Strain Elastography - How To Do It?

Ultrasound elastography for the differential diagnosis of benign and malignant gastrointestinal stromal tumors

BACKGROUND

Preoperative distinguishing between benign and malignant gastrointestinal stromal tumors (GISTs) poses a challenge. Ultrasound elastography has emerged as a promising diagnostic tool; however, further investigation is needed to assess its diagnostic accuracy in evaluating GISTs.

AIM

To evaluate the accuracy of ultrasound elastography for differentiating between benign and malignant GISTs.

METHODS

This prospective study included 110 patients with 103 histopathologically confirmed GISTs between January 2021 and December 2023. All tumors underwent conventional ultrasound examination, strain elastography (SE), and shear-wave elastography (SWE) before surgical resection. The study evaluated elastographic parameters such as strain ratio, elastographic patterns, mean elastic modulus, and heterogeneity index. Diagnostic performance was evaluated using receiver operating characteristic curve analysis, with histopathological diagnosis as the reference standard.

RESULTS

Of the 103 GISTs, 45 (43.7%) were benign and 58 (56.3%) were malignant based on modified National Institutes of Health criteria. Malignant GISTs exhibited significantly higher strain ratios (4.82 ± 1.73 vs 2.31 ± 0.89; P < 0.001) and mean elastic modulus values (45.6 ± 15.8 kPa vs 21.3 ± 8.4 kPa; P < 0.001) than benign tumors. The optimal cutoff values were 3.45 for the strain ratio (sensitivity: 84.5%, specificity: 86.7%) and 32.5 kPa for the mean elastic modulus (sensitivity: 87.9%, specificity: 88.9%). The areas under the curve were 0.892 and 0.918, respectively. Interobserver agreement was excellent for both SE [intraclass correlation coefficient (ICC) = 0.88] and SWE (ICC range: 0.85-0.93) measurements.

CONCLUSION

Ultrasound elastography shows high diagnostic accuracy in distinguishing between benign and malignant GISTs. Combining SE and SWE provides complementary parameters for preoperative risk stratification.

Elastography and Applications in the Musculoskeletal System in Veterinary Medicine: From Physical Basis to Image Formation

Musculoskeletal ultrasound is a versatile imaging technique, surpassing conventional radiographic examinations in detecting certain alterations in the musculoskeletal system and showing effectiveness comparable to magnetic resonance imaging in assessing articular and periarticular soft tissues. The objective of this review is to discuss the physical principles of ultrasound elastography and its applications in the musculoskeletal system of veterinary medicine. This bibliographic review compiles relevant studies exploring elastography's physical basis, its technological development, and its clinical applications in veterinary contexts. Elastography complements B-mode ultrasound by assessing tissue stiffness, offering unique diagnostic insights beyond acoustic impedance and flow properties. Studies have demonstrated the potential of elastography in evaluating tendon injuries, muscle disorders, and bone healing, with promising results in dogs, horses and experimental models like sheep. Techniques such as compression elastography and shear wave elastography provide qualitative and quantitative data, enhancing the assessment of pathological changes. Shear wave elastography enables precise measurements of tissue elasticity, aiding the diagnosis, monitoring of healing and evaluation of therapeutic interventions. Despite technical challenges, elastography is a valuable tool that can optimize musculoskeletal diagnostics and treatment planning. Its expanding use in veterinary medicine underscores its clinical relevance and potential for widespread adoption as a complementary imaging modality.

Liver Elastography Methods for Diagnosis of De Novo and Recurrent Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a common consequence of chronic liver disease, ranks among the most prevalent cancers globally and contributes significantly to cancer-related mortality. Liver fibrosis is intimately associated with hepatic function and the likelihood of future HCC occurrence. Despite the fact that liver biopsy continues to be the gold standard for diagnosing fibrosis, its utility is hindered by cost and invasiveness, along with patient unease, procedural rejection, and potential adverse effects. Liver elastography has become a leading noninvasive means of assessing tissue stiffness with considerable diagnostic precision. Malignant tumors generally exhibit higher cellularity in comparison to benign ones, resulting in increased stiffness. Elastography techniques capitalize on alterations in tissue elasticity stemming from specific pathological or physiological processes. Technological innovations, such as advanced ultrasound imaging and artificial intelligence (AI)-integrated systems, are paving the way for enhanced diagnostic accuracy and risk prediction. Recent research underscores the potential of elastography in managing HCC patients, presenting novel clinical applications, including prediction of HCC development, differentiation between malignant and benign liver lesions, evaluating treatment response, and forecasting recurrence post-treatment, though certain findings remain contentious. Therefore, this review aims to sum up the latest advancements in liver elastography for HCC patients, outlining its applications while addressing existing limitations and avenues for future progress.

