Shear Wave Elastography Technique Research Articles

Viscoelastic parameter estimation using simulated shear wave motion and convolutional neural networks

Ultrasound shear wave elastography (SWE) techniques have been very useful for the analysis of tissue rheological properties, but there are still obstacles for robust evaluation of viscoelastic tissue properties. In this proof-of-concept study, we investigate whether convolutional neural networks (CNN) are capable of retrieving the elasticity and viscosity parameters from simulated shear wave motion images. Staggered-grid finite difference simulations based on a Kelvin-Voigt rheological model were used to generate data for this study. The wave motion datasets were created using Kelvin-Voigt shear elasticity values ranging from 1 to 25 kPa, shear viscosities ranging from 0 to 10 Pa⋅s, and two different push profiles using f-numbers of 1 and 2. The CNN architectures, optimized using mean squared error loss, were then trained to retrieve a specific viscoelastic parameter. Both elasticity and viscosity values were successfully retrieved, with regression R2 values above 0.99 when correlating the estimated mechanical properties versus the true mechanical properties. The CNN performance was also compared to estimation of shear elasticity and viscosity from fitting dispersion curves estimated from two-dimensional Fourier transform analysis. The results demonstrated that the CNN models were robust to noise, vertical position and partially to f-number. The architecture was proven to be robust to multiple push profiles if trained properly. The CNN results showed higher accuracy over the full viscoelastic parameter range compared to the Fourier-based analysis. The overall results showed the CNNs’ potential to be an alternative to complex mathematical analyses such as Fourier analysis and dispersion curve estimation used currently for shear wave viscoelastic parameter estimation.

Intraoperative Ultrasound Shear-Wave Elastography in Focal Cortical Dysplasia Surgery.

Previous studies reported interest in intraoperative shear-wave elastography (SWE) guidance for brain-tumor and epilepsy surgeries. Focal cortical dysplasia (FCD) surgery is one of the most appropriate indications for using SWE guidance. The aim of this study was to evaluate the efficacy of ultrasound SWE techniques for the intraoperative detection of FCDs. We retrospectively analyzed data from 18 adult patients with drug-resistant epilepsy associated with FCD who had undergone SWE-guided surgery. Conventional B-mode images detected FCD in 2 patients (11.1%), while SWE detected FCD in 14 patients (77.8%). The stiffness ratios between MRI-positive and -negative cases were significantly different (3.6 ± 0.4 vs. 2.2 ± 0.6, respectively; p < 0.001). FCDs were significantly more frequently detected by interoperative SWE in women (OR 4.7, 95% CI (1.7–12.7); p = 0.004) and in patients in whom FCD was visible on magnetic resonance imaging (MRI; OR 2.3, 95% CI (1.3–4.3); p = 0.04). At 1 year after surgery and at last follow-up (mean = 21 months), seizure outcome was good (International League Against Epilepsy (ILAE) Class 1 or 2) in 72.2% and 55.6% of patients, respectively. Despite some limitations, our study highlighted the potential of SWE as an intraoperative tool to detect FCD. Future technical developments should allow for optimizing intraoperative surgical-cavity evaluation from the perspective of complete FCD resection. Interobserver reliability of SWE measurements should also be assessed by further studies.

Magnetic resonance shear wave elastography using transient acoustic radiation force excitations and sinusoidal displacement encoding

A magnetic resonance (MR) shear wave elastography technique that uses transient acoustic radiation force impulses from a focused ultrasound (FUS) transducer and a sinusoidal-shaped MR displacement encoding strategy is presented. Using this encoding strategy, an analytic expression for calculating the shear wave speed in a heterogeneous medium was derived. Green’s function-based simulations were used to evaluate the feasibility of calculating shear wave speed maps using the analytic expression. Accuracy of simulation technique was confirmed experimentally in a homogeneous gelatin phantom. The elastography measurement was compared to harmonic MR elastography in a homogeneous phantom experiment and the measured shear wave speed values differed by less than 14%. This new transient elastography approach was able to map the position and shape of inclusions sized from 8.5 to 14 mm in an inclusion phantom experiment. These preliminary results demonstrate the feasibility of using a straightforward analytic expression to generate shear wave speed maps from MR images where sinusoidal-shaped motion encoding gradients are used to encode the displacement-time history of a transiently propagating wave-packet. This new measurement technique may be particularly well suited for performing elastography before, during, and after MR-guided FUS therapies since the same device used for therapy is also used as an excitation source for elastography.

