk stratification systems, notably Thyroid Imaging Reporting and Data System (TI-RADS), allow improved thyroid nodule characterization and management guidance. Radioactive iodine-131 (RAI) has long played a role in management of differentiated thyroid cancer (DTC), with recent literature emphasizing its effectiveness for intermediate-high risk cancers, exploring use of dosimetry for personalized medicine, and potential for retreatment with RAI following tumor redifferentiation. Iodine-124 positron emission tomography/computed tomography (PET/CT) has promising application for DTC staging and dosimetry. F18-fluorodeoxyglucose (FDG) PET/CT is used for staging of high risk DTC and identification of noniodine-avid disease recurrences, with metabolic uptake consistently portending poor prognosis. Poorly differentiated and anaplastic thyroid cancers are best assessed with anatomic imaging and F18-FDG PET/ CT, though recent studies show a potential theranostic role for Ga68/Lu177-prostate-specific membrane antigen. Medullary thyroid cancers are evaluated with ultrasound, CT, magnetic resonance imaging, and various positron-emitting radiotracers for PET imaging (F18-DOPA, F18-FDG, and recently Ga68-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE)); the latter may enable treatment with Lu177-DOTATATE.

SUMMARY

Multidisciplinary collaboration is essential to streamline appropriate management, given the wide array of available imaging and new therapies for metabolic and genetically complex cancers.

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.

Validating and Comparing C-TIRADS, K-TIRADS and ACR-TIRADS in Stratifying the Malignancy Risk of Thyroid Nodules

The thyroid imaging reporting and data system (TIRADS) was proposed by experts for optimal ultrasound evaluation of malignancy risk of thyroid focal lesions. There are several versions of TIRADS, some of them have been validated sufficiently, and the others have not been well assessed. In this study, a recently launched Chinese version of TIRADS (C-TIRADS) for malignancy risk stratification of thyroid nodules was validated, and the performance was compared to that of the Korean TIRADS (K-TIRADS) and American College of Radiology(ACR) TIRADS (ACR-TIRADS). Archives of 2177 patients who had undergone thyroid ultrasound examination, coarse needle tissue biopsy and/or surgery were reviewed, and 1978 patients with 1982 thyroid nodules were assessed according to the three TIRADSs. The histopathology was taken as the golden standard. The results showed the 1982 thyroid nodules were consisted of 1306 benign nodules and 676 malignant nodules. The malignancy risk accounted for 1.09%, 2.14%, 10.34%, 49.28%, 88.19% and 85.29% of the total nodules that were categorised as C-TIRADS 2, 3, 4A, 4B, 4C and 5, respectively; 0.00%, 1.64%, 2.87%,18.71% and 82.22% of the total nodules that were categorised as ACR-TIRADS 1, 2, 3, 4 and 5, respectively; 0.85%, 3.27%, 24.27% and 80.96% of the total nodules that were categorised as K-TIRADS 2, 3, 4 and 5, respectively. The correlation between the category of TIRADS and percentile of malignancy was 0.94 in the C-TIRADS, 1.00 in the ACR-TIRADS, and 1.00 in the K-TIRADS, respectively. The highest values of accuracy(AUC) of ROC curves of C-TIRADS 4B, K-TIRADS 5 and ACR-TIRADS 5 were taken as the cut-off values for risk stratification, respectively. The sensitivity, specificity, positive and negative predictive values and AUC by C-TIRADS 4B, K-TIRADS 5 and ACR-TIRADS 5 for malignancy risk stratification of thyroid nodules were 90.83%, 84.23%, 74.88% and 94.66% and 0.88, respectively; 83.58%, 89.82%, 80.95%, 91.36% and 0.87, respectively; and 85.50%, 90.35%, 82.10%, 92.33% and 0.88, respectively (P>0.05 for all). We concluded that the C-TIRADS has excellent performance in the malignancy risk stratification of thyroid nodules by the optimized cut-off value, which is comparable to that in K-TIRADS and ACR-TIRADS.

