Elastography for the diagnosis of high-suspicion thyroid nodules based on the 2015 American Thyroid Association guidelines: a multicenter study

Use of ultrasound elastography in differentiating benign from malignant thyroid nodules: a prospective study

Purpose

Elastography is a real-time non-invasive ultrasonography modality wherein the tissue stiffness is evaluated by calculating the degree of tissue distortion in response to an external force. This study was undertaken to assess the diagnostic value of elastography in differentiating benign from malignant thyroid nodules.

Methodology

In this prospective comparative study, a total of 52 thyroid nodules from 44 euthyroid patients undergoing fine needle aspiration cytology were assessed. Elastography was performed by a single experienced sonologist, wherein the nodules were graded as per elastography scoring (ES), and the strain ratio (SR) for each nodule was computed. Final histopathology findings of the patients undergoing surgery were compared to elastography findings, and measures of diagnostic accuracy to differentiate between benign and malignant nodules were determined for ES and SR.

Results

Thirty (68.2%) females and 14 (31.8%) males, with a mean age of 45.18 ± 11.23 years, were assessed. Fourteen (31.8%) patients underwent thyroidectomy, and histopathology was reported for 18 (34.6%) nodules. In all, nine (17.3%) nodules were malignant, and 43 (82.7%) nodules were considered benign. ES demonstrated a sensitivity of 88.9%, specificity of 88.3%, PPV of 61.5%, NPV of 97.4%, and accuracy of 88.5% to identify benign thyroid nodules. The mean SR for benign nodules was significantly lower as compared to malignant nodules (2.72 ± 0.62 vs. 4.52 ± 0.75, P < 0.0001). The optimal cut-point value for SR to differentiate benign and malignant thyroid nodules was determined to be 3.8, with the sensitivity, specificity, PPV, NPV, and accuracy being 88.9%, 95.4%, 80%, 94.6%, and 94.2%, respectively.

Conclusion

Ultrasound elastography (ES and SR) demonstrated good diagnostic efficacy to differentiate benign thyroid nodules from the malignant ones, and can be a good supplementary tool to gray-scale ultrasonography. It can also help in reducing the rates of unnecessary fine needle-aspiration biopsy.

[Elastography in thyroid nodules]

BACKGROUND

Elastography is an imaging method to examine the elasticity of tissue. In the meantime, various elastography methods have been developed, which are subdivided according to the type of stimulus applied. In principle, a distinction should be made between strain elastography (SE) and shear wave elastography (SWE). Both methods provide another means of assessing thyroid disease in addition to conventional B-mode sonography.

OBJECTIVE

The aim is to provide an overview of elastography techniques including physical basics and their importance in the clarification algorithm of thyroid nodules.

MATERIALS AND METHODS

International guidelines and recent publications on elastography were selectively assessed.

RESULTS

Elastography provides additional information compared to conventional B-mode sonography. The change in shear stiffness is the essential physical mechanism for tissue contrast in all elastograms. In addition to the qualitative assessment of elasticity in SE, quantification is possible with SWE. In the international literature, elastography was analyzed as a single method or in comparison or combination with conventional B-mode sonography and especially with standardization using a risk stratification system (RSS, TIRADS). The results are quite controversial. In nodules with unclear findings on fine-needle biopsy (Bethesda III/IV), the combination of morphologic criteria and elastography improved diagnostic accuracy. In particular, the high negative predictive value of soft nodules represents a relevant added value. This strength of the method can play an important role in the clarification of nodules with intermediate malignancy risk or of unclear FNB results. Elastography has previously only been incorporated into French-TIRADS. Although the procedure is mentioned in the EU-TIRADS as a complementary method, integration has not been described. Limitations of the method are idealized basic assumptions, dependence of manufacturer and examiner, and artifacts.

CONCLUSION

Elastography can be a useful adjunct to standard diagnostic procedures in the evaluation of thyroid nodules, especially in nodules with intermediate risk of malignancy and unclear results on fine needle aspiration.

Diagnostic Accuracy of Strain Ultrasound Elastography in Thyroid Lesions Compared to Fine-Needle Aspiration Cytology

Introduction

Strain ultrasound-guided elastography (USE) could be used to differentiate malignant from benign thyroid lesions if its sensitivity and specificity are significantly high. Data on whether to rely on USE in differentiating thyroid nodules are unavailable, and fine-needle aspiration cytology (FNAC) remains the gold standard. However, FNAC carries a significant financial burden on hospitals and psychological stress on patients. Therefore, we conducted this study to determine the diagnostic accuracy of strain USE in thyroid lesions.

Methodology

We conducted a descriptive cross-sectional study at the Radiology Department, Benazir Bhutto Hospital, Rawalpindi, from December 6, 2020, to June 5, 2021. The study included adult patients aged between 20 to 70 years who were referred with thyroid nodules or lesions found clinically or on routine neck ultrasound. The study excluded patients who had previous history of surgery or previously diagnosed with malignant thyroid lesions and recurrent thyroid nodules. Strain USE was performed on thyroid nodules, and the degree of strain was color-coded on a scale from red (soft, greatest elasticity) to green (intermediate, average strain) to blue (hard, no elasticity/strain). Lesions were given an elasticity score on a five-point scale. The lesion was given a score of one if the entire lesion was uniformly shaded in green. A lesion with mosaic pattern of green and blue was scored as two. A score of three denoted a lesion with green periphery and blue center on strain elastography. A score of four indicated uniform blue in the entire lesion, with green in the lesion's periphery. The highest score of five was given if the lesion and its surroundings demonstrated blue color. Ultrasound-guided FNAC of the thyroid nodules was performed following USE. Data was analyzed using IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. Mean ± standard deviation for calculating quantitative variables. Frequencies and percentages were calculated for qualitative variables. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of strain USE was calculated taking FNAC as gold standard. We also conducted a receiver operating characteristic curve analysis to quantify the diagnostic accuracy of strain USE in thyroid lesions.

