Sonographic features of thyroid follicular carcinoma in comparison with thyroid follicular adenoma

Malignancy Risk of Follicular Neoplasm (Bethesda IV) With Variable Cutoffs of Tumor Size: A Systemic Review and Meta-Analysis

CONTEXT

The decision on diagnostic lobectomy for follicular neoplasms (FN) is challenging.

OBJECTIVE

This meta-analysis investigates whether an appropriate size cutoff exists for recommending surgery for thyroid nodules diagnosed as FN by fine needle aspiration.

METHODS

The Ovid-Medline, EMBASE, Cochrane, and KoreaMed databases were searched for studies reporting the malignancy rate of FN/suspicious for FN (FN/SFN) according to tumor size, using search terms "fine needle aspiration," "follicular neoplasm," "lobectomy," "surgery," and "thyroidectomy."

RESULTS

Fourteen observational studies comprising 2016 FN/SFN nodules with postsurgical pathologic reports were included, and 2 studies included malignancy rates with various tumor sizes. The pooled malignancy risk of FN/SFN nodules according to size was: odds ratio (OR) 2.29 (95% CI, 1.68-3.11) with cutoff of 4 cm (9 studies), OR 2.39 (95% CI, 1.45-3.95) with cutoff of 3 cm (3 studies), and OR 1.81 (95% CI, 0.94-3.50) with cutoff of 2 cm (5 studies). However, tumors ≥2 cm also showed a higher risk (OR 2.43; 95% CI, 1.54-3.82) based on the leave-one-out meta-analysis after removal of 1 influence study. When each cutoff size was evaluated by summary receiver operating characteristic (sROC) curves, the cutoff of 4 cm showed the highest summary area under the curve (sAUC, 0.645) compared to other cutoffs (sAUC, 0.58 with 2 cm, and 0.62 with 3 cm), although there was no significant difference.

CONCLUSION

Although the risk of malignancy increases with increasing tumor size, the risk remains significant at all tumor sizes and no cutoff limit can be recommended as a decision-making parameter for diagnostic surgery in Bethesda IV thyroid nodules.

Risk Factors and Prediction Models for Postoperative Pathologically Malignant TI-RADS 3 Thyroid Nodules

Objective: Our goal was to detect the risk factors for malignant TI-RADS 3 nodule and to construct a predictive model. Patients and Methods: All 199 patients with TI-RADS 3 nodule underwent first-time thyroid surgery from January 2018 to September 2021. Univariate analysis identified potential risk covariates and then incorporated these covariates into multivariate logistic regression to determine the risk factors for malignant TI-RADS 3 nodule and construct a predictive model. Results: Binary logistic regression analysis showed that age [odds ratio (OR): 0.926, 95% CI: 0.865-0.992; P = .029), low level of parathyroid hormone (OR: 0.940, 95% CI: 0.890-0.993; P = .027), and preoperative ultrasound features of TI-RADS 3 nodule, such as echogenicity (OR: 8.496, 95% CI: 1.377-52.406; P = .021), echogenic foci (OR: 8.611, 95% CI: 1.484-49.957; P = .016), and maximum tumor diameter (OR: 0.188, 95% CI: 0.040-0.888; P = .035) were independent risk factors for malignant TI-RADS 3 nodule. Based on these independent risk factors, a logistic regression model was established. The area under curve of the prediction model for TI-RADS 3 thyroid cancer was 0.921 (95% CI: 0.856-0.986, P < 0.001). The maximum Youden index was 0.698. The cut-off value, sensitivity, and specificity were 0.074, 84.6%, and 85.2%, respectively. Conclusion: Young age, iso/hypo/very hypo echo, echogenic foci, nodule diameter <30 mm, and low level of PTH are independent risk factors for TI-RADS 3 thyroid carcinomas. This prediction model has a high sensitivity and specificity. A prediction model value of more than 0.074 implies that the TI-RADS 3 nodule has undergone a malignant transformation, and fine needle aspiration is recommended in these cases.

Ultrasonographic predictors of thyroid cancer in Bethesda III and IV thyroid nodules

Background

Bethesda III and IV thyroid nodules continue to be difficult to manage. Although molecular testing may assist in decision-making, it is expensive, not widely available, and not without pitfalls. The objective of this study is to assess whether certain thyroid ultrasonographic features may predict the risk of thyroid cancer in patients with Bethesda III and IV thyroid nodules and be used as additional decision-making tools to complement cytopathological results in deciding on diagnostic thyroidectomy.

Methods

We retrospectively evaluated the ultrasonographic features of Bethesda categories III and IV thyroid nodules in patients who underwent subsequent thyroidectomy. We used the final histopathological examination of the surgical specimens as the gold-standard test and analyzed individual preoperative ultrasonographic features as predictors of malignancy.

Results

Of the 278 patients who were diagnosed with Bethesda III and IV thyroid nodules on fine needle aspiration cytology (FNAC), 111 (39.9%) had thyroid cancer, and 167 (59.9%) exhibited benign nodules. The malignancy rate was higher in patients with Bethesda IV nodules (28/50, 56%) than those with Bethesda III nodules (83/228, 36.4%; p=0.016). In univariate analysis, hypoechogenicity (55.6% in malignant vs. 35.3% in benign, p=0.006) and calcifications (54.5 in malignant vs. 35.4% in benign, p=0.008) were significantly different between the benign and malignant pathology groups, whereas the size of the dominant nodule, number of nodules, irregular borders, taller-than-wide shape, and the presence of lymph nodes were comparable between the two groups. These two ultrasonographic features (hypoechogenicity and calcifications) remained significantly associated with the risk of malignancy in multivariate logistic regression analysis (for hypoechogenicity, p=0.014, odds ratio: 2.1, 95% CI:1.0-3.7 and for calcifications, p=0.019, odds ratio: 1.98, 95% CI:1.12-3.50). The sensitivity, specificity, positive and negative predictive values, and accuracy were 31.5%, 83%, 55.6%,64.7%, and 62.6%, for hypoechogenicity, respectively and 32.4%, 82%, 54.5%, 67.8%, and 62%, for calcification, respectively.

Conclusions

Hypoechogenicity and calcifications in Bethesda III and IV thyroid nodules are strong predictors of thyroid cancer and associated with a two-fold increased risk of malignancy.

Association of Ultrasonography Features of Follicular Thyroid Carcinoma With Tumor Invasiveness and Prognosis Based on WHO Classification and TERT Promoter Mutation

OBJECTIVE

To investigate the association of ultrasound (US) features of follicular thyroid carcinoma (FTC) with tumor invasiveness and prognosis based on the World Health Organization (WHO) classification and telomerase reverse transcriptase (TERT) promoter mutations.

MATERIALS AND METHODS

This retrospective study included 54 surgically confirmed FTC patients with US images and TERT promoter mutations (41 females and 13 males; median age [interquartile range], 40 years [30-51 years]). The WHO classification consisted of minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTCs. Alternative classifications included Group 1 (MI-FTC and EA-FTC with wild type TERT), Group 2 (WI-FTC with wild type TERT), and Group 3 (EA-FTC and WI-FTC with mutant TERT). Each nodule was categorized according to the US patterns of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and American College of Radiology-TIRADS (ACR-TIRADS). The Jonckheere-Terpstra and Cochran-Armitage tests were used for statistical analysis.