The Future of Thyroid Nodule Risk Stratification

Clinical evidence supports the association of ultrasound features with benign or malignant thyroid nodules and serves as the basis for sonographic stratification of thyroid nodules, according to an estimated thyroid cancer risk. Contemporary guidelines recommend management strategies according to thyroid cancer risk, thyroid nodule size, and the clinical scenario. Yet, reproducible and accurate thyroid nodule risk stratification requires expertise, time, and understanding of the weight different ultrasound features have on thyroid cancer risk. The application of artificial intelligence to overcome these limitations is promising and has the potential to improve the care of patients with thyroid nodules.

Systematic Review and Meta-Analysis of American College of Radiology TI-RADS Inter-Reader Reliability for Risk Stratification of Thyroid Nodules

Purpose

To investigate the inter-reader agreement of using the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) for risk stratification of thyroid nodules.

Methods

A literature search of Web of Science, PubMed, Cochrane Library, EMBASE, and Google Scholar was performed to identify eligible articles published from inception until October 31, 2021. We included studies reporting inter-reader agreement of different radiologists who applied ACR TI-RADS for the classification of thyroid nodules. Quality assessment of the included studies was performed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool and Guidelines for Reporting Reliability and Agreement Studies. The summary estimates of the inter-reader agreement were pooled with the random-effects model, and multiple subgroup analyses and meta-regression were performed to investigate various clinical settings.

Results

A total of 13 studies comprising 5,238 nodules were included in the current meta-analysis and systematic review. The pooled inter-reader agreement for overall ACR TI-RADS classification was moderate (κ = 0.51, 95% CI 0.42–0.59). Substantial heterogeneity was presented throughout the studies, and meta-regression analyses suggested that the malignant rate was the significant factor. Regarding the ultrasound (US) features, the best inter-reader agreement was composition (κ = 0.58, 95% CI 0.53–0.63), followed by shape (κ = 0.57, 95% CI 0.41–0.72), echogenicity (κ = 0.50, 95% CI 0.40–0.60), echogenic foci (κ = 0.44, 95% CI 0.36–0.53), and margin (κ = 0.34, 95% CI 0.24–0.44).

Conclusions

The ACR TI-RADS demonstrated moderate inter-reader agreement between radiologists for the overall classification. However, the US feature of margin only showed fair inter-reader reliability among different observers.

Diagnostic Accuracy of Five Different Classification Systems for Thyroid Nodules: A Prospective, Comparative Study

OBJECTIVE

To compare the diagnostic performance of five different thyroid ultrasound classification systems, and determine which system is optimal for evaluating thyroid nodules and reducing the unnecessary biopsy rate.

METHODS

In this prospective study, 1,010 nodules referred for biopsy during a 2-year period were classified using five classification systems: the Kwak Thyroid Imaging Reporting and Data System (Kwak TI-RADS), the European TI-RADS (EU TI-RADS, the Korean TI-RADS (K TI-RADS), the American College of Radiology TI-RADS (ACR TI-RADS), and the American Thyroid Association (ATA) classification. After fine needle aspiration biopsy, all classifications were compared for all nodules and also particularly for nodules sized 1-3 cm. Sensitivity, specificity, and interobserver agreement were evaluated for each classification system.

RESULTS

Of the 939 nodules (after exclusion of Bethesda 3 nodules) finally classified according to the surgical histopathology and cytology results, 73 (7.8%) were malignant and 866 nodules were benign (92.2%). The sensitivity was highest (94.5%) for the ACR TI-RADS and lowest for the Kwak TI-RADS (69%). After exclusion of small (<1 cm) and large nodules (>3 cm); while sensitivity was highest for ATA (97.8%), ACR TI-RADS was the second best classification (91.3%). There was substantial agreement among all classification systems except the Kwak TI-RADS (fair agreement).

