The application of Virtual Touch tissue quantification (VTQ) in diagnosis of thyroid lesions: A preliminary study

Comparative evaluation of shear wave elastography elasticity values in thyroid nodules with cytology results and TI-RADS scoring in differentiation of benign-malignant nodules

PURPOSE

The aim of this prospective study was to investigate the diagnostic performance of shear wave elastography (SWE) in differentiating benign and malignant thyroid nodules and their correlation with the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS).

METHODS

This prospective study included 370 thyroid nodules in 308 patients aged 18-70 years. All the patients underwent B-mode ultrasound (US), Doppler examination, and SWE and were given an ACR TI-RADS risk score before fine needle aspiration biopsy (FNAB) and/or surgery. The correlation between SWE parameters and ACR TI-RADS categories was investigated statistically and compared with histopathologic results. Additionally, the diagnostic performance of SWE was evaluated to distinguish malignant and benign thyroid nodules.

RESULTS

One hundred and thirty-five of the 370 thyroid nodules were malignant, and 235 nodules were benign. The mean shear wave velocity (SWV) value of the malignant nodules (3.70 ± 0.98 m/s) was statistically higher than that of the benign nodules (2.70 ± 0.37 m/s). The best cutoff value of the mean SWV for differentiating benign and malignant nodules was found to be 2.94 m/s (sensitivity 90.4%, specificity 89.9%, positive predictive value 81.3%, negative predictive value 94.1%, p < 0.001). The average score of the nodules according to the ACR TI-RADS was 3.57 ± 1.83 in benign nodules and 7.38 ± 2.69 in malignant nodules (p ≤ 0.001).

CONCLUSION

This study showed that combining SWE and TI-RADS improves the specificity of TI-RADS alone in differentiating benign and malignant nodules.

Association between diagnostic efficacy of acoustic radiation force impulse for benign and malignant thyroid nodules and the presence or absence of non-papillary thyroid cancer: A meta-analysis

Purpose

The aim of this study was to investigate the diagnostic efficacy of Acoustic Radiation Force Impulse (ARFI) for benign and malignant thyroid nodules in the presence and absence of non-papillary thyroid cancer (NPTC) and to determine the cut-off values of Shear Wave Velocity (SWV) for the highest diagnostic efficacy of Virtual Touch Quantification (VTQ) and Virtual Touch Tissue Imaging and Quantification (VTIQ).

Methods

The diagnostic accuracy of ARFI for benign and malignant thyroid nodules was assessed by pooling sensitivity, specificity and area under the curve (AUC) in each group in the presence and absence of both non-papillary thyroid glands, using histology and cytology as the gold standard. All included studies were divided into two groups according to VTQ and VTIQ, and each group was ranked according to the magnitude of the SWV cutoff value to determine the SWV cutoff interval with the highest diagnostic efficacy for VTQ and VTIQ.

Results

A total of 57 studies were collected on the evaluation of ARFI for the diagnosis of benign and malignant thyroid nodules. The results showed that the presence of non-papillary thyroid carcinoma led to differences in the specificity of VTIQ for the identification of benign and malignant thyroid nodules, and the differences were statistically significant. In addition, the diagnostic efficacy of VTQ was best when the cutoff value of SWV was in the interval of 2.48-2.55 m/s, and the diagnostic efficacy of VTIQ was best when the cutoff value of SWV was in the interval of 3.01-3.15 m/s.

Conclusion

VTQ and VTIQ have a high diagnostic value for benign and malignant thyroid nodules; however, when the malignant nodules in the study contain non-papillary thyroid carcinoma occupying the thyroid gland, the findings should be viewed in a comprehensive manner.

MALİGN VE BENİGN TIROİD NODÜLLERİNİN AYRIMINDA ARFI ELASTOGRAFİ

AMAÇ: Malign ve benign tiroid nodüllerini ayırd etmede “Acoustic Radiation Force Impulse” (ARFI) elastografinin “virtual touch tissue elastografi” modunun tanısal performansını değerlendirmek MATERYAL VE METOD: Çapı &gt; 5 mm olan ikiyüzdört adet solid ve ağırlıklı solid nodül prospektif olarak ultrasonografi, ARFI elastografinin VTQ modu, ince iğne aspirasyon biyopsisi ve endike olduğunda doku patolojisi ile değerlendirildi. Yüzdoksanaltı nodülde üç makaslama dalgası hızı (shear wave velocity-SWV) ölçümü yapıldı. Her bir nodül için SWV oranı, nodülün SWV'sinin ortalama değerinin komşu parankimin ortalama değerine bölünmesiyle hesaplandı. SWV değeri ve SWV oranının tanısal performansı, ROC analizi ile değerlendirildi. SONUÇLAR: Benign ve malign tiroid nodüllerinde normal parankimdeki ortalama SWV değeri sırasıyla 2,13±0,44 m/s, 2,06±0,80 m/s ve 2,06±0,88 m/s idi. SWVoranları benign tiroid nodülleri için 0.97±0.37 ve malign tiroid nodülleri için 1.02±0.40 idi. Ortalama SWV değerleri (t=0,008) (P=0,994) veya SWV oranları (t=0,596; P=0,527) açısından benign ve malign nodüller arasında anlamlı fark yoktu. Maligniteyi öngörmek için herhangi bir cut-off noktası bulunmadı. Alt grup analizinde, SWV ve SWV oranı için AUC'ler, ˂10 mm ve ≥10 mm nodüller arasında önemli ölçüde farklıydı. Bunun dışında herhangi iki grup arasında anlamlı fark saptanmadı (tümü P&gt;0.05). SWV ve SWV oranı için en iyi cut-off noktaları, &lt;10 mm nodüller için sırasıyla SWV için 2.59 m/s ve SWV oranı için 1.0 idi. SONUÇ: ARFİ görüntülemenin VTQ modu, maligniteyi saptamak için iyi bir tanısal performansa sahip değildir ve gereksiz tiroid biyopsilerinin azaltılmasına katkıda bulunamaz.