RESULTS

Among 54 patients, 29 (53.7%) had MI-FTC, 16 (29.6%) had EA-FTC, and nine (16.7%) had WI-FTC. In both the classifications, lobulation, irregular margins, and final assessment categories showed significant differences (all Ps ≤ 0.04). Furthermore, the incidences of lobulation, irregular margin, and high suspicion category tended to increase with increasing tumor invasiveness and worse prognosis (all Ps for trend ≤ 0.006). In the WHO groups, hypoechogenicity differed significantly among the groups (P = 0.01) and tended to increase in proportion as tumor invasiveness increased (P for trend = 0.02). In the alternative group, punctate echogenic foci were associated with prognosis (P = 0.03, P for trend = 0.03).

CONCLUSION

Increasing tumor invasiveness and worsening prognosis in FTC based on the WHO classification and TERT promoter mutation results were positively correlated with US features that indicate malignant probability according to both K-TIRADS and ACR-TIRADS.

Semi-supervised graph convolutional networks for the domain adaptive recognition of thyroid nodules in cross-device ultrasound images

BACKGROUND

Ultrasound plays a critical role in the early screening and diagnosis of cancers. Although deep neural networks have been widely investigated in the computer-aided diagnosis (CAD) of different medical images, diverse ultrasound devices, and image modalities pose challenges for clinical applications, especially in the recognition of thyroid nodules having various shapes and sizes. More generalized and extensible methods need to be developed for the cross-devices recognition of thyroid nodules.

PURPOSE

In this work, a semi-supervised graph convolutional deep learning framework is proposed for the domain adaptative recognition of thyroid nodules across several ultrasound devices. A deep classification network, trained on a source domain with a specific device, can be transferred to recognize thyroid nodules on the target domain with other devices, using only few manual annotated ultrasound images.

METHODS

This study presents a semi-supervised graph-convolutional-network-based domain adaptation framework, namely Semi-GCNs-DA. Based on the ResNet backbone, it is extended in three aspects for domain adaptation, that is, graph convolutional networks (GCNs) for the connection construction between source and target domains, semi-supervised GCNs for accurate target domain recognition, and pseudo labels for unlabeled target domains. Data were collected from 1498 patients comprising 12 108 images with or without thyroid nodules under three different ultrasound devices. Accuracy, Sensitivity and Specificity were used for the performance evaluation.

RESULTS

The proposed method was validated on six groups of data for a single source domain adaptation task, the mean Accuracy was 0.9719 ± 0.0023, 0.9928 ± 0.0022, 0.9353 ± 0.0105, 0.8727 ± 0.0021, 0.7596 ± 0.0045, 0.8482 ± 0.0092, which achieved better performance in comparison with the state-of-the-art. The proposed method was also validated on three groups of multiple source domain adaptation tasks. In particular, when using X60 and HS50 as the source domain data, and H60 as the target domain, it can achieve the Accuracy of 0.8829 ± 0.0079, Sensitivity of 0.9757 ± 0.0001, and Specificity of 0.7894 ± 0.0164. Ablation experiments also demonstrated the effectiveness of the proposed modules.

CONCLUSION

The developed Semi-GCNs-DA framework can effectively recognize thyroid nodules on different ultrasound devices. The developed semi-supervised GCNs can be further extended to the domain adaptation problems for other modalities of medical images.

US Risk Stratification System for Follicular Thyroid Neoplasms

Background Preoperative assessment of follicular thyroid neoplasms is challenging using the current US risk stratification systems (RSSs) that are applicable to papillary thyroid neoplasms. Purpose To develop a US feature-based RSS for differentiating between follicular thyroid adenoma (FTA) and follicular thyroid carcinoma (FTC) in biopsy-proven follicular neoplasm and compare it with existing RSSs. Materials and Methods This retrospective multicenter study included consecutive adult patients who underwent conventional US and received a final diagnosis of follicular thyroid neoplasm from seven centers between January 2018 and December 2022. US images from a pretraining data set were used to improve readers' understanding of the US characteristics of the FTC and FTA. Univariable and multivariable logistic regression analyses were used to assess the association of qualitative US features with FTC in a training data set. Features with P < .05 were used to construct a prediction model (follicular tumor model, referred to as F model) and RSS for follicular neoplasms using the Thyroid Imaging Reporting and Data System (TI-RADS). Area under the receiver operating characteristic curve (AUC) was compared between follicular TI-RADS (hereafter, F-TI-RADS) and existing RSS (American College of Radiology [ACR] TI-RADS, Korean Society of Thyroid Radiology and Korean Society of Radiology TI-RADS [hereafter, referred to as K-TI-RADS], and Chinese TI-RADS [hereafter, referred to as C-TI-RADS]) in a validation data set. Results The pretraining, training, and validation data sets included 30 (mean age, 47.6 years ± 16.0 [SD]; 16 male patients; FTCs, 30 of 60 [50.0%]), 703 (mean age, 47.9 years ± 14.5; 530 female patients; FTCs, 188 of 703 [26.7%]), and 155 (mean age, 49.9 years ± 13.3 [SD]; 155 female patients; FTCs, 43 of 155 [27.7%]) patients. In the validation data set, the F-TI-RADS showed improved performance for differentiating between FTA and FTC (AUC, 0.81; 95% CI: 0.71, 0.86) compared with ACR TI-RADS (AUC, 0.74; 95% CI: 0.66, 0.80; P = .02), K-TI-RADS (AUC, 0.69; 95% CI: 0.61, 0.76; P = .002), and C-TI-RADS (AUC, 0.68; 95% CI: 0.60, 0.75; P = .002). Conclusion F-TI-RADS outperformed existing RSSs for differentiating between FTC and FTA. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Baumgarten in this issue.

Value of CEUS features in diagnosing thyroid nodules with halo sign on B-mode ultrasound

BACKGROUND

The results of halo sign in the differential diagnosis of thyroid nodules were conflicting, and the value of contrast-enhanced ultrasound (CEUS) in characterization of thyroid nodules with halo has not been fully evaluated. This study was therefore designed to investigate the value of contrast-enhanced ultrasound features in the differential diagnosis of thyroid nodules with halo sign on B-mode ultrasound.

MATERIAL AND METHODS

Seventy-four consecutive thyroid nodules with halo sign on B-mode ultrasound were pathologically confirmed by surgery or fine needle aspiration, including 43 benign and 31 malignant lesions. All these lesions underwent pre-operative CEUS examination. The CEUS features, including enhanced time, enhanced intensity and homogeneity, and presence of enhancing ring, were compared between benign and malignant ones.