Feasibility of shear wave elastography (2D -SWE) to evaluate cristalline lens in healthy dogs

BACKGROUND

2D shear wave elastography (2D SWE) is an emerging technique in veterinary medicine able to assess tissue stiffness in a non-invasive way. Nowadays no report is yet available about its application in assessing the mechanical properties of canine lenses.

OBJECTIVES

This study aimed to evaluate the repeatability and reproducibility of 2D SWE in assessing normal lens elasticity in healthy and ageing dogs.

METHODS

Trans-corneal lens 2D SWE was performed under physical restraint on 33 dogs by two operators who collected triplicate kPa and m/s measures, with the aim to assess reproducibility and reliability of the technique, followed by the evaluation of eventual difference of stiffness in different ages (G1 < 1.5 years, G2 1.5 years-7 years and G3 > 7 years). The project has been approved by the CEISA Ethical Committee (Prot. N. 12/2019 361 CEISA). Written informed consent was obtained by all the owners.

RESULTS

Mean elasticity values were respectively 4.78 ± 1.48 m/s and 74.9 ± 43.7 kPa for the left eye and 4.45 ± 0.98 m/s and 75.9 ± 43.6 kPa for the right eye. Despite a slight difference observed in the measurements obtained in m/s between the two operators, the intra-observer assessment was excellent in the overall population of dogs for both values in KPa and m/s, as well as the inter-observer one (ICC > 0.75). All the sCV% computed evidence a low measurement dispersion (< 12%). Mean lens stiffness for G1 was 3.1 ± 0.5 m/s and 28.9 ± 9.3 kPa, for G2 4.61 ± 0.62 m/s and 65 ± 18.4 kPa and for G3 6.46 ± 0.36 m/s and 126 ± 14.5 kPa; a significant difference P (< 0.001) was detected between all the groups.

CONCLUSIONS

It can be concluded that 2D SWE is a rapid and non-invasive US-based technique able to assess lens mechanical properties in companion animals since it is characterized by high reliability and reproducibility, providing also information regarding lens stiffness in aging dogs.

The role of strain wave elastography in the evaluation of renal fibrosis in patients with kidney diseases

BACKGROUND

A renal biopsy represents the gold standard in the diagnosis, prognosis and management of patients with chronic kidney disease and glomerulonephritis. Strain wave elastography (SE) is a developing technique to assess tissue elasticity. The aim of this study was to correlate between the strain index value of renal parenchyma and degree of renal fibrosis detected with renal biopsy.

METHOD

For 68 patients who were referred for a kidney biopsy, SE test was performed. The Banff scoring system was utilized to classify the IFTA grading of kidney fibrosis that assigns a severity level of mild, moderate, or severe. Receiver operating characteristic curve (ROC) was utilized to correlate between the severity of renal fibrosis and the grade of renal elasticity determined by SE.

RESULTS

In total, 38 males and 30 females, the echogenicity, qualitative and semiquantitative elastography showed significant positive correlation with serum creatinine, percentage of fibrosis, G score and tubular atrophy and significant negative correlation with eGFR. ROC curve of SE for diagnosis of interstitial fibrosis shown that echogenicity has sensitivity 100.0%, specificity 62.5%, positive predictive value (PPV) 75.0%, negative predictive value (NPV) 100.0% with area under curve (AUC) 0.906, while qualitative elastography has sensitivity 77.8%, specificity 75.0%, PPV 77.8%, NPV 75.0%, AUC 0.833, semi quantitative elastography has sensitivity 83.3%, specificity 93.8%, PPV 93.8%, NPV 83.3% with AUC 0.915.