Malign ve benign tiroid nodüllerinin ayrımında ARFI elastografi

Aim: To examine the diagnostic performance of virtual touch tissue quantification (VTQ) mode of Acoustic Radiation Force Impulse (ARFI) elastography imaging in differentiating benign and malignant thyroid nodules. Materials and Methods: Two hundred four solid and mostly solid nodules >5mm were prospectively evaluated with ultrasonography, VTQ mode of ARFI elastography, fine needle aspiration biopsy, and when indicated with tissue pathology. Three shear-wave velocities (SWV) measurements were done in 196 nodules. The SWV ratio for each nodule was calculated as the mean value of the SWV of the nodule divided by the mean value of the adjacent parenchyma. The diagnostic performance of SWV value and SWV-ratio were assessed by a receiver-operating characteristic (ROC) curve analysis. Results: The mean SWV value in the normal parenchyma, in benign and malign thyroid nodules, were 2.13±0.44 m/s, 2.06±0.80 m/s, and 2.06±0.88 m/s respectively. The SWV-ratios were 0.97±0.37 for benign thyroid nodules and 1.02±0.40 for malignant thyroid nodules. There was no significant difference between benign and malign nodules in terms of mean SWV values (t=0.008) (P=0.994) or SWV-ratios (t =0.596; P=0.527). No cut-off point was found to predict malignancy. In subgroup analysis, AUCs for the SWV and SWV-ratio were significantly different between nodules ˂10 mm and those ≥10 mm, but not with any other two groups (all P>0.05) (Table-2). The cutoff points for the differential diagnosis were 2.59 m/s for SWV and 1.0 for SWV- ratio respectively for nodules

Are the Currently Available Elastography Methods Useful in the Assessment of Chronic Kidney Disease? A Systematic Review and a Meta-Analysis

Background: We require an quantitative imaging technique for the diagnosis and assessment of chronic kidney disease (CKD). Renal elastography has been widely used in recent years in different studies; however, the results across them are not consistent and, as a result, we conducted a meta-analysis of the published literature on this topic. Methods: The databases of PubMed, Medscape, Medline were searched for all studies published in English from 2010 until November 2021 that evaluated kidney shear wave speed (SWS) by elastography in patients with CKD. Trial design, methodological information, patient characteristics, interventions, results, and outcome data were all collected from each study according to a set protocol. Results: We found 37 publications, yet only 18 studies that utilized point shear wave elastography (Virtual Touch Quantification—VTQ system) were compared because the values achieved using different types of elastography are not evaluable. Finally, 1995 attendees (1241 patients with CKD versus 781 healthy subjects as the control group) were included. When comparing mean values of kidney SWS between studies we found increased heterogeneity Q = 513.133; DF = 10; p < 0001, I2 (inconsistency) = 98.12% (95% CI for I2 97.52–98.57%). With a standardized mean difference of −0.216, patients with CKD have a lower kidney SWS than healthy controls. A positive association between kidney SWS and eGFR was also discovered across the presented studies, with a pooled correlation coefficient of 0.38 (Z = 10.3, p < 0.001), Q = 73.3, DF = 5, p < 000.1, I2 = 93.18% (95% CI for I2 87.86 to 96.18). The pooled area under the ROC curve for kidney SWS to predict chronic kidney disease was 0.831 (95% CI, p < 0.001), Q = 28.32, DF = 6, p = 0.0001, I2 = 78.8% (95% CI for I2 56.37 to 89.72). In the four articles that used the Elast-PQ method, the data presented were insufficient for statistical analysis: area under the curve (AUC) values are used to compare distinct characteristics (differentiating kidney SWS between mildly and moderately impaired kidneys, between non-diabetic/prediabetic/diabetic patients, or kidney SWS between the CKD and control group), therefore not being suitable for further evaluation. Conclusions: The results show that patients with CKD have a lower kidney SWS than healthy controls. However, the number of studies involving renal elastography that have been published is limited and show an increased heterogeneity. Further research is needed to determine which factors actually influence kidney SWS in CKD patients and, as a result, to specify the role and indication of renal elastography in clinical practice.

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.

Comparison of the diagnostic value of virtual touch tissue quantification and virtual touch tissue imaging quantification in infants with biliary atresia

OBJECTIVE

This study aimed to compare the diagnostic performance of vital touch tissue quantification (VTQ) and virtual touch tissue imaging quantification (VTIQ) in diagnosing infants with biliary atresia (BA) from jaundiced infants.

METHODS

In this study, 26 jaundiced infants with BA, 33 jaundiced infants without BA, and 40 normal infants were enrolled. The hepatic shear wave velocity (SWV) of each infant was determined by VTQ and VTIQ examinations, respectively. Then, the receiver operating characteristic (ROC) curves were drawn and the area under the curve (AUC) and optimal cut-off values were calculated to evaluate the sensitivities and specificities of VTIQ and VTQ for BA.