Results

The study included 207 adult patients (117 women, 56.52%; 90 men, 43.48%). The study population's mean age was 50.0 ± 11.8 years (range, 20 to 70 years). Most patients (56.52%) were aged 46 to 70 years. FNAC confirmed malignant thyroid nodules in 100 cases (true positive), and nine cases (false positive) had no malignant lesions on FNAC. In USE-negative patients, 91 were true negative, while seven were false negative. Strain USE's overall sensitivity was 93.46%, specificity was 91.0%, PPV was 91.74%, NPV was 92.86%, and diagnostic accuracy was 92.27% compared to the gold standard FNAC.

Conclusions

Strain USE in thyroid lesions is a noninvasive modality of choice with high diagnostic accuracy and has dramatically improved our ability to diagnose malignant thyroid nodules preoperatively. Strain USE also helps the surgeons in proper decision-making. Strain USE should be used routinely in all patients with thyroid lesions to help diagnose malignant thyroid nodules preoperatively and inform proper surgical and treatment plans.

Deep learning in ultrasound elastography imaging: A review

It is known that changes in the mechanical properties of tissues are associated with the onset and progression of certain diseases. Ultrasound elastography is a technique to characterize tissue stiffness using ultrasound imaging either by measuring tissue strain using quasi-static elastography or natural organ pulsation elastography, or by tracing a propagated shear wave induced by a source or a natural vibration using dynamic elastography. In recent years, deep learning has begun to emerge in ultrasound elastography research. In this review, several common deep learning frameworks in the computer vision community, such as multilayer perceptron, convolutional neural network, and recurrent neural network are described. Then, recent advances in ultrasound elastography using such deep learning techniques are revisited in terms of algorithm development and clinical diagnosis. Finally, the current challenges and future developments of deep learning in ultrasound elastography are prospected. This article is protected by copyright. All rights reserved.

US-Elastography With Different Techniques for Thyroid Nodule Characterization: Systematic Review and Meta-analysis

Background

Thyroid nodules are frequent in adult population and thyroid cancer incidence has increased dramatically over the past three decades. The aim of this systematic review and meta-analysis was to evaluate the US-Elastosonography (USE) diagnostic performance in assessing the thyroid nodules malignancy risk.

Methods

PubMed and Embase databases were searched from January 2011 to July 2021. We extracted data from selected studies and calculated the overall diagnostic accuracy of qualitative USE, semi-quantitative USE and quantitative USE. Summary receiver operating characteristic (ROC) curve was elaborated to show the results. All statistical tests were performed using Metadisc and Medcal software package.

Results

Finally 72 studies with 13,505 patients and 14,015 thyroid nodules (33% malignant) undergoing elastography were included. The pooled sensitivity, specificity and AUC were 84%, 81%, and 0.89 respectively for qualitative USE; 83%, 80%, and 0.93 for semi-quantitative USE and 78%, 81% and 0.87, for quantitative USE. The qualitative and semiquantitative USE present very similar diagnostic accuracy values and both better than the quantitative USE.

Conclusions

USE is a useful imaging tool for thyroid nodule characterization. In accordance with recent guidelines and meta-analyses, the USE could be used daily in thyroid nodule malignancy risk stratification.

Systematic Review Registration

PROSPERO: CRD42021279257.

Suspected Malignant Thyroid Nodules in Children and Adolescents According to Ultrasound Elastography and Ultrasound-Based Risk Stratification Systems-Experience from One Center

The risk of malignancy in thyroid nodules correlates with the presence of ultrasonographic features. In adults, ultrasound risk-classification systems have been proposed to indicate the need for further invasive diagnosis. Furthermore, elastography has been shown to support differential diagnosis of thyroid nodules. The purpose of our study was to assess the application of the American Thyroid Association (ATA), British Thyroid Association (BTA) ultrasound risk-classification systems and strain elastography in the management of thyroid nodules in children and adolescents from one center. Seventeen nodules with Bethesda III, IV, V and VI were selected from 165 focal lesions in children. All patients underwent ultrasonography and elastography followed by fine needle aspiration biopsy. Ultrasonographic features according to the ATA and BTA stratification systems were assessed retrospectively. The strain ratio in the group of thyroid nodules diagnosed as malignant was significantly higher than in benign nodules (6.07 vs. 3.09, p = 0.036). According to the ATA guidelines, 100% of malignant nodules were classified as high suspicion and 73% of benign nodules were assessed as low suspicion. Using the BTA U-score classification, 80% of malignant nodules were classified as cancerous (U5) and 20% as suspicious for malignancy (U4). Among benign nodules, 82% were classified as indeterminate or equivocal (U3) and 9% as benign (U2). Our results suggest that application of the ATA or BTA stratification system and elastography may be a suitable method for assessing the level of suspected malignancy in thyroid nodules in children and help make a clinical decision about the need for further invasive diagnosis of thyroid nodules in children.