Strain Elastography - How To Do It?

Soft tissue elasticity at teeth and implant sites. A novel outcome measure of the soft tissue phenotype

AIM

To assess ultrasonographic tissue elasticity at teeth and implant sites and its variation after peri-implant soft tissue augmentation with a connective tissue graft (CTG).

METHODS

Twenty-eight patients, each contributing with one clinically healthy dental implant exhibiting a soft tissue dehiscence (PSTD), were included. Implant sites were augmented with CTG and monitored over 12 months. Ultrasonographic strain elastography, expressed as strain ratios (SR1, SR2, and SR3, respectively) was assessed at baseline, 6-, and 12-month, and compared with the corresponding contralateral homologous natural tooth. SR1 assessed the strain/elasticity of the midfacial coronal portion of the soft tissue in comparison to the natural tooth crown/implant-supported crown, SR2 evaluated the strain of the midfacial coronal soft tissue in relation to the one of the alveolar mucosa, while SR3 depicted the strain of the midfacial soft tissue in relation to the interproximal soft tissue on the transverse ultrasound scan.

RESULTS

SR1 in natural dentition and at implant sites was 0.20 ± 0.08 and 0.30 ± 0.14, respectively (p = .002), indicating that the coronal portion of the soft tissue around teeth is generally more elastic than its counterpart around dental implants. Soft tissue augmentation with CTG promoted an increased stiffness of the midfacial coronal portion of the soft tissue over 12 months (p < .001 for SR1, SR2, and SR3). Strain ratios at the 12-month time points were significantly higher than the values observed at 6 months (p < .001). Regression analysis demonstrated that strain elastography ratios in natural dentition were significantly associated with keratinized gingiva width, and gingival thickness. At implant sites, SR1 was significantly associated with keratinized mucosa width and mucosal thickness (p < .001 for both correlations), SR2 was significantly associated with keratinized mucosa width (p = .013), and SR3 was significantly associated with the surgical technique performed in combination with CTG (p = .022).

CONCLUSION

Ultrasound strain elastography captures and quantifies tissue elasticity and its changes after soft tissue augmentation. A different baseline tissue elasticity was observed between teeth and dental implants in the most coronal aspect of the soft tissue. The main factors affecting tissue elasticity-related outcomes were the keratinized tissue width, and mucosal thickness.

Evaluation of testicular stiffness in boys with unilateral cryptorchidism after orchiopexy by ultrasound strain elastography

PURPOSE

We assessed the stiffness of unilateral undescended testes after orchiopexy, examining its value in tracking histopathological changes and fertility potential during postoperative follow-up. Additionally, we explored the optimal timing for surgery based on testicular stiffness.

PATIENTS AND METHODS

Thirty-six boys who had been diagnosed with unilateral undescended testis and treated with orchiopexy were included in the study. Testicular stiffness was evaluated several times over respective follow-up periods by ultrasound strain elastography after orchiopexy. The strain ratios were measured as the ratios of the elasticities of the descended testis to those of the operated testes. The patients were divided into two groups based on the age at which they underwent orchiopexy:under < 2 years (Group A) and ≥ 2 years (Group B).

RESULTS

The mean strain ratios were 0.90 ± 0.32 and 0.92 ± 0.20 in Groups A and B, respectively. In Group A, the strain ratio was constant regardless of postoperative months (r = 0.01, p = 0.99); however, in Group B, it tended to increase with postoperative months (r = 0.42, p = 0.07).

CONCLUSIONS

Evaluation of testicular stiffness may be useful for the estimation of histopathological changes and fertility potential in boys with unilateral undescended testes at follow-up appointments after orchiopexy. Our data indicate that performing orchiopexy as early as possible may be recommended to avoid testicular damage.

Shear-Wave Elastography of the Achilles tendon: reliability analysis and impact of parameters modulating elasticity values

PURPOSE

Shear wave elastography (SWE) has seen many advancements in Achilles tendon evaluation in recent years, yet standardization of this technique is still problematic due to the lack of knowledge regarding the optimal way to perform the examination. The purpose of this study was to evaluate the effects of ankle position, probe frequency and physical effort on the shear modulus of the Achilles tendon, but also to determine the intra and inter-observer reliability of the technique.

METHODS

37 healthy volunteers were included; SWE protocol was performed by two examiners. We analyzed the shear modulus of the tendon with the ankle in neutral, maximum dorsiflexion and maximum plantar flexion using two different high frequency probes. Afterwards, the subjects performed a brief physical exercise and SWE measurements were repeated.

RESULTS

The L18-5 probe showed the highest ICC values (ICC = 0.798, 95% CI 0.660-0.880, p < 0.001) when positioned at 2 cm from the calcaneal insertion with the ankle in a neutral state. Conversely, utilizing the same L18-5 probe at 1 cm from the insertion during maximum plantar flexion of the ankle resulted in the lowest ICC (ICC = 0.422, 95% CI 0.032-0.655, p = 0.019). Significant variations in elasticity values were noted among different ankle positions and probe types, while no significant changes in elasticity were observed post-physical exercise.

CONCLUSION

Ankle position and probe frequency are factors that influence elasticity values of the Achilles tendon. An ankle position between 10 and 20 degrees of plantar flexion is the most suitable for SWE evaluation. However, more research focusing on Achilles tendon SWE is essential due to the challenges encountered in standardizing this region.

Advances in imaging techniques to assess kidney fibrosis

As a sign of chronic kidney disease (CKD) progression, renal fibrosis is an irreversible and alarming pathological change. The accurate diagnosis of renal fibrosis depends on the widely used renal biopsy, but this diagnostic modality is invasive and can easily lead to sampling error. With the development of imaging techniques, an increasing number of noninvasive imaging techniques, such as multipara meter magnetic resonance imaging (MRI) and ultrasound elastography, have gained attention in assessing kidney fibrosis. Depending on their ability to detect changes in tissue stiffness and diffusion of water molecules, ultrasound elastography and some MRI techniques can indirectly assess the degree of fibrosis. The worsening of renal tissue oxygenation and perfusion measured by blood oxygenation level-dependent MRI and arterial spin labeling MRI separately is also an indirect reflection of renal fibrosis. Objective and quantitative indices of fibrosis may be available in the future by using novel techniques, such as photoacoustic imaging and fluorescence microscopy. However, these imaging techniques are susceptible to interference or may not be convenient. Due to the lack of sufficient specificity and sensitivity, these imaging techniques are neither widely accepted nor proposed by clinicians. These obstructions must be overcome by conducting technology research and more prospective studies. In this review, we emphasize the recent advancement of these noninvasive imaging techniques and provide clinicians a continuously updated perspective on the assessment of kidney fibrosis.

Dynamic Quantitative Imaging of the Masseter Muscles in Bruxism Patients with Myofascial Pain: Could It Be an Objective Biomarker?

We aimed to investigate whether the collaboration of shear wave elastosonography (SWE) and B-mode ultrasonography (US) could be offered as diagnostic tools to assess the presence, severity, and progress of bruxism, as well as a biomarker for the effectiveness of treatment in daily clinical practice. The study was designed as a quantitative evaluation of the masseter muscles (MMs) of the clinically diagnosed bruxism patients suffering from myofascial pain and MMs of the healthy individuals. Clinical examinations were made according to the diagnostic criteria for temporomandibular disorders (DC/TMD), and pain was assessed using a visual analog scale (VAS). Painful MMs with VAS scores ≥ 4 were assigned to Group A, and healthy MMs were assigned to Group B. Also, the MMs of the painful bruxers were analyzed based on wearing occlusal splints. Group A was divided into two subgroups as splint users (Group AI) and non-users (Group AII). All the participants were scanned with dynamic US and SWE to quantify the size and stiffness of the MMs. Measurements of each muscle pair while the jaw is in a resting position (relaxation) and clenching position (contraction) were recorded. The significant differences in stiffness and thickness became visible in the relaxation state. Bruxism patients with myofascial pain had significantly harder and thinner MMs than healthy individuals. During the relaxation, the mean thickness and elasticity values were 9.17 ± 0.40 mm and 39.13 ± 4.52 kPa for Group A and 10.38 ± 0.27 and 27.73 ± 1.92 for Group B, respectively. Also, stiffer MMs were measured in Group AII (38.16 ± 3.61 kPa) than in Group AI (26.91 ± 2.13 kPa). In conclusion, the combination of SWE and US using a dynamic examination technique has the potential to be a valuable tool for the management of bruxism patients suffering from myofascial pain.

Could ultrasound and muscle elastography be associated with clinical assessment, laboratory and nailfold capillaroscopy in juvenile dermatomyositis patients?

BACKGROUND

Juvenile Dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children. Imaging exams are useful for muscle assessment, with ultrasonography (US) being a promising tool in detecting disease activity and tissue damage. There are few studies about muscle elastography.

OBJECTIVES

Our aim was to associate clinical, laboratory, and nailfold capillaroscopy (NC) assessments with US in JDM patients; and to compare the findings of US and Strain Elastography (SE) from patients and healthy controls.

