Shear Wave Elastography

allow tumour positioning and eliminate artefacts during acquisition. The US probe was partially immersed in a nylon pocket water bath and degassed US gel (Skintact ® , Leonhard Lang GmbH, Innsbruck, Austria) was applied to the scanning area for better coupling. Two B-mode and elasticity images, one in the transverse and one in the sagittal plane, at the centre of each tumour were obtained in each acquisition. A total of 144 ultrasound shear wave elastography measurements were performed. An example of an image is shown in Fig. 2.

Abstract: We explored the relationship between shear wave elastography (SWE) findings and papillary thyroid carci- noma (PTC) pathology. BCPAP cells were subcutaneously injected into the thighs of nude mice. The resulting lesions were divided into two groups according to tumor size: diameter 5-10 mm, papillary thyroid microcarcinoma (PTMC) group; diameter 11-15 mm, PTC group. All tumors were examined using SWE. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and microvessel density (MVD) were assessed immunohistochemically. The elastic values (E mean and E max ) on SWE were significantly higher in the PTC group (26.695 ± 5.986 and 41.338 ± 9.643 kPa, respectively) than those in the PTMC group (16.842 ± 5.317 and 23.989 ± 6.315 kPa, respectively; P < 0.05). The PDGF expression and MVD were significantly higher in PTCs than those in PTMCs (P < 0.05). The elastic values were positively correlated with PDGF and MVD (P < 0.05). Maximum tumor diameter was positively correlated with elastic parameters, PDGF, and MVD (P < 0.05). We concluded that tumor stiffness was correlated with PDGF and MVD in PTCs and PDGF might play an important role in PTC development.

Abstract: Objective: To investigate the application of shear wave elastography (SWE) in chronic allograft nephropa- thy. Methods: 82 patients with renal transplantation were all treated with conventional ultrasound and shear wave elastography. Group status: normal renal function group after treating with renal transplantation (Scr <134 mol/L, 36 patients), chronic allograft nephropathy (CAN) group after renal transplantation over 6 months (Scr >134 mol/L, 46 patients). Results: 1. The SWE values of renal cortex in CAN group were higher than those in normal renal func- tion group, P<0.05. 2. There was a positive correlation between SWE values and Scr, and meanwhile, the difference between them was statistically significant, P<0.05. 3. The ROC curves of each SWE value showed that the sensitivity and specificity of Mean were as high as 92.9%. Conclusion: Shear wave elastography is helpful for the judgment of the hardness of chronic allograft nephropathy, which is expected to provide a new, noninvasive and convenient method for the monitoring of renal function and renal hardness after renal transplantation.

Shear wave elastography (Aixplorer Super Sonic) overlays the elastographic image on the B-mode, providing a real-time map of elasticity. The operator should also pay attention not to apply any kind of pressure on the probe [40]. The region of interest (ROI) is positioned on the area of interest (in our case hyperplastic parathyroid gland) and in the surrounding thyroid tissue and surrounding muscle. For each of the ROIs, the ultrasound software calculates the mean, minimum, and maximum stiffness, as well as the standard deviation. It can also provide the elasticity–shear wave ratio (SWR) between two ROIs. There are no elastography scale recommendations for parathyroid evaluation, so thyroid elastography scale can be used and set at 100 kPa [41].

[18] Yoon JH, Lee JM, Joo I, Lee ES, Sohn JY, Jang SK, Lee KB, Han JK and Choi BI. Hepatic fibro- sis: prospective comparison of MR elastogra- phy and US shear-wave elastography for evalu- ation. Radiology 2014; 273: 772-782. [19] Zheng J, Guo H, Zeng J, Huang Z, Zheng B, Ren

It is assumed that pathological mechanisms associated with fibrotic change cause the inflamed tissue to increase stiffness [3–5]. As inflammation in the islets of Langerhans (insulitis) and fibrosis also occur in T1D [8–10], questions arise as to whether the inflammatory process and the asso- ciated alteration in tissue consistency can be measured by shear wave elastography and whether changes can be de- tected even in the prediabetic phase, when an insulitic process is already taking place. As the results of the various elastographic studies show a certain lack of agreement re- garding both examination precision and current clinical relevance [3, 5], this procedure has still to be established for the diagnostic investigation of pancreatic disease.