Decreased Size of Mammary Tumors Caused by Preoperative Treatment with Aglepristone in Female Domestic Dogs (Canis familiaris) Do Not Influence the Density of the Benign Neoplastic Tissue Measured Using Shear Wave Elastography Technique.

Simple SummaryShear wave elastography (SWE) is a new diagnostic method allowing for a non-invasive differential diagnosis between benign and malignant mammary tumors. Mammary tumors in dogs are often hormone-dependent, and a surgical approach is currently the most recommended method for the treatment of mammary neoplasia. However, preoperative, pharmacological therapy eliminating hormonal stimulation can sometimes be indicated to reduce the size of the tumor and facilitate subsequent surgery. The aim of this study was to evaluate the influence of the reduction in the benign tumor size observed after treatment with the use of aglepristone on the shear wave elastography results, obtained before and after therapy. We noticed that a fast and significant reduction in tumor size, as a consequence of preoperative pharmacological treatment, did not influence the diagnosis performed using the SWE technique. These results seem to indicate the accuracy and usefulness of this new diagnostic method, and confirm the hypothesis that tumor tissue density is a valuable parameter when determining the benignancy of mammary tumors in dogs. Shear wave elastography (SWE) can be useful to discriminate between malignant and benign mammary tumors. In dogs with elevated progesterone levels compared to the baseline and fast-growing tumors, treatment with the use of aglepristone allows for tumor size reduction, which facilitates surgery. This study aimed to evaluate the influence of the preoperative treatment of benign mammary tumors (BMTs), performed with the use of aglepristone, on the density of the tumor tissue measured by SWE. Twelve female dogs with diagnosed BMTs and increased levels of progesterone were treated with aglepristone (Alizine, Virbac, France) at 10 mg/kg s.c. (Subcutaneous injection). twice, with a 24 h interval. The density of the tumor was evaluated by SWE before and after the treatment. The type of tumor was evaluated by fine needle aspiration cytology before treatment, and a histopathological examination was made after surgical removal, performed after the aglepristone treatment. In all the cases, a significant reduction in the mammary tumor’s size was observed following treatment, with no influence on the density of the tumor’s tissue measured by SWE. Similar studies on malignant mammary tumors are warranted to verify if in these cases, density will also be a constant parameter that is not dependent on the tumor size.

Usefulness of Elastography for the Evaluation of Subcentimeter Solid Breast Nodules

The accurate diagnosis of subcentimeter lesions is controversial, and therefore a standardized diagnosis algorithm is needed. The objective of the present work was to study the value of the elastography patterns obtained through the use of the shear wave elastography (SWE) technique with respect to histopathology for the evaluation of nodular breast lesions ≤1 cm. A retrospective study was conducted which included 65 sub-centimeter lesions from 57 patients with an average age of 45.6 ± 11.9. For all the cases, a B-mode ultrasound study, shear wave elastography, and a posterior anatomopathological study were conducted. The lesions had a diameter greater than 7.5 ± 1.7 mm (range: 4–9 mm). Through elastography, the distribution of the patterns was: cyst artifact (n = 13), pattern 1 (n = 4), pattern 2 (n = 31), pattern 3 (n = 13), and pattern 4 (n = 4). Of the 65 lesions, 15 were cysts, 46 were solid benign lesions, and 3 were malignant lesions. The sensitivity of the elastography was 75%, with a specificity of 98.46% and a correct diagnosis in 96.92% of the cases (n = 63). The results from this study show the usefulness of SWE for the evaluation of sub-centimeter breast lesions. In addition, this diagnostic strategy helps with the differential diagnosis between benign and malignant lesions and contributes to the early detection of malignant breast lesions.