CONCLUSIONS

The ACR TI-RADS was the most sensitive ultrasound risk stratification system for all nodules, while the Kwak TI-RADS was the most specific, ie, the most capable of excluding benign nodules based on the combined cytological and histopathological results. ATA and ACR-TIRADS were the most sensitive classification systems for nodules 1 to 3 cm in size. The ACR TI-RADS had higher sensitivity than the Bethesda classification system when compared according to the histopathological results.

Consistency of TI-RADS Reporting in Community-Based Imaging Centers vs. a Large Tertiary Hospital

OBJECTIVE

In our country, thyroid nodules are sonographically evaluated in health maintenance organization (HMO) imaging centers, and patients are referred to tertiary hospitals for ultrasound-guided fine needle aspiration (FNA) biopsy when indicated. We evaluated the concordance in Thyroid Imaging Reporting and Data System (TI-RADS) classification reporting between these sites.

METHODS

We conducted a retrospective cohort study reviewing the sonographic features of thyroid nodules evaluated both at the HMO and a large tertiary center between January 2018 and December 2019. The primary outcome was concordance between the TI-RADS classification at both sites. Additional endpoints included correlation of TI-RADS to the Bethesda category following FNA and correlation of TI-RADS with malignancy on final pathology at each site.

RESULTS

The records of 336 patients with 370 nodules were reviewed. The level of concordance was poor (19.8%), with 277 (74.8%) nodules demonstrating higher TI-RADS and 20 (5.4%) lower TI-RADS at the HMO compared to the hospital (p<0.001, weighted Kappa = 0.120). FNA results were available for 236 (63.8%) nodules. The Bethesda category strongly correlated with the hospital TI-RADS (p<0.001), yet not with HMO TI-RADS (p=0.123). In the 57 nodules surgically removed, a strong correlation was identified between malignancy on final pathology and TI-RADS documented at the hospital (p<0.001), yet not at the HMO (p=0.259).

CONCLUSIONS

There is poor agreement between TI-RADS classification on ultrasound performed in the HMO compared to a tertiary hospital. The hospital TI-RADS strongly correlated with Bethesda category and final risk of malignancy unlike the HMO.

Malignancy risk of thyroid nodules: quality assessment of the thyroid ultrasound report

Background

Thyroid nodules are a challenge in clinical practice and thyroid ultrasonography is essential for assessing the risk of malignancy. The use of ultrasound-based malignancy risk classification systems has been recommended by several scientific societies but radiologist’s adherence to these guidelines may vary. The authors aimed to analyze the quality of the information provided by the thyroid ultrasound report, to assess the malignancy risk of thyroid nodules, in Portugal.

Methods

Multicenter and retrospective study, conducted in three of the five Portuguese NUTS2 corresponding to about 88.3% of the mainland population. We included 344 consecutive unselected participants aged ≥ 18 years who underwent thyroid ultrasonography in 2019. The description of six features of the dominant thyroid nodule was analyzed: maximum size, shape, margins, composition, echogenicity and echogenic foci. A utility score, including these six features, was used as an indicator of the report’s quality. A score of 4 was considered as a minimum value.

Results

Maximum diameter was reported for all nodules. Shape, margins, composition, echogenicity and echogenic foci were reported in 8.1%, 25.0%, 76.5%, 53.2% and 20.9%, respectively. Only 21.8% of the nodules had a score ≥ 4. At least one of four suspicious features, including marked hypoechogenicity, microcalcifications, irregular margins and non-oval shape, was identified in 8.7% of the nodules. Cervical lymph nodes’ status was reported in 93% of the exams. The risk category was only reported in 7.8% of the participants.

Conclusion

The adherence of Portuguese radiologists to a standardized reporting model and to an ultrasound-based malignancy risk stratification system is still low and has implications for the correct characterization of the malignancy risk of nodules and the decision to perform fine-needle aspiration biopsy.

Can ultrasensitive thyroglobulin immunoassays avoid the need for ultrasound in thyroid cancer follow-up?