Abstract: Purpose: The aim of the present study is to evaluate and compare the values of velocities measured by the shear wave elastography (SWE), and those of the liver attenuation index (LAI) determined by the computerized tomography (CT) densitometry, in the nonalcoholic fatty liver disease (NAFLD). In other words, we aimed to com- pare the values of density measured by CT and the stiffness determined by elastography, in the liver steatosis. In addition, it is to investigate the effect of NAFLD on the liver volume. Materials and methods: Forty five cases with hepatosteatosis who had undergone abdominal CT and 50 individuals who did not exist with fatty liver clinically and radiologically, were investigated by ultrasonography (US) and SWE. The liver and spleen attenuation values were then measured in the images of non-contrast CT, and the LAI indices were calculated. Contrast images of abdomen were processed by the CT-Volume software and measurements of liver volume were performed using the interactive and automatic liver segmentation techniques together. Values of the liver volume, LAI, liver dimensions, and the shear wave velocities were determined and recorded in the patients with hepatosteatosis and controls; statistical comparisons were performed then. Results: In the nonalcoholic fatty liver, the mean value of velocity measured by SWE was found to be 1.08 (±0.11) m/s, and that of LAI measured by CT densitometry was 13.68 (±10.6). No cor- relation was observed between these two parameters (P>0.05). A high statistically significant difference between the patient and control groups in terms of the liver volume, LAI values and liver size has been observed (P<0.01). Direct correlations existed between the liver volume and LAI values, and the grades in US, and highly significant differences were determined (P<0.01). The mean values of the liver volume in the patient and control groups were determined to be 1917.4 (±425.9) cm 3 and 1311.4 (±241.4) cm 3 , respectively. A high statistically significant dif-

We searched PubMed, Embase, Web of Science, and the Cochrane Library for studies published between January 1, 1990, and November 30, 2018, to identify articles evaluating SWE for distinguishing malignant and benign liver lesions. The following search strategy including Medical Subject Heading (MeSH) terms and a series of relevant keywords was used: ((liver lesion) OR (liver neo- plasm) OR (liver cancer) OR (hepatic lesion) OR (hep- atic tumor)) AND ((shear wave elastography) OR (SWE) OR (acoustic radiation force impulse) OR (ARFI) OR (virtual touch tissues quantification) OR (VTQ) OR (ultrasound elastography)) AND ((diagnosis) OR (differ- entiation) OR (evaluation) OR (distinguishing) OR (dis- criminate)). We also retrieved the reference lists of related studies manually and searched for other studies that might be omitted in electronic retrieval. The search was limited to journal articles written in English.

Shear wave elastography was performed with a curved 2–5 MHz broadband transducer on a two-port Aixplorer ultrasound system (Supersonic Imagine, Paris, France). A single board-certified radiologist (AES) with 13 years of sonography experience performed all SWE scans for this study. Participants were scanned in the typical man- ner renal sonographic images are obtained clinically, in the position offering the shortest distance to either kidney, typically the left decubitus or supine positions. Body position was not recorded. SWE measurements were obtained in a single region of interest (minimum diameter 6 mm) an area of renal parenchyma at least 1 cm deep of the capsule in the renal cortex, with spe- cific avoidance of renal pyramids as the operator was able. Measurements where obtained where the acoustic window was optimal, typically in the lower renal pole. Distance from the skin to the region of interest was re- corded as kidney depth and listed in Table 1 for cases and controls. Eight to twelve readings were taken per subject and a median SWE value was recorded as YM in kPa (Fig. 1). YM was calculated by Aixplorer software under the assumption of target tissue at body temperature using the formula E = ρ x c 2 , where E is tissue elasti- city in kPa, ρ is tissue density in kg/m 3 and c is shear wave velocity in m/s [27]. SWE measurements were obtained at end-expiration. All patients had confirm- ation of absence of hydronephrosis by traditional ultra- sound prior to undergoing SWE. In all cases, imaging began with the right kidney. If the kidney was readily ac- cessible SWE measurements were obtained. If the right kidney was deep or the acoustic window was considered suboptimal by the radiologist, SWE measurements were obtained from the left kidney. Eighty eight per- cent of participants underwent SWE on the right kidney.