RESULTS

The mean values of SWV of the control group measured by VTQ and VTIQ were (1.09 ± 0.18) m/s and (1.36 ± 0.21) m/s, respectively. The mean values of SWV of the non-BA group measured by VTQ and VTIQ were (1.30 ± 0.28) m/s and (1.52 ± 0.29) m/s, respectively. The mean values of SWV of the BA group measured by VTQ and VTIQ were (2.36 ± 0.36) m/s and (2.43 ± 0.29) m/s, respectively. The diagnostic threshold of VTQ and VTIQ to diagnose BA was 1.77 and 1.92 m/s. The sensitivities of VTQ and VTIQ to diagnose BA were 90.9% and 95.5%. The specificities of VTQ and VTIQ to diagnose BA were 68.4% and 78.9%.

CONCLUSION

Vital touch tissue quantification and VTIQ could help distinguish infants with BA from jaundiced infants by measuring the liver SWV values. VTIQ has higher sensitivity and specificity than VTQ.

Clinical efficacy of novel elastography using acoustic radiation force impulse (ARFI) for diagnosis of malignant thyroid nodules

Objective

Acoustic radiation force impulse (ARFI) imaging is a recent ultrasound elastography technique; consequently, its efficacy is not fully known. In this study, we compared ARFI imaging with conventional strain elastography (SE) and shear wave velocities (SWVs) to evaluate the utility of ARFI imaging for diagnosing thyroid nodules.

Subjects and Methods

In this study we examined 233 thyroid nodules (183 benign nodules and 50 malignant nodules) isolated from human patients. The nodules were evaluated with SE and ARFI imaging, and SWVs of the nodules were simultaneously measured. ARFI images were classified using a four‐point score based on grayscale intensity of the images. The sensitivity, specificity, and diagnostic accuracy were compared between SE and ARFI imaging. Finally, SWVs for each score of SE and ARFI imaging were compared.

Results

The new scoring system for ARFI imaging can be divided into four virtual touch imaging (VTI) scores. Nodules with a VTI score of 3 or 4 as determined by ARFI imaging were determined to be malignant. The sensitivity, specificity, and diagnostic accuracy, respectively, were 63.2%, 66.3%, and 65.6% for SE, compared with 80.0%, 86.3%, and 85.0% for ARFI imaging. The median SWVs of the nodules were 1.57 m/s, 1.73 m/s, 1.88 m/s, and 2.09 m/s for VTI scores of 1, 2, 3, and 4, respectively. The SWVs of VTI scores 3 and 4 were significantly higher than those of VTI scores 1 and 2.

Conclusions

The diagnostic accuracy of ARFI imaging for differentiating malignant thyroid nodules was higher than that of SE. The VTI scores of the nodules accurately reflected their SWVs.

Level of Evidence

4

Is Kidney Stiffness Measured Using Elastography Influenced Mainly by Vascular Factors in Patients with Diabetic Kidney Disease?

Studies published so far using ultrasound-based elastography in the kidneys, lack to prove a clear relationship between kidney shear wave speed (KSWS) and renal disease progression. Taking into account that the kidney is a highly vascularized organ, the present study aims to find a relationship between KSWS and vascular factors (blood pressure [BP], arterial stiffness). Our study included 38 diabetic kidney disease patients (mean age 56.52 ± 16.12 years, 19 female, 19 male). KSWS, an indicator of renal stiffness, was measured using point Shear Wave Elastography (pSWE; Siemens Acuson S2000). In every patient, we recorded BP, and we measured aortic augmentation index (AAI) and brachial pulse wave velocity (PWV), using oscillometry. We found statistically significant indirect correlations of KSWS with indicators of arterial stiffness, such as PWV ( r = -.41, p = .036), and AAI ( r = -.37, p = .031). We found also an indirect correlation of KSWS with diastolic BP ( r = -.65, p = .02) and systolic BP ( r = -.54, p = .008). We found no correlation of KSWS with estimated glomerular filtration rate (eGFR), urinary albumin/creatinine ratio, stage of diabetic retinopathy, or glycated hemoglobin. Our study shows that high BP and the progression of arteriosclerosis (high PWV and AAI), leads to a decrease of renal stiffness. Thus, it seems that KSWS is influenced by renal blood flow, rather than other factors, such as albuminuria or chronic kidney disease stage.

Role of Virtual Touch Tissue Quantification in Hashimoto's Thyroiditis

We investigated the role of the virtual touch tissue quantification (VTQ) technique in diagnosing Hashimoto's thyroiditis (HT) and in distinguishing various HT-related thyroid dysfunctions. Two hundred HT patients and 100 healthy volunteers (the control group) were enrolled. The diagnostic performance of VTQ in predicting HT was calculated as the area under the receiver operating characteristic curve (A_Z). The HT patients were further classified into three subgroups on the basis of serologic tests of thyroid function: hyperthyroidism, euthyroidism and hypothyroidism. Comparisons of shear wave velocity (SWV) between three subgroups were evaluated by analysis of variance. The mean SWV of the control group was significantly lower than that of the HT group (1.93 ± 0.33 m/s vs. 2.32 ± 0.49 m/s, p <0.001). A_z was 0.734 with a cut-off value of 1.86 m/s for performance of SWV in distinguishing between HT and a healthy thyroid; the sensitivity and specificity were 82.5% and 50.0%, respectively. Mean SWV values in the three HT subgroups (hyperthyroidism [2.07 ± 0.37 cm/s] vs. euthyroidism [2.20 ± 0.40 cm/s] vs. hypothyroidism [2.49 ± 0.46 cm/s]) were significantly different (p <0.05). Our results suggest that VTQ is a promising technique for assessing HT and HT-related thyroid dysfunction.