PURPOSE

Differentiated thyroid cancer (DTC) is the most common endocrine neoplasm, with a rising incidence and a long life expectancy. It has recently been suggested that patients with low- and intermediate-risk DTC with a good response to treatment at one year could be followed up using only highly sensitive immunoassays for thyroglobulin (Tg). The aim of this study was to examine the serum Tg levels in a series of DTC patients with histologically proven persistent or recurrent diseases.

METHODS

The study involved 50 consecutive patients being routinely followed up at our center, whose clinical, histological, and biochemical data were retrospectively collected.

RESULTS

The false-negative rate of ultrasensitive serum Tg assay was 14.3% (5/35) overall, and limited to anti-thyroglobulin autoantibodies (TgAb)-negative patients. Among them, only one patient had an excellent response to treatment at one-year follow-up and was diagnosed with a 4 mm recurrence, after more than seven years of periodic ultrasounds. The size of the neck lesion documented in the histological report was slightly larger in patients with detectable as opposed to negative Tg values (P < 0.05).

CONCLUSIONS

Serum highly sensitive Tg is undetectable in a proportion of patients with a proven persistent or recurrent DTC. The reasons behind this phenomenon are still unknown. However, in low/intermediate-risk patients cured at one-year follow-up, highly sensitive Tg without neck US seems an appropriate strategy for patients' management.

A Fusion NLP Model for the Inference of Standardized Thyroid Nodule Malignancy Scores from Radiology Report Text

Radiology reports are a rich resource for advancing deep learning applications for medical images, facilitating the generation of large-scale annotated image databases. Although the ambiguity and subtlety of natural language poses a significant challenge to information extraction from radiology reports. Thyroid Imaging Reporting and Data Systems (TI-RADS) has been proposed as a system to standardize ultrasound imaging reports for thyroid cancer screening and diagnosis, through the implementation of structured templates and a standardized thyroid nodule malignancy risk scoring system; however there remains significant variation in radiologist practice when it comes to diagnostic thyroid ultrasound interpretation and reporting. In this work, we propose a computerized approach using a contextual embedding and fusion strategy for the large-scale inference of TI-RADS final assessment categories from narrative ultrasound (US) reports. The proposed model has achieved high accuracy on an internal data set, and high performance scores on an external validation dataset.

Non-Marked Hypoechogenic Nodules: Multicenter Study on the Thyroid Malignancy Risk Stratification and Accuracy Based on TIRADS Systems Comparison

Background and Objectives: The aim of the study was to evaluate the predictive value of the ultrasound criterion “non-marked hypoechogenicity” for malignancy and to determine whether classification of these nodules as TIRADS 3 could improve the overall accuracy of consequently adjusted M-TIRADS score. Materials and Methods: A total of 767 patients with 795 thyroid nodules were subject to ultrasonography examination and ultrasound-guided fine needle aspiration biopsy. Nodules were classified by Kwak TIRADS and modified (M-TIRADS) categories 4A, 4B, and 5 according to number of suspicious US features (marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, taller-than-wide shape, metastatic lymph nodes). Non-marked hypoechoic nodules were classified as TIRADS 3. Results: Thyroid nodules were classified as TIRADS 2, 3, 4A, 4B, and 5 in 14.5, 57.5, 14.2, 8.1, and 5.7%, respectively. Only histopathologic results (125 nodules underwent surgery) and highly specific cytology results (Bethesda II, VI) were accepted as a standard of reference, forming a sub-cohort of 562/795 nodules (70.7%). Malignancy was found in 7.7%. Overall, M-TIRADS showed sensitivity/specificity of 93.02/81.31%, and for PPV/NPV, these were 29.2/99.29%, respectively (OR—18.62). Irregular margins showed the highest sensitivity and specificity (75.68/93.74%, respectively). In TIRADS 3 category, 37.2% nodules were isoechoic, 6.6% hyperechoic, and 52.2% hypoechoic (there was no difference of malignancy risk in hypoechoic nodules between M-TIRADS and Kwak systems—0.9 vs. 0.8, respectively). Accuracy of M-TIRADS classification in this cohort was 78.26% vs. 48.11% for Kwak. Conclusions: The non-marked hypoechoic nodule pattern correlated with low risk of malignancy; classification of these nodules as TIRADS 3 significantly improved the predictive value and overall accuracy of the proposed M-TIRADS scoring with malignancy risk increase in TIRADS 4 categories by 20%; and no significant alteration of malignancy risk in TIRADS 3 could contribute to reducing overdiagnosis, obviating the need for FNA.

