Shear Wave Elastography Imaging Research Articles

Shear Wave Elastography Can Differentiate between Radiation-Responsive and Non-responsive Pancreatic Tumors: An ex Vivo Study with Murine Models

Neither contrast-enhanced computed tomography nor magnetic resonance imaging can monitor changes in the pancreatic ductal adenocarcinoma microenvironment during therapy. We hypothesized that shear wave elastography could overcome this limitation. To test this hypothesis, we measured the shear modulus of two groups of murine pancreatic tumors (KCKO, n = 30; PAN02, n = 30) treated with stereotactic body radiation therapy (SBRT). The mean shear modulus of KCKO tumors was 7.651 kPa higher than that of PAN02 tumors (p < 0.001). SBRT reduced the shear modulus in KCKO tumors by 8.914 kPa (p < 0.001). No significant difference in the shear modulus of SBRT-treated PAN02 tumors was observed. Additionally, necrotic and collagen densities were reduced only in the SBRT-treated KCKO tumors. Shear modulus was dependent on collagen distribution and histological texture parameters (i.e., entropy and fractional dimension). Shear wave elastography imaging differentiates between SBRT-responsive (KCKO) and non-responsive (PAN02) tumors.

Grayscale Ultrasound Radiomic Features and Shear-Wave Elastography Radiomic Features in Benign and Malignant Breast Masses.

To identify and compare diagnostic performance of radiomic features between grayscale ultrasound (US) and shear-wave elastography (SWE) in breast masses. We retrospectively collected 328pathologically confirmed breast masses in 296 women who underwent grayscale US and SWE before biopsy or surgery. A representative SWE image of the mass displayed with a grayscale image in split-screen mode was selected. An ROI was delineated around the mass boundary on the grayscale image and copied and pasted to the SWE image by a dedicated breast radiologist for lesion segmentation. A total of 730 candidate radiomic features including first-order statistics and textural and wavelet features were extracted from each image. LASSO regression was used for data dimension reduction and feature selection. Univariate and multivariate logistic regression was performed to identify independent radiomic features, differentiating between benign and malignant masses with calculation of the AUC. Of 328 breast masses, 205 (62.5 %) were benign and 123 (37.5 %) were malignant. Following radiomic feature selection, 22 features from grayscale and 6 features from SWE remained. On univariate analysis, all 6 SWE radiomic features (P < 0.0001) and 21 of 22 grayscale radiomic features (P < 0.03) were significantly different between benign and malignant masses. After multivariate analysis, three grayscale radiomic features and two SWE radiomic features were independently associated with malignant breast masses. The AUC was 0.929 for grayscale US and 0.992 for SWE (P < 0.001). US radiomic features may have the potential to improve diagnostic performance for breast masses, but further investigation of independent and larger datasets is needed.

Stiffness and Anisotropy Effect on Shear Wave Elastography: A Phantom and in Vivo Renal Study

Tissue elasticity is related to the pathologic state of kidneys and can be measured using shear wave elastography (SWE). However, SWE quantification has not been rigorously validated. The aim of this study was to evaluate the accuracy of SWE-measured stiffness and the effect of tissue anisotropy on SWE measurements. Point SWE (pSWE), 2-D SWE and dynamic mechanical analysis (DMA) were used to measure stiffness and evaluate the effect of tissue anisotropy on the measurements. SWE and DMA were performed on phantoms of different gelatin concentrations. In the tissue anisotropy study, SWE and DMA were performed on the outer cortex of sheep kidneys. In the in vivo study, 15 patients with different levels of interstitial fibrosis were recruited for pSWE measurements. Another 10 healthy volunteers were recruited for tissue anisotropy studies. SWE imaging revealed a non-linear increase with gelatin concentration. There was a significant correlation between pSWE and 2-D SWE, leading to the establishment of a linear regression equation between the two SWE ultrasound measurements. In the anisotropy study, the median difference in stiffness between shear waves oriented at 0° and 90° towards the pyramid axis was significant. In the in vivo study, there was a strong positive linear correlation between pSWE and the percentage of interstitial fibrosis. There was a significant difference in the Young's modulus (YM) between severities of fibrosis. The mean YM values were lower in control patients than in patients with mild, moderate and severe fibrosis. YM values were also significantly higher when shear waves were oriented at 0° toward the pyramid axis. Tissue stiffness and anisotropy affects SWE measurements. These factors should be recognized before applying SWE for the interpretation of measured values.