METHODS

An analytic cross-sectional study was performed with JDM patients and healthy controls. Patients underwent clinical exam to access muscle strength and completed questionnaires about global assessment of the disease and functional capacity. Patients were submitted to NC and measurement of muscle enzymes. All subjects underwent US assessment, using gray scale, Power Doppler (PD), and SE.

RESULTS

Twenty-two JDM patients and fourteen controls, aged between 5 and 21 years, matched for age and sex were assessed. In qualitative and semi-quantitative gray scale, we observed a higher frequency of alterations in patients (p < 0.001), while in PD, there was a higher frequency of positivity in patients' deltoids and anterior tibialis (p < 0.001). Active disease was associated with an important change in the semi-quantitative gray scale in deltoids (p = 0.007), biceps brachii (p = 0.001) and quadriceps femoris (p = 0.005). The SE demonstrated a high negative predictive value of 87.2.

CONCLUSION

US was able, through gray scale, to differentiate JDM patients from controls, while PD achieved such differentiation only for deltoids and anterior tibialis. The semi-quantitative gray scale showed disease activity in proximal muscles. SE was not able to differentiate patients from controls.

Visualizing tactile feedback: an overview of current technologies with a focus on ultrasound elastography

Tissue elasticity remains an essential biomarker of health and is indicative of irregularities such as tumors or infection. The timely detection of such abnormalities is crucial for the prevention of disease progression and complications that arise from late-stage illnesses. However, at both the bedside and the operating table, there is a distinct lack of tactile feedback for deep-seated tissue. As surgical techniques advance toward remote or minimally invasive options to reduce infection risk and hasten healing time, surgeons lose the ability to manually palpate tissue. Furthermore, palpation of deep structures results in decreased accuracy, with the additional barrier of needing years of experience for adequate confidence of diagnoses. This review delves into the current modalities used to fulfill the clinical need of quantifying physical touch. It covers research efforts involving tactile sensing for remote or minimally invasive surgeries, as well as the potential of ultrasound elastography to further this field with non-invasive real-time imaging of the organ's biomechanical properties. Elastography monitors tissue response to acoustic or mechanical energy and reconstructs an image representative of the elastic profile in the region of interest. This intuitive visualization of tissue elasticity surpasses the tactile information provided by sensors currently used to augment or supplement manual palpation. Focusing on common ultrasound elastography modalities, we evaluate various sensing mechanisms used for measuring tactile information and describe their emerging use in clinical settings where palpation is insufficient or restricted. With the ongoing advancements in ultrasound technology, particularly the emergence of micromachined ultrasound transducers, these devices hold great potential in facilitating early detection of tissue abnormalities and providing an objective measure of patient health.

Stretchable ultrasonic arrays for the three-dimensional mapping of the modulus of deep tissue

Serial assessment of the biomechanical properties of tissues can be used to aid the early detection and management of pathophysiological conditions, to track the evolution of lesions and to evaluate the progress of rehabilitation. However, current methods are invasive, can be used only for short-term measurements, or have insufficient penetration depth or spatial resolution. Here we describe a stretchable ultrasonic array for performing serial non-invasive elastographic measurements of tissues up to 4 cm beneath the skin at a spatial resolution of 0.5 mm. The array conforms to human skin and acoustically couples with it, allowing for accurate elastographic imaging, which we validated via magnetic resonance elastography. We used the device to map three-dimensional distributions of the Young's modulus of tissues ex vivo, to detect microstructural damage in the muscles of volunteers before the onset of soreness and to monitor the dynamic recovery process of muscle injuries during physiotherapies. The technology may facilitate the diagnosis and treatment of diseases affecting tissue biomechanics.

Assessment of spinal cord injury using ultrasound elastography in a rabbit model in vivo

The effect of the mechanical micro-environment on spinal cord injury (SCI) and treatment effectiveness remains unclear. Currently, there are limited imaging methods that can directly assess the localized mechanical behavior of spinal cords in vivo. In this study, we apply new ultrasound elastography (USE) techniques to assess SCI in vivo at the site of the injury and at the time of one week post injury, in a rabbit animal model. Eleven rabbits underwent laminectomy procedures. Among them, spinal cords of five rabbits were injured during the procedure. The other six rabbits were used as control. Two neurological statuses were achieved: non-paralysis and paralysis. Ultrasound data were collected one week post-surgery and processed to compute strain ratios. Histologic analysis, mechanical testing, magnetic resonance imaging (MRI), computerized tomography and MRI diffusion tensor imaging (DTI) were performed to validate USE results. Strain ratios computed via USE were found to be significantly different in paralyzed versus non-paralyzed rabbits. The myelomalacia histologic score and spinal cord Young's modulus evaluated in selected animals were in good qualitative agreement with USE assessment. It is feasible to use USE to assess changes in the spinal cord of the presented animal model. In the future, with more experimental data available, USE may provide new quantitative tools for improving SCI diagnosis and prognosis.

Ultrasonography and Sonoelastography Characteristics of Benign vs. Malignant Mesenteric Lymph Nodes in Cats: An Update

(1) Background: Strain elastography (SE) is an ultrasound-based technique able to non-invasively assess tissue elasticity, with malignant tissues being stiffer than normal tissues. The purpose of the study was to evaluate the diagnostic performance of SE to differentiate feline mesenteric benign and malignant lymph nodes (LNs) using a multivariate approach including both SE results and B-mode ultrasound and color Doppler findings. (2) Methods: Feline enlarged mesenteric LNs were evaluated using B-mode ultrasound, color Doppler ultrasonography, and SE. Short-to-long axis ratios, borders, echogenicity, hilum, vascular flow distribution, elastographic patterns, and strain ratios were recorded. Histological and/or cytological diagnosis was available for each LN. (3) Results: A total of 88 LNs were included, 46 (52.3%) benign and 42 (47.7%) malignant; in the benign group, 40 LNs had a diagnosis of reactive hyperplasia (group A) and 6 eosinophilic sclerosing lymphadenitis (group B), while in the malignant group 42 had a diagnosis of lymphoma (group C). The principal component analysis approach showed evidence that by combining B-mode- and color Doppler-based scores with SE scores, the three groups of LNs can be accurately distinguished. (4) Conclusions: Our results demonstrate that a multivariate sonographic approach combining B-mode ultrasound, color Doppler ultrasonography, and SE can accurately distinguish benign from malignant LNs, thus helping in the clinical advice of feline patients.

Sono-Elastography: An Ultrasound Quantitative Non-Invasive Measurement to Guide Bacterial Pneumonia Diagnosis in Children

Lung ultrasound (LUS) is, at present, a standard technique for the diagnosis of acute lower respiratory tract infections (ALRTI) and other lung pathologies. Its protocolised use has replaced chest radiography and has led to a drastic reduction in radiation exposure in children. Despite its undeniable usefulness, there are situations in which certain quantitative measurements could provide additional data to differentiate the etiology of some pulmonary processes and thus adapt the treatment. Our research group hypothesises that several lung processes such pneumonia may lead to altered lung tissue stiffness, which could be quantified with new diagnostic tests such as lung sono-elastography (SE). An exhaustive review of the literature has been carried out, concluding that the role of SE for the study of pulmonary processes is currently scarce and poorly studied, particularly in pediatrics. The aim of this review is to provide an overview of the technical aspects of SE and to explore its potential usefulness as a non-invasive diagnostic technique for ALRTI in children by implementing an institutional image acquisition protocol.

Diagnostic accuracy of cervical elastography for predicting preterm delivery: Systematic review and meta-analysis

OBJECTIVE

Cervical elastography has been used in pregnant women to diagnose preterm births. However, there is a variability in the measured elasticity parameters and imaging mode used. We evaluated the precision of cervical elastography in identifying preterm births.

METHODS

Extensive and methodical searches were made in the databases such as Scopus, Embase, Cochrane Library, PubMed Central, Medline, ScienceDirect, and Google Scholar from the inception until November 2022, for studies that report diagnostic accuracy of cervical elastography for preterm deliveries in antenatal women.

RESULTS

The pooled sensitivity and specificity value of cervical elastography for preterm deliveries were 82% (95%CI: 73%-89%) and 77% (95%CI: 64%-86%), respectively with area under curve (AUC) of 0.87 (95%CI: 0.72-0.95). The diagnostic odds ratio (DOR) was 15 (95%CI: 8-28), positive likelihood ratio (LRP) was 3.5 (95%CI: 2.3-5.5) and negative likelihood ratio LRN was 0.23 (0.16-0.34). Pooled sensitivity and specificity of shear wave elastography was 88% and 71%, respectively. Pooled sensitivity and specificity of strain elastography was 80% and 79%, respectively. Heterogeneity was significant, as indicated by chi-square test and an I2 statistic of over 75.

CONCLUSIONS

Cervical elastography can be used for predicting preterm deliveries with moderate to high level of accuracy.