The Significance of Transcapsular Blood Flow for Assessing Moderate to Severe Extrathyroidal Extension: Results of a Two-Center Study

Background

Materials and Methods

Results

Conclusion

Effect of training on resident inter-reader agreement with American College of Radiology Thyroid Imaging Reporting and Data System

BACKGROUND

The American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) was introduced to standardize the ultrasound characterization of thyroid nodules. Studies have shown that ACR-TIRADS reduces unnecessary biopsies and improves consistency of imaging recommendations. Despite its widespread adoption, there are few studies to date assessing the inter-reader agreement amongst radiology trainees with limited ultrasound experience. We hypothesize that in PGY-4 radiology residents with no prior exposure to ACR TI-RADS, a statistically significant improvement in inter-reader reliability can be achieved with a one hour training session.

AIM

To evaluate the inter-reader agreement of radiology residents in using ACR TI-RADS before and after training.

METHODS

A single center retrospective cohort study evaluating 50 thyroid nodules in 40 patients of varying TI-RADS levels was performed. Reference standard TI-RADS scores were established through a consensus panel of three fellowship-trained staff radiologists with between 1 and 14 years of clinical experience each. Three PGY-4 radiology residents (trainees) were selected as blinded readers for this study. Each trainee had between 4 to 5 mo of designated ultrasound training. No trainee had received specialized TI-RADS training prior to this study. Each of the readers independently reviewed the 50 testing cases and assigned a TI-RADS score to each case before and after TI-RADS training performed 6 wk apart. Fleiss kappa was used to measure the pooled inter-reader agreement. The relative diagnostic performance of readers, pre- and post-training, when compared against the reference standard.

RESULTS

There were 33 females and 7 males with a mean age of 56.6 ± 13.6 years. The mean nodule size was 19 ± 14 mm (range from 5 to 63 mm). A statistically significant superior inter-reader agreement was found on the post-training assessment compared to the pre-training assessment for the following variables: 1. “Shape” (k of 0.09 [slight] pre-training vs 0.67 [substantial] post-training, P < 0.001), 2. “Echogenic foci” (k of 0.28 [fair] pre-training vs 0.45 [moderate] post-training, P = 0.004), 3. ‘TI-RADS level’ (k of 0.14 [slight] pre-training vs 0.36 [fair] post-training, P < 0.001) and 4. ‘Recommendations’ (k of 0.36 [fair] pre-training vs 0.50 [moderate] post-training, P = 0.02). No significant differences between the pre- and post-training assessments were found for the variables 'composition', 'echogenicity' and 'margins'. There was a general trend towards improved pooled sensitivity with TI-RADS levels 1 to 4 for the post-training assessment while the pooled specificity was relatively high (76.6%-96.8%) for all TI-RADS level.

CONCLUSION

Statistically significant improvement in inter-reader agreement in the assigning TI-RADS level and recommendations after training is observed. Our study supports the use of dedicated ACR TI-RADS training in radiology residents.

Advanced Ultrasound Techniques for Differentiation of Benign Versus Malignant Thyroid Nodules: A Review

ABSTRACT

Grayscale ultrasound (US) is decisive in stratifying which thyroid nodules benefit from fine-needle aspiration to evaluate for malignancy. Unfortunately, a significant percentage of nodules remain indeterminate.Herein, we review the clinical considerations and diagnostic accuracy of advanced US, Doppler US, contrast-enhanced US, and US elastography techniques in the evaluation of indeterminate nodules.We conclude that these techniques may be used in combination with grayscale US to improve the assessment of lesion vascularity and tissue property.