The Preciseness in Diagnosing Thyroid Malignant Nodules Using Shear-Wave Elastography

Our study aimed to identify more accurate results about the diagnostic role of shear-wave elastography (SWE) for thyroid malignant nodules through a meta-analysis.

Potential articles were searched in PubMed, Embase, and the Cochrane Library databases. Overall sensitivity and specificity with 95% confidence intervals (CIs) was used to represent the diagnostic accuracy of SWE. Summary receiver operating characteristic (ROC) curve was constructed to illustrate the results. In addition, χ² and I² tests were performed to assess heterogeneity. A value of p≤0.05 indicated significant heterogeneity. All the analysis was conducted in Meta-DiSc version 1.4 software.

Twenty studies were included in the analysis. There were a total of 2,907 patients and 3,397 thyroid nodules included in the meta-analysis. Overall sensitivity and specificity were 0.68 (95% CI: 0.66–0.70) and 0.85 (95% CI: 0.84–0.87), respectively. The results showed the area under curve (AUC) was 0.9041, suggesting high accuracy of SWE for differentiating benign and malignant thyroid nodules.

SWE showed high accuracy in identifying thyroid malignant nodules, suggesting it could serve as a diagnostic biomarker in thyroid nodules.

Ultrasound-Based Shear Wave Elastography in the Assessment of Patients with Diabetic Kidney Disease

In previous studies of acoustic radiation force impulse (ARFI) elastography, using Virtual Touch tissue quantification (VTQ) (Siemens Acuson S2000), it was reported that the measurement of renal shear wave speed in patients with chronic kidney disease (CKD) is not influenced exclusively by renal fibrosis. The purpose of the present study was to analyze the role of VTQ in patients with diabetic kidney disease, considered the main cause of CKD. The study group included 164 patients: 80 patients with diabetic kidney disease (DKD) and 84 without renal disease or diabetes mellitus. In each subject in lateral decubitus, five valid VTQ measurements were performed in each kidney and a median value was calculated, the result being expressed in meters/second. The following means of the median values were obtained In DKD patients, the means of the median values were for VTQ right kidney, 2.21 ± 0.71 m/s, and for VTQ left kidney, 2.13 ± 0.72 m/s, whereas in the normal controls statistically significant higher values were obtained: 2.58 ± 0.78 m/s for VTQ right kidney (p = 0.0017) and 2.46 ± 0.81 m/s for VTQ left kidney (p = 0.006). Patients with an estimated glomerular filtration rate (eGFR) >60 mL/min (DKD stages 1 and 2 together with normal controls) had a significantly higher kidney shear wave speed compared with patients with an eGFR <60 mL/min (2.53 m/s vs. 2.09 m/s, p < 0.05). In the DKD group, there was a significant correlation between eGFR and VTQ levels for the right kidney (r = 0.28, p = 0.04). There was no correlation of VTQ values with proteinuria level, stage of diabetic retinopathy or glycated hemoglobin. Our study indicates that shear wave speed values in patients with diabetic kidney disease and eGFRs <60 mL/min are significantly lower compared with those of patients with eGFRs >60 mL/min (either normal controls or diabetic patients with DKD stages 1 and 2), and values decrease with the decrease in eGFR. However, proteinuria, diabetic retinopathy and glycated hemoglobin have no influence on VTQ.

Virtual touch tissue imaging and quantification (VTIQ) in the evaluation of thyroid nodules: the associated factors leading to misdiagnosis

To evaluate the associated factors leading to misdiagnosis with VTIQ for differentiation between benign from malignant thyroid nodules (TNs). The study included 238 benign TNs and 150 malignant TNs. Conventional ultrasound (US) features and VTIQ parameters were obtained and compared with the reference standard of histopathological and/or cytological results. Binary logistic regression analysis was performed to select independent variables leading to misdiagnosis. The maximum shear wave speed (SWS) (SWS-max), mean SWS (SWS-mean), SWS-ratio and standard deviation of SWS (SWS-_SD) were significantly higher for malignant TNs compared with benign TNs (all P < 0.001). SWS-mean achieved the highest diagnostic performance with a cut-off value of 3.15 m/s. False positive rate was 13.4% (32/238) while false negative rate was 35.3% (53/150). Intranodular calcification (OR: 1.715) was significantly associated with false positive VTIQ findings, while nodule size (OR: 0.936) and echotexture of the thyroid gland (OR: 0.033) were negatively associated with them. Nodule depth (OR: 0.881) and TI-RADS category (OR: 0.563) were negatively associated with false negative VTIQ findings. These US characteristic of TNs should be taken into consideration when interpreting the results of VTIQ examinations.

Virtual Touch Tissue Imaging and Quantification in the Evaluation of Thyroid Nodules

OBJECTIVES

To investigate the diagnostic performance of a 2-dimensional shear wave elastographic technique (Virtual Touch tissue imaging and quantification [VTIQ]; Siemens Medical Solutions, Mountain View, CA) for predicting thyroid malignancy.