Translating new breast ultrasound techniques into clinical practice: evaluating their intended uses and describing other unexpected uses for them

Several new ultrasound tools have been developed to further evaluate breast lesions detected on B-mode ultrasound. Strain elastography (SRE) was developed to assess the likelihood of malignancy of lesions based on their stiffness. This has been incorporated into the latest edition of the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) lexicon and atlas. However, no agreed cut-off stiffness values have been established to distinguish benign from malignant lesions making the translation into routine clinical practice difficult. Superb microvascular imaging (SMI) was developed to better evaluate the vascularity within sonographic lesions and assess their likelihood of malignancy. However, there is also no agreed cut-off value for vascular index (VI) to distinguish between benign and malignant lesions. MicroPure was developed to better visualize and evaluate calcifications seen on ultrasound. Its effective use in breast screening and evaluating the calcifications detected for likelihood of malignancy have not been established. This article describes the original intended uses of these applications and reviews the studies evaluating them, showing the varying success of the translation of these tools into routine clinical practice. Also described are some other uses of these tools for which they were not originally intended. This illustrates the importance of being perceptive to alternative uses of imaging tools in their translation from bench to bedside.

A Comparative Analysis of Strain and 2D Shear Wave Elastography in the Diagnosis of Autoimmune Thyroiditis in Pediatric Patients

This paper aims to assess the usefulness of shear-wave elastography (SWE) and strain elastography (SE) for identifying and monitoring thyroid gland changes in children diagnosed with chronic autoimmune thyroiditis (CAT). Our study included 77 children between the ages of six and eighteen. Of these, 45 were diagnosed with CAT, while 32 had no thyroid pathology. Following a clinical examination and laboratory tests, an ultrasound was carried out, and then a SE (using a Hitachi Preirus machine) and SWE (using an Aixplorer Mach 30, Supersonic imagine, France) were performed in the same session. The median thyroid elastic index (EI) in the CAT group was 13.8 (13.3-17) kPa compared to 10.1 (9.3-11.2) kPa in healthy children (p < 0.0001). We found a median strain ratio (SR) of 1.2 (1.2-1.3) for CAT compared to 0.7 (0.6-0.9) for healthy thyroid tissue (p < 0.0001). The optimal cut-off value for predicting the presence of CAT in children using SR was >1 (Se = 82.2%, Sp = 87.5%, PPV = 90.2%, and NPV = 77.8%, AUROC = 0.850), while using SWE, the optimal cut-off value for predicting the presence of CAT in children was >12 kPa (Se = 88.9%, Sp = 93.7%, PPV = 95.2%, and NPV = 85.5%, AUROC = 0.943). Both techniques are useful for measuring thyroid tissue elasticity, and their diagnostic accuracy and reliability are comparable.

The Role of Transabdominal Ultrasound Elastography in Gastrointestinal Non-Liver Diseases: Current Application and Future Prospectives

Ultrasound imaging is the first-line investigation for patients with abdominal symptoms, as it effectively depicts the gastrointestinal tract and enables the diagnosis of multiple pathological conditions. Among different recent ultrasound technological advancements, elastography enables the evaluation of various tissue characteristics, such as neoplastic transformation or fibroinflammatory status. In recent years, ultrasound elastography has been utilized extensively for the study of liver diseases and in numerous other clinical settings, including gastrointestinal diseases. Current guidelines suggest the use of transabdominal ultrasound elastography to characterize bowel wall lesions, to assess gastrointestinal contractility, to diagnose and grade chronic pancreatitis; however, no specific indications are provided. In the present paper, we summarize the evidence concerning the application of different ultrasound elastography modalities in gastrointestinal non-liver diseases.

Peritumoural Strain Elastography of Newly Diagnosed Breast Tumours: Does Maximum Peritumoural Halo Depth Correlate with Tumour Differentiation and Grade?

To evaluate the diagnostic utility of the maximum ultrasound strain elastography (SE) halo depth in newly diagnosed and histologically confirmed breast lesions, a retrospective study approval was granted by the local Ethical Review Board. Overall, the maximum strain elastography peritumoural halos (SEPHmax)-the maximum distance between the SE stiffening area and the B-mode lesion size-in 428 cases with newly diagnosed breast lesions were retrospectively analysed alongside patient age, affected quadrant, tumour echogenicity, size, acoustic shadowing, and vascularity. Statistical analysis included an ordinary one-way ANOVA to compare the SEPHmax between BI-RADS 2, 3, and 5 groups and between tumour grades 1, 2, and 3. A binary regression analysis was used to determine the correlation between tumour malignancy and the above-mentioned demographic and imaging factors. SEPHmax was significantly higher in BI-RADS 5 tumours (5.5 ± 3.9 mm) compared to BI-RADS 3 (0.9 ± 1.7 mm, p < 0.0001) and 2 (0.6 ± 1.4 mm, p < 0.0001). The receiver operating characteristic area under the curve was 0.933 for the detection of BI-RADS 5 lesions. Furthermore, tumour grades 2 (5.6 ± 3.6 mm, p = 0.001) and 3 (6.8 ± 4.2 mm, p < 0.0001) exhibited significantly higher SEPHmax than grade 1 tumours (4.0 ± 3.9 mm). Similarly, St. Gallen Ki67-stratified low-risk (p = 0.005) and intermediate-risk (p = 0.013) tumours showed smaller SEPHmax than high-risk tumours. Multivariate analysis revealed a significant correlation between malignant differentiation and SEPHmax (standardized regression coefficient 3.17 [95% confidence interval (CI) 2.42-3.92], p < 0.0001), low tumour echogenicity (1.68 [95% CI 0.41-3.00], p = 0.03), and higher patient age (0.89 [95% CI 0.52-1.26], p < 0.0001). High SEPHmax is a strong predictor for tumour malignancy and a higher tumour grade and can be used to improve tumour characterisation before histopathological evaluation. It may also enable radiologists to identify lesions warranting observation rather than immediate biopsy.

Can ultrasound strain elastography (USE) improve management of suspicious thyroid nodules measuring <10 mm? A systematic review

INTRODUCTION

Current UK guidelines state that suspicious thyroid nodules <10 mm do not require FNA. These are often followed up with serial ultrasound scans. Ultrasound Strain Elastography (USE) could provide a more accurate alternative and preclude the need for follow-up. Can USE identify nodules at greater risk of malignancy and streamline patient management?

METHODS

Systematic review methodology used. Inclusion criteria are: - Population: patients with suspicious thyroid nodules <10 mm.- Intervention: USE.- Comparator: Ultrasound features of nodules.- Outcome measure: FNA or surgical removal of nodules. Searches performed on 6 commercial databases, along with grey literature anddissertation databases. The QUADAS-2 diagnostic study checklist used for quality assessment.

RESULTS

8 studies included and a narrative analysis performed due to heterogeneity of results. The mean USE sensitivity is 74.3%, mean specificity 80.5%. Mean overall ultrasound sensitivity is 80.4%, specificity 71.0%. Results suggest that USE is not superior to ultrasound for detecting malignancy. Some study limitations, particularly the heterogeneity of reporting the ultrasound features preclude meaningful conclusion from being drawn.

CONCLUSION

USE is more accurate at identifying benign nodules than ultrasound. Nodules appearing benign on USE could be excluded from serial ultrasound follow-up. No significant difference was found between USE and ultrasound at identifying malignant nodules.

IMPLICATIONS FOR PRACTICE

As FNA is not recommended for suspicious thyroid nodules <10 mm, these are often followed up with multiple scans and clinician reviews. This increases pressure on healthcare systems and uncertainty for the patient. This review shows that USE is more accurate at identifying benign nodules than ultrasound alone, meaning that these nodules could potentially be excluded from serial follow up. This would streamline patient management, freeing-up vital resources in ENT and ultrasound departments.

Liver Ultrasound Elastography in Non-Alcoholic Fatty Liver Disease: A State-of-the-Art Summary

Non-alcoholic fatty liver disease (NAFLD) is a chronic disease which is currently the most common hepatic disorder affecting up to 38% of the general population with differences according to age, country, ethnicity and sex. Both genetic and acquired risk factors such as a high-calorie diet or high intake of saturated fats have been associated with obesity, diabetes and, finally, NAFLD. A liver biopsy has always been considered essential for the diagnosis of NAFLD; however, due to several limitations such as the potential occurrence of major complications, sampling variability and the poor repeatability in clinical practice, it is considered an imperfect option for the evaluation of liver fibrosis over time. For these reasons, a non-invasive assessment by serum biomarkers and the quantification of liver stiffness is becoming the new frontier in the management of patients with NAFLD and liver fibrosis. We present a state-of-the-art summary addressing the methods for the non-invasive evaluation of liver fibrosis in NAFLD patients, particularly the ultrasound-based techniques (transient elastography, ARFI techniques and strain elastography) and their optimal cut-off values for the staging of liver fibrosis.