Interobserver Variability of Ultrasound Features Based on American College of Radiology Thyroid Imaging Reporting and Data System Lexicon in American College of Radiology Thyroid Imaging Reporting and Data System System: A Single-Center Study With Radiologists and Radiology Residents

ABSTRACT

The aim of this study is to evaluate the variability of selecting the ultrasound features used in American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TIRADS) and in assigning the ACR-TIRADS level in a single center among radiologists and radiology residents. The study cohort consisted of 108 thyroid nodules in 102 patients who had definite cytology results after thyroid fine needle aspiration biopsy (Bethesda category II, VI) or surgery. Seven observers including 3 radiologists and 4 radiology residents evaluated the nodules according to 5 ultrasound feature categories. The evaluation process was performed after a joint meeting session, in which the "white papers" of the ACR-TIRADS committee were discussed regarding the thyroid ultrasound reporting lexicon, and final TIRADS system. Variability of ultrasound features and assigning ACR-TIRADS level was measured using Fleiss kappa statistics. Agreement for ultrasound features was "substantial" to "almost perfect" among all observers, with composition (κ = 0.86), macrocalcification (κ = 0.89) and peripheral calcification (κ = 0.92) at the highest level of agreement. The level of agreement for large comet tail artifacts and punctate echogenic foci was "moderate" in residents, whereas in radiologists, that level was "substantial." The agreement for assigning ACR-TIRADS level was moderate in resident as well as in radiologist subgroup. Agreement of thyroid ultrasound features was "substantial to almost perfect" among all observers. Although the level of agreement among resident group decreased to "moderate" level, ACR-TIRADS is a useful system in thyroid nodule management.

Concordance of the ACR TI-RADS

BACKGROUND

Ultrasonography (US) is the method of choice for evaluating thyroid nodules. In 2017, the American College of Radiology (ACR) created a classification system based on US characteristics. For the system to be adopted, it must be reproducible.

OBJECTIVES

To determine the intraobserver and interobserver variability of the ACR TI-RADS.

METHODS

Cross-sectional study; three radiologists with different levels of experience used the ACR TI-RADS to classify 100 nodules on two occasions one month apart, and we calculated the intraobserver and interobserver variability.

RESULTS

Regarding intraobserver variability, the first radiologist had nearly perfect concordance for composition, echogenicity, shape, and margins and substantial concordance for echogenic foci; the second radiologist had nearly perfect concordance for composition, echogenicity, shape, and margins and substantial concordance for echogenic foci, and the third radiologist had nearly perfect concordance for composition, echogenicity, and shape and substantial concordance for margins and echogenic foci. The interobserver concordance was calculated for the two readings; the concordance was substantial except for shape in the first reading and for echogenicity and margins in the second reading, which had moderate concordance.

CONCLUSIONS

The ACR TI-RADS classification system is reproducible.

The impact of the use of the ACR-TIRADS as a screening tool for thyroid nodules in a cancer center

BACKGROUND

The Thyroid Imaging Reporting and Data System (TIRADS) was created to assess risk of thyroid nodules through ultrasound. Plenty classifications methods for thyroid nodules have already been created, but none of them have yet achieved global utilization. This study analyzed the performance of the American College of Radiology (ACR) TIRADS, its reproducibility and the impact of its utilization as a screening method in a large Cancer Center cohort.

METHODS

Thyroid nodules which underwent fine-needle aspiration (FNA) in a 1-year period were selected, with their ultrasound images retrospectively classified according to the ACR TI-RADS. Cytological evaluation of the nodules and final histology (whenever available) was used to assess risk of neoplasm (RON) and risk of malignancy (ROM) associated to each ACR-TIRADS category. Further analyses were also carried out according to recommendation or not of FNA by the ACR-TIRADS and nodule size. Inter-observer agreement for the system was also assessed.