Shear wave elastography for intracranial epidermoid tumors

BackgroundUltrasound elastography (USE) is a novel technique that assesses the mechanical properties of body tissues in real time. Based on elasticity measurements, USE enables the differentiation of tumor tissue from surrounding normal tissue. ObjectivesWe aimed to evaluate an intraoperative SWE technique for differentiating tumor tissue (epidermoid cyst) from the surrounding normal brain tissue based on elastic properties. MethodsWe prospectively report the intraoperative elasticity assessments of four patients diagnosed with epidermoid cysts. Along with standard ultrasonography, intraoperative shear wave elastography (SWE) was used to identify tumor tissue and assess the elasticity of each tumor and the surrounding normal brain. ResultsUSE enabled the differentiation between epidermoid cysts and the surrounding normal brain tissue in real time intraoperatively; visual data (SWE elasticity map) and quantitative data (elasticity measurements in kilopascals) were utilized to identify the epidermoid cyst based on its elastic properties. The area representing the epidermoid cyst had an increased elasticity on SWE view and high mean elasticity values (193.7 ± 70.9 kPa in case 1, 168 ± 24.5 kPa in case 2, 205.1 ± 6.7 kPa in case 3, and 101.3 ± 12.6 kPa in case 4). The area representing the adjacent normal brain tissue on SWE view had lower mean elasticity values (14.9 ± 1.9 kPa in case 1, 22.6 ± 8.3 kPa in case 2, and 23.8 ± 1.4 kPa in case 4). ConclusionThis study demonstrates the feasibility and promising value of SWE as an intraoperative tool during epidermoid cyst resection. Epidermoid tissue remnants that are hidden from the microscopic view can be detected using SWE.

Ultrasonographic assessment in vivo of the excursion and tension of flexor digitorum profundus tendon on different rehabilitation protocols after tendon repair

Study designInterpretive description study. PurposeIn management of patients with flexion tendon injuries, passive, control active and active motion protocols were proposed after repair to minimize tendon adhesion. The purpose of this study was to compare the excursion distance and the tension of Flexor Digitorum Profundus (FDP) during simulated active and passive motion using ultrasonography techniques using normal subjects. MethodsUltrasonographic assessment of FDP tendon of the middle finger was performed at the wrist level on 20 healthy college students using 3 types of treatment protocols: modified Kleinert protocol, modified Duran protocol, and active finger flexion protocol. The excursion distance was measured following the musculotendinous junction of FDP using the B mode ultrasound system. The elasticity of FDP tendon was measured using the shear wave elastography technique. The excursion distance and the elasticity value were compared among 3 protocols using one-way ANOVA analysis. ResultsTwelve male and 8 female students with mean age of 22.6 ± 1.8 years were invited to join the study. The excursion distance of FDP was 21.82 ± 3.77 mm using the active finger flexion protocol, 8.59 ± 2.59 mm using the modified Duran protocol, and 12.26 ± 2.71 mm using the modified Kleinert protocol. The elasticity was significantly higher in extension position when compared to passive flexion positions, but found lower than active flexion position. DiscussionThe active finger protocol was found to require strongest tension of the tendon and with longest excursion. There was similar tension generated using both passive motion protocols. The modified Duran protocol appeared to create less excursion upon movements than the modified Kleinert approach using the objective ultrasonic evaluation. It is suggested that if the surgical repair was strong and without any complications, the active flexion protocol might work best to regain tension excursion. However, if there are complex problems involved, then the Kleinert approach or Duran approach would be chosen.