Elastography Assisted BI-RADS in the Preoperative Breast Magnetic Resonance Imaging 4a Lesions in China

OBJECTIVES

A considerable number of benign lesions, especially category 4a lesions on Breast Imaging Reporting and Data System Magnetic Resonance Imaging (BI-RADS-MRI), were biopsied according to BI-RADS-MRI, which was a diagnostic imaging challenge. This study aimed to evaluate the diagnostic performance of ultrasound elastography (UE) assisted Breast Imaging Reporting and Data System (BI-RADS) for BI-RADS-MRI category 4a lesions.

METHODS

Between January 2017 and December 2019, 228 breast lesions categorized as BI-RADS-MRI 4a were included. Conventional ultrasound (US) and UE were performed to evaluate each lesion. Pathology results were used as the gold standard. The diagnostic performances of different UE methods and our re-assessment proposal were evaluated.

RESULTS

When BI-RADS-MRI category 4a, BI-RADS-US category 3-4a, the stiffness of soft or intermediate in elasticity assessment according to the fifth edition of the BI-RADS atlas, strain ratio < 1.335, age ≤ 52 years, and the maximum diameter of lesion ≤20 mm were simultaneously met, an ultrasound-guided empty needle biopsy was not recommended, but short-term ultrasound follow-up for 3-6 months was recommended, and biopsy was performed after changes in evaluation. In this way, 95 of 228 BI-RADS-MRI category 4a lesions avoided biopsies, and the number of patients with biopsies decreased by 41.7%.

CONCLUSIONS

UE offers benefits in the characterization of BI-RADS-MRI category 4a lesions. Ultrasound and elastography can help optimize therapy recommendations for BI-RADS-MRI category 4a lesions by our re-assessment proposal.

Elasticity imaging using physics-informed neural networks: Spatial discovery of elastic modulus and Poisson's ratio

Elasticity imaging is a technique that discovers the spatial distribution of mechanical properties of tissue using deformation and force measurements under various loading conditions. Given the complexity of this discovery, most existing methods approximate only one material parameter while assuming homogeneous distributions for the others. We employ physics-informed neural networks (PINN) in linear elasticity problems to discover the space-dependent distribution of both elastic modulus (E) and Poisson's ratio (ν) simultaneously, using strain data, normal stress boundary conditions, and the governing physics. We validated our model on three examples. First, we experimentally loaded hydrogel samples with embedded stiff inclusions, representing tumorous tissue, and compared the approximations against ground truth determined through tensile tests. Next, using data from finite element simulation of a rectangular domain containing a stiff circular inclusion, the PINN model accurately localized the inclusion and estimated both E and ν. We observed that in a heterogeneous domain, assuming a homogeneous ν distribution increases estimation error for stiffness as well as the area of the stiff inclusion, which could have clinical importance when determining size and stiffness of tumorous tissue. Finally, our model accurately captured spatial distribution of mechanical properties and the tissue interfaces on data from another computational model, simulating uniaxial loading of a rectangular hydrogel sample containing a human brain slice with distinct gray matter and white matter regions and complex geometrical features. This elasticity imaging implementation has the potential to be used in clinical imaging scenarios to reliably discover the spatial distribution of mechanical parameters and identify material interfaces such as tumors. STATEMENT OF SIGNIFICANCE: Our work is the first implementation of physics-informed neural networks to reconstruct both material parameters - Young's modulus and Poisson's ratio - and stress distributions for isotropic linear elastic materials by having deformation and force measurements. We comprehensively validate our model using experimental measurements and synthetic data generated using finite element modeling. Our method can be implemented in clinical elasticity imaging scenarios to improve diagnosis of tumors and for mechanical characterization of biomaterials and biological tissues in a minimally invasive manner.

Compression Elastography and Shear Wave Ultrasound Elastography for Measurement of Brain Elasticity in Full-Term and Premature Neonates: A Prospective Study

OBJECTIVES

To investigate the brain tissue elasticity in normal term and premature neonates using compression elastography and shear wave elastography.

METHODS

This prospective observational study enrolled term and premature neonates admitted to the Third Affiliated Hospital of Guangzhou Medical University between July 2019 and December 2020.

RESULTS

A total of 106 neonates, including 65 premature neonates and 41 term neonates, were enrolled. The elastic modulus of the frontal white matter in males was significantly lower than in females (11.67 ± 0.98 versus 12.25 ± 1.31, P = .030), but the shear wave velocity of the thalamus in males was significantly lower than in females (1.18 ± 0.13 versus 1.82 ± 0.10, P < .001). There was no significant correlation between real-time body weight and brain tissue elasticity including elastic modulus and shear wave velocity. But, the shear wave velocity of parietal white matter (r = 0.319, P = .014) and thalamus (r = -0.268, P = .040) and the elastic modulus of parietal white matter (r = 0.356, P = .006) were correlated with corrected gestational age.

CONCLUSIONS

Clinicians may consider using elastography to determine brain tissue elasticity in term and preterm neonates.

Quantitative Assessment of Breast-Tumor Stiffness Using Shear-Wave Elastography Histograms

Purpose: Shear-wave elastography (SWE) measures tissue elasticity using ultrasound waves. This study proposes a histogram-based SWE analysis to improve breast malignancy detection. Methods: N = 22/32 (patients/tumors) benign and n = 51/64 malignant breast tumors with histological ground truth. Colored SWE heatmaps were adjusted to a 0−180 kPa scale. Normalized, 250-binned RGB histograms were used as image descriptors based on skewness and area under curve (AUC). The histogram method was compared to conventional SWE metrics, such as (1) the qualitative 5-point scale classification and (2) average stiffness (SWEavg)/maximal tumor stiffness (SWEmax) within the tumor B-mode boundaries. Results: The SWEavg and SWEmax did not discriminate malignant lesions in this database, p > 0.05, rank sum test. RGB histograms, however, differed between malignant and benign tumors, p < 0.001, Kolmogorov−Smirnoff test. The AUC analysis of histograms revealed the reduction of soft-tissue components as a significant SWE biomarker (p = 0.03, rank sum). The diagnostic accuracy of the suggested method is still low (Se = 0.30 for Se = 0.90) and a subject for improvement in future studies. Conclusions: Histogram-based SWE quantitation improved the diagnostic accuracy for malignancy compared to conventional average SWE metrics. The sensitivity is a subject for improvement in future studies.

Role of the elastography strain ratio using transrectal ultrasonography in the diagnosis of prostate cancer and clinically significant prostate cancer

This study investigated the efficacy of the elastography strain ratio (ESR) as a predictor of prostate cancer (PCa) in targeted prostate biopsy. In total, 257 patients who underwent magnetic resonance imaging-targeted biopsy were enrolled. Before biopsy, we placed regions of interest (zone A and B) in the lesion and levator ani. The ESR was measured as zone A/zone B. Multivariate analyses were performed to predict PCa and clinically significant PCa. There were 206 (71.5%) positive cancer lesions. No difference in digit rectal examination findings was found between patients with and without PCa. For predicting clinically significant PCa, an ESR ≥ 6.8 was significantly higher in the PCa (+) group than in the PCa (-) group (p < 0.001). The area under the receiver operating characteristic curve (AUC) for the conventional variables (model 1) plus the ESR was 0.845, which was significantly higher than that for model 1 (p = 0.001). In prostate imaging reporting and data system score 3 lesions, an ESR ≥ 4.6 was a significant predictor of PCa (p = 0.002). The AUC in model 1 plus the ESR was 0.856, which was significantly higher than that in model 1 alone (p = 0.017). The ESR is useful for predicting clinically significant PCa.

Comparative study between conventional ultrasound strain elastography and an AI-enabled elastography software in differentiating breast masses

Background

Conventional ultrasound elastography is a relatively novel noninvasive imaging study that assesses tissue stiffness and helps in the characterization of breast lesions. However, strain elastography is not available in some ultrasound machines especially those before 2003 and is susceptible by motion artifacts. Our aim was to compare the results of conventional ultrasound elastography and the results of an advanced intelligence-enabled elastography software. Also, we aimed to assess the feasibility of the AI-enabled elastography software to overcome the unavailability of the conventional elastography software in some new ultrasound machines.

Results

The study included 53 patients, who had breast lesions either clinically felt or detected during screening. All patients were subjected to both grayscale US imaging and conventional ultrasound elastography; quasi-static compression was applied during acquiring one of the cine-loops of the grayscale US imaging. Also, the cine-loops of the grayscale US imaging while quasi-static compression were processed by an AI-enabled elastography software. Then, the results of the strain ratio (SR) calculated by conventional elastography software and those by AI-enabled elastography software were compared. The strain ratio calculated using the AI-enabled elastography software showed better results than conventional ultrasound elastography strain ratio. The AI-enabled software shows better specificity, sensitivity, positive predictive values, and negative predictive values than the conventional ultrasound elastography.

Conclusion

The AI-enabled elastography software shows promising results compared to the conventional US elastography. Elastography does not have the potential to replace conventional B-mode US for the detection of breast cancer but may complement the conventional US to improve diagnostic performance.