In summary, we showed that the stiffness measurements of the sciatic nerve were significantly higher in patients with LDH than in healthy subjects. In addition, this study dem- onstrates that the shear wave elastography of the sciatic nerve in patients with LDH is influenced by symptom dur- ation. Moreover, VAS scores is positively correlated with symptom duration. Although this preliminary study show that shear wave elastography can detect the relationship of the sciatic nerve stiffness、symptom duration and VAS scores, further investigations are required to determine the clinical utility of this technique.

of predisposing risk factors, there is no definitive way to pre- dict which patients will develop serious bleeding. Therefore, a noninvasive method may be preferred for assessing the severity and progression of chronic renal changes, particu- larly in cases in which it is advisable to avoid performing a kidney biopsy, such as in DKD patients with a single kidney or in those who are receiving anticoagulant therapy. Thus, shear wave elastography (SWE) imaging may be applied as a simple tool for assessing the severity of chronic mor- phologic changes and for establishing categories of severity based on cortical stiffness measurements, at least in cases in which renal biopsy should be avoided or is contraindicated. Certainly, other studies are needed to establish the correla- tions between cortical stiffness, morphologic changes, and renal function.

Materials and Methods: A total of 140 breast cancer patients were evaluated. Tumor stiffness was quantitatively measured by shear-wave elastography in preoperative ultrasound examination, calculated as mean elasticity value (kPa). Slides of resected breast cancer specimens were reviewed for most fibrotic area associated with tumor. D2-40 immunohistochemical staining was applied for fibrotic areas to detect the lymphatic spaces. Microlymphatic density, tumor stiffness, and clinicopathologic data were analyzed.

Abstract: Objective: The aim of this study was to compare grayscale ultrasound (US), shear wave elastography (SWE), and combination of US and SWE for differentiating small (≤20 mm) breast masses, and to investigate factors related to false-finding SWE result for small breast masses. Methods: The US and SWE images of 141 pathologically proven breast lesions in 122 patients were assessed. Both Breast Imaging Reporting and Data System (BI-RADS) final assessment, and qualitative and quantitative SWE measurements were assessed. US and SWE were combined according to the cutoff value. The diagnostic performance of US, SWE, and the combination of two modalities were compared using receiver-operating characteristic curve (ROC) analysis. Results: The false finding of the pattern classification and Emax only showed significant differences in mass size. The area under the curve (AUC) of ROC was 0.795 for US alone, 0.878 for US combined with pattern classification, 0.873 for US combined with Emax, and 0.918 for US combined with both pattern classification and Emax. The specificities of US alone, US combined with pattern classification, US combined with Emax, and US combined with both pattern classification and Emax were 53.1%, 77.1%, 76.0%, and 89.6% respectively (p < 0.05); and the sensitivities were 95.6%, 93.3%, 93.3% and 88.9% respectively (p>0.05). Conclusions: Mass size is the cause of false SWE in small breast masses. The combination of US and SWE has a better diagnostic performance than US alone. US combined with both pattern classification and Emax may have a higher specificity.

Ultrasound elastography (USE) is a recent technology that has experienced major developments in the past two decades. The assessment of the main mechanical properties of tissues can be made with this technology by characterisation of their response to stress. This article reviews the two major techniques used in musculoskeletal elastography, compression elastography (CE) and shear-wave elastography (SWE), and evaluates the studies published on major electronic databases that use both techniques in the context of tendon pathology. CE accounts for more studies than SWE. The mechanical properties of tendons, particularly their stiffness, may be altered in the presence of tendon injury. CE and SWE have already been used for the assessment of Achilles tendons, patellar tendon, quadriceps tendon, epicondylar tendons and rotator cuff tendons and muscles. Achilles tendinopathy is the most studied tendon injury with USE, including the postoperative period after surgical repair of Achilles rupture tendon. In relation to conventional ultrasound (US), USE potentially increases the sensitivity and diagnostic accuracy in tendinopathy, and can detect pathological changes before they are visible in conventional US imaging. Several technical limitations are recognised, and standardisation is necessary to ensure repeatability and comparability of the results when using these techniques. Still, USE is a promising technique under development and may be used not only to promote an early diagnosis, but also to identify the risk of injury and to support the evaluation of rehabilitation interventions.

2D shear wave elastography (SWE) is relatively recent tool in the era of liver fibrosis grading as a non-invasive tool which uses the usual 2D US probe, yet with produc- tion of a focused acoustic beam to generate shear wave within the liver with the degree of liver fibrosis reflected upon the speed of this wave within the liver parenchyma and affects the degree of reflected wave. The same probe can track the reflected wave then calculate the degree of liver fibrosis using the machine software which is pre- sented with meter per second [10, 11].