Biomedical Acoustics: Breaking old barriers in science and medicine

The Technical Committee on Biomedical Acoustics (BATC) is one of the most diverse groups in the Acoustical Society of America. BATC is comprised of scientists and engineers who study a wide range of biomedical applications using ultrasound from imaging fetuses to ablating fibroids and treating brain disorders. Diagnostic ultrasound has expanded to include exciting new techniques such as shear wave elastography and opto-acoustic imaging. Therapeutic ultrasound applications include physiotherapy, lithotripsy, as well as the treatment of tumors via thermal ablation, i.e., HITU, or mechanical ablation, i.e., histotripsy. The most recent developments in therapeutic ultrasound involve neuromodulation and transcranial magnetic resonance guided focused ultrasound for the treatment of various brain disorders, including essential tremor, neuropathic pain, and Parkinson’s disease. The ability to temporarily open the blood-brain barrier using focused ultrasound has been demonstrated in animals and, more recently, in humans. Opening of the blood-brain barrier could allow the transmission of drugs to treat brain diseases. Diagnostic and therapeutic ultrasound applications continue to advance the field of medicine and are integral to the advancement of both diagnosis and treatment of debilitating diseases.

Wide Field-of-View Ultrafast Curved Array Imaging Using Diverging Waves.

Ultrafast ultrasound imaging provides great opportunities for very high frame rate applications, such as shear wave elastography and microvascular imaging. However, ultrafast imaging with curved array transducers remains challenging in terms of element directivity and a limited field-of-view (FOV) for a fully synthetic area. In this paper, a wide FOV ultrafast curved array imaging method based on diverging wave transmissions is presented for high frame rate abdominal ultrasound applications. For this method, a theoretical model for a diverging wave solution based on a virtual point source originating from a circular line is proposed, and the FOV and element directivity are analyzed by this model. Furthermore, an integrated model for plane wave and diverging wave imaging along the location of the virtual point source is derived. The proposed method was evaluated with simulation, phantom, and in vivo studies. In the simulation and phantom studies, the image quality (i.e., spatial resolution, cystic resolution, and contrast-to-noise ratio), and effective FOV were assessed. For the in vivo study, a preliminary result from abdominal microvascular imaging, where diverging wave excitation was utilized to depict the vasculature, was also presented. In the renal cortex microvessels, the diverging wave imaging yielded a higher signal-to-clutter ratio value than the plane wave imaging, i.e., 6.35 vs. 4.26dB, due to the wider synthetic field. These studies demonstrated that the proposed ultrafast curved array imaging technique based on diverging wave excitation allowed for an extended FOV with high spatiotemporal resolution.

Relationships between cardiovascular disease risk factors and Achilles tendon structural and mechanical properties in people with Type 2 Diabetes

Background. Patients with diabetes have 44% greater risk of tendon rupture requiring hospitalisation. Despite this, in vivo research of the associations of diabetes and other cardiovascular disease risk factors on structural and mechanical properties of the Achilles tendon are sparsely studied.Methods. Inactive individuals with type 2 diabetes (n=33) underwent ultrasound and shear wave elastography imaging of their Achilles tendons bilaterally to measure thickness and shear wave velocity (SWV), an index of tendon elastic modulus. In a separate session, participants underwent assessment of body composition, cardiorespiratory fitness and blood biomarkers. Seven inactive individuals without type 2 diabetes were recruited for comparison of tendon structural and mechanical properties.Results. In participants with diabetes, free tendon SWV displayed large negative correlations with hip circumference (r=-0.67, P <0.001), waist circumference (r=-0.59, P <0.001) and body mass index (r=-0.52, P <0001), and a moderate positive correlation with VO2 peak (r=0.34, P =0.006). SWV was lower in participants with diabetes taking statins compared to not taking statins (Free tendon: median difference 8%, P=0.004); insertion: 11%, P =0.001). Compared to the control group, the diabetes group had thicker Achilles free tendon (median difference 15%, P<0.001) and Achilles insertion (17%, P=0.006), but no differences in SWV (P=0.490 or 0.577 respectively).Conclusions. Achilles tendons from individuals with type 2 diabetes were thicker compared to inactive individuals without diabetes. Adiposity, statin use and low cardiorespiratory fitness were associated with inferior Achilles tendon mechanical properties in people with diabetes.

Prediction of Postprostatectomy Biochemical Recurrence Using Quantitative Ultrasound Shear Wave Elastography Imaging.