SWAVE 2.0 Imaging of Placental Elasticity and Viscosity: Potential Biomarkers for Placenta-Mediated Disease Detection

Pregnancy complications such as pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are associated with structural and functional changes in the placenta. Different elastography techniques with an ability to assess the mechanical properties of tissue can identify and monitor the pathological state of the placenta. Currently available elastography techniques have been used with promising results to detect placenta abnormalities; however, limitations include inadequate measurement depth and safety concerns from high negative pressure pulses. Previously, we described a shear wave absolute vibro-elastography (SWAVE) method by applying external low-frequency mechanical vibrations to generate shear waves and studied 61 post-delivery clinically normal placentas to explore the feasibility of SWAVE for placental assessment and establish a measurement baseline. This next phase of the study, namely, SWAVE 2.0, improves the previous system and elasticity reconstruction by incorporating a multi-frequency acquisition system and using a 3-D local frequency estimation (LFE) method. Compared with its 2-D counterpart, the proposed system using 3-D LFE was found to reduce the bias and variance in elasticity measurements in tissue-mimicking phantoms. In the aim of investigating the potential of improved SWAVE 2.0 measurements to identify placental abnormalities, we studied 46 post-delivery placentas, including 26 diseased (16 IUGR and 10 PE) and 20 normal control placentas. By use of a 3.33-MHz motorized curved-array transducer, multi-frequency (80,100 and 120 Hz) elasticity measures were obtained with 3-D LFE, and both IUGR (15.30 ± 2.96 kPa, p = 3.35e^-5) and PE (12.33 ± 4.88 kPa, p = 0.017) placentas were found to be significantly stiffer compared with the control placentas (8.32 ± 3.67 kPa). A linear discriminant analysis (LDA) classifier was able to classify between healthy and diseased placentas with a sensitivity, specificity and accuracy of 87%, 78% and 83% and an area under the receiver operating curve of 0.90 (95% confidence interval: 0.8-0.99). Further, the pregnancy outcome in terms of neonatal intensive care unit admission was predicted with a sensitivity, specificity and accuracy of 70%, 71%, 71%, respectively, and area under the receiver operating curve of 0.78 (confidence interval: 0.62-0.93). A viscoelastic characterization of placentas using a fractional rheological model revealed that the viscosity measures in terms of viscosity parameter n were significantly higher in IUGR (2.3 ± 0.21) and PE (2.11 ± 0.52) placentas than in normal placentas (1.45 ± 0.65). This work illustrates the potential relevance of elasticity and viscosity imaging using SWAVE 2.0 as a non-invasive technology for detection of placental abnormalities and the prediction of pregnancy outcomes.

Comparing the accuracy of shear wave elastography and strain elastography in the diagnosis of breast tumors: A systematic review and meta-analysis

BACKGROUND

Shear wave elastography (SWE) and strain elastography (SE) are 2 new ultrasonic technologies which have developed rapidly in recent years. Elastography transforms the elastic information of tissue into optical information for display, thus more intuitive display of tissue elasticity. Conflicting results have been obtained in different scholars' studies on the accuracy comparison of the 2 elastography technologies in the diagnosis of breast tumors. This meta-analysis aims to compare the accuracy of the 2 elastography technologies in the diagnosis of breast tumors, and provide a reference for clinical decision making.

METHODS

We have searched Chinese and English literatures on the accuracy of SWE and SE in the diagnosis of breast tumors from PubMed, Web of Science, China national knowledge infrastructure and Wanfang databases, and the time was up to December30, 2020. Two literature reviewers screened the literatures according to the screening criteria, and Quality Assessment of Diagnostic Accuracy Study tool was used to evaluate the quality of included literatures. Meta Disc1.4 and Stata14.0 softwares were used to perform heterogeneity test, sensitivity analysis and publication bias test.

RESULTS

Ten literatures included 1599 patients and 1709 breast lesions. The final results in the SWE as follow: The pooled sensitivity was 0.852 (95% confidence interval [CI] [0.826-0.874]), the pooled specificity (Spe) was 0.799 (95% CI [0.776-0.820]), the pooled positive likelihood ratio was 4.758 (95% CI [3.443-6.576]), the pooled negative likelihood ratio was 0.192 (95% CI [0.147-0.250]), the pooled diagnostic odds ratio was 29.071 (95% CI [16.967-49.811]), and the area under the summary receiver operating characteristic curve was 0.9159. The final results in the SE as follow: The pooled sensitivity was 0.843 (95% CI [0.817-0.866]), the pooled Spe was 0.766 (95% CI [0.743-0.789]), the pooled positive likelihood ratio was 4.387 (95% CI [3.088-6.233]), the pooled negative likelihood ratio was 0.216 (95% CI [0.179-0.261]), the pooled diagnostic odds ratio was 22.610 (95% CI [15.622-32.724]), and the area under the summary receiver operating characteristic curve was 0.8987.

CONCLUSION

The sensitivity and Spe of SWE were higher than those of SE, suggesting that SWE may have a higher accuracy in the diagnosis of breast tumors.

REGISTER NAME

PROSPERO. Registration number: CRD42021251110.

Diagnostic Value of Different 3-D Shear Wave Elastography Sections in the Diagnosis of Thyroid Nodules

The aim of the study was to explore the value of 3-D shear wave elastography (SWE) in differentiating malignant from benign thyroid nodules. A total of 188 patients with 216 nodules who underwent conventional ultrasound, 2-D SWE and 3-D SWE were included in this study. All patients underwent surgical excision, and the pathological results were the gold standard. Receiver operating characteristic (ROC) curves of the American College of Radiology's Thyroid Imaging Reporting and Data System (ACR TI-RADS), 2-D SWE and 3-D SWE were plotted, and the areas under the curves (AUCs) were compared using a Z-test. There were 62 benign thyroid nodules and 154 malignant thyroid nodules in this study. Young's modulus (E_min, E_mean, E_max, E_sd) values of thyroid malignant nodules in different sections of 2-D SWE and 3-D SWE were significantly higher than those of thyroid benign nodules (p < 0.001). The AUC of E_max in 2-D SWE transverse sections was significantly lower than that in 3-D SWE transverse sections and 3-D SWE sagittal sections (0.768 vs. 0.831 and 0.844, p < 0.05). The AUC of 3-D S-E_max combined with ACR TI-RADS was 0.859; the specificity increased from 54.84% to 85.71%, and the diagnostic accuracy increased from 74.54% to 85.19%, compared with ACR TI-RADS. The difference was statistically significant (p < 0.05). Three-dimensional SWE combined with ACR TI-RADS for the diagnosis of thyroid nodules significantly improved the diagnostic ability of ACR TI-RADS, and was significantly better than 2-D SWE combined with ACR TI-RADS.

On the dielectric and mechanical characterization of tissue‐mimicking breast phantoms

Objective. In this paper, we focus on the dielectric and mechanical characterization of tissue-mimicking breast phantoms. Approach. Starting from recipes previously proposed by our research group, based on easy-to-handle, cheap and safe components (i.e. sunflower oil, deionized water, dishwashing liquid and gelatin), we produced and tested, both dielectrically and mechanically, more than 100 samples. The dielectric properties were measured from 500 MHz to 14 GHz, the Cole–Cole parameters were derived to describe the dielectric behaviour in a broader frequency range, and the results were compared with dielectric properties of human breast ex vivo tissues up to 50 GHz. The macroscale mechanical properties were measured by means of unconfined compression tests, and the impact of the experimental conditions (i.e. preload and test speed) on the measured Young’s moduli was analysed. In addition, the mechanical contrast between healthy- and malignant-tissue-like phantoms was evaluated. Main results. The results agree with the literature in the cases in which the experimental conditions are known, demonstrating the possibility to fabricate phantoms able to mimic both dielectric and mechanical properties of breast tissues. Significance. In this work, for the first time, a range of materials reproducing all the categories of breast tissues were experimentally characterized, both from a dielectric and mechanical point of view. A large range of frequency were considered for the dielectric measurements and several combinations of experimental conditions were investigated in the context of the mechanical characterization. The proposed results can be useful in the design and testing of complementary or supplementary techniques for breast cancer detection based on micro/millimetre-waves, possibly in connection with other imaging modalities.