What does liver elastography measure? Technical aspects and methodology

Elastography can be thought as an extension of the ancient technique of palpation. After giving a short introduction to the history of elastography, the different technologies that are nowadays available and the physics behind them, the article focuses on the assessment of liver stiffness in patients with diffuse liver disease using shear wave elastography (SWE). Practical advices on how to perform the SWE techniques and on the factors that should be taken into account for a correct interpretation of the results are given. This paper aims to provide a practical guide for beginners and advanced clinical users to better understand technical aspects, methodologies and terminology.

Deep learning networks on chronic liver disease assessment with fine-tuning of shear wave elastography image sequences

Chronic liver disease (CLD) is currently one of the major causes of death worldwide. If not treated, it may lead to cirrhosis, hepatic carcinoma and death. Ultrasound (US) shear wave elastography (SWE) is a relatively new, popular, non-invasive technique among radiologists. Although many studies have been published validating the SWE technique either in a clinical setting, or by applying machine learning on SWE elastograms, minimal work has been done on comparing the performance of popular pre-trained deep learning networks on CLD assessment. Currently available literature reports suggest technical advancements on specific deep learning structures, with specific inputs and usually on a limited CLD fibrosis stage class group, with limited comparison on competitive deep learning schemes fed with different input types. The aim of the present study is to compare some popular deep learning pre-trained networks using temporally stable and full elastograms, with or without augmentation as well as propose suitable deep learning schemes for CLD diagnosis and progress assessment. 200 liver biopsy validated patients with CLD, underwent US SWE examination. Four images from the same liver area were saved to extract elastograms and processed to exclude areas that were temporally unstable. Then, full and temporally stable masked elastograms for each patient were separately fed into GoogLeNet, AlexNet, VGG16, ResNet50 and DenseNet201 with and without augmentation. The networks were tested for differentiation of CLD stages in seven classification schemes over 30 repetitions using liver biopsy as the reference. All networks achieved maximum mean accuracies ranging from 87.2%–97.4% and area under the receiver operating characteristic curves (AUCs) ranging from 0.979–0.990 while the radiologists had AUCs ranging from 0.800–0.870. ResNet50 and DenseNet201 had better average performance than the other networks. The use of the temporal stability mask led to improved performance on about 50% of inputs and network combinations while augmentation led to lower performance for all networks. These findings can provide potential networks with higher accuracy and better setting in the CLD diagnosis and progress assessment. A larger data set would help identify the best network and settings for CLD assessment in clinical practice.

Three-dimensional shear wave elastography on conventional ultrasound scanners with external vibration

Two-dimensional (2D) ultrasound shear wave elastography (SWE) has been widely used for soft tissue properties assessment. Given that shear waves propagate in three dimensions (3D), extending SWE from 2D to 3D is important for comprehensive and accurate stiffness measurement. However, implementation of 3D SWE on a conventional ultrasound scanner is challenging due to the low volume rate (tens of Hertz) associated with limited parallel receive capability of the scanner’s hardware beamformer. Therefore, we developed an external mechanical vibration-based 3D SWE technique allowing robust 3D shear wave tracking and speed reconstruction for conventional scanners. The aliased shear wave signal detected with a sub-Nyquist sampling frequency was corrected by leveraging the cyclic nature of the sinusoidal shear wave generated by the external vibrator. Shear wave signals from different sub-volumes were aligned in temporal direction to correct time delays from sequential pulse-echo events, followed by 3D speed reconstruction using a 3D local frequency estimation algorithm. The technique was validated on liver fibrosis phantoms with different stiffness, showing good correlation (r = 0.99, p < 0.001) with values measured from a state-of-the-art SWE system (GE LOGIQ E9). The phantoms with different stiffnesses can be well-differentiated regardless of the external vibrator position, indicating the feasibility of the 3D SWE with regard to different shear wave propagation scenarios. Finally, shear wave speed calculated by the 3D method correlated well with magnetic resonance elastography performed on human liver (r = 0.93, p = 0.02), demonstrating the in vivo feasibility. The proposed technique relies on low volume rate imaging and can be implemented on the widely available clinical ultrasound scanners, facilitating its clinical translation to improve liver fibrosis evaluation.