Objectives: To determine the prognostic significance of tissue stiffness measurement using transrectal ultrasound shear wave elastography in predicting biochemical recurrence following radical prostatectomy for clinically localized prostate cancer.Patients and Methods: Eligible male patients with clinically localized prostate cancer and extraperitoneal laparoscopic radical prostatectomy between November 2013 and August 2017 were retrospectively selected. Information of potential biochemical recurrence predictors, including imaging (ultrasound shear wave elastography and magnetic resonance imaging), clinicopathological characteristics, and preoperative prostate specific antigen (PSA) levels were obtained. Recurrence-free survival (Kaplan–Meier curve) and a multivariate model were constructed using Cox regression analysis to evaluate the impact of shear wave elastography as a prognostic marker for biochemical recurrence.Results: Patients experienced biochemical recurrence in an average of 26.3 ± 16.3 months during their follow-up. A cutoff of 144.85 kPa for tissue stiffness measurement was estimated for recurrence status at follow-up with a sensitivity of 74.4% and a specificity of 61.7%, respectively (p < 0.05). In univariate analysis, shear wave elastography performed well in all preoperative factors compared to biopsy Gleason Score, PSA and magnetic resonance imaging; in multivariate analysis with postoperative pathological factors, shear wave elastography was statistically significant in predicting postoperative biochemical recurrence, which improved the C-index of predictive nomogram significantly (0.74 vs. 0.70, p < 0.05).Conclusions: The study revealed that quantitative ultrasound shear wave elastography-measured tissue stiffness was a significant imaging marker that enhanced the predictive ability with other clinical and histopathological factors in prognosticating postoperative biochemical recurrence following radical prostatectomy for clinically localized prostate cancer.

Qualitative Classification of Shear Wave Elastography for Differential Diagnosis Between Benign and Metastatic Axillary Lymph Nodes in Breast Cancer.

Purpose: To examine diagnostic performance of qualitative shear wave elastography (SWE) for evaluation of status of axillary lymph nodes (ALN) in comparison with conventional ultrasonograghy (US) and quantitative SWE parameters.Methods: A total of 118 patients were enrolled, who were all scheduled for breast cancer surgery and core needle biopsy. Conventional US and SWE were performed before biopsy. Based on qualitative evaluation of each ALN, the SWE images were classified into four color patterns: Color Pattern 1: homogeneous; Color Pattern 2: filling defect within lymph node (LN); Color Pattern 3: homogeneous within LN with a localized colored area at the margin; and Color Pattern 4: filling defect within LN with a localized colored area at the margin. The diagnostic performances of the three methods were compared.Results: There were 60 metastatic nodes and 61 benign nodes in the 121 ALNs. Benign ALNs were presented as Color Pattern 1 while metastatic ALNs usually were presented as Color Pattern 2 to 4 (p < 0.05). The AUC of qualitative SWE classification was 0.983, higher than that of quantitative SWE parameters and conventional US (p<0.05). The highest diagnostic performance, with AUC of 0.998, could be achieved if both conventional US and qualitative SWE were applied.Conclusion: The qualitative SWE classification of ALNs proposed in our study exhibited better diagnostic performance than quantitative SWE parameters and conventional US, especially for differentiating metastatic ALNs from benign reactive ALNs. More accurate diagnosis could be reached with this new method and unnecessary biopsy might be avoided in the meantime.

Diagnostic Performance of Ultrasound Shear Wave Elastography in Solid Small (≤4 cm) Renal Parenchymal Masses

The aim of the study was to analyze the diagnostic performance of shear wave elastography (SWE) in differentiating between malignant and benign solid renal parenchymal masses ≤4 cm, compared with conventional ultrasound. A total of 20 healthy volunteers and 117 patients had been included in this study. Conventional ultrasound and SWE were performed in all volunteers and patients. The elasticity of healthy cortex and the elastic parameters of tumors such as mean elasticity (Emean), minimum elasticity (Emin), maximum elasticity (Emax), standard deviation and elasticity ratio of the lesion to surrounding cortex (Eratio) were measured on SWE images. Diagnostic performance of SWE was compared with that of conventional ultrasound. The cortical elasticity values of healthy right and left kidneys were 4.7 ± 1.7 and 4.5 ± 1.5 kPa, respectively. Of the 117 renal tumors, 68 were renal cell carcinomas (RCCs) and 49 were benign. Emean, Emin and Eratio were significantly lower in RCCs compared with benign lesions: Emean 7.2 ± 2.5 kPa versus 10.0 ± 2.4 kPa, Emin 2.5 ± 2.4 kPa versus 5.6 ± 2.3 kPa, Eratio 1.6 ± 0.5 versus 2.2 ± 0.6 (all p values < 0.001). The cutoff values of 9.15 kPa for Emean, 3.55 kPa for Emin and 1.99 for Eratio had the highest areas under the receiver operating characteristics curve (0.801 for Emean, 0.832 for Emin and 0.806 for Eratio). Combining Emean, Emin and Eratio with conventional ultrasound improved the specificity for predicting RCCs to 87.8%, but the sensitivity was not increased.