RESULTS

Enhanced intensity was significant different between benign and malignant lesions with halo. Hypo-enhancement was more frequently detected in malignant nodules than that in benign ones, compared with iso-enhancement and hyper-enhancement (p = 0.013, and = 0.014, respectively). Detection rate of high-enhancing ring was significantly higher in benign nodules than that in malignant group (p = 0.001). While in nodules > 10 mm, only high-enhancing ring was the distinguishing feature between benign and malignant nodules.

CONCLUSIONS

Enhanced intensity and high-enhancing ring may be helpful in the differential diagnosis of thyroid nodules with halo sign on B-mode ultrasound.

ACR TI-RADS classification combined with number of nodules, halo features optimizes diagnosis and prediction of follicular thyroid cancer

OBJECTIVES

To investigate the application value of The American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) category combined with other ultrasound features of nodules in distinguishing follicular thyroid carcinoma (FTC) from thyroid follicular adenoma (FTA).

METHODS

We collected and retrospectively analyzed clinical and ultrasound data for 118 and 459 patients with FTCs and FTAs, respectively, at our hospital. Next, we used ACR TI-RADS classification combined with other ultrasound features of nodules to distinguish FTC from FTA. Multivariate Logistic regression was used to screen independent risk factors for FTC, which were subsequently used to construct a nomogram for predicting FTC.

RESULTS

ACR TI-RADS categories 4 and 5, unilateral multiple nodules, and halo thickness≥2 mm were independent risk factors for FTC. ACR TI-RADS category combined with number of nodules, halo features of the nodule was a significantly better prediction model for FTC diagnosis (AUC = 0.869) than that of ACR TI-RADS classification alone (AUC = 0.756).

CONCLUTIONS

Clinicians need to pay attention to the halo of nodules when distinguishing FTA from FTC. Notably, ACR TI-RADS combined with other nodule ultrasound features has superior predictive performance in diagnosis of FTC compared to ACR TI-RADS classification alone, thus can provide an important reference value for preoperative diagnosis of FTC.

Differentiate Thyroid Follicular Adenoma from Carcinoma with Combined Ultrasound Radiomics Features and Clinical Ultrasound Features

Noninvasive differentiating thyroid follicular adenoma from carcinoma preoperatively is of great clinical value to decrease the risks resulted from excessive surgery for patients with follicular neoplasm. The purpose of this study is to investigate the accuracy of ultrasound radiomics features integrating with ultrasound features in the differentiation between thyroid follicular carcinoma and adenoma. A total of 129 patients diagnosed as thyroid follicular neoplasm with pathologically confirmed follicular adenoma and carcinoma were enrolled and analyzed retrospectively. Radiomics features were extracted from preoperative ultrasound images with manually contoured targets. Ultrasound features and clinical parameters were also obtained from electronic medical records. Radiomics signature, combined model integrating radiomics features, ultrasound features, and clinical parameters were constructed and validated to differentiate the follicular carcinoma from adenoma. A total of 23 optimal features were selected from 449 extracted radiomics features. Clinical and ultrasound parameters of sex (p = 0.003), interior structure (p = 0.035), edge (p = 0.02), platelets (p = 0.007), and creatinine (p = 0.001) were associated with the differentiation between benign and malignant follicular neoplasm. The values of area under curves (AUCs) of the radiomics signature, clinical model, and combined model were 0.772 (95% CI: 0.707-0.838), 0.792 (95% CI: 0.715-0.869), and 0.861 (95% CI: 0.775-0.909), respectively. A final corrected AUC of 0.844 was achieved for the combined model after internal validation. Radiomics features from ultrasound images combined with ultrasound features and clinical factors are feasible to differentiate thyroid follicular carcinoma from adenoma noninvasive before operation to decrease the unnecessary of diagnostic thyroidectomy for patients with benign follicular adenoma.

Ultrasonographic and cytologic assessments of follicular neoplasms of the thyroid: Predictive features differentiating follicular carcinoma from follicular adenoma

Background

The preoperative diagnosis of follicular neoplasm of the thyroid is challenging due to difficulties in the assessment of capsular invasion. This study aimed to identify ultrasonographic (US) and cytopathologic features that are characteristic of follicular adenoma and carcinoma to aid in their differential diagnosis.

Methods

A total of 98 surgically resected nodules diagnosed as follicular neoplasms between 2011 and 2012 were analyzed. US findings were reviewed according to the Korean Thyroid Imaging Reporting and Data System (K-TIRADS). Six cytologic features (high cellularity, abundant microfollicles, cell crowding/nuclear overlapping, isolated cells, homogeneous nuclei, abundant colloid) were reviewed quantitatively. The radiologic findings and quantification of cytologic features were correlated with final diagnoses.

Results

In total, 70 (71.4%) and 28 (28.6%) of the nodules were follicular adenomas and follicular carcinomas, respectively. US findings of a heterogeneous echogenicity, speculated/ill-defined margin, and presence of calcifications were significantly associated with follicular carcinoma (p<0.05). Calcifications had a predilection for pericapsular areas than for stromal areas in follicular carcinomas, whereas their location was more varied in follicular adenomas. No cytologic feature was significantly different between follicular adenomas and carcinomas.

Conclusion

Distinct from follicular adenomas, follicular carcinomas are characterized by heterogeneous echogenicity, speculated/ill-defined margin, and presence of calcifications on US. Thus, US findings can be helpful to differentiate between these two follicular neoplasms.

Reconceptualize tall-cell variant papillary thyroid microcarcinoma: From a "sonographic histology" perspective

OBJECTIVE

This study aimed to examine the relationship between sonographic features and histological manifestations in the tall-cell variant of papillary thyroid microcarcinoma (TCV-PTMC), thus proposing the concept of "sonographic histology" and examine its value in the clinical management of the aggressive tall-cell variant.

METHODS

This study retrospectively included 104 participants who were admitted to Peking University Third Hospital from 2015 to 2022 and were histopathologically confirmed as having TCV-PTMC or classical PTMC. We mainly compared the general characteristics, sonographic characteristics, and pathological specimens between the two cohorts.

RESULTS

Hypoechoic nodules with a localized central isoechoic lesion and hypoechoic halo around nodules were most often observed in TCV-PTMC, which correlated with circumferentially distributed tumor epithelium and densely distributed tumor stroma histopathologically. Additionally, TCV-PTMC showed nodules with a more regular margin and less microcalcification than classical PTMC, which led to an underestimation of the risk of TCV-PTMC.

CONCLUSION

The good association between the ultrasound echo pattern and tissue cell arrangement was defined as sonographic histology in this study and can be applied in the preoperative identification of TCV-PTMC. This concept may provide novel insight for the identification of special subtypes of thyroid tumors and may modify pitfalls of the Thyroid Imaging Reporting and Data System in aggressive variants of microcarcinoma.

Logistic regression analysis of contrast-enhanced ultrasound and conventional ultrasound of follicular thyroid carcinoma and follicular adenoma

Background

Follicular thyroid carcinoma (FTC) is prone to recurrence and hematogenous metastasis, preoperative accurate diagnosis is still needed to help clinicians select the best surgical methods to improve the prognosis of patients. The aim of this study was to find specific conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) characteristics of FTC and to explore their diagnostic value in the differential diagnosis between FTC and follicular adenoma (FA).

