Comparison of muscle-to-nodule and parenchyma-to-nodule strain ratios in the differentiation of benign and malignant thyroid nodules: which one should we use?

Ultrasound elastography

Physicians have used palpation as a diagnostic examination to understand the elastic properties of pathology for a long time since they realized that tissue stiffness is closely related to its biological characteristics. US elastography provided new diagnostic information about elasticity comparing with the morphological feathers of traditional US, and thus expanded the scope of the application in clinic. US elastography is now widely used in the field of diagnosis and differential diagnosis of abnormality, evaluating the degree of fibrosis and assessment of treatment response for a range of diseases. The World Federation of Ultrasound Medicine and Biology divided elastographic techniques into strain elastography (SE), transient elastography and acoustic radiation force impulse (ARFI). The ARFI techniques can be further classified into point shear wave elastography (SWE), 2D SWE, and 3D SWE techniques. The SE measures the strain, while the shear wave-based techniques (including TE and ARFI techniques) measure the speed of shear waves in tissues. In this review, we discuss the various techniques separately based on their basic principles, clinical applications in various organs, and advantages and limitations and which might be most appropriate given that the majority of doctors have access to only one kind of machine.

Efficacy of Ultrasound and Shear Wave Elastography for the Diagnosis of Breast Cancer-Related Lymphedema

OBJECTIVES

To assess the feasibility of ultrasound and shear wave elastography (SWE) in the diagnosis of breast cancer-related lymphedema.

METHODS

Forty-one patients with a history of unilateral breast surgery and axillary dissection or sentinel lymph node excision were included in this prospective study. The patients were classified as having normal findings, latent lymphedema, and clinical lymphedema on the basis of a physical examination, lymphedema index scores, and limb circumference measurements. The thickness and stiffness of the cutaneous and subcutaneous tissue of the forearm and arm were measured by ultrasound and SWE. The thickness and stiffness of the cutaneous and subcutaneous tissue of the affected limb and contralateral limbs of the normal, latent lymphedema, and clinical lymphedema groups were compared.

RESULTS

The mean age ± SD of the 41 patients was 55.42 ± 10.12 years. There were 15 patients with normal findings, 10 with latent lymphedema, and 16 with clinical lymphedema. In the latent lymphedema group, the thickness measurements of the cutaneous tissue of the affected forearm and the cutaneous and subcutaneous tissue of the affected arm were significantly greater than those of the contralateral forearm and arm (P = .034; P = .022; and P = .002, respectively), and the stiffness measurements of the cutaneous and subcutaneous tissue of the affected forearm were significantly greater than those of the contralateral forearm (P = .011; and P = .002). In the clinical lymphedema group, the thickness and stiffness measurements of the cutaneous and subcutaneous tissue of the affected forearm and arm were significantly greater than those of the contralateral limb (P < .001-P = .032).

CONCLUSIONS

Ultrasound and SWE are effective for diagnosing breast cancer-related lymphedema even at a latent stage.

TI-RADS Diagnostic Performance: Which Algorithm is Superior and How Elastography and 4D Vascularity Improve the Malignancy Risk Assessment

Given the increased prevalence of thyroid nodules in the general population (~50%), the real challenge resides in correctly recognizing the suspicious ones. This study proposes to compare four important Thyroid Imaging and Reporting Data Systems (TI-RADS) and evaluate the contribution of elastography and 4D Color Doppler assessment of vascularity in estimating the risk of malignancy. In the study, 133 nodules with histopathological examination were included. Of these, 35 (26.31%) proved to be malignant. All nodules were classified using the four selected systems and our proposed improved score. The American College of Radiology (ACR) and EU TI-RADS had good sensitivity (94.28%, 97.14%) and NPV (93.33%, 95.83%), but fairly poor specificity (31.81%, 23.46%) and PPV (35.48%, 31.19%), with an accuracy of 42.8% and 45.8%, respectively. Horvath TI-RADS had better accuracy of 66.9% and somewhat improved specificity (62.24%), but poorer sensitivity (80%). Russ’ French TI-RADS includes elastography in the risk assessment strategy. This classification proved superior in all aspects (Se: 91.42%, Sp:82.65%, NPV:96.42%, PPV:65.30%, and Acc of 84.96%). The mean strain ratio (SR) value for malignant lesions was 5.56, while the mean SR value for benign ones was significantly lower, 2.54 (p < 0.05). It also correlated well with the response variable: histopathological result (p < 0.001). Although, adding 4D vascularity to the French score generated a similar calculated accuracy and from a statistical point of view, the parameter itself proved beneficial for predicting the malignancy risk (p < 0.001) and may add important knowledge in uncertain situations. Advanced ultrasound techniques definitely improved the risk estimation and should be used more extensively.

Which Is the Best Reference Tissue for Strain Elastography in Predicting Malignancy in Thyroid Nodules, the Sternocleidomastoid Muscle or the Thyroid Parenchyma?

OBJECTIVES

This study aimed to compare 2 types of strain ratios (SRs) in thyroid nodules. Two reference points were used: the sternocleidomastoid (SCM) muscle and the thyroid parenchyma.