RESULTS

A total of 1112 thyroid nodules were included. RON for each category according to final cytological diagnosis was 0% for TR1 and TR2, 2.1% for TR3; 15.6% for TR4 and 68.9% for TR5. No significant difference was observed between the RON of the categories for cases above or below 1.0 cm. Nodules that met the criteria for FNA had 3 times greater chance of a positive outcome. Substantial agreement (kappa 0.77) was seen between two different observers.

CONCLUSIONS

ACR TI-RADS scoring system has demonstrated to be an accurate method to stratify thyroid nodules in a Cancer Center, with a high reproducibility.

Evaluation of thyroid nodules by shear wave elastography: a review of current knowledge

PURPOSE

Shear wave elastography (SWE), as a tool for diagnosing thyroid malignancy, has gathered considerable attention during the past decade. Diverging results exist regarding the diagnostic performance of thyroid SWE.

METHODS

A comprehensive literature review of thyroid SWE was conducted using the terms "Thyroid" and "shear wave elastography" in PubMed.

RESULTS

The majority of studies found SWE promising for differentiating malignant and benign thyroid nodules on a group level, whereas results are less convincing on the individual level due to huge overlap in elasticity indices. Further, there is lack of consensus on the optimum outcome reflecting nodule elasticity and the cut-off point predicting thyroid malignancy. While heterogeneity between studies hinders a clinically meaningful meta-analysis, the results are discussed in a clinical perspective with regard to applicability in clinical practice as well as methodological advantages and pitfalls of this technology.

CONCLUSION

Technological as well as biological hindrances seem to exist for SWE to be clinically reliable in assessing benign and malignant thyroid nodules. Structural heterogeneity of thyroid nodules in combination with operator-dependent factors such as pre-compression and selection of scanning plane are likely explanations for these findings. Standardization and consensus on the SWE acquisition process applied in future studies are needed for SWE to be considered a clinically reliable diagnostic tool for detection of thyroid cancer.

Differences in the ultrasonographic appearance of thyroid nodules after radiofrequency ablation

CONTEXT

Radiofrequency ablation (RFA) is a well-tolerated approach to treating benign thyroid nodules (TNs), but no index can predict its success. Other than size decrease, little is known about TN appearance on ultrasonography (US) after RFA.

OBJECTIVE

This study aimed to (a) assess the effectiveness of single-session RFA treatment, (b) determine whether pre-ablation US characteristics correlate with its effectiveness, and (c) demonstrate TN characteristics on baseline and follow-up US.

DESIGN

Retrospective cohort study among the patients who underwent single-session RFA for the treatment of benign TNs at a referral medical center between January 2018 and April 2019.

PATIENTS

A total of 116 patients (137 nodules) were included in the study.

MEASUREMENTS

Characteristics were quantified using commercial software. TNs were classified into 2015 American Thyroid Association (ATA) sonographic patterns and American College of Radiology Thyroid Imaging Reporting and Data System (ACR-TI-RADS) categories.

RESULTS

The average volume reduction ratio (VRR) was 74.51% in 1 year (95% confidence interval, 70.63%-78.39%). The only pre-ablation US feature significantly different between nodules with VRR <50% and VRR >50% was the cyst composition (0.05 vs. 0.02, p-value = .02). The VRR and margin change in the first 3 months after ablation were found to be leading indicators significantly correlated to the VRR in 6 months with correlation coefficients (r) = .72 and -.28 (p-value < .0001 and = .0008) and VRR in 1 year with r = .65 and -.17 (p-value < .0001 and = .046), respectively. After RFA, more TNs became ATA high suspicion (2.9% vs. 19.7%, p < .0001) and more appeared to be the non-ATA patterns (12.4% vs. 23.4%, p < .0001). Also, a greater number of post-RFA TNs were classified as ACR-TI-RADS categories 4 and 5 (40.1% vs. 70.1%, p < .0001).

CONCLUSIONS

Radiofrequency ablation therapy is effective for treating TNs. Pre-ablation cyst components, 3-month post-ablation volume reduction and margin change of TNs were related to the 6-month and 1-year response. Clinicians should consider that TNs would appear peculiar on US after RFA, mistakenly suggesting malignant potential.