Methods

This retrospective study included 258 thyroid follicular neoplasms (172 FAs and 86 FTCs) in 244 consecutive patients who underwent preoperative conventional US, and 72 of them underwent both conventional US and CEUS. Sonograms were reviewed in consensus by two experienced radiologists for various conventional US and CEUS features. Multivariate logistic regression analysis was performed to determine independent risk factors for FTC.

Results

Independent risk factors of conventional US for FTC were heterogenicity (OR =7.477, 95% CI: 2.848-19.629), unevenly thick halo (OR =5.643, 95% CI: 3.234-9.848) and calcifications (OR =1.748, 95% CI: 1.098-2.783). While independent risk factors determined with the combination of CEUS and conventional US were unevenly thick halo (OR =5.770, 95% CI: 1.310-25.409) and absent or irregular rim enhancement (OR =27.000, 95% CI: 2.445-298.178). The area under the receiver operating characteristic curve of the final two logistic regression models was 0.835 and 0.838.

Conclusions

Conventional US is an efficient diagnostic tool in the differential diagnosis of FTC and FA to help clinicians in making appropriate decisions while CEUS failed to provide additional diagnostic value in the study, thus the value of CEUS remains to be verified by further studies with larger sample sizes.

2021 Korean Thyroid Imaging Reporting and Data System and Imaging-Based Management of Thyroid Nodules: Korean Society of Thyroid Radiology Consensus Statement and Recommendations

Incidental thyroid nodules are commonly detected on ultrasonography (US). This has contributed to the rapidly rising incidence of low-risk papillary thyroid carcinoma over the last 20 years. The appropriate diagnosis and management of these patients is based on the risk factors related to the patients as well as the thyroid nodules. The Korean Society of Thyroid Radiology (KSThR) published consensus recommendations for US-based management of thyroid nodules in 2011 and revised them in 2016. These guidelines have been used as the standard guidelines in Korea. However, recent advances in the diagnosis and management of thyroid nodules have necessitated the revision of the original recommendations. The task force of the KSThR has revised the Korean Thyroid Imaging Reporting and Data System and recommendations for US lexicon, biopsy criteria, US criteria of extrathyroidal extension, optimal thyroid computed tomography protocol, and US follow-up of thyroid nodules before and after biopsy. The biopsy criteria were revised to reduce unnecessary biopsies for benign nodules while maintaining an appropriate sensitivity for the detection of malignant tumors in small (1-2 cm) thyroid nodules. The goal of these recommendations is to provide the optimal scientific evidence and expert opinion consensus regarding US-based diagnosis and management of thyroid nodules.

Development and Validation of an Ultrasonic Diagnostic Model for Differentiating Follicular Thyroid Carcinoma from Follicular Adenoma

Background

High-resolution ultrasound is the first choice for the diagnosis of thyroid nodules, but it is still difficult to distinguish between follicular thyroid carcinoma (FTC) and follicular adenoma (FA). Our research aimed to develop and validate an ultrasonic diagnostic model for differentiating FTC from FA.

Methods

This study retrospectively analyzed 196 patients who were diagnosed as FTC (n=83) and FA (n=113). LASSO regression analysis was used to screen clinical and ultrasonic features. Multivariate logistic regression analysis was used to establish the ultrasonic diagnostic model of FTC. Nomogram was used for the visualization of diagnostic models. C-index, ROC, and calibration curves analysis were used to evaluate the accuracy of the diagnostic model. Decision curve analysis (DCA) was used to evaluate the net benefits of the ultrasonic diagnostic model for FTC diagnosis under different threshold probabilities. The bootstrap method was used to verify the ultrasonic diagnostic model.

Results

After Lasso regression analysis, 10 clinical and ultrasonic features were used to construct the ultrasonic diagnostic model of FTC. The C-index and AUC of the model were 0.868 and 0.860, respectively. DCA showed that the ultrasonic model had good clinical application value. The C-index in the validation group was 0.818, which was close to the C-index in the model.

Conclusion

Ultrasonic diagnostic model constructed with 10 clinical and ultrasonic features can better distinguish FTC from FA.

The Value of Sonography in Distinguishing Follicular Thyroid Carcinoma from Adenoma

Purpose

Differentiation between follicular thyroid carcinomas (FTCs) and follicular thyroid adenomas (FTAs) is difficult and the sonographic features of FTC are not yet fully established. The purpose of this study is to explore the sonographic features of FTC and the value of sonography in differentiating FTCs from FTAs.

Patients and Methods

A total of 28 pathologically proven FTCs and 53 FTAs in 78 patients who were performed thyroid surgery were included in this retrospective study. The sonographic features of each tumor including an interrupted halo, satellite nodule(s) with or without halo ring, local irregularity of margin and cluster of grapes sign were evaluated. A mode image of FTC halo was built up in our study. The frequencies of the sonographic features were compared by chi-square test or Fisher exact test between FTCs and FTAs. The relative risk of malignancy was assessed by logistic regression analysis.

Results

Logistic regression analysis showed that a thick, irregular and/or interrupted halo with or without satellite nodule(s), hypoechoic or marked hypoechoic echogenicity, a predominantly solid pattern, cluster of grapes sign, micro-or macro-calcifications, rim calcifications correlated with significant increases in relative risk for FTCs (odds ratio 11.48 (1.37-96.56), 6.74 (1.05-43.30), 17.51 (1.78-172.53), 9.55 (1.44-63.46), 9.36 (1.25-70.15) and 17.45 (1.04-292.65), respectively, p<0.05). Two new sonographic features, an interrupted halo and satellite nodule(s) with or without halo ring, can only be found in FTCs.

Conclusion

An interrupted halo and satellite nodule(s) with or without halo ring are specific sonographic features for FTCs. Sonography could play a role in differentiating follicular thyroid carcinoma from adenoma.

Sonographic Features Differentiating Follicular Thyroid Cancer from Follicular Adenoma-A Meta-Analysis

Simple Summary

The risk of thyroid malignancy assessment may include certain ultrasound features. The analysis is lacking for the differentiation of follicular thyroid adenomas and cancers (FTAs and FTCs). Our meta-analysis aimed to identify sonographic features suggesting malignancy in the case of follicular lesions, potentially differentiating FTA and FTC. Based on twenty studies describing sonographic features of 10,215 nodules, we found that the most crucial feature associated with an increased risk of FTC were tumor protrusion (odds ratios—OR = 10.19), microcalcifications or mixed type of calcifications: 6.09, irregular margins: 5.11, marked hypoechogenicity: 4.59, and irregular shape: 3.6.