A preliminary study on ultrasound techniques applied to cicatricial alopecia.

Cicatricial alopecia (CA) is a group of disorder characterized by permanent destruction of the hair follicle. Shear wave elastography (SWE) and superb microvascular imaging (SMI) are noninvasive ultrasonic techniques which evaluate thickness, stiffness, and vascular index of tissues. This study explored the ranges of cicatricial alopecia area and normal scalp with a combined modality of SMI and SWE and investigated the feasibility of their use in assessing these diseases. Seventeen patients diagnosed with CA and twenty healthy controls were included in the study. SWE and SMI were performed with an Aplio 500 ultrasound system. The mean age of patient group was 37.00±13.16, and the mean age of the healthy controls were 36.00±11.79. SWE results as m/s in cicatricial plaques ( =5191) were higher than non-alopecic scalp areas ( =4460) in patient group (t (16)=2260; P=0.038<0.05). SMI values in patient group (cicatricial plaques) ( =1200) were significantly higher than control group SMI values ( =0.005) (t (35)=3.075; P=0.012<0.05). To the best of our knowledge, this is the first study to evaluate SWE and SMI scores in cicatricial alopecia. We found higher stiffness and vascularity in patient group. We conclude that SWE and SMI can show fibrosis and inflammation like previous studies. Especially, SWE as m/s is more sensitive than as kPa for cicatricial alopecia.

Acoustic Fountains and Atomization at Liquid Surfaces Excited by Diagnostic Ultrasound

Pulmonary capillary hemorrhage (PCH) has been found in mammalian lungs exposed to diagnostic ultrasound (DUS), although the mechanism is poorly understood. This work investigates acoustic atomization and fountains at liquid-air interfaces subjected to DUS, which has been suggested as a possible PCH damage mechanism. Primarily using a SuperSonic Imagine Aixplorer DUS machine (SuperSonic Imagine, Aix-en-Provence, France), blood and water surfaces were excited in vitro by DUS and recorded with a high-speed camera. The surface was driven by B-mode, color Doppler, pulsed Doppler, and shear wave elastography imaging modes with center frequencies from 5.0–7.2 MHz and mechanical indexes (MI) up to 1.7. Fountains and atomization were only observed for SWE, for MI as low as 1.0. A comparison of the SWE waveforms with the surface dynamics suggests that fountains and atomization were driven by push-pulses and depended on pulse duration and intensity. However, we conclude that atomization and fountaining are unlikely primary mechanisms behind all DUS-induced PCH because neither phenomenon occurred for traditional diagnostic imaging modes.

Effects of static stretching duration on muscle stiffness and blood flow in the rectus femoris in adolescents.

To compare the effects of 2 and 5 min of passive static stretching (SS) on stiffness and blood flow in the rectusfemoris in adolescent athletes using shear wave elastography (SWE) and superb microvascular imaging (SMI).Material andmethods: This prospective study included 20 male athletes with median age of 14.5 (12.5-16.5) years. The subjects weredivided into two groups based on the SS duration as follows: 2 min (n=10) and 5 min (n=10). At rest and after 2 and 5 minof SS, stiffness and blood flow values were compared in the rectus femoris for each group. Inter-operator reliability was alsoanalysed. There was no significant difference between resting and 2 min of SS in terms of stiffness. The stiffnessvalues decreased significantly from resting to 5 min of SS. The blood flow increased significantly from resting to 2 and 5 minof SS. Inter-operator reliability was moderate to perfect for SWE and SMI measurements (ICC: 0.52-0.83). SWE and SMI can be used to acquire reliable quantitative data about muscle stiffness and blood flow in adolescents. Whilestiffness parameters significantly decreased from resting after only 5 min, blood flow significantly increased both after 2 and5 min. For physical rehabilitation protocols, 5 min of SS may be chosen to reduce stiffness. For competitions, 2 min of SSmay be sufficient for warm-up exercise because it increases the blood flow optimally. Five min of SS may be preferred for thecool-down exercise to enhance recovery.