Transvaginal Ultrasound Combined with Strain-Ratio Elastography for the Concomitant Diagnosis of Uterine Fibroids and Adenomyosis: A Pilot Study

Uterine fibroids (UFs) and adenomyosis (AM) represent two benign uterine conditions that can affect fertility and are most frequently commonly responsible for abnormal uterine bleeding and chronic pelvic pain. Their differential diagnosis still represents a challenge, and several authors advise the addition of elastography to transvaginal ultrasound (TVUS) for a more accurate imagistic recognition. Through this study, we aimed to assess the diagnostic accuracy of TVUS combined with strain-ratio elastography (SRE) in concomitant AM and UFs. We conducted a study on 17 patients diagnosed with concomitant UFs and AM undergoing hysterectomy and 46 healthy patients. TVUS combined with SRE was conducted in each patient, focusing on identifying rigidity patterns of the lesions. Significantly higher mean SR and maximum SR values were identified among both AM and UF lesions as opposed to controls (p < 0.01), with the highest tissue stiffness being encountered among AM lesions, which allows for the differentiation of UF (p < 0.01) and concomitant identification of both lesions. These results are reflected by higher cut-off values obtained for AM, both for mean SR (5.42 vs. 2.85) and maximum SR (5.80 vs. 3.30). TVUS combined with SRE showed good diagnostic performance in identifying coexisting UFs and AM within the same uterine specimen. Future studies on wider populations are required to validate our findings.

Early detection of pancreatic tumors by advanced EUS imaging

The early detection of pancreatic ductal adenocarcinoma (PDAC) dramatically improves outcome. All available state-of-the-art imaging methods allow early detection with EUS being the best technique for exclusion of PDAC and detection of very early PDAC. Etiological differentiation of small SPL is important to guide individually tailored patients' management including radical surgery in resectable PDAC, medical (neoadjuvant or palliative intended) treatment in patients with non-resectable malignancy, pancreatic parenchyma saving strategies in some non-PDAC, and follow-up in particular in low-grade PanNEN or other small benign lesions. Multimodality EUS imaging including B-Mode assessment, elastography, contrast-enhancement and EUS-guided sampling is the most appropriate technique for diagnosis and risk assessment of small SPL. We present a review discussing modern (endoscopic) ultrasound imaging techniques including contrast enhanced ultrasound and elastography for the early detection and characterization of solid pancreatic lesions.

Comparing the accuracy between shear wave elastography and strain elastography in the diagnosis of breast tumors: Systematic review and meta-analysis

BACKGROUND

Shear wave elastography and strain elastography are two new ultrasonic techniques developed rapidly in recent years. Changes in tissue elasticity occur after normal tissue changes. Elastography technique transforms the elastic information of tissue into optical information for display. Thus more intuitive display of tissue elasticity. Due to the differences in principles and related imaging parameters between the two elastic imaging methods, and the acquisition and interpretation of image data in strain elastic imaging method largely depends on the experience of inspectors, and due to the significant differences between the techniques of inspectors, As a result, conflicting results have been obtained in different scholars' studies on the accuracy comparison of the two elastography techniques in the diagnosis of breast tumors. This meta-analysis aims to compare the accuracy of the two elastography methods in the diagnosis of breast tumors, so as to provide more accurate diagnostic means for patients with breast tumors. The final results will show which elastography method is more accurate in the diagnosis of breast tumors, reduce unnecessary biopsies and provide a reference for clinical decision making.

METHODS

We will examine published and unpublished randomized controlled trials, observational studies and abstracts without publication type or language restrictions, and search relevant literatures in PubMed, Web of Science, Wanfang Database, CNQI and other databases until December 30, 2020. The authors will independently search relevant literature records, scan titles and abstracts, full text, collect data and assess the risk of bias. Data will be analyzed by using Meta Disc1.4 software and Stata14.0 software. Heterogeneity tests and combined sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio, and area under the summary receiver operating characteristic curve will be performed by using Meta Disc1.4 software. Stata14.0 software will be used for sensitivity analysis and publication bias test.

RESULTS

The results of this systematic review will demonstrate the accuracy of the two elastography methods in the diagnosis of breast tumors.

DISCUSSION

The results will provide useful evidence for the comparison of the diagnostic accuracy of shear wave elastography and strain elastography in breast tumors.

OTHER

This study was not funded. Register name: PROSPERO. Registration number: CRD42021251110.

Suspected Malignant Thyroid Nodules in Children and Adolescents According to Ultrasound Elastography and Ultrasound-Based Risk Stratification Systems-Experience from One Center

The risk of malignancy in thyroid nodules correlates with the presence of ultrasonographic features. In adults, ultrasound risk-classification systems have been proposed to indicate the need for further invasive diagnosis. Furthermore, elastography has been shown to support differential diagnosis of thyroid nodules. The purpose of our study was to assess the application of the American Thyroid Association (ATA), British Thyroid Association (BTA) ultrasound risk-classification systems and strain elastography in the management of thyroid nodules in children and adolescents from one center. Seventeen nodules with Bethesda III, IV, V and VI were selected from 165 focal lesions in children. All patients underwent ultrasonography and elastography followed by fine needle aspiration biopsy. Ultrasonographic features according to the ATA and BTA stratification systems were assessed retrospectively. The strain ratio in the group of thyroid nodules diagnosed as malignant was significantly higher than in benign nodules (6.07 vs. 3.09, p = 0.036). According to the ATA guidelines, 100% of malignant nodules were classified as high suspicion and 73% of benign nodules were assessed as low suspicion. Using the BTA U-score classification, 80% of malignant nodules were classified as cancerous (U5) and 20% as suspicious for malignancy (U4). Among benign nodules, 82% were classified as indeterminate or equivocal (U3) and 9% as benign (U2). Our results suggest that application of the ATA or BTA stratification system and elastography may be a suitable method for assessing the level of suspected malignancy in thyroid nodules in children and help make a clinical decision about the need for further invasive diagnosis of thyroid nodules in children.

Mid- and Long-Term Results Using 448 kHz Stimulation on the Elasticity of the Supraspinatus Tendon Measured by Quantitative Ultrasound Elastographyin Badminton Professionals: Prospective Randomized Double-Blinded Clinical Trial with Nine Months of Follow-Up

The aim of this study is to analyse the changes that occur in the elasticity of the supraspinatus tendon after the application of a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) at 3, 6 and 9 months in professional badminton players. A randomized double-blinded clinical trial that included 9 months of follow-up was used. A private care practice was used to recruit the participants of this study. They were randomly assigned either the CRMR treatment (n = 19) or the placebo treatment (n = 19). The experimental group received a total of nine treatments of 448 kHz CRMR divided into three treatments per week. The control group received the same regimen but with no radiofrequency. Quantitative ultrasound strain elastography was used to report the main values for three areas of the supraspinatus tendon. These were measured at the start (T1) and directly after (T2), one week after, (T3), three months after (T4), six months after (T5) and nine months after (T6) the completion of the intervention program. There were statistically significant differences in the supraspinatus tendon elasticity immediately after (p ≤ 0.001), one week after (p ≤ 0.001) and three months after (p = 0.01) the intervention program. No significant changes were found six or nine months after the intervention program. A three-week intervention program using 448 kHz produced significant changes in the elasticity of the supraspinatus tendon, with the changes lasting up to approximately three months when compared to the control group.

Applications of endoscopic ultrasound elastography in pancreatic diseases: From literature to real life

Elastography is a non-invasive method widely used to measure the stiffness of the tissues, and it is available in most endoscopic ultrasound machines, using either qualitative or quantitative techniques. Endoscopic ultrasound elastography is a tool that should be applied to obtain a complementary evaluation of pancreatic diseases, together with other imaging tests and clinical data. Elastography can be informative, especially when studying pancreatic masses and help the clinician in the differential diagnosis between benign or malignant lesions. However, further studies are necessary to standardize the method, increase the reproducibility and establish definitive cut-offs to distinguish between benign and malignant pancreatic masses. Moreover, even if promising, elastography still provides little information in the evaluation of benign conditions.

Impact of Applying a Skin Compression With the Ultrasound Probe on Carotid Artery Strain Elastography

OBJECTIVE

To study the impact of varying the external compression exerted by the ultrasound probe when performing a carotid strain elastography exam.

METHODS

Nine healthy volunteers (mean age 43 years ±13 years; 6 men) underwent a vascular ultrasound elastography exam using a custom made sound feedback handle embedding the probe, and allowing the sonographer to adjust the applied compression. A clinical standard practice (SP) force was first recorded, and then predetermined compression (PDC) forces were applied, ranging from 0 to 5 N for the left common carotid artery (CCA) or 2-12 N for the left internal carotid artery (ICA). Six carotid elastography features, namely maximum and cumulated axial strains, maximum and cumulated shear strains, cumulated axial translation, and cumulated lateral translation were assessed with noninvasive vascular elastography (NIVE) on near and far walls of carotids. The carotid intima media thickness (IMT) and diameter were also measured.

RESULTS

All elastography features on the near wall of both CCA and ICA decreased statistically significantly as the PDC force increased; this association was also observed for half of the features on the far wall. Three NIVE features at the lowest PDC force (out of 72 that were tested) were statistically significantly different than values at the SP force. Overall, NIVE showed some variance to probe compression with linear regression slopes revealing changes of 10.1%-45.6% in magnitude over the whole compression range on both walls. The maximum IMT for the ICA near wall, and carotid lumen diameters of both CCA and ICA were statistically significantly associated with PDC forces; these features underwent a decrease of 10.2%, 36.2%, and 17.6%, respectively, over the whole range of PDC force increase. Other IMT measurements were not statistically significantly associated with applied PDC forces.