METHODS

A total of 302 thyroid nodules underwent conventional sonography and VTIQ before fine-needle aspiration examination or surgery. Compared with histopathologic or cytologic results in combination with follow-up, the diagnostic performance of various shear wave speed (SWS) indices (minimum [SWS_min ], maximum [SWS_max ], and mean [SWS_mean ]) on VTIQ as well as conventional sonographic features for predicting thyroid malignancy was evaluated in all of the nodules.

RESULTS

Sixty-five malignant and 237 benign thyroid nodules were histopathologically or cytologically confirmed. All SWS indices on VTIQ were lower in benign nodules than thyroid malignancy (all P < .001). For discrimination between malignant and benign nodules, all VTIQ SWS indices were better than conventional sonographic features, such as a solid component, a taller-than-wide shape, microcalcification, a poorly defined margin and hypoechogenicity, in predicting thyroid malignancy (all P < .05). By applying a cutoff SWS_mean value of 2.60 m/s, VTIQ achieved sensitivity and negative predictive values of 84.6% and 94.3%, respectively, for differentiating nodules. The areas under the receiver operating characteristic curve of SWS_max (0.862 versus 0.717), SWS_min (0.866 versus 0.717), and SWS_mean (0.891 versus 0.725) for nodules larger than 10 mm were higher than those for nodules of 10 mm or smaller (all P < .05). Interoperator and intraoperator reproducibility was proven to be excellent, with all interclass correlation coefficient values higher than 0.80 (range, 0.813-0.905) CONCLUSIONS: Virtual Touch tissue imaging and quantification is a useful and reproducible tool for predicting thyroid malignancy.

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.

Reproducibility of Acoustic Radiation Force Impulse Imaging in Thyroid and Salivary Glands with Experienced and Inexperienced Examiners

Acoustic radiation force impulse (ARFI) imaging enables the sonographic measurement of tissue stiffness. The aim of this study was to evaluate if experience in ARFI imaging influences the reproducibility of ARFI imaging of the head and neck. Three experienced sonographers and three inexperienced sonographers performed ARFI imaging of thyroid, submandibular and parotid glands in 10 healthy volunteers. The examination was repeated after 2 wk. Ten single ARFI measurements were done in every gland. Inter-rater and intra-rater reliability was analyzed using the intra-class correlation coefficient (ICC). Moderate agreement was observed between experienced and inexperienced examiners (ICC = 0.46). In salivary glands, agreement was fair between the groups (ICC = 0.33), whereas in separate evaluations, inter-rater reliability in the submandibular glands was moderate (ICC = 0.52), and that in the parotid glands, only poor (ICC = 0.09). For ARFI imaging of the thyroid gland, there was moderate agreement between the groups (ICC = 0.50). The intra-rater reliability for the salivary and thyroid glands together and separately was strong in both groups. ARFI imaging of the thyroid and salivary glands did exhibit good reproducibility. ARFI imaging of the thyroid gland reached the highest levels of inter- and intra-observer agreement in both groups. ARFI imaging in salivary glands is only reproducible with experienced examiners.

Calcification of thyroid nodules increases shear-wave speed (SWS) measurement: using multiple calcification-specific SWS cutoff values outperforms a single uniform cutoff value in diagnosing malignant thyroid nodules

Conventional ultrasound cannot satisfactorily distinguish malignant and benign thyroid nodules. Shear-wave elastography (SWE) can evaluate tissue stiffness and complement conventional ultrasound in diagnosing malignant nodules. However, calcification of nodules may affect the results of SWE. The purposes of this study are to compare the differences of shear-wave speed (SWS) measurement among different calcification groups and compare the diagnostic performance between using a single uniform SWS cutoff value and multiple individual calcification-specific cutoff values using technique of point SWS measurement. We retrospectively identified 517 thyroid nodules (346 benign and 171 malignant nodules) examined by conventional ultrasound and point SWS measurement. There were 177 non-calcified, 159 micro-calcified and 181 macro-calcified nodules. The diagnostic performance was evaluated by receiver operating characteristic (ROC) curve and area under the curve (AUC) was computed. The mean SWS in malignant nodules more than doubled that of benign nodules (4.81±2.03 m/s vs. 2.29±0.99 m/s, p<0.001). The mean SWS of nodules progressively increased from the non-calcification (2.60±1.49 m/s), to micro-calcification (3.27±1.85 m/s) and to macro-calcification (3.68±2.26 m/s) groups (p<0.001), which was true in both the benign and malignant nodules. If we used individual SWS cutoff values for non- (SWS >2.42 m/s), micro- (SWS >2.88 m/s) and macro-calcification (SWS >3.59 m/s) nodules in the whole group, the AUC was 0.859 (95% confidence interval [CI], 0.826-0.888), which was significantly better than the AUC of 0.816 (95% CI, 0.780-0.848) if a single uniform cutoff value (SWS >2.72 m/s) was applied to all the nodules regardless of calcification status (p=0.011). The cutoff values of SWS for different calcified nodules warrant future prospective validation.