Abstract

Certain ultrasound features are associated with an increased risk of thyroid malignancy. However, they were studied mainly in papillary thyroid cancers (PTCs); these results cannot be simply extrapolated for the differentiation of follicular thyroid adenomas and cancers (FTAs and FTCs). The aim of our study was to perform a meta-analysis to identify sonographic features suggesting malignancy in the case of follicular lesions, potentially differentiating FTA and FTC. We searched thirteen databases from January 2006 to December 2020 to find all relevant, full-text journal articles written in English. Analyses assessed the accuracy of malignancy detection in case of follicular lesions, potentially differentiating FTA and FTC included the odds ratio (OR), sensitivity, specificity, positive and negative predictive values. A random-effects model was used to summarize collected data. Twenty studies describing sonographic features of 10,215 nodules met the inclusion criteria. The highest overall ORs to increase the risk of malignancy were calculated for tumor protrusion (OR = 10.19; 95% confidence interval: 2.62–39.71), microcalcifications or mixed type of calcifications (coexisting micro and macrocalcifications): 6.09 (3.22–11.50), irregular margins: 5.11 (2.90–8.99), marked hypoechogenicity: 4.59 (3.23–6.54), and irregular shape: 3.6 (1.19–10.92). The most crucial feature associated with an increased risk of FTC is capsule protrusion, followed by the presence of calcifications, irrespectively of their type.

EU-TIRADS-Based Omission of Fine-Needle Aspiration and Cytology from Thyroid Nodules Overlooks a Substantial Number of Follicular Thyroid Cancers

BACKGROUND

The classification of nodules by Thyroid Imaging Reporting and Data Systems (TIRADS) is important in guiding management. Whether sensitivity in identifying thyroid cancers varies with thyroid cancer phenotype remains unclarified.

METHODS

The ultrasound (US) characteristics of nodules of 26,908 nodular goiter patients were recorded. Fine-needle aspiration cytology (FNA) was performed in all nodules >1 cm irrespective of US findings (n = 25,025) and in nodules between 5 mm and 10 mm with suspicious US characteristics (n = 1,883). Of the 3281 operated cases, 221, 30, and 23 were papillary (PTC), follicular (FTC), and medullary (MTC) cancers, respectively. The US-based indication of FNA, as defined by EU-TIRADS scores, combined with lesion size, was calculated. This study design is unique in avoiding the common selection bias when TIRADS' sensitivity is tested in a cohort selected for FNA and surgery based on the same US characteristics on which TIRADS is based.

RESULTS

The EU-TIRADS score influences decision of FNA in the 10-20 mm range. In such nodules (n = 118), the number of suspicious features (marked hypoechogenicity, microcalcifications, irregular shape, and irregular border) per lesion was lower in FTC (0.7 ± 0.6) than in PTC (1.7 ± 1.0) or MTC (1.8 ± 0.7; p < 0.02), resulting in EU-TIRADS scores of 4.1 ± 0.6, 4.8 ± 0.3, and 4.9 ± 0.2, respectively (p < 0.01). The EU-TIRADS-based FNA indication rate was lower in FTC (55.5%) compared to PTC (85.0%) and MTC (88.9%) (p=0.02).

CONCLUSIONS

EU-TIRADS-defined suspicious US features are less common in FTC than in PTC and MTC. Therefore, a substantial number of FTCs in the 10-20 mm range escape surgery.

2020 Chinese guidelines for ultrasound malignancy risk stratification of thyroid nodules: the C-TIRADS

Thyroid nodules are very common all over the world, and China is no exception. Ultrasound plays an important role in determining the risk stratification of thyroid nodules, which is critical for clinical management of thyroid nodules. For the past few years, many versions of TIRADS (Thyroid Imaging Reporting and Data System) have been put forward by several institutions with the aim to identify whether nodules require fine-needle biopsy or ultrasound follow-up. However, no version of TIRADS has been widely adopted worldwide till date. In China, as many as ten versions of TIRADS have been used in different hospitals nationwide, causing a lot of confusion. With the support of the Superficial Organ and Vascular Ultrasound Group of the Society of Ultrasound in Medicine of the Chinese Medical Association, the Chinese-TIRADS that is in line with China's national conditions and medical status was established based on literature review, expert consensus, and multicenter data provided by the Chinese Artificial Intelligence Alliance for Thyroid and Breast Ultrasound.

Conventional ultrasound characteristics, TI-RADS category and shear wave speed measurement between follicular adenoma and follicular thyroid carcinoma

The purpose of the study was to explore the differences of conventional ultrasound characteristics, thyroid imaging reporting and data system (TI-RADS) category and shear wave speed (SWS) measurement between follicular adenoma (FA) and follicular thyroid carcinoma (FTC). Twenty-eight FTCs and 67 FAs proven by surgery were retrospectively included for analysis. Conventional ultrasound and point-shear wave elastography (p-SWE) were performed in all of the included patients. The ultrasound features, American Thyroid Association (ATA) TI-RADS category and American College of Radiology (ACR) TI-RADS category, SWS measurement were compared between the two groups. Receiver operating characteristic (ROC) curve was performed and area under ROC curve (AUC) was obtained for significant features. There were no statistical differences in mean age (46.9±15.7years vs. 48.6±13.6years, P = 0.639), gender (9 males, 32.1% vs. 18 males, 29.0%, P = 0.766) and mean diameter (28.3±16.2 mm vs. 33.8±11.9 mm, P = 0.077) between FTCs and FAs. Hypoechogenicity, lobulated or irregular margin, macrocalcification were more common in FTCs than FAs (all P < 0.05). Mean SWS of FTCs (2.29±0.64 m/s) was slightly higher than that of FAs (1.94±0.68 m/s) (P = 0.023). The AUCs were 0.655, 0.744, and 0.744 with the cut-off SWS≥1.89 m/s, ACR TI-RADS category 4 and intermediate suspicion of ATA TI-RADS category. The sensitivity and AUC were 82.1% and 0.812 with combined ultrasound features of hypoechogenicity, lobulated or irregular margin and macrocalcification. In Conclusion, SWS measurement and TI-RADS categories were useful for the identification of FTCs from FAs.

Differentiation of follicular carcinomas from adenomas using histogram obtained from diffusion-weighted MRI

AIM

To evaluate the role of histogram analysis of apparent diffusion coefficient (ADC) maps from diffusion-weighted imaging (DWI) in the differentiation of follicular thyroid carcinoma (FTC) from follicular adenoma (FA) in nodules indeterminate on ultrasound-guided core needle biopsy (USCNB).

MATERIALS AND METHODS

This study was performed with institutional review board approval. Seventeen patients who were planned to undergo diagnostic lobectomy for an indeterminate thyroid nodule (atypical of unknown significance/follicular lesion of undetermined significance [AUS/FLUS] or suspicious for follicular neoplasm/follicular neoplasm [SFN]) on USCNB were enrolled prospectively. All patients underwent DWI on the day before surgery. Histogram parameters were derived from ADC values obtained from the whole extent of the tumours. The parameters were compared with the final diagnosis based on histopathological examination after surgery. The accuracy of the parameters in differentiating FTC from FA was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Twelve patients were confirmed as having FA and five patients as having FTC. Histogram parameters including the 10^th (ADC₁₀), 25^th (ADC₂₅), and 50^th (ADC₅₀) percentiles of the ADC values were significantly lower in FA than in FTC (p < 0.05, all). ROC curve analysis revealed that ADC₂₅ resulted in the highest AUC (0.867; confidence interval, 0.616-0.980), with a cut-off value of 0.352×10^-3 mm²/s.