Diagnostic effect of shear wave elastography imaging for differentiation of malignant liver lesions: a meta-analysis

BackgroundShear wave elastography (SWE) imaging have been proposed for characterization of focal liver lesions. We conducted a meta-analysis to evaluate the accuracy and clinical utility of SWE imaging for differentiation of malignant and benign hepatic lesions.MethodsPubMed, Embase, Web of Science, and the Cochrane Library were systematically reviewed to search for studies published between January 1, 1990, and November 30, 2018. The studies published in English relating to the evaluation the diagnostic accuracy of SWE imaging for distinguishing malignant and benign liver lesions were retrieved and examined for pooled sensitivity, specificity, likelihood ratios, and diagnostic odds ratios, using bivariate random-effects models. The hierarchical summary receiver operating characteristic (HSROC) curve was estimated to assess the SWE imaging accuracy. The clinical utility of SWE imaging for differentiation of malignant liver lesions was evaluated by Fagan plot.ResultsA total of 15 studies, involving 1894 liver lesions in 1728 patients, were eligible for the meta-analysis. The pooled sensitivity and specificity for identification of malignant liver lesions were 0.82 (95% CI: 0.77–0.86) and 0.82 (95% CI: 0.76–0.87), respectively. The AUC was 0.89 (95% CI: 0.86–0.91). When the pre-test probability was 50%, after SWE imaging measurement over the cut-off value (positive result), the corresponding post-test probability for the presence of malignant liver lesions was 82%; the post-test probability was 18% after negative measurement.ConclusionsSWE imaging showed high sensitivity and specificity in differentiating malignant and benign liver lesions and may be promising for noninvasive evaluation of liver lesions.Trial registrationThe review was registered in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42018104510.

Functional integrity of the shoulder joint and pectoralis major following subpectoral implant breast reconstruction.

Subpectoral implants for breast reconstruction after mastectomy requires the surgical disinsertion of the sternocostal fiber region of the pectoralis major. This technique is associated with significant shoulder strength and range of motion deficits, but it is unknown how it affects the underlying integrity of the shoulder joint or pectoralis major. The aim of this study was to characterize the long-term effects of this reconstruction approach on shoulder joint stiffness and pectoralis major material properties. Robot-assisted measures of shoulder strength and stiffness and ultrasound shear wave elastography images from the pectoralis major were acquired from 14 women an average of 549 days (range: 313-795 days) post reconstruction and 14 healthy, age-matched controls. Subpectoral implant patients were significantly weaker in shoulder adduction (p < 0.001) and exhibited lower shoulder stiffness when producing submaximal adduction torques (p = 0.004). The underlying material properties of the clavicular fiber region of the pectoralis major were altered in subpectoral implant patients, with significantly reduced shear wave velocities in the clavicular fiber region of the pectoralis major when generating adduction torques (p = 0.023). The clinical significance of these findings are that subpectoral implant patients do not fully recover shoulder strength or stability in the long-term, despite significant recovery time, and substantial shoulder musculature left intact. The impact of these procedures extends to the remaining, intact volume of the pectoralis major. Optimization of shoulder function should be a key aspect of the post-reconstruction standard of care. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1610-1619, 2019.

Temporal stability assessment in shear wave elasticity images validated by deep learning neural network for chronic liver disease fibrosis stage assessment.

