Ultrasound elastography using carotid artery pulsation in the differential diagnosis of sonographically indeterminate thyroid nodules

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.

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.

Effect of the location and size of thyroid nodules on the diagnostic performance of ultrasound elastography: A retrospective analysis

OBJECTIVES

Ultrasound-guided fine-needle aspiration biopsies are recommended for the detection of suspicious thyroid nodules. However, the best approach regarding suspicious ultrasound features for thyroid nodules is still unclear. This study aimed to evaluate the effect of location and size of thyroid nodules on the diagnostic performance of strain ultrasound elastography. In addition, this study evaluated whether ultrasound elastography predicts malignancy in thyroid nodules.

METHODS

Data regarding the size, depth, and distance from the carotid artery of nodules, the elasticity contrast index, and the nature of nodules were analyzed.

RESULTS

There was no significant difference in the depth (p=0.092) and the distance from the carotid artery (p=0.061) between benign and suspicious nodules. Suspicious nodules were smaller than benign nodules (p<0.0001, q=23.84) and had a higher elasticity contrast index (p<0.0001, q=21.05). The depth of nodules and the size of the nodule were not associated with the correct value of the elasticity contrast index (p>0.05 for both). The diagnostic performance of ultrasound elastography was not affected by the distance of the nodules from the carotid artery if they were located ≥15 mm from the carotid artery (p=0.5960). However, if the suspicious nodules were located <15 mm from the carotid artery, the diagnostic accuracy was hampered (p=0.006).

CONCLUSIONS

The strain ultrasound elastography should be carefully evaluated when small thyroid nodules are located near the carotid artery.

The Value of Elasticity Contrast Index in the Differential Diagnosis of Thyroid Solid Nodules

OBJECTIVES

To assess the clinical value of elasticity contrast index (ECI) in differentiating malignant thyroid nodules from benign ones.

METHODS

Conventional ultrasound and elastography with pulsation of the carotid artery used as the compression source were retrospectively reviewed on 175 patients (143 females and 32 males; mean ± SD age, 45.17 ± 11.45 years) with 236 solid nodules (113 malignant and 123 benign). All nodules were confirmed by fine-needle aspiration or surgery to be accurately diagnosed. Elasticity contrast index values were computed and used to quantify local stiffness contrast within a nodule as determined with elastography. Elasticity contrast index values between the malignant and benign groups were compared and then related with pathological results. Diagnostic performance of this method was evaluated with use of the receiver operating characteristic curve.

RESULTS

Mean ± SD ECI values for malignant thyroid nodules were significantly greater than those for benign nodules (3.67 ± 1.20 vs 1.80 ± 0.74, P < 0.01). Area under the receiver operating characteristic curve of ECI values was 0.907 (95% confidence interval, 0.867-0.948), and the best cutoff point was 2.16, leading to a sensitivity of 90.3%, specificity of 82.9%, positive predictive value of 83.7% and negative predictive value of 91.2%.

CONCLUSIONS

Elasticity contrast index values can serve as a useful parameter in the differential diagnosis of solid thyroid nodules. With the use of ECI values, objective quantitative information on the tumor stiffness can be achieved to improve diagnostic confidence.

Complementary Role of Elastography Using Carotid Artery Pulsation in the Ultrasonographic Assessment of Thyroid Nodules: A Prospective Study

Objective

The aim of this study was to evaluate the diagnostic performance of gray-scale ultrasonography (US), Doppler scan, and elastography using carotid artery pulsation in the diagnosis of thyroid nodules and to find a complementary role of elastography.

Materials and Methods

A total 197 thyroid nodules with 91 malignant and 106 benign pathologic results from 187 patients (41 males and 146 females; age range, 20-83 years; mean age, 49.4 years) were included in this prospective study. The gray-scale, Doppler US images, elastography with elasticity contrast index (ECI), and stiffness color were assessed. The diagnostic performances of each dataset were assessed in order to differentiate benign from malignant thyroid nodules.

Results

The optimal cut-off value of the ECI was 1.71. The area under receiver operating characteristic curve (Az value) was 0.821 for gray-scale US, 0.661 for the ECI, 0.592 for stiffness color, and 0.539 for Doppler US. The Az value for a combined assessment of gray-scale US and the ECI was higher than that for the gray-scale US alone; however, there was no statistical difference between the two (p = 0.219). The median ECI values of follicular thyroid carcinoma (FTC) and follicular variant of papillary thyroid carcinoma (FVPTC) were significantly lower than those of the other malignant lesions (p = 0.005). Meanwhile, the diffuse sclerosing variant of PTC and a metastatic nodule showed the two highest median values of the ECI.

Conclusion

For differentiating thyroid nodules, the diagnostic performances of the combination of gray-scale US and elastography with the ECI were similar to, but not superior, to those of gray-scale US alone. FVPTC and FTC have a significantly lower ECI value than those of the other malignant lesions.

Qualitative and Semiquantitative Elastography for the Diagnosis of Intermediate Suspicious Thyroid Nodules Based on the 2015 American Thyroid Association Guidelines

OBJECTIVES

To evaluate qualitative and semiquantitative elastography for the diagnosis of intermediate suspicious thyroid nodules based on the 2015 American Thyroid Association (ATA) guidelines.

METHODS

Through a retrospective search of our institutional database, 746 solid thyroid nodules found on grayscale ultrasonography, strain elastography, and ultrasound-guided fine-needle aspiration between June and November 2009 were collected. Among them, 80 nodules from 80 patients with an intermediate suspicion of malignancy based on the 2015 ATA guidelines that were 10 mm or larger were recruited as the final study nodules. Elastographic findings were categorized according to the criteria of Rago et al (J Clin Endocrinol Metab 2007; 92:2917-2922) and Asteria et al (Thyroid 2008; 18:523-531), and strain ratio values were calculated and recorded. The independent 2-sample t test and χ² test (or Fisher exact test) were used to evaluate differences in clinical parameters between benign and malignant thyroid nodules. All variables were compared by univariate and multivariate logistic regression analyses, and odds ratios with 95% confidence intervals were calculated.