CONCLUSION

Histogram parameters from ADC maps could differentiate FTC from FA effectively in indeterminate nodules on USCNB, with ADC₂₅ being the most promising parameter.

Ultrasound-guided fine-needle aspiration or core needle biopsy for diagnosing follicular thyroid carcinoma?

OBJECTIVE

We evaluated the preoperative diagnostic values of ultrasound (US), fine-needle aspiration (FNA) and core needle biopsy (CNB) leading to surgery in patients with FTC.

METHODS

From October 1994 to July 2016, 298 patients with FTC who had preoperative US images and underwent US-guided FNA or CNB and surgery were included in this study. We evaluated the results of preoperative FNA or CNB based on the Bethesda system and the US findings according to the Korean thyroid imaging reporting and data system (K-TIRADS).

RESULTS

Predominant US features of FTC showed solid, hypo- or iso-echogenicity, oval smooth margin and halo with no calcification. Based on K-TIRADS, 140 (47.0%) patients with FTC were categorized as low suspicion, 133 (44.63%) as intermediate suspicion and 25 (8.4%) as high suspicion at US. Considering only FNA cytology (n = 230), 6.9% were revealed as Bethesda class I, 16.1% as class II, 37.0% as class III, 29.1% as class IV and 10.9% as class V. Considering the 68 cases with CNB results, 2.9% were revealed as class I, 4.4% as class II, 20.6% as class III and 72.1% as class IV. Despite multiple FNAs, 16.7% of the 84 patients with FTC still obtained Bethesda class I or class II. CNB results in patients with FTC had a significantly higher rate of Bethesda class IV compared to the FNA results (P < .001). FTCs with distant metastasis exhibited a significantly higher rate of Bethesda classes IV and V compared to those without distant metastasis (P = .004).

CONCLUSION

Surgery for FTC is deferred only with preoperative US and FNA. CNB in patients with FTC can lead to surgery better than FNA. Therefore, if the US feature is characteristic and a serially growing large nodule is suspected, the first attempt of CNB may be helpful in selecting a surgical candidate.

Application of machine learning to ultrasound images to differentiate follicular neoplasms of the thyroid gland

Purpose

This study was conducted to evaluate the diagnostic performance of machine learning in differentiating follicular adenoma from carcinoma using preoperative ultrasonography (US).

Methods

In this retrospective study, preoperative US images of 348 nodules from 340 patients were collected from two tertiary referral hospitals. Two experienced radiologists independently reviewed each image and categorized the nodules according to the 2015 American Thyroid Association guideline. Categorization of a nodule as highly suspicious was considered a positive diagnosis for malignancy. The nodules were manually segmented, and 96 radiomic features were extracted from each region of interest. Ten significant features were selected and used as final input variables in our in-house developed classifier models based on an artificial neural network (ANN) and support vector machine (SVM). The diagnostic performance of radiologists and both classifier models was calculated and compared.

Results

In total, 252 nodules from 245 patients were confirmed as follicular adenoma and 96 nodules from 95 patients were diagnosed as follicular carcinoma. As measures of diagnostic performance, the average sensitivity, specificity, and accuracy of the two experienced radiologists in discriminating follicular adenoma from carcinoma on preoperative US images were 24.0%, 84.0%, and 64.8%, respectively. The sensitivity, specificity, and accuracy of the ANN and SVM-based models were 32.3%, 90.1%, and 74.1% and 41.7%, 79.4%, and 69.0%, respectively. The kappa value of the two radiologists was 0.076, corresponding to slight agreement.

Conclusion

Machine learning-based classifier models may aid in discriminating follicular adenoma from carcinoma using preoperative US.

Sonographic features of follicular variant of papillary thyroid carcinoma (FV-PTC) and diagnostic performance of the 2017 ACR TI-RADS in FV-PTC

PURPOSE

To find the sonographic features of follicular variant of papillary thyroid carcinoma (FV-PTC) and evaluate the diagnostic performance of 2017 ACR TI-RADS in FV-PTC.

METHODS

From June 2017 to June 2019, 104 FV-PTC patients (106 nodules) and 337 classic papillary thyroid carcinoma (C-PTC) patients (343 nodules) with both sonograms and pathologic results were included. Sonographic features of FV-PTC and C-PTC were evaluated and compared, and 2017 ACR TI-RADS scores and levels were calculated.

RESULTS

Pathologically, the incidence of Hashimoto's thyroiditis and extrathyroidal extension was higher in the FV-PTC group. Most of both the FV-PTC and C-PTC groups were diagnosed as PTC or suspicious PTC by fine-needle aspiration biopsy (FNAB). FV-PTC tended to be isoechoic, while most nodules of C-PTC were hypoechoic or very hypoechoic. Compared with C-PTC, FV-PTC had lower percentages of a taller-than-wide shape (11.3% vs. 46.6%) and lobulated or irregular margin (33.0% vs. 61.8%), and a higher percentage of extrathyroidal extension (20.8% vs. 8.2%). FV-PTC featured macrocalcifications, whereas punctate echogenic foci were more frequently seen in the C-PTC group. Other characteristic US appearances of FV-PTC included uneven hypoechoic halo and peripheral vascularity. The mean TI-RADS score of FV-PTC cases was lower in the FV-PTC group, 11.3%, 44.3%, and 42.5% of which were categorized as TI-RADS 3, 4, and 5, respectively.

CONCLUSIONS

FV-PTC features isoechoic appearance, macrocalcifications, uneven hypoechoic halo, and peripheral vascularity on US, with lower incidences of microcalcifications and taller-than-wide shape, and tends to have lower TI-RADS scores and levels. For the nodules categorized as TI-RADS 3 or 4, the FNAB criteria should be broaden when these nodules have FV-PTC US features.

Preoperative sonographic features of follicular thyroid carcinoma predict biological behavior: A retrospective study

Little is known regarding biological behavior of follicular thyroid carcinomas (FTCs) according to ultrasonography features. We investigated whether there was a difference in biological behavior between benign-looking FTCs (B-FTCs) and malignant-looking FTCs (M-FTCs).A total of 55 cases of FTC between January 2000 and December 2015 were included. B-FTCs were defined as showing none of the accepted ultrasonography criteria for malignancy, and M-FTCs were defined as showing at least one of the accepted ultrasonography criteria for malignancy. Clinicopathologic factors and sonographic features were compared between B-FTCs and M-FTCs. Based on the degree of invasiveness, FTCs were divided into minimally invasive FTCs (MI-FTCs) and widely invasive FTCs (WI-FTCs) on pathology. Sonographic features were compared between MI-FTCs and WI-FTCs.Compared with the patients with B-FTCs (31/55, 56.4%), the patients with M-FTCs showed a significantly higher prevalence of WI-FTCs, central lymph node metastases, lateral lymph node metastases as well as extrathyroidal extension (P < .001, P = .012, P = .031, and P = .032, respectively). M-FTCs with more than one malignancy features on ultrasonography showed a significantly higher prevalence of extrathyroidal extension than M-FTCs with only one ultrasonography malignancy feature (P = .022). Compared with MI-FTCs (41/55, 74.5%), an irregular shape, a spiculated/microlobulated boundary, no peripheral halo ring, hypoechogenicity and microcalcification were more frequent in WI-FTCs (P < .001, P = .003, P = .002, P = .015, and P = .016, respectively).Our results demonstrated that B-FTCs had better prognostic indicators than M-FTCs. Therefore, preoperative US features can serve as a useful tool for predicting biological behavior in FTC.