Spleen and Liver Stiffness for Predicting High-Risk Varices in Patients with Compensated Liver Cirrhosis

The study evaluates the utility of spleen (SS) and liver stiffness (LS) associated with spleen size (SSZ) as non-invasive markers for predicting high-risk varices (HRV). One hundred thirty-two patients with compensated liver cirrhosis who underwent abdominal ultrasound SS (SSM) and LS measurements (LSM) using a 2-D shear wave elastography (2-D-SWE) technique from General Electric and upper endoscopy were included. Similar rates of reliable SSM and LSM were obtained (95.4% and 97.7% respectively); therefore, 124 patients were included in the final analysis. The optimal cutoff values for SS, LS and SSZ for predicting HRV were 13.2 kPa (area under the receiver operating characteristic curve [AUROC] = 0.84), 12.1 kPa (AUROC = 0.86) and 12.9 cm (AUROC = 0.71), respectively. Including these factors in multiple regression analysis, we obtained the scores for predicting HRV: 0.053 × SS + 0.054 × LS + 0.059 × SSZ – 1.84. The score's optimal cutoff value for predicting HRV was >0.34 (AUROC = 0.93). By comparing the AUROC's, the score including SSZ, SSM and LSM performed better than each independent factor for predicting HRV (p = 0.0091; p = 0.0341; p < 0.0001).

Elastography for Pediatric Chronic Liver Disease: A Review and Expert Opinion.

In adults with chronic liver diseases, ultrasound and magnetic resonance shear wave elastography (SWE) can replace liver biopsy in several clinical scenarios. Several guidelines on the use of ultrasound SWE for the adult population have been published. However, the number of publications in the pediatric population is limited, and available guidelines on SWE do not specifically address pediatric chronic liver diseases. In this article, we review the literature on the use of SWE for pediatric chronic liver diseases and provide expert opinion on how to use SWE, both ultrasound and magnetic resonance techniques, in the pediatric population.

Comparative Study Between the Diagnostic Performance of Point and 2-D Shear-Wave Elastography for the Non-invasive Assessment of Liver Fibrosis in Patients With Chronic Hepatitis C Using Transient Elastography as Reference

The study compared the diagnostic performance of two shear-wave elastography techniques, elastography point quantification (ElastPQ) and 2-D shear-wave elastography by General Electric (2-D-SWE.GE), for the non-invasive assessment of liver fibrosis in a cohort of patients with chronic hepatitis C virus (HCV) infection, using transient elastography (TE) as the reference method. There was no significant difference between the feasibility rates of TE, ElastPQ and 2-D-SWE.GE (p = 0.507). A good correlation was found between the liver stiffness (LS) values obtained using the two elastographic methods (r = 0.78). The mean LS values obtained using the ElastPQ technique were significantly higher than those obtained using 2-D-SWE.GE (12.1 ± 7.3 kPa vs. 10.4 ± 4.0 kPa, p < 0.0001). Pairwise comparisons of receiver operator characteristics curves between 2-D-SWE.GE and ElastPQ have shown that there are no significant differences in their performance for staging F ≥ 2 fibrosis (p = 0.89), F ≥ 3 fibrosis (p = 0.76) and F = 4 fibrosis (p = 0.86) in patients with chronic HCV infection.

Virtual Touch Quantification using Acoustic Radiation Force Impulse Imaging Technology versus Transient Elastography for the Noninvasive Assessment of Liver Fibrosis in Patients with Chronic Hepatitis B or C using Liver Biopsy as the Gold Standard.