CONCLUSION

These results suggest the need of technical guidelines for carotid strain elastography. Using the lowest probe compression while allowing a good B-mode image quality is recommended to improve the robustness of NIVE measurements.

Determining the elastography strain ratio cut off value for differentiating benign from malignant breast lesions: systematic review and meta-analysis

Background

Elastography is an addition to grey-scale ultrasonic examination that has gained substantial traction within the last decade. Strain ratio (SR) has been incorporated as a semiquantitative measure within strain elastography, thus a potential imaging biomarker. The World Federation for Ultrasound in Medicine and Biology (WFUMB) published guidelines in 2015 for breast elastography. These guidelines acknowledge the marked variance in SR cut-off values used in differentiating benign from malignant lesions. The objective of this review was to include more recent evidence and seek to determine the optimal strain ratio cut off value for differentiating between benign and malignant breast lesions.

Methods

Comprehensive search of MEDLINE and Web of Science electronic databases with additional searches via Google Scholar and handsearching set from January 2000 to May 2020 was carried out. For retrieved studies, screening for eligibility, data extraction and analysis was done as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Diagnostic Test Accuracy (PRISMA-DTA) Statement guidelines of 2018. Quality and risk of bias assessment of the studies were performed using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

Results

A total of 424 articles, 412 from electronic database and 12 additional searches were retrieved and 65 studies were included in the narrative synthesis and subgroup analysis. The overall threshold effect indicated significant heterogeneity among the studies with Spearman correlation coefficient of Logit (TPR) vs Logit (FPR) at − 0.301, p-value = 0.015. A subgroup under machine model consisting seven studies with 783 patients and 844 lesions showed a favourable threshold, Spearman’s correlation coefficient,0.786 (p = 0.036).

Conclusion

From our review, currently the optimal breast SR cut-off point or value remains unresolved despite the WFUMB guidelines of 2015. Machine model as a possible contributor to cut-off value determination was suggested from this review which can be subjected to more industry and multi-center research determination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-022-00447-5.

Concurrent validity and intrarater reliability of two ultrasound-based methods for assessing patellar tendon stiffness

Introduction

Assessment of tendon stiffness in vivo traditionally involves maximal muscle contractions, which can be challenging in pain populations. Alternative methods are suggested, although the clinimetric properties are sparse. This study investigated the concurrent validity and the intrarater reliability of two ultrasound-based methods for assessing patellar tendon stiffness.

Methods

Patellar tendon stiffness was assessed in 17 healthy adults with (a) the dynamometer and B-mode ultrasonography method (DBUS) and (b) the strain elastography method. Correlations between the two methods were analysed using Kendall’s Tau-b. The relative reliability of both methods was evaluated using intraclass correlation coefficient (ICC). The absolute reliability was presented by Bland–Altman plots, standard error of measurement (SEM) and minimum detectable change (MDC).

Results

No correlation was found between the two methods, irrespective of reference tissue in strain elastography (Kendall’s Tau-b Hoffa = –0.01 (p = 1.00), Kendall’s Tau-b subcutis = 0.04 (p = 0.87)). Tracking of the tendon elongation in the DBUS method had good to excellent relative reliability (ICC = 0.95 (95% confidence interval – CI: 0.85–0.98)) and high absolute reliability (SEM = 0.04 mm (1%), MDC = 0.11 mm (3%)). The strain elastography method had good to excellent relative reliability, regardless of reference tissue (ICC Hoffa = 0.95 (95% CI: 0.86–0.98), ICC subcutis = 0.94 (95% CI: 0.82–0.98)), but low absolute reliability (SEM Hoffa = 0.06 (20%), MDC Hoffa = 0.18 (60%), SEM subcutis = 0.12 (41%), MDC subcutis = 0.32 (110%)).

Conclusions

No concurrent validity existed for DBUS and strain elastography, suggesting that the two methods measure different tendon properties. The overall reliability for the DBUS method was high, but the absolute reliability was low for strain elastography stiffness ratios. Therefore, the strain elastography method may not be recommended for tracking differences in patellar tendon stiffness in healthy adults.

Assessment of myocardial viscoelasticity with Brillouin spectroscopy in myocardial infarction and aortic stenosis models

Heart diseases are associated with changes in the biomechanical properties of the myocardial wall. However, there is no modality available to assess myocardial stiffness directly. Brillouin microspectroscopy (mBS) is a consolidated mechanical characterization technique, applied to the study of the viscoelastic and elastic behavior of biological samples and may be a valuable tool for assessing the viscoelastic properties of the cardiac tissue. In this work, viscosity and elasticity were assessed using mBS in heart samples obtained from healthy and unhealthy mice (n = 6 per group). Speckle-tracking echocardiography (STE) was performed to evaluate heart deformation. We found that mBS was able to detect changes in stiffness in the ventricles in healthy myocardium. The right ventricle showed reduced stiffness, in agreement with its increased compliance. mBS measurements correlated strongly with STE data, highlighting the association between displacement and stiffness in myocardial regions. This correlation was lost in pathological conditions studied. The scar region in the infarcted heart presented changes in stiffness when compared to the rest of the heart, and the hypertrophied left ventricle showed increased stiffness following aortic stenosis, compared to the right ventricle. We demonstrate that mBS can be applied to determine myocardial stiffness, that measurements correlate with functional parameters and that they change with disease.

Ultrasound Elastography in Ocular and Periocular Tissues: A Review

Ultrasound elastography has become available in everyday practice, allowing direct measurement of tissue elasticity with important and expanding clinical applications. Several studies that have evaluated pathological and non-pathological tissues have demonstrated that ultrasound elastography can actually improve the diagnostic accuracy of the underlying disease process by detecting differences in their elasticity. Ocular and periocular tissues can also be characterized by their elastic properties. In this context, a comprehensive review of literature on ultrasound elastography as well as its current applications in Ophthalmology is presented.

Diagnosis of Fibrotic Distal Ileum Stenosis after Ischemic Enteritis Using Transabdominal Ultrasonography

Ischemic enteritis (IE) is a rare disorder which is caused by inadequate blood flow to small intestine. The diagnostic procedure of this disease has not sufficiently established because of its rarity. Here, we report a case of IE in a hemodialysis-dependent 70-year-old man and summarize the diagnostic options for IE. The patient was admitted to our hospital because of acute abdominal distention and vomiting. He presented with mild tenderness in the lower abdomen and slightly elevated C-reactive protein level as revealed by blood tests. Radiographic imaging showed small bowel obstruction due to a stricture in the distal ileum. Contrast-enhanced abdominal ultrasonography revealed a 7-cm stenotic site with increased intestinal wall thickening, which preserved mucosal blood perfusion. Elastography revealed a highly elastic alteration of the stenotic lesion, indicating benign fibrotic changes resulting from chronic insufficient blood flow. Based on a clinical diagnosis of IE with fibrous stenosis, a partial ileostomy was performed. After surgical treatment, oral intake was initiated without recurrence of intestinal obstruction. Pathological findings revealed deep ulceration with inflammatory cell infiltration at the stenotic site. Occlusion and hyalinization of the venules in the submucosal layer indicated IE. In addition to current case, we reviewed past case reports of IE. Through this case presentation and literature review, we summarize the usefulness and safety of transabdominal ultrasonography for diagnosing IE.

Incidental Findings and How to Manage Them: Testis- A WFUMB Position Paper

Testicular incidentalomas are non-palpable, asymptomatic lesions, most frequently detected on ultrasound examinations. Each incidentaloma should undergo a standardized diagnostic workup to exclude malignancy and recognize other potentially significant non-malignant conditions that may first present with an incidental finding on scrotal ultrasound. This position statement of the World Federation of Ultrasound in Medicine and Biology (WFUMB) summarizes the available evidence on management of testicular incidentalomas and describes efficient management strategies with particular reference to the role of ultrasound techniques.

Ultrasound Elastography in the Assessment of the Intestinal Changes in Inflammatory Bowel Disease-Systematic Review

Inflammatory bowel disease (IBD) is a chronic condition affecting primarily the gastrointestinal tract and characterized by growing incidence worldwide. Complex diagnostic process of IBD as well as evaluation of disease activity and intestinal complications that are crucial for the therapeutic decisions, require repetitive, invasive, expensive, time-consuming and poorly tolerated tests. In contrast to endoscopy and computed tomography, ultrasound elastography (UE) is non-invasive, non-radiating and non-contrasting dependent tool which might be utilized in IBD patients for the assessment of the intestinal changes. Therefore, we performed the systematic review to evaluate the possible application of the ultrasound elastography for assessment of the intestinal changes in IBD. After the search of three databases: PubMed, World of Knowledge and Scopus, we identified 12 papers which were included in the final analysis. The majority of the studies were focused on the evaluation of the symptomatic ileal/ileocolonic strictures in Crohn's disease patients that required surgical resection. Only one study concerned ulcerative colitis. The authors evaluated different UE techniques: strain elastography (SE), acoustic radiation force impulse (ARFI) and shear wave elastography (SWE). Results were expressed with semi-quantitative color mapping and strain measurement. Histological scores of inflammation and fibrosis in Crohn's disease were used as a reference test in the majority of studies. Ultrasound elastography seems to be a promising novel imaging technique supporting evaluation of the intestinal strictures in Crohn's disease patients in respect to fibrosis detection as well as differentiation between fibrosis and inflammation. However, further research is needed to establish the position of ultrasound elastography in IBD management.