Follicular thyroid cancer and Hürthle cell carcinoma: challenges in diagnosis, treatment, and clinical management

Follicular thyroid cancer is the second most common differentiated thyroid cancer histological type and has been overshadowed by its more common counterpart-papillary thyroid cancer-despite its unique biological behaviour and less favourable outcomes. In this Review, we comprehensively review the literature on follicular thyroid cancer to provide an evidence-based guide to the management of these tumours, to highlight the lack of evidence behind guideline recommendations, and to identify changes and challenges over the past decades in diagnosis, prognosis, and treatment. We highlight that correct identification of cancer in indeterminate cytological samples is challenging and ultrasonographic features can be misleading. Despite certain unique aspects of follicular thyroid cancer presentation and prognosis, no specific recommendations exist for follicular thyroid cancer and Hürthle cell carcinoma in evidence-based guidelines. Efforts should be made to stimulate additional research in this field.

Tumour growth rate of follicular thyroid carcinoma is not different from that of follicular adenoma

OBJECTIVE

Distinguishing malignancy from benign thyroid nodule has always been challenging, especially in follicular lesions. Thyroid nodules with small size and indeterminate cytology do not lead to immediate surgery. We tried to evaluate whether tumour size and tumour growth rate can distinguish follicular thyroid carcinoma (FTC) from follicular adenoma (FA).

DESIGN AND PATIENTS

This retrospective study included patients with pathologically proven FTCs (n = 50) and FAs (n = 110) who underwent preoperative serial neck ultrasonography (US) at least 3 times: it comprises 30% of all follicular tumours (32% FAs and 25% FTCs). The growth rates of follicular tumours on serial US were measured using at least 3 consecutive examinations during a median follow-up of 4.1 years (range, 0.7-13.3 years) by experienced radiologists.

RESULTS

The FA and FTC groups showed no significant difference in clinicopathological characteristics, including age, proportion of large nodules (>4 cm) and preoperative cytology. The maximum diameter of thyroid nodule was gradually increased in both groups with statistical significance (P < .001 and P < .001, respectively). No significant differences in change of maximum diameter of thyroid nodule (P = .132) and tumour volume (P = .208) were found between the FA and FTC groups during the follow-up. The median time to a significant tumour growth from baseline was not different between the FA and FTC groups (1.4 years and 1.7 years, respectively, P = .556). When we divided the patients into four groups (rapid, moderate, slow and no growth) according to the growth velocity of the thyroid tumours, no significant difference in growth velocity was found among the groups.

CONCLUSIONS

The tumour size and growth rate of the thyroid nodule itself could not predict malignancy. Diagnostic approaches that use molecular markers would be more important than clinical features for the decision of diagnostic surgery for patients with follicular tumours.

Subclassification of Bethesda Atypical and Follicular Neoplasm Categories According to Nuclear and Architectural Atypia Improves Discrimination of Thyroid Malignancy Risk

BACKGROUND

Although The Bethesda System for Reporting Thyroid Cytopathology has provided clinicians with a standardized classification scheme for the diagnosis of thyroid fine-needle aspiration cytology (FNAC) specimens, the indeterminate categories of Bethesda III (B3)-atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS)-and Bethesda IV (B4)-follicular neoplasm/suspicious for follicular neoplasm (FN/SFN)-continue to pose challenges with regards to ideal diagnostic and therapeutic management. Having previously demonstrated the presence of nuclear atypia as a high-risk subgroup in B3, the objective of this study was to evaluate the malignancy rates in the B4 subgroup with nuclear atypia.

METHODS

A retrospective review of all thyroid FNACs diagnosed as B4 (FN/SFN) between 2008 and 2015 was conducted at a tertiary referral center in Singapore. Data on patient demographics, sonographic features, and final histological diagnosis were collected. This was compared to data from a previous analysis on all nodules diagnosed as B3 (AUS/FLUS) over a similar period.

RESULTS

A total of 137/309 (44.3%) and 88/111 (79.3%) FNACs diagnosed as B3 and B4, respectively, underwent surgical excision yielding final histopathological diagnoses. The malignancy rate of B4 was 31/88 (35.2%) compared to B3, which was 37/137 (27.0%). Subclassification based on the presence of architectural versus nuclear atypia showed significantly higher malignancy rates in B4 nodules with nuclear atypia (21.8% vs. 57.6%; p < 0.01). These findings corroborate previous results within the B3 category (malignancy rate of 14.7% vs. 36.8%; p < 0.01). The only sonographic features predictive of malignancy were the presence of macrocalcifications in B4 compared to irregularity of margins in B3.

CONCLUSION

The presence of nuclear atypia identifies subgroups with significant differential malignancy risks within both the B3 and B4 categories. This supports the notion that subclassification is a useful risk stratification tool that can guide diagnostic and therapeutic management of indeterminate thyroid nodules with heterogenous risk profiles.

European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules in Adults: The EU-TIRADS

Thyroid ultrasound (US) is a key examination for the management of thyroid nodules. Thyroid US is easily accessible, noninvasive, and cost-effective, and is a mandatory step in the workup of thyroid nodules. The main disadvantage of the method is that it is operator dependent. Thyroid US assessment of the risk of malignancy is crucial in patients with nodules, in order to select those who should have a fine needle aspiration (FNA) biopsy performed. Due to the pivotal role of thyroid US in the management of patients with nodules, the European Thyroid Association convened a panel of international experts to set up European guidelines on US risk stratification of thyroid nodules. Based on a review of the literature and on the American Association of Clinical Endocrinologists, American Thyroid Association, and Korean guidelines, the panel created the novel European Thyroid Imaging and Reporting Data System, called EU-TIRADS. This comprises a thyroid US lexicon; a standardized report; definitions of benign and low-, intermediate-, and high-risk nodules, with the estimated risks of malignancy in each category; and indications for FNA. Illustrated by numerous US images, the EU-TIRADS aims to serve physicians in their clinical practice, to enhance the interobserver reproducibility of descriptions, and to simplify communication of the results.

Korean Thyroid Imaging Reporting and Data System features of follicular thyroid adenoma and carcinoma: a single-center study

PURPOSE

This study aimed to assess the diagnostic efficacy of Korean Thyroid Imaging Reporting and Data System (K-TIRADS) features for distinguishing follicular thyroid adenoma (FTA) from follicular thyroid carcinoma (FTC).