Our aim was to assess the diagnostic performance of transient elastography (TE) and Virtual Touch Quantification (VTQ), a point Shear Wave Elastography (pSWE) technique, using Acoustic Radiation Force Impulse (ARFI) technology, for liver fibrosis assessment, as compared to percutaneous liver biopsy (LB), in patients with chronic hepatitis B or C. We analyzed 157 patients (80 with chronic hepatitis B and 77 with chronic hepatitis C) with reliable liver stiffness (LS) measurements, in whom we compared TE and VTQ to the LB performed during the same session (evaluated according to the Metavir scoring system: F0-F4). LS was assessed by TE (FibroScan, EchoSens, Paris, France) and VTQ using the Siemens Acuson S2000TM ultrasound system (Siemens AG, Erlangen, Germany). We defined reliable LS measurements as the median value of 10 measurements with an IQR/M <30% for both TE (obtained using the M probe) and VTQ. The areas under receiver operating characteristic curves (AUROCs) were used to assess the diagnostic performance of TE and VTQ. Correlation analysis determined the relationship between LSM values and liver histology. On LB 31 (19.7%) patients had no fibrosis, 35 (22.3%) had F1, 43 (27.4%) had F2, 28 (17.8%) had F3 and 20 (12.7%) had cirrhosis. The mean size of the liver specimen in LB was 27 mm. A strong, linear correlation (Spearman ρ=0.826; p<0.001) with 95% confidence interval for rho (0.769- 0.870), was found between the TE and VTQ measurements. By comparing the AUROC curves, TE and VTQ had similar predictive values for the presence of F≥1 Metavir: AUROC TE=0.876, AUROC VTQ=0.832, p=0.358, for F≥2 Metavir: AUROC TE=0.826, AUROC VTQ=0.862, p=0.313, for F≥3 Metavir: AUROC TE=0.907, AUROC VTQ=0.880, p=0.434 and for F=4 Metavir: AUROC TE=0.981, AUROC VTQ=0.974, p= 0.423. Both methods, TE and VTQ (pSWE) offer excellent diagnostic accuracy for liver fibrosis assessment in patients with chronic hepatitis B or C with similar performance.

Impact of respiratory motion on liver stiffness measurements according to different shear wave elastography techniques and region of interest methods: a phantom study.

PurposeThis study quantified the impact of respiratory motion on liver stiffness measurements according to different shear wave elastography (SWE) techniques and region of interest (ROI) methods, using liver fibrosis phantoms.MethodsThree operators measured stiffness values in four phantoms with different stiffness on a moving platform with two SWE techniques (point-SWE [pSWE] and 2-dimensional SWE [2D-SWE]), three types of motion (static mode and moving mode at low and high speeds), and four ROI methods in 2D-SWE (circle, point, box, and multiple). The circular ROI method was used to compare the two SWE techniques. The occurrence of technical failure and unreliable measurements, stiffness values, and measurement time were evaluated.ResultsTechnical failure was observed only in moving mode for pSWE and 2D-SWE (n=1 for both). Unreliable measurements were also only observed in moving mode and were significantly less common in 2D-SWE (n=1) than in pSWE (n=12) (P<0.001). No statistically significant differences in the technical failure rate or stiffness values were noted between the static and moving modes for both SWE techniques. The technical failure and unreliable measurement rates were not significantly different among the ROI methods for 2D-SWE. Stiffness values did not differ significantly according to the ROI method used in any moving mode. However, the multiple ROI method had significantly shorter measurement times than the circular ROI method for all moving modes.Conclusion2D-SWE may be preferable for evaluating liver fibrosis in patients with poor breath-hold. Furthermore, 2D-SWE with multiple ROIs enables rapid measurements, without affecting liver stiffness values.

Performance and cutoffs for liver fibrosis staging of a two-dimensional shear wave elastography technique.