To automatically detect and isolate areas of low and high stiffness temporal stability in shear wave elastography (SWE) image sequences and define their impact in chronic liver disease (CLD) diagnosis improvement by means of clinical examination study and deep learning algorithm employing convolutional neural networks (CNNs). Two hundred SWE image sequences from 88 healthy individuals (F0 fibrosis stage) and 112 CLD patients (46 with mild fibrosis (F1), 16 with significant fibrosis (F2), 22 with severe fibrosis (F3), and 28 with cirrhosis (F4)) were analyzed to detect temporal stiffness stability between frames. An inverse Red, Green, Blue (RGB) colormap-to-stiffness process was performed for each image sequence, followed by a wavelet transform and fuzzy c-means clustering algorithm. This resulted in a binary mask depicting areas of high and low stiffness temporal stability. The mask was then applied to the first image of the SWE sequence, and the derived, masked SWE image was used to estimate its impact in standard clinical examination and CNN classification. Regarding the impact of the masked SWE image in clinical examination, one measurement by two radiologists was performed in each SWE image and two in the corresponding masked image measuring areas with high and low stiffness temporal stability. Then, stiffness stability parameters, interobserver variability evaluation and diagnostic performance by means of ROC analysis were assessed. The masked and unmasked sets of SWE images were fed into a CNN scheme for comparison. The clinical impact evaluation study showed that the masked SWE images decreased the interobserver variability of the radiologists' measurements in the high stiffness temporal stability areas (interclass correlation coefficient (ICC)=0.92) compared to the corresponding unmasked ones (ICC=0.76). In terms of diagnostic accuracy, measurements in the high-stability areas of the masked SWE images (area-under-the-curve (AUC) ranging from 0.800 to 0.851) performed similarly to those in the unmasked SWE images (AUC ranging from 0.805 to 0.893). Regarding the measurements in the low stiffness temporal stability areas of the masked SWE images, results for interobserver variability (ICC=0.63) and diagnostic accuracy (AUC ranging from 0.622 to 0.791) were poor. Regarding the CNN classification, the masked SWE images showed improved accuracy (ranging from 82.5% to 95.5%) compared to the unmasked ones (ranging from 79.5% to 93.2%) for various CLD stage combinations. Our detection algorithm excludes unreliable areas in SWE images, reduces interobserver variability, and augments CNN's accuracy scores for many combinations of fibrosis stages.

Performance of Shear Wave Elastography in Delineating the Radiofrequency Ablation Boundary: An in Vivo experiment

This study was aimed at exploring the cutoff value of Young's modulus of ablated tissue and the optimal scale at which shear wave elastography (SWE) can delineate the ablation boundary. The livers of 30 rabbits were radiofrequency (RF) ablated, and ultrasonic imaging, including SWE and contrast-enhanced ultrasound (CEUS), was performed. The ablation boundary in the SWE image was located using CEUS, and the SWE parameters of the boundary were measured to calculate the cutoff value of Young's modulus. The cutoff value of the ablated tissue was 48–50 kPa 2 h to 28 d post-ablation. The regions of increased stiffness in SWE images at a scale of 0–50 kPa overlapped well with the non-enhanced regions of CEUS images in 88% of specimens. Therefore, elasticity values differed significantly between ablated and non-ablated tissues, and the cutoff value for Young's modulus differentiated these tissues. SWE delineated the ablation boundary well at the optimal SWE scale with respect to the cutoff value.

Comparative Analysis of Diagnostic Value for Shear Wave Elastography and Real-Time Elastographic Imaging for Thyroid Nodules

Objective: To compare the diagnostic value of shear wave elastography (SWE) and real-time elastography (RTE) in the diagnosis of benign and malignant thyroid nodules. Methods: A total of 34 patients who ever received thyroidectomy in our hospital from January 2016 to January 2018 were identified. Meanwhile, all the patients received SWE and RTE before surgery, and all the diagnoses were confirmed by pathological examinations. With respect to SWE technique, the Subject Operating Characteristics (ROC) curves were drawn, in order to obtain the optimal threshold and then make differential diagnoses of benign and malignant thyroid nodules. In terms of RTE, the Rago 5 scoring method was utilized to make differential diagnoses of benign and malignant thyroid nodules. Besides, the pathological examinations after surgery could be considered as the golden standard. At last, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of SWE and RTE were calculated, respectively. Results: A total of 51 thyroid nodules were identified, and 41 nodules were benign, 10 nodules were malignant. On the basis of ROC curves, with respect to SWE, the best threshold for differential diagnosis of benign and malignant thyroid nodules is 38.3 kPa. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of SWE were 72.7% (8/11), 85% (34/40), 82.4% (42/51), 68.4% (13/19), and 87.5% (35/40), respectively. And the diagnostic indicators of RTE were 81.8% (9/11), 87.5% (35/40), 84.3% (43/51), 73.7% (14/19), and 90.0% (36/40). The sensitivity of quasi-static elastography in differential diagnosis of benign and malignant thyroid nodules with diameter ≤1 cm was 87.5% (7/8), and the sensitivity of SWE was 50.0% (5/10). In addition, the accuracy of SWE in differential diagnosis of benign and malignant thyroid nodules with diameter ≥3 cm was 100% (6/6), and the accuracy of RTE for this kind of thyroid nodules was 66.7% (4/6). Conclusion: Both SWE and RTE technology have good application value in differential diagnosis of benign and malignant thyroid nodules. But, SWE is preferable when making diagnosis of benign and malignant thyroid nodules with diameter ≥3 cm, and RTE was superior in detecting benign and malignant thyroid nodules with diameter ≤1 cm.