Elasticity variation with varying renal perfusion ex vivo The YM values of the three compartments of the kidney were measured with varying renal perfusion in six beagles ex vivo (Fig. 5). Regardless of the ligation state (no ligation, renal vein only and combined ligation with ureter), the YM values of the renal cortex, medulla and sinus all increased significantly with the elevating artery perfusion from 0 mmHg to 150 mmHg (Table 3). When 75 mmHg was firstly applied, the increase of YM in the renal cortex was larger than the increased in the medulla and sinus, and the difference was statistically significant at no ligation and vein ligation (P all <0.01). The in- crease in cortex was also larger than those of the medulla and sinus when combined ligation with ureter, although the difference was relatively small (P = 0.027 and P = 0.108, respectively). However, the increase of sinus became more obviously compared with the cortex Table 1 Measurement of normal renal elasticity by shear wave elastography (SWE)

Our results are not in agreement with those of Chang et al [38], who reported similar diagnostic performance of shear wave elastography and strain elastography in a study included 150 patients. However he found discrepant results between the two techniques in some cases, and he found the SWE to have higher sensitivity and the strain elastography to have higher specificity. In our study, we found SWE to have higher both sensitivity and specificity. The difference between our results may be due to we used different ultrasound equipments. Also they included in their study a cohort of women with small breasts, in our study we included mostly females with moderate or large breasts which is known technical limitation of strain elastography. There may be different reasons for the discrepancy between the SWE and SE in the same patient. First, the two techniques differ in forces being measured and the images produced. Second, technical errors may affect one elastographic technique than the other, with the use of suboptimal technique may affect the results. High inter and intra-observer variability was reported in SE because of the variability of degree of compression [9]. On the other hand false positive results may be reported in SWE because of pre-compression of the tissues resulting in increased SWV [16, 39]. Third, mal-placement of the ROI due to breathing movement, slipping of the probe during data acquisition may lead to false or false negative results in both techniques [20, 40].

Abstract: Objective: To investigate the diagnostic performance of qualitative shear wave elastography (SWE) in the characterization of thyroid nodules, compared with quantitative SWE and grayscale ultrasound (US). Methods: A total of 174 thyroid nodules from 174 patients were preoperatively evaluated by grayscale US and SWE. The quan- titative SWE metrics were measured. For the qualitative SWE analysis, a four-pattern classification was established according to the color distribution features of the elastic maps and assigned for each enrolled nodule, as 1 for no meaningful findings, 2 for a capsule-related color, 3 for marginal color, and 4 for interior color. Results: Intra- observer and inter-observer agreement of the qualitative classification proposed in this study were substantial (κ=0.793 and 0.756, respectively). The area under the receiver operating characteristic curve (AUC) of the proposed classification was similar to that of grayscale US (P=0.73) and quantitative SWE metrics (P=0.90). Compared with the quantitative SWE, the qualitative classification yielded a higher sensitivity (P < 0.05) and a similar specificity (P=0.75). Adding SWE features to grayscale US, either qualitatively or quantitatively, improved the overall specificity (both P < 0.001). Among all data sets, the optimal diagnostic performance came from the combined set of grayscale US and the qualitative classification (AUC, 0.890), with 84.4% sensitivity and 94.6% specificity. Conclusion: The qualitative four-pattern classification proposed in this study was feasible and highly reproducible in the SWE evalua- tion of thyroid nodules. SWE imaging features, especially the qualitative classification, have the potential to facilitate ultrasound diagnosis for thyroid nodules.

The evaluation of liver fibrosis is said to be one of the factors of the liver cancer development. The noninvasive testing is considered for abdominal echography, MRI, a blood marker in various ways. We announce the evaluation as an article by liver fibrosis using the probe for the heart before, too. This time is shear wave elastography using the echo probe for the abdomen (SWE). We used and examined it in normal, chronic hepatitis patients with cirrhosis. We tried it, but, in the patients with cirrhosis, there was no examination in the change in a value after ascites time and ascitic drainage. The future examination thinks about a comparison with the liver biopsy, the comparison with the liver fibrosis marker. Also, we think that a malignancy and the benign differentiation should be possible for a liver tumor.

the types of myositis and the effects of the medications includ- ing steroid and disease-modifying agents is also unknown. Inter-reader reproducibility for SWE was not analysed owing to the unavailability of a secondary reader. Cut-off values were not computed to calculate sensitivity and specificity ow- ing to the unbefitting study design and small sample size. We did not compare SWE with grey-scale and Doppler findings, as it is not well demonstrated in the literature and not currently used as a routine investigation for myositis. Despite these Table 5 The association between MRI and shear wave elastography in IIM patients