To assess performance and cutoffs of the 2-dimensional shear wave elastography technique available on the Aplio i800 ultrasound system (Canon Medical Systems, Japan), using transient elastography as reference standard, and to assess the correlation of shear-wave-speed dispersion with liver fibrosis or steatosis. This was a single-center cross-sectional study. The correlations between values obtained with transient elastography and 2-dimensional-shear wave elastography, and between shear-wave-speed dispersion and fibrosis or steatosis, were assessed with Pearson's r. The diagnostic performance of the 2-dimensional-shear wave elastography for staging significant fibrosis and severe fibrosis compared to transient elastography was assessed using the area under the receiver operating characteristic curve analysis. Three hundred sixty-seven patients (198 males and 169 females) were studied. There was a high correlation between 2-dimensional-shear wave elastography and transient elastography (r = 0.87, P < 0.0001). The area under the receiver operating characteristics of 2-dimensional-shear wave elastography for staging significant fibrosis (F2) and severe fibrosis (F3-F4), respectively, were 0.97 (95% confidence interval, 0.91-0.98) and 0.97 (95% confidence interval, 0.95-0.99). The best cutoffs for significant fibrosis and severe fibrosis, respectively, were > 7 and > 9 kPa. Shear-wave-speed dispersion showed a high correlation with fibrosis (r = 0.85, P < 0.0001), whereas there was a very weak correlation with steatosis. The results of this study show that this 2-dimensional-shear wave elastography technique is accurate for staging liver fibrosis. Shear-wave-speed dispersion is highly correlated with liver fibrosis but not with steatosis.

Diagnosis of carpal tunnel syndrome: A comparative study of shear wave elastography, morphometry and artificial intelligence techniques

Ultrasonography is an acceptable modality to evaluate median nerve (MN) in patients with carpal tunnel syndrome (CTS). Additional investigations are needed to evaluate sonographic parameters and compare their performances with artificial intelligence (AI) methods. The aim of this study is to compare the performance of shear wave elastography, morphometry, and AI techniques to predict MN entrapment accurately. 200 wrists including 100 CTS and 100 control wrists were included. Twelve morphological and five elasticity parameters were measured from each MN. Two AI techniques namely, support vector machine (SVM), and convolutional neural network (CNN) were used to diagnose CTS. MN area with area under receiver-operating characteristic curve (AUC) of 0.949 and mean elasticity with AUC of 0.942 showed the highest performance to differentiate CTS from control wrists among morphological and elasticity parameters, respectively. The CNN achieved the best performance with AUC of 0.980, while SVM obtained AUC of 0.943 in testing dataset to diagnose CTC. MN is larger, stiffer, more irregular and extended in CTS patients. Deep learning technique yielded the highest performance in diagnosing CTS automatically. AI methods have vast potential to be implemented in clinical practice as an auxiliary tool for the assessment of CTS with high accuracy.

Suggested amendment of TI-RADS classification of thyroid nodules by shear wave elastography.

The application of the ultrasound elastography and Thyroid Imaging Reporting and Data System (TI-RADS) classification further expands the scope of ultrasound differential diagnosis between benign and malignant thyroid nodules. To investigate the value of the quantitative parameter of ultrasonic shear waves in optimizing the TI-RADS classification of thyroid nodules. A total of 168 thyroid nodules, initially classified using TI-RADS and scanned by shear wave elastography (SWE), were retrospectively analyzed. All cases were diagnosed by fine needle aspiration and histology following surgery. The benign rate of TI-RADS 3 nodules was 76.5%, while the benign rate of TI-RADS 4a nodules was 71.7%. Furthermore, the malignant rate of TI-RADS 4b nodules was 69.7%, while the malignant rate of TI-RADS 4c nodules was 85.7%. In differentiating benign from malignant nodules, the combination of TI-RADS classification and Emean had the largest area under the receiver operating characteristic curve (AUC). Using an Emean value of 42.25 kpa as the cut-off point, the malignant rate of TI-RADS 4a nodules decreased from 28.3% to 23.5%, while the malignant rate of TI-RADS 4b nodules increased from 69.7% to 79.4%. Compared to conventional ultrasound alone, the sensitivity, negative predictive value, and AUC of conventional ultrasound combined with SWE in the diagnosis of benign and malignant thyroid nodules significantly improved (P=0.012, 0.029, 0.001). The SWE technique can be used to further determine the benign and malignant nature of TI-RADS 4 lesions, providing further reference for the choice of clinical treatment. The TI-RADS classification system corrected by SWE is more significant in the diagnosis of benign and malignant thyroid nodules.