Arterial Stiffness Assessment by Shear Wave Elastography and Ultrafast Pulse Wave Imaging: Comparison with Reference Techniques in Normotensives and Hypertensives

Shear wave elastography and ultrafast imaging of the carotid artery pulse wave were performed in 27 normotensive participants and 29 age- and sex-matched patients with essential hypertension, and compared with reference techniques: carotid–femoral pulse wave velocity (cfPWV) determined via arterial tonometry and carotid stiffness (carPWV) determined via echotracking. Shear wave speed in the carotid anterior (a–SWS) and posterior (p-SWS) walls were assessed throughout the cardiac cycle. Ultrafast PWV was measured in early systole (ufPWV–FW) and in end-systole (dicrotic notch, ufPWV-DN). Shear wave speed in the carotid anterior appeared to be the best candidate to evaluate arterial stiffness from ultrafast imaging. In univariate analysis, a-SWS was associated with carPWV (r = 0.56, p = 0.003) and carotid-to-femoral PWV (r = 0.66, p < 0.001). In multivariate analysis, a–SWS was independently associated with age (R² = 0.14, p = 0.02) and blood pressure (R² = 0.21, p = 0.004). Moreover, a–SWS increased with blood pressure throughout the cardiac cycle and did not differ between normotensive participants and patients with essential hypertension when compared at similar blood pressures.

Shear wave elastography of the healing human patellar tendon following ACL reconstruction

PurposeAnterior cruciate ligament (ACL) ruptures are common and are frequently reconstructed using a patellar tendon (PT) autograft. Unfortunately, the time course of PT healing after ACL reconstruction is not particularly well understood. Thus, the primary objective of this study was to use shear wave elastography (SWE) to evaluate the extent to which shear wave speed (SWS) is associated with time after ACL reconstruction. MethodsLongitudinal SWE images were acquired from lateral, central, and medial regions of the PT from two groups: 30 patients who had undergone ACL reconstruction with a PT autograft within the preceding 40 months, and 30 age-matched asymptomatic control subjects. SWE images were acquired at 20° and 90° of passive flexion from both knees. In each subject group, statistical analyses assessed changes in mean SWS with time post-surgery, as well as differences in mean SWS between PT regions and limbs. ResultsIn the ACL reconstruction patients, mean SWS increased with time post-surgery in the lateral region of the involved knee (p = 0.025) and decreased with time post-surgery in the central region of the contralateral knee (p = 0.022). ConclusionThe findings suggest that there is an association between the mechanical properties of the PT and time post-surgery in both the involved and contralateral limbs after ACL reconstruction. These changes are likely due to maturation of the donor site tissue and changes in gait/loading patterns following ACL rupture and reconstruction. Level of evidenceLevel II — Prospective Cohort.

The Impact of Strenght Electromyostimulation Training on Muscle Stiffness and Blood Flow: An Exploration Using Shear Wave Elastography and Superb Microvascular Imaging

To assess the acute effect of strength exercises combined with EMS on blood flow and muscle stiffness using SMI and SWE. This prospective study included 20 participants. Subjects were divided into groups base on calisthenics strength training with EMS and without EMS. Rectus femoris (RF) blood flow was measured at rest and post-exercise with the vascularity index (%) and stiffness was measured in kPa mode to compare the groups. When values are compared at rest and post-exercise, all cases had significantly increased blood flow and stiffness increase in RF post-exercise (resting mean VI [%]: 1.42±0.58 and post-exercise mean VI [%]: 5.36±3.03; resting mean stiffness [kPa]: 8.85±1.38) and post-exercise mean stiffness [kPa]: 10.57±1.79). The blood flow and stiffness values in the group with EMS and exercise had greater increases than the group with exercise without EMS (p=0.007, p=0.05, respectively). Calisthenics strength training increases RF blood flow and stiffness in the acute period. SMI and SWE are beneficial and practical radiological methods that may be used to show these variations. Strength exercises using EMS may be associated with better athletic performance.