METHODS

A total of 101 nodules in 83 patients were prospectively enrolled in the study. For the semiquantitative analysis, 2 types of SRs were used: SR1, the ratio of the SCM muscle strain to the thyroid nodule strain; and SR2, the ratio of the surrounding normal thyroid tissue strain to the thyroid nodule strain. For each nodule, the SR1 and SR2 elastographic values were calculated, and their averages were compared.

RESULTS

Eighty-one (80.2%) of 101 thyroid nodules were benign, and 20 (19.8%) were malignant. In both benign and malignant histopathologic types, the SR1 averages were significantly higher than the SR2 averages (P = .001; P < .001, respectively). Both the SR1 and SR2 values were found to be significantly successful in differentiating benign from malignant histopathologic types (P < .001 for both). The areas under the curve were then compared for the methods, and the difference was found to be statistically significant (P = .046). The diagnostic accuracy of the SR1 was superior to that of the SR2.

CONCLUSIONS

The SR1 and SR2 are effective adjunctive diagnostic tools for identifying malignant thyroid nodules. Using the SCM muscle as a reference point instead of thyroid tissue may be a more valuable way to measure SRs.

Shear wave versus strain elastography in the differentiation of benign and malignant breast lesions

Background/aim

To evaluate and compare the diagnostic performances of shear wave elastography (SWE) and strain elastography (SE) in the differentiation of benign and malignant breast lesions.

Materials and methods

The current study included 87 breast lesions in 84 patients. The Breast Imaging Reporting and Data System (BIRADS) categories were determined with ultrasound features. The maximum shear wave velocity (SWV), mean SWV, maximum SWV to fat SWV ratio, and mean SWV to fat SWV ratio were measured using SWE. The strain ratio (SR) was calculated as the ratio of lesion strain to the adjacent fat strain using SE. Receiver operating characteristic (ROC) curves were constructed to assess and compare the diagnostic performances of each parameter.

Results

Forty-five benign and 42 malignant lesions were diagnosed. The sensitivity and specificity of the BIRADS classification was 100% and 35.6%, respectively. Selecting a cutoff SR value of 3.22 led to an 88.1% sensitivity and an 88.4% specificity (AUC: 0.913 [95% CI: 0.854–0.971], P < 0.001). Selecting cutoff maximum SWV value of 3.41 m/s led to an 88.1% sensitivity and an 86.7% specificity (AUC: 0.918 [95% CI: 0.858–0.978], P < 0.001). The diagnostic performance of the maximum SWV, mean SWV, and maximum SWV to fat SWV ratio were similar to the diagnostic performance of the SR (P = 1.00, P = 1.00, P = 0.629, respectively).

Conclusion

SE and SWE are both feasible imaging modalities in the differentiation of malignant and benign breast lesions with similar diagnostic performances.

Expression of BANCR promotes papillary thyroid cancer by targeting thyroid stimulating hormone receptor

Papillary thyroid carcinoma (PTC) is the most common form of non-medullary thyroid cancer, accounting for ~80% of all cases of thyroid cancer. The aim of the present study was to explore the role of BRAF-activated long noncoding RNA (BANCR) in the development of PTC. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the mRNA expression levels of BANCR, thyroid-stimulating hormone receptor (TSHR) and cyclin D1 between PTC and benign control thyroid nodule tissue samples from 60 patients were determined. Using RT-qPCR and western blot analysis, the expression levels of TSHR and cyclin D1 mRNA and protein were determined in cells transfected with BANCR-small interfering (si)RNA. An MTT assay and flow cytometry were used to analyze the effect of BANCR knockdown on the proliferation and cell cycle distribution of IHH-4 PTC cells. The expression of BANCR, TSHR and cyclin D1 was increased in the PTC group compared with the control group based on the RT-qPCR data. The transfection of IHH-4 cells with BANCR-siRNA induced the inhibition of TSHR and cyclin D1 expression compared with a transfection control. In addition, the proliferation of the IHH-4 cells transfected with BANCR-siRNA was suppressed, relative to the transfection control, and cells arrested in the G0/G1 phase, potentially due to the inhibition of the expression of cyclin D1. The data suggested that the expression of BANCR may promote the development of malignant thyroid nodules via the modulation of TSHR expression and its downstream effector, cyclin D1.

Strain Elastography - How To Do It?

Tissue stiffness assessed by palpation for diagnosing pathology has been used for thousands of years. Ultrasound elastography has been developed more recently to display similar information on tissue stiffness as an image. There are two main types of ultrasound elastography, strain and shear wave. Strain elastography is a qualitative technique and provides information on the relative stiffness between one tissue and another. Shear wave elastography is a quantitative method and provides an estimated value of the tissue stiffness that can be expressed in either the shear wave speed through the tissues in meters/second, or converted to the Young's modulus making some assumptions and expressed in kPa. Each technique has its advantages and disadvantages and they are often complimentary to each other in clinical practice. This article reviews the principles, technique, and interpretation of strain elastography in various organs. It describes how to optimize technique, while pitfalls and artifacts are also discussed.

WFUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography: Part 4. Thyroid

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced guidelines for the use of elastography techniques including basic science, breast and liver. Here we present elastography in thyroid diseases. For each available technique, procedure, reproducibility, results and limitations are analyzed and recommendations are given. Finally, recommendations are given based on the level of evidence of the published literature and on the WFUMB expert group's consensus. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of thyroid diseases.

Prediction of cervical lymph node metastasis in patients with papillary thyroid cancer using combined conventional ultrasound, strain elastography, and acoustic radiation force impulse (ARFI) elastography

OBJECTIVES

To investigate the value of combined conventional ultrasound (US), strain elastography (SE) and acoustic radiation force impulse (ARFI) elastography for prediction of cervical lymph node metastasis (CLNM) in papillary thyroid cancer (PTC).

METHODS

A consecutive series of 203 patients with 222 PTCs were preoperatively evaluated by US, SE, and ARFI including virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ). A multivariate analysis was performed to predict CLNM by 22 independent variables. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance.

RESULTS

Multivariate analysis demonstrated that VTI area ratio (VAR) > 1 was the best predictor for CLNM, followed by abnormal cervical lymph node (ACLN), capsule contact, microcalcification, capsule involvement, and multiple nodules (all P < 0.05). ROC analyses of these characteristics showed the areas under the curve (Az), sensitivity, and specificity were 0.600-0.630, 47.7 %-93.2 %, and 26.9 %-78.4 % for US, respectively; and they were 0.784, 83.0 %, and 73.9 %, respectively, for VAR > 1. As combination of US characteristics with and without VAR, the Az, sensitivity, and specificity were 0.803 and 0.556, 83.0 % and 100.0 %, and 77.6 % and 11.2 %, respectively (P < 0.001).

CONCLUSIONS

ARFI elastography shows superior performance over conventional US, particularly when combined with US, in predicting CLNM in PTC patients.

KEY POINTS

• Conventional ultrasound is useful in predicting cervical lymph node metastasis preoperatively. • Virtual touch tissue imaging area ratio is the strongest predicting factor. • Predictive performance is markedly improved by combining ultrasound characteristics with VAR. • Acoustic radiation force impulse elastography may be a promising complementary tool.

Assessment of Diffuse Thyroid Disease by Strain Ratio in Ultrasound Elastography

The goal of this study was to explore the value of strain ratio from real-time elastography in the semi-quantitative assessment of diffuse thyroid disease. Fifty-one patients with primary hyperthyroidism, 70 with Hashimoto's thyroiditis, 8 with subacute thyroiditis and 43 with normal healthy thyroids were recruited to measure the strain ratio (SR) of thyroid tissue and sternocleidomastoid muscle (on the same side of the thyroid). SR values of all groups were subjected to statistical analysis. The SRs (mean ± standard deviation) of patients with hyperthyroidism, Hashimoto's thyroiditis and subacute thyroiditis were 2.30 ± 1.08, 7.04 ± 7.74 and 24.09 ± 13.56, respectively. The SR of the control group was 1.76 ± 0.54. SR values ranked in ascending order were control group < hyperthyroidism group < Hashimoto's thyroiditis group < subacute thyroiditis group. There were statistically significant (p < 0.05) differences in thyroid hardness between groups with different diffuse thyroid diseases. SR values of the hyperthyroidism and control groups did not statistically differ (p > 0.05). It is feasible to assess diffuse thyroid disease with strain ratios obtained with ultrasound elastography.

Comparison of intrahepatic vein-to-liver parenchyma and intercostal muscle-to-liver parenchyma strain ratios in the assessment of liver fibrosis: which one should we use?

PURPOSE

The aims of this study were to investigate whether there is a difference in diagnostic value between vein to parenchyma strain ratio (VPSR) and muscle to parenchyma strain ratio (MPSR).

METHODS

VPSR and MPSR were calculated via sonoelastography, and were recorded for comparison with histopathology. ROC analysis, the Mann-Whitney U test, the Kruskal-Wallis test, and Spearman's rank correlation test were used for statistical analysis.

RESULTS

The study included 59 cases of individuals who underwent biopsy (29 women, 30 men). When the threshold value for VPSR was set at 3.23, the sensitivity was 96.2% and the specificity was 83.3% (p < 0.001, F ≥ 1). When the threshold value was set at 3.01 for MPR, the sensitivity was 88.7% and the specificity was 83.3% (p < 0.001, F ≥ 1). The areas under the curve values were VPSR 0.95 and MPSR 0.92 for F ≥ 1, VPSR 0.94 and MPSR 0.92 for F ≥ 2, and VPSR 1.00 and MPSR 0.76 for F = 3 (p < 0.001). The Spearman's correlation coefficient was 0.75, and a high positive concordance was found between VPSR and MPSR (p < 0.001).

CONCLUSIONS

In this study, a high positive correlation was observed between two strain ratios, and VPSR was found to be more reliable than MPSR in determining liver fibrosis.