METHODS

From January 2013 to July 2016, 46 follicular neoplasms in 45 patients who underwent preoperative thyroid ultrasonography (US) and thyroid surgery were included. The US features of each thyroid nodule were retrospectively evaluated by a single radiologist using a picture archiving and communication system. The diagnostic indices of K-TIRADS for follicular neoplasms were calculated according to whether K-TIRADS category 4 lesions were excluded or classified as benign or malignant.

RESULTS

Of the 46 follicular neoplasms (mean size, 3.1±1.6 cm), 37 were FTAs (mean size, 3.1±1.7 cm) and nine were FTCs (mean size, 3.0±1.5 cm). A statistically significant difference was found between FTAs and FTCs regarding the margin (P=0.035), while no significant differences were observed in the composition, echogenicity, shape, orientation, calcification, or vascularity of the lesions (P<0.05). The FTAs belonged to K-TIRADS categories 3 (n=22) and 4 (n=15), while the FTCs belonged to K-TIRADS categories 3 (n=4), 4 (n=4), and 5 (n=1). However, there was no statistically significant difference in the distribution of K-TIRADS categories between FTAs and FTCs (P=0.184).

CONCLUSION

K-TIRADS features were not helpful for distinguishing FTA from FTC, although follicular neoplasms showed a high prevalence of K-TIRADS categories 3 and 4.

"Nodule in Nodule" on Thyroid Ultrasonography: Possibility of Follicular Carcinoma Transformed from Benign Thyroid Tumor

BACKGROUND

It is generally considered impossible to differentiate follicular carcinomas from follicular adenomas by means of ultrasonography or cytology before surgery. Therefore, follicular carcinoma is histopathologically diagnosed by verifying capsular and/or vascular invasion after surgery. However, ultrasonography may play an important role in diagnosing follicular carcinoma preoperatively in a small number of cases.

CASE DESCRIPTION

Four cases of follicular carcinoma or follicular neoplasm that transformed from a benign thyroid tumor and demonstrated a "nodule in nodule" appearance on ultrasonography are presented in this report. Characteristic ultrasound features of such patients are: (1) a "nodule in nodule" appearance, (2) a well-defined boundary line between the nodules, and (3) separate distribution of blood signals within each nodule.

CONCLUSION

A small number of patients with follicular carcinomas or follicular neoplasms may present with a "nodule in nodule" appearance on ultrasonography. It was suggested a long time ago that follicular carcinomas may develop from benign thyroid tumors. The fact that follicular carcinomas appear within benign tumors may be evidence of thyroid tumorigenesis.

Ultrasonographic Differentiation Between Nodular Hyperplasia and Neoplastic Follicular-Patterned Lesions of the Thyroid Gland

We evaluate the gray-scale ultrasonographic characteristics that differentiate between nodular hyperplasia (NH) and neoplastic follicular-patterned lesions (NFPLs) of the thyroid gland. Ultrasonographic features of 750 patients with 832 thyroid nodules (NH, n = 361; or NFPLs, follicular adenoma, n = 123; follicular carcinoma, n = 159; and follicular variant papillary carcinoma, n = 189) were analyzed. Except for echogenicity, over two-thirds of the cases of NH and NFPLs share the ultrasonographic characteristics of solid internal content, a well-defined smooth margin and round-to-ovoid shape. Independent predictors for NH were non-solid internal content (sensitivity 27.1%, specificity 90.2%), isoechogenicity (sensitivity 69.5%, specificity 63.5%) and an ill-defined margin (sensitivity 18.8%, specificity 94.5%). Independent predictors for NFPLs were hypoechogenicity (sensitivity 60.5%, specificity 70.4%), marked hypoechogenicity (sensitivity 2.8%, specificity 99.4%) and taller-than-wide shape (sensitivity 6.6%, specificity 98.1%). Although NH and NFPLs commonly share ultrasonographic characteristics, non-solid internal content and ill-defined margin are specific to NH and marked hypoechogenicity and taller-than-wide shape are specific to NFPLs.

Primary follicular thyroid carcinoma metastasis to the kidney and widespread dissemination: A case report

Distant metastases are more common in follicular thyroid carcinoma (FC) than in papillary thyroid carcinoma. However, FC metastasis to the kidney with eggshell calcification, as observed in the present case, is rare. The current report presents a case of a 67-year-old woman exhibiting a solitary tumor in the mid pole of the left kidney. Radical nephrectomy was performed, as the tumor was diagnosed as a primary renal carcinoma using contrast-enhanced computed tomography. Once the tumor was confirmed to be FC, total thyroidectomy was performed. Following administration of an oral therapeutic dose of 100 mCi ¹³¹I, functional imaging demonstrated the presence of multifocal metastases in the chest and abdomen. Euthyrox^® was prescribed orally to aid normal thyroid function. Follow-up 6 months later using radionuclide imaging demonstrated the disappearance of the multifocal metastases in the chest and abdomen. The distant metastasis of FC may represent the initial symptom of the primary lesion, which was neglected. Ultrasound is an effective method to examine nodules located on the thyroid.

Computerized quantification of ultrasonic heterogeneity in thyroid nodules

To test whether computerized quantification of ultrasonic heterogeneity can be of help in the diagnosis of thyroid malignancy, we evaluated ultrasonic heterogeneity with an objective and quantitative computerized method in a prospective setting. A total of 400 nodules including 271 benign thyroid nodules and 129 malignant thyroid nodules were evaluated. Patient clinical data were collected, and the grading of heterogeneity on conventional gray-scale ultrasound images was retrospectively reviewed by a thyroid specialist. Quantification of ultrasonic heterogeneity (heterogeneity index, HI) was performed by a proprietary program implemented with methods proposed in this article. HI values differed significantly between benign and malignant nodules, diagnosed by a combination of fine-needle aspiration and surgical pathology results (p < 0.001, area under the curve = 0.714). The ultrasonic heterogeneity of these samples, as assessed by an experienced clinician, could not significantly differentiate between benign and malignant thyroid nodules. However, nodules with marked ultrasonic heterogeneity had higher HI values than nodules with homogeneous nodules. These results indicate that the new computer-aided diagnosis method for evaluation of the ultrasonic heterogeneity of thyroid nodules is an objective and quantitative method that is correlated with conventional ultrasonic heterogeneity assessment, but can better aid in the diagnosis of thyroid malignancy.

Imaging findings of thyroidal sarcoma

From 1997 to 2013, 8849 patients with several disorders of the thyroid were treated in our surgical department. In nine patients (0.1%), primary thyroid sarcoma (PTS) was diagnosed. In eight patients, PTS manifested as a thyroid mass (range, 25-90 mm). In one case, a global enlargement of the thyroid was seen. Clinically, all patients presented with neck swelling. On ultrasound, PTS was predominantly hypoechoic. On computed tomography, the sarcomas were hypodense. On magnetic resonance imaging, PTS had inhomogeneous signal increase on T2-weighted images and signal decrease on T1-weighted images with inhomogeneous enhancement.