CONCLUSION

SE approach is simple to use, and can differentiate between varying stages of renal fibrosis. However, further research is required before it can be frequently used in clinical practice.

Multiparametric ultrasound (MPUS) evaluation of the testes of normozoospermic dogs - a pilot study

Ultrasound is an important tool in small animal andrology for assessing the integrity of the testes. This study explores ultrasound's role in assessing the canine testes and understanding the correlation of sonographic parameters to sperm quality. It investigates B-mode and Doppler ultrasound techniques alongside advanced methods like Shear-wave Elastography (SWE) and Contrast-enhanced ultrasound (CEUS). The aim was to standardize a multiparametric ultrasound (MPUS) evaluation protocol using these techniques in normozoospermic dogs. Eight healthy male dogs were assessed. B-mode assessed testicular morphology, while Doppler evaluated testicular artery waveform morphology and velocimetric parameters. SWE measured testicular stiffness, and CEUS assessed testicular perfusion. Seminal parameters were also analyzed. Results revealed normal B-mode sonographic findings and some correlations between Doppler parameters and sperm quality. SWE demonstrated consistent testicular stiffness regardless of the depth of evaluation, with correlations of the stiffness of the head of the epididymis to the ejaculate volume. CEUS identified blood flow differences between testes and some perfusion parameters correlated with sperm features. This comprehensive ultrasound assessment provides valuable insights into canine reproductive health, providing basis for further studies on dogs with abnormal sperm quality and with different fertility statuses.

Comparison Between Strain and 2D Shear Wave Elastography of Testes in Healthy Dogs

Sonoelastography is a rapid and non-invasive ultrasound-based technique to assess tissue elasticity. Interest in this technique's application in veterinary medicine is progressively increasing, with preliminary reports also available to assess canine testicular parenchyma abnormalities. Since elastographic techniques are different and it is of paramount importance to standardize procedures, this work aimed to compare two different elastographic techniques, SE and 2D SWE, on the same testes and compare the data with the current literature. Thirty healthy canine testes were included, and complete B-mode, color and power Doppler examinations were performed on each one. SE was performed qualitatively through an elastogram evaluation and semiquantitatively comparing the parenchyma with peripheral skin. 2D SWE was performed and m/s measurements were taken. Each measurement was collected in the cranial, middle and caudal portions, considering the sections above and below the mediastinum separately. The healthy testes appeared to be intermediate in stiffness with differences in the various portions for SE and expressed a mean value from 1.3 m/s to 1.4 m/s for 2D SWE, consistent with the previous literature. Considering the technical specifics of the software for the two elastography methods, both of them are valuable in assessing canine testis stiffness and are potentially clinically appliable.

Multimodal Elastography of the Main Salivary Glands-A Narrative Review

Elastography has emerged as a valuable imaging technique that evaluates tissue stiffness and offers complementary insights into conventional ultrasonography. The aim of this article is to review the utility of elastography in assessing salivary gland pathologies. The review categorizes findings by pathology and the physical principles underlying each elastographic modality. Key modalities discussed include strain elastography, shear wave elastography, and novel hybrid techniques, such as viscoelastography, highlighting their strengths, limitations, and clinical applications in salivary gland imaging.

Predictive value of renal shear wave elastography in liver cirrhosis

BACKGROUND

In liver cirrhosis, prognosis is profoundly affected by renal function. This study evaluates the usefulness of renal stiffness measurement by point-shear wave elastography and renal perfusion by duplex.

METHODS

In this case-control study, organ stiffness was quantified using point-shear wave elastography and duplex sonography to calculate the arterial resistive (RI) and pulsatility indices (PI) in 123 patients, including patients with liver cirrhosis with (LC+A) and without ascites (LC-A) and patients without liver cirrhosis (NLC).

RESULTS

PI and RI were significantly increased in LC-A and LC+A compared to NLC (p<0.001) and correlated with MELD and Child Pugh scores. Point-shear wave elastography showed significantly lower renal stiffness in LC+A compared to LC-A (p<0.01) and NLC (p<0.001). Renal stiffness correlated