RESULTS

Of the 80 nodules, 6 (7.5%) were malignant, and 74 (92.5%) were benign. No significant differences were observed in age, sex, nodule size, elasticity score, and strain ratio between benign and malignant nodules. No variables significantly predicted thyroid malignancy on the univariate analysis. On the multivariate logistic regression analysis, there were no independent variables associated with thyroid malignancy, including the elasticity score and strain ratio (all P > .05).

CONCLUSIONS

Elastographic analysis using the elasticity score and strain ratio has limited ability to characterize the benignity or malignancy of thyroid nodules with an intermediate suspicion of malignancy based on the 2015 ATA guidelines.

US Elastography Using Carotid Artery Pulsation May Increase the Diagnostic Accuracy for Thyroid Nodules with US-Pathology Discordance

This study evaluated the diagnostic performance of ultrasound elastography (USE) using carotid arterial pulsation and determined the reproducibility of USE for thyroid nodules. A total of 148 patients with 173 thyroid nodules participated. The mean elasticity contrast index (ECI) was significantly higher in malignant nodules (3.1 ± 1.5) than in benign nodules (1.7 ± 0.8) (p < 0.001). When a cut-off ECI value of 3.5 was used, the diagnostic accuracy (78.6%) of gray-scale ultrasound (US) + ECI was the highest compared with that of the gray-scale US (76.9%) and ECI (67.1%). In 16 of 43 nodules (37.2%) with US-pathology, discordance could be correctly reclassified as benign (8 of 11) or malignant (8 of 32). The intra-class correlation coefficient for inter-observer agreement was 0.96, and those for intra-observer agreement were 0.97 and 0.98. Thyroid nodules with ECI values of >3.5 may have an additional value to increase the diagnostic accuracy for nodules with US-pathology discordance with reproducible results.

Diagnostic value of strain elastography for differentiating benign and malignant soft tissue masses

The aim of the current study was to investigate the importance of strain elastography (SE) in the differential diagnosis of benign and malignant soft tissue masses. SE was adopted to examine 61 patients with superficial masses, classify their elastic scores and assess their strain ratios (SRs) between the masses and the surrounding structures. Significantly increased SR values and elastic scores were observed in the malignant masses compared with the benign masses (5.42±3.47 vs. 1.80±2.10, P<0.001; 3.13±0.34 vs. 2.03±0.99, P<0.001). Area under receiver operating characteristic curve values of the SRs and elastic scores were 0.87 (P<0.001) and 0.805 (P=0.001), respectively. With an SR of >2.295 as the optimal threshold value, the sensitivity, specificity and positive and negative predictive values for diagnosing a malignant mass were 93.8, 80.5, 65.2 and 97.1%, respectively; whilst using an elastic score of ≥3 as the optimal threshold value, the sensitivity, specificity and positive and negative predictive values for diagnosing a malignant mass were 100, 51.6, 51.6 and 100%, respectively. SR values and elastic scores were significantly different between the malignant and benign soft tissue masses. Therefore, SE may be used to effectively differentiate between malignant and benign soft tissue masses.

Assessment of Measurement Repeatability and Reliability With Virtual Touch Tissue Quantification Imaging in Cervical Lymphadenopathy

OBJECTIVES

The purpose of this study was to prospectively assess the repeatability and reliability of 2 measurements of cervical lymphadenopathy using Virtual Touch tissue quantification (VTQ) imaging (Siemens Medical Solutions, Mountain View, CA) and to analyze the factors affecting the reliability of the measurements, including pathologic findings, lesion size and location, and shear wave velocities (SWVs).

METHODS

In this Institutional Review Board-approved prospective study, 92 patients underwent conventional sonography and 2 VTQ measurements by acoustic radiation force impulse imaging in a single session. The repeatability and reliability of the SWV measurement was determined by using an average coefficient of variation (standard deviation/mean) and intraclass correlation coefficient (ICC), respectively. By comparing ICCs with a 95% confidence interval, the effects of pathologic findings, depth, size, SWV, and distance from the carotid artery on reliability were assessed.

RESULTS

The mean age of the 92 patients included in the study was 51 years (range, 14-77 years). The average coefficient of variation was 19.4%. The overall reliability of the 2 measurements was excellent (ICC, 0.837), but ICCs were significantly decreased in lymph nodes in a superficial location (<1 cm) and those with a low SWV (<1.8 m/s). No significant effect was found on reliability in relation to pathologic findings, lesion size, or distance from the carotid artery to the lymph nodes.

CONCLUSIONS

For SWV measurement by VTQ imaging, the repeatability was 19.4%, and reliability was excellent. However, caution is warranted in the use of VTQ imaging for superficial soft cervical lymph nodes, as both a superficial location and a soft composition tend to be characterized by low reliability of SWV findings.

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Risk stratification of thyroid nodules on ultrasonography with the French TI-RADS: description and reflections

The widespread use of ultrasonography places it in a key position for use in the risk stratification of thyroid nodules. The French proposal is a five-tier system, our version of a thyroid imaging reporting and database system (TI-RADS), which includes a standardized vocabulary and report and a quantified risk assessment. It allows the selection of the nodules that should be referred for fine-needle aspiration biopsies. Effort should be directed towards merging the different risk stratification systems utilized around the world and testing this unified system with multi-center studies.