Quantitative Shear Wave Velocity Measurement on Acoustic Radiation Force Impulse Elastography for Differential Diagnosis between Benign and Malignant Thyroid Nodules: A Meta-analysis

The aim of this study was to evaluate the diagnostic performance of quantitative shear wave velocity (SWV) measurement on acoustic radiation force impulse (ARFI) elastography for differentiation between benign and malignant thyroid nodules using meta-analysis. The databases of PubMed and the Web of Science were searched. Studies published in English on assessment of the sensitivity and specificity of ARFI elastography for the differentiation of thyroid nodules were collected. The quantitative measurement of ARFI elastography was evaluated by SWV (m/s). Meta-Disc Version 1.4 software was used to describe and calculate the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio and summary receiver operating characteristic curves. We analyzed a total of 13 studies, which included 1,854 thyroid nodules (including 1,339 benign nodules and 515 malignant nodules) from 1,641 patients. The summary sensitivity and specificity for differential diagnosis between benign and malignant thyroid nodules by SWV were 0.81 (95% confidence interval [CI]: 0.77-0.84) and 0.84 (95% CI: 0.81-0.86), respectively. The pooled positive and negative likelihood ratios were 5.21 (95% CI: 3.56-7.62) and 0.23 (95% CI: 0.17-0.32), respectively. The pooled diagnostic odds ratio was 27.53 (95% CI: 14.58-52.01), and the area under the summary receiver operating characteristic curve was 0.91 (Q* = 0.84). In conclusion, SWV measurement on ARFI elastography has high sensitivity and specificity for differential diagnosis between benign and malignant thyroid nodules and can be used in combination with conventional ultrasound.

Applicability of shear wave elastography of the major salivary glands: values in healthy patients and effects of gender, smoking and pre-compression

Our aim in this study was to determine normal shear wave elastography (SWE) values for the parenchyma of the major salivary glands and to evaluate the influences of gender, smoking, side and type of gland and varying amounts of ultrasound probe pressure on SWE values. Twenty-five consecutive healthy patients were examined with ultrasound. SWE velocities were measured with acoustic radiation force imaging in the hilum and central region of both glands with "normal" and very low pressure. Mean SWE velocities were 1.854 m/s for the parotid gland and 1.932 m/s for the submandibular gland. No statistically significant differences were detected between males and females, smokers and non-smokers, parotid and submandibular gland and left and right sides. Greater pre-compression with the ultrasound probe resulted in a statistically significant increase in the SWE values of both salivary glands (p < 0.000). The degree of pre-compression by the ultrasound transducer should be standardized, so that the reliability and reproducibility of this innovative method can be improved.

Acoustic radiation force impulse imaging (ARFI) for differentiation of benign and malignant thyroid nodules--A meta-analysis

OBJECTIVES

Work-up of thyroid nodules remains challenging. Acoustic radiation force impulse imaging (ARFI)-generated shear wave elastography, which can measure quantitatively tissue stiffness (virtual touch tissue quantification) is used as a complement to conventional sonography for improving the diagnosis of thyroid nodules. This meta-analysis was performed to expand on a previous meta-analysis to assess the diagnostic power of ARFI in differentiating benign and malignant thyroid nodules.

METHODS

The MEDLINE, PubMed, SpringerLink databases up to December 31, 2014, were searched. The pooled sensitivity, specificity, and summary receiver operating characteristic curve were obtained from individual studies with a random effects model.

RESULTS

Sixteen studies that included a total of 2436 nodules in 2147 patients for ARFI studies were analyzed. The overall mean sensitivity and specificity of ARFI for differentiation of thyroid nodules were 0.80 (95% confidence interval [CI], 0.73-0.87) and 0.85 (95% CI, 0.80-0.90), respectively. A significant heterogeneity was found for both sensitivity and specificity of the different studies (P<0.001). The area under the curve for the ARFI was 0.91.

CONCLUSIONS

ARFI has high sensitivity and specificity for identification of thyroid. This technique might be useful to select patients with thyroid nodules for surgery.

Diagnosis of thyroid nodules using virtual touch tissue quantification value and anteroposterior/transverse diameter ratio

This paper proposes an effective approach to differential diagnosis of thyroid nodules using a hierarchical classification model based on the Virtual Touch tissue quantification (VTQ) value and anteroposterior/transverse diameter (A/T) ratio. One hundred twenty nodules (92 benign, 28 malignant) were analyzed using this approach by combining the quantitative elastic characteristic with the conventional sonographic feature. First, nodules were classified as benign (VTQ values <2.27 m/s), malignant (VTQ values >2.73 m/s) and indeterminate (2.27 m/s ≤ VTQ values ≤2.73 m/s) using two cutoff points selected on the basis of receiver operating characteristic analysis. Second, the indeterminate nodules were separated into malignant and benign nodules using an A/T ratio ≥1. The advantage of this approach was that it could alleviate the limitation of an overlap in VTQ values between benign and malignant nodules. According to the pathologic results, the accuracy of this approach was 95%. The proposed approach may potentially improve diagnostic accuracy.