Non-destructive vacuum-assisted measurement of lung elastic modulus

In living tissues, mechanical stiffness and biological function are intrinsically linked. Alterations in the stiffness of tissues can induce pathological interactions that affect cellular activity and tissue function. Underlying connections between tissue stiffness and disease highlights the importance of accurate quantitative characterizations of soft tissue mechanics, which can improve our understanding of disease and inform therapeutic development. In particular, accurate measurement of lung mechanical properties has been especially challenging due to the anatomical and mechanobiological complexities of the lung. Discrepancies between measured mechanical properties of dissected lung tissue samples and intact lung tissues in vivo has limited the ability to accurately characterize integral lung mechanics. Here, we report a non-destructive vacuum-assisted method to evaluate mechanical properties of soft biomaterials, including intact tissues and hydrogels. Using this approach, we measured elastic moduli of rat lung tissue that varied depending on stress-strain distribution throughout the lung. We also observed that the elastic moduli of enzymatically disrupted lung parenchyma increased by at least 64%. The reported methodology enables assessment of the nonlinear viscoelastic characteristics of intact lungs under normal and abnormal (i.e., injured, diseased) conditions and allows measurement of mechanical properties of tissue-mimetic biomaterials for use in therapeutics or in vitro models. STATEMENT OF SIGNIFICANCE: Accurate quantification of tissue stiffness is critical for understanding mechanisms of disease and developing effective therapeutics. Current modalities to measure tissue stiffness are destructive and preclude accurate assessment of lung mechanical properties, as lung mechanics are determined by complex features of the intact lung. To address the need for alternative methods to assess lung mechanics, we report a non-destructive vacuum-based approach to quantify tissue stiffness. We applied this method to correlate lung tissue mechanics with tissue disruption, and to assess the stiffness of biomaterials. This method can be used to inform the development of tissue-mimetic materials for use in therapeutics and disease models, and could potentially be applied for in-situ evaluation of tissue stiffness as a diagnostic or prognostic tool.

Value of Strain-Ratio Elastography in the Diagnosis and Differentiation of Uterine Fibroids and Adenomyosis

Benign uterine disorders, including uterine fibroids (UF) and adenomyosis (AM), can impact the life quality and fertility of women of reproductive age. Transvaginal ultrasound (TVUS) has long been used for their early identification, but its combined use with elastography seems to improve diagnostic accuracy of UF and AM. Thus, a prospective pilot study was conducted on 79 patients who underwent hysterectomy (25 microscopically diagnosed with AM and 53 with UF), with the aim of assessing the ability of TVUS combined with strain ratio elastography (SE) to accurately diagnose and distinguish UF and AM. Significantly higher mean and maximal strain ratio (SR) values were identified for patients with histologically confirmed AM as opposed to those with UF (p < 0.001). Diagnostic sensitivity and specificity, calculated in comparison with histology results, were higher for UF than AM. Receiver operating characteristic (ROC) analysis was applied between the two study groups, revealing cutoff values of 7.71 for mean SR and 8.91 for maximal SR, respectively, with good sensitivity and specificity parameters (100% and 96.23%; 96% and 96.23%). Our results support the use of TVUS in combination with SE for the positive and differential diagnosis of UF and AM, through identification of their particular tissue stiffness features.

Advancements in the Application of Ultrasound Elastography in the Cervix

Ultrasound elastography is a modern imaging technique that has developed rapidly in recent years. It enables objective measurement of tissue stiffness, a physical property intuitive to the human sense of touch. This novel technology has become a hotspot and plays a major role in scientific research and academic practice. Presently, ultrasound elastography has been used in the identification of benign and malignant tumors in superficial organs, such as breast and thyroid, providing clinically accurate diagnosis and treatment. The method has also been widely used for the liver, kidney, prostate, lymph nodes, blood vessels, skin and muscle system. In the application of cervical lesions, ultrasound elastography can distinguish normal cervix from abnormal cervix and differentiate benign from malignant lesions. It can significantly improve the diagnostic specificity for cervical cancer and is also useful for assessing infiltration depth and stage of cervical cancer, as well as predicting chemoradiotherapy treatment response. For cervical evaluation during pregnancy, ultrasound elastography is useful for assessing cervical softening and predicting premature delivery and outcome of induced labor. This article reviews the principles of ultrasound elastography as well as the current status and limitations in its application for cervical lesions and the cervix during pregnancy.

How muscle stiffness affects human body model behavior

BACKGROUND

Active human body models (AHBM) consider musculoskeletal movement and joint stiffness via active muscle truss elements in the finite element (FE) codes in dynamic application. In the latest models, such as THUMS™ Version 5, nearly all human muscle groups are modeled in form of one-dimensional truss elements connecting each joint. While a lot of work has been done to improve the active and passive behavior of this 1D muscle system in the past, the volumetric muscle system of THUMS was modeled in a much more simplified way based on Post Mortem Human Subject (PMHS) test data. The stiffness changing effect of isometric contraction was hardly considered for the volumetric muscle system of whole human body models so far. While previous works considered this aspect for single muscles, the effect of a change in stiffness due to isometric contraction of volumetric muscles on the AHBM behavior and computation time is yet unknown.

METHODS

In this study, a simplified frontal impact using the THUMS Version 5 AM50 occupant model was simulated. Key parameters to regulate muscle tissue stiffness of solid elements in THUMS were identified for the material model MAT_SIMPLIFIED_FOAM and different stiffness states were predefined for the buttock and thigh.

RESULTS

During frontal crash, changes in muscle stiffness had an effect on the overall AHBM behavior including expected injury outcome. Changes in muscle stiffness for the thigh and pelvis, as well as for the entire human body model and for strain-rate-dependent stiffness definitions based on literature data had no significant effect on the computation time.

DISCUSSION

Kinematics, peak impact force and stiffness changes were in general compliance with the literature data. However, different experimental setups had to be considered for comparison, as this topic has not been fully investigated experimentally in automotive applications in the past. Therefore, this study has limitations regarding validation of the frontal impact results.

CONCLUSION

Variations of default THUMS material model parameters allow an efficient change in stiffness of volumetric muscles for whole AHBM applications. The computation time is unaffected by altering muscle stiffness using the method suggested in this work. Due to a lack of validation data, the results of this work can only be validated with certain limitations. In future works, the default material models of THUMS could be replaced with recently published models to achieve a possibly more biofidelic muscle behavior, which would even allow a functional dependency of the 1D and 3D muscle systems. However, the effect on calculation time and model stability of these models is yet unknown and should be considered in future studies for efficient AHBM applications.

Ultrasound Elastography in the Assessment of the Stiffness of Spastic Muscles: A Systematic Review

The incidence of muscle spasticity is high in patients with diseases of the central nervous system. This condition leads to significant limitations in movement and impaired functional capacities. Muscle spasticity manifests as changes in the mechanical properties of the muscles. This muscle disorder is generally assessed using qualitative methods, whose validity, reliability and sensitivity are questionable. In recent years, ultrasound elastography (USE) has been used as a non-invasive technique for characterizing the stress response and mechanical properties of individual muscles in the evaluation of spasticity. This article presents a systematic review of the USE techniques, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) declaration guidelines, used for the evaluation of muscle stiffness caused by spasticity. The articles selected in this study were evaluated using the Quality Appraisal of Diagnostic Reliability (QAREL) tool. Mainly, studies on the assessment of spasticity involving the evaluation of muscle stiffness with USE techniques (i.e., shear-wave elastography [SWE] or compression elastography [CE]) were selected. Then, common topics related to the assessment of spastic muscles and the statistical results of these studies were classified. Of 21 articles, nine used only CE, 10 used only SWE and two used both techniques. In the studies, statistically significant differences were observed in the measurements of muscle stiffness between the paretic and non-paretic sides as well as between patients and healthy patients. The clinical measurements obtained, devices used and assessment and probe positions for both techniques were discussed. The most frequently studied muscles were the biceps (n = 7) and gastrocnemius (n = 11). On applying the QAREL tool, we found that only two studies showed compliance at 80%-90%, seven studies at 50%-70% and the remaining 12 at 10%-40%. The results showed that USE techniques have limitations in spasticity assessment, such as subjectivity because of the lack of standardized protocols. A deficit of studies on intra-operator and inter-operator measurements indicates that this technique is not yet mature for spasticity diagnosis, although it is a promising diagnostic tool for designing treatment plans and monitoring the effectiveness of therapeutic modalities.