Shear Wave Elastography in Diagnosing Secondary Hyperparathyroidism.

This study evaluates the diagnostic value of two-dimensional shear wave elastography (2 D-SWE) technique in the evaluation of hyperplastic parathyroid glands in cases with secondary and tertiary hyperparathyroidism. A total of 59 patients (end-stage renal disease, under supplemental dialysis program) with visible parathyroid hyperplastic glands on ultrasound, confirmed by biochemical assay and scintigraphy, were enrolled; they were examined on grayscale ultrasound and 2 D shear wave elastography. We determined the elasticity index (EI) in the parathyroid gland, thyroid parenchyma and surrounding muscles, and the elasticity ratio of hyperplastic parathyroid glands compared to muscle, specifically sternocleidomastoid muscle. Patients presented fibrocystic bone disease with secondary hyperparathyroidism induced by end-stage chronic kidney disease; being on prolonged chronic dialysis therapy, they had positive sestamibi scintigraphy and high values of serum parathormone (1141.04 pg/mL). Nodules placed posterior to the thyroid capsule that were cystic, had a hypoechoic aspect, and were homogenous with an independent afferent artery were found. Mean EI in the parathyroid gland was 7.83 kPa, the median value in thyroid parenchyma was 13.76 kPa, and mean muscle EI value was 15.78 kPa. The observed mean parathyroid/muscle SWE ratio was 0.5356 and the value for parathyroid/normal thyroid parenchyma was 0.5995. Using receiver operating characteristic (ROC) analysis, we found that EI below 9.74 kPa correctly identifies parathyroid tissue, with a sensitivity of 94.8%, specificity of 90.7%, and accuracy of 92.26% when compared to normal thyroid tissue. Compared with the muscle tissue, we identified that EI below 9.98 kPa has a sensitivity, specificity, and accuracy of 93.8%, 90.7%, and 91.75%, respectively. Ultrasound elastography is a helpful tool in identifying parathyroid hyperplasia in patients with chronic kidney disease. A cutoff value of 9.98 kPa can be used in 2 D-SWE for accurate diagnosis of parathyroid disease.

Two-Point Frequency Shift Method for Shear Wave Attenuation Measurement.

Ultrasound shear wave elastography (SWE) is an increasingly used noninvasive modality for quantitative evaluation of tissue mechanical properties. SWE typically uses an acoustic radiation force to produce laterally propagating shear waves that are tracked in the spatial and temporal domains, in order to obtain the wave velocity. One of the ways to study the viscoelasticity is through studying the shear wave phase velocity dispersion curves. Shear wave attenuation can be also characterized in viscoelastic tissues with methods that use multiple lateral data samples. In this article, we present an alternative method for measuring the shear wave attenuation without using a rheological model two-point frequency shift (2P-FS). The technique uses information related to the amplitude spectra FS of shear waves measured at only two lateral locations. The theoretical basis for the 2P-FS is derived and validated. We examined how the first signal position and the distance between the two locations affect the shear wave attenuation estimation in the 2P-FS method. We tested this new method on digital phantom data created using the local interaction simulation approach (LISA) in viscoelastic media. Moreover, we tested data acquired from custom-made tissue-mimicking viscoelastic phantom experiments and ex vivo porcine liver measurements. We compared results from the 2P-FS method with the other two techniques used for assessing a shear wave attenuation: the FS-based method and the attenuation-measuring ultrasound shear wave elastography (AMUSE) technique. In addition, we evaluated the 2P-FS algorithm with different levels of added white Gaussian noise to the shear wave particle velocity using numerical phantoms. Tests conducted showed that the 2P-FS method gives robust results based on only two measurements and can be used to measure attenuation of viscoelastic soft tissues.