Acoustic radiation force impulse elastography for differentiation of benign and malignant thyroid nodules with concurrent Hashimoto's thyroiditis

The purpose of the study was to explore the diagnostic performance of acoustic radiation force impulse (ARFI) elastography in differential diagnosis between benign and malignant thyroid nodules in patients with coexistent Hashimoto's thyroiditis (HT). A total of 141 pathological proven nodules in 141 HT patients (7 males and 134 females, mean age 50.1 years, range 23-75 years) received conventional ultrasound (US), elasticity imaging (EI) and ARFI elastography, including virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ), before surgery. Shear wave velocity (SWV) and SWV ratio were measured for each nodule on VTQ. The US, EI and ARFI elastography features were compared between benign and malignant nodules in HT patients. Receiver operating characteristic curve (ROC) analyses and area under curve (AUC) were performed to assess the diagnostic performance. Pathologically, 70 nodules were benign and 71 nodules were malignant. Significant differences were found between benign and malignant nodules in HT patients for EI (EI score) and ARFI (VTI grade and SWV) (all P value <0.05). The AUCs for EI, VTI, SWV and SWV ratio were 0.68 [95% confidence interval (CI): 0.59-0.77], 0.90 (95% CI: 0.84-0.95), 0.77 (95%CI: 0.70-0.85) and 0.74 (95%CI: 0.66-0.82), respectively. The cut-off points were EI score ≥3, VTI grade ≥4, SWV ≥2.58 m/s and SWV ratio ≥1.03, respectively. In conclusion, ARFI elastography is useful for differentiation between benign and malignant thyroid nodules in HT patients. The diagnostic performance of ARFI elastography is better than EI.

Comb-push ultrasound shear elastography (CUSE) for evaluation of thyroid nodules: preliminary in vivo results

In clinical practice, an overwhelming majority of biopsied thyroid nodules are benign. Therefore, there is a need for a complementary and noninvasive imaging tool to provide clinically relevant diagnostic information about thyroid nodules to reduce the rate of unnecessary biopsies. The goal of this study was to evaluate the feasibility of utilizing comb-push ultrasound shear elastography (CUSE) to measure the mechanical properties (i.e., stiffness) of thyroid nodules and use this information to help classify nodules as benign or malignant. CUSE is a fast and robust 2-D shear elastography technique in which multiple laterally distributed acoustic radiation force beams are utilized simultaneously to produce shear waves. Unlike other shear elasticity imaging modalities, CUSE does not suffer from limited field of view (FOV) due to shear wave attenuation and can provide a large FOV at high frame rates. To evaluate the utility of CUSE in thyroid imaging, a preliminary study was performed on a group of five healthy volunteers and 10 patients with ultrasound-detected thyroid nodules prior to fine needle aspiration biopsy. The measured shear wave speeds in normal thyroid tissue and thyroid nodules were converted to Young's modulus (E), indicating a measure of tissue stiffness. Our results indicate an increase in E for thyroid nodules compared to normal thyroid tissue. This increase was significantly higher in malignant nodules compared to benign. The Young's modulus in normal thyroid tissue, benign and malignant nodules were found to be 23.2 ±8.29 kPa, 91.2±34.8 kPa, and 173.0±17.1 kPa, respectively. Results of this study suggest the utility of CUSE in differentiating between benign and malignant thyroid nodules.

Factors that influence kidney shear wave speed assessed by acoustic radiation force impulse elastography in patients without kidney pathology

Our aim was to assess kidney shear wave speed by means of acoustic radiation force impulse (ARFI) elastography in patients without kidney pathology ("normal" patients) and to identify the factors that influence it. We analyzed 91 "normal" patients in whom kidney shear wave speed was assessed by means of ARFI elastography. Five valid ARFI elastographic measurements were obtained in all "normal" patients in both kidneys. In univariate analysis, age (r = -0.370, p = 0.003), gender (female vs. male, r = -0.305, p = 0.003) and measurement depth (r = -0.285, p = 0.01) were significantly correlated with kidney shear wave speed values assessed by ARFI elastography, whereas body mass index, kidney length and renal parenchyma thickness were not correlated. In multivariate analysis, only age (p = 0.006) and gender (p = 0.03) were significantly correlated with kidney shear wave speed values. In conclusion, kidney shear wave speed values assessed by ARFI elastography in "normal" patients are influenced mainly by age and gender and less by measurement depth.

Diagnostic performance of shear wave elastography in the identification of malignant thyroid nodules: a meta-analysis

OBJECTIVE

This meta-analysis aimed to assess the performance of shear wave elastography (SWE) in the identification of malignant thyroid nodules.

METHODS

Web of Science, Scopus, PubMed, and the references of narrative reviews were searched for relevant studies with a publication date through October 2013. The methodological quality was assessed using QUADAS tools. Data synthesis was calculated using the bivariate mixed-effects regression model.

RESULTS

Of the 131 studies identified, 15 (11.5 %) were included, in which SWE, point-SWE or 2D SWE, was used to evaluate 1,867 thyroid nodules in 1,525 patients. Methodological assessment revealed study quality was moderate to high. The pooled sensitivity, specificity, and area under the summary receiver operating characteristic curve of SWE for detecting malignant thyroid nodules were 84.3 % (95 % confidence interval [CI], 76.9-89.7 %), 88.4 % (95 % CI, 84.0-91.7 %), and 93 % (95 % CI, 90-95 %), respectively. As a screening tool, positive and negative predictive values were 27.7-44.7 % and 98.1-99.1 %, respectively, calculated with a malignance prevalence of 5-10 % in thyroid nodules. A publication bias regression test revealed no significant small-study bias.

CONCLUSIONS

SWE is a highly accurate diagnostic modality for the identification of malignant thyroid nodules, with promise for integration into routine imaging protocols for thyroid nodules.

KEY POINTS

• Shear wave elastography (SWE) is a group of novel ultrasound-based technologies. • Meta-analysis was employed to assess relevant studies of SWE of thyroid nodules. • SWE had high sensitivity and specificity in identifying malignant thyroid nodules. • The high negative predictive value of SWE can reduce unnecessary biopsies.

Use of acoustic radiation force impulse elastography to diagnose acute pancreatitis at hospital admission: comparison with sonography and computed tomography

OBJECTIVES

To compare the diagnostic success rate of acoustic radiation force impulse (ARFI) elastography with those of sonography and computed tomography (CT) for acute pancreatitis at hospital admission.

METHODS

B-mode sonography and ARFI elastography were performed on 88 patients with symptoms of acute pancreatitis and 50 healthy control participants who were admitted to our hospital between February 2013 and July 2013. Acute pancreatitis was verified in the 88 patients based on clinical and laboratory findings. Computed tomography was performed on 41 patients, and the CT results from these patients were compared with those of ARFI elastography. The appearances of the pancreases of the patients were classified into 6 groups using visual color encodings obtained with ARFI elastography. The elasticity values of pancreatic head, body, and tail regions were evaluated with Virtual Touch imaging and Virtual Touch tissue quantification (Siemens Medical Solutions, Mountain View, CA). The success rates of sonography, CT, and ARFI elastography for diagnosing acute pancreatitis at hospital admission were compared.

RESULTS

Forty-six of the 88 patients had a diagnosis of pancreatitis by B-mode sonography; pancreatitis was diagnosed in all patients by ARFI elastography; and 10 of 41 patients could not be diagnosed by CT. The sensitivity and specificity of Virtual Touch tissue quantification were 100% and 98%, respectively, when a cutoff value of 1.63 m/s was used. The control group had color scores of 1 or 2, whereas all patients with pancreatitis had color scores of 3 to 6 on color scale evaluation with Virtual Touch imaging.

CONCLUSIONS

Acoustic radiation force impulse elastography is a rapid, radiation-free, and noninvasive tool for diagnosis of acute pancreatitis at initial hospital admission, with a higher success rate for diagnosis of acute pancreatitis than the grayscale sonography and CT.

Comparison of diagnostic efficacy of contrast-enhanced ultrasound, acoustic radiation force impulse imaging, and their combined use in differentiating focal solid thyroid nodules

BACKGROUND

A key limitation of conventional ultrasound (US) includes poor differentiation of benign from malignant thyroid nodules. Contrast-enhanced US (CEUS) and acoustic radiation force impulse (ARFI) could provide better characterization of focal thyroid nodules; however, no studies have compared their efficacies.

OBJECTIVE

To evaluate the diagnostic efficacy of conventional US,CEUS, ARFI, and their combined use in differentiating focal solid thyroid nodules.

METHODS

One-hundred-forty-six Chinese patients with 175 thyroid nodules (119 benign and 56 malignant) were prospectively enrolled. Each patients underwent conventional US, CEUS and ARFI, respectively. The diagnostic performance of the conventional US, CEUS, ARFI, combined use of either CEUS or ARFI and combined use of the three modalities were assessed and compared using Pathological diagnosis (histological/cytological) as the reference method.

RESULTS

There were no significant differences between individual groups (CEUS vs US, P = 0.279, ARFI vs US, P = 0.372, CEUS vs ARFI, P = 0.849), combined use of US and CEUS or combined use of US and ARFI yielded significant difference compared to US. (combination of US & CEUS vs US, P = 0.021; combination of US & ARFI vs US, P = 0.036). The combination of three modalities significantly improved the diagnostic accuracy compared with either combination of conventional US and CEUS or combination of conventional US and ARFI (P = 0.045 and P  = 0.027, respectively).

CONCLUSIONS

CEUS and ARFI can be used as an additional tool in the diagnostic work up of thyroid nodules. The combination of CEUS with ARFI can significantly improve the diagnostic accuracy.

Phantom experiment and clinical utility of quantitative shear wave elastography for differentiating thyroid nodules

Shear wave elastography (SWE) using acoustic radiation force impulse (ARFI) is a novel ultrasonography technique. The aim of this study was to investigate the clinical usefulness of quantitative SWE for differentiating thyroid nodules. For phantom study, we measured the shear wave velocities (SWVs) of the four spheres of 2- and 1-cm diameters with varying hardness. For clinical study, the SWVs of normal thyroid glands and thyroid nodules, that were classified as benign or malignant according to either cytological or pathological findings, were measured. The SWVs of each thyroid patient were compared with that of a normal thyroid and each other. In phantom study, the SWVs for the 2-cm spheres correlated with the hardness of the targets, whereas the values for the 1-cm spheres did not. In clinical study, 112 nodules identified in 167 patients and 94 normal thyroid glands were analyzed according to the criteria for the study. The nodules included 84 benign nodules, and 28 papillary carcinoma. The mean SWVs of each group were 1.64 ± 0.47 m/s for normal thyroid, 1.88 ± 0.62 m/s for benign nodules and 2.67 ± 0.76 m/s for papillary carcinoma. The SWVs of papillary carcinoma were significantly higher than those of benign nodules (P < 0.001). The area under the ROC curve was 0.809 with a cut-off value of 2.01 m/s. The sensitivity and specificity were 85.7% and 62.0% respectively. Results showed that SWE provides new information on tumor characteristics, such as hardness and larger nodules tended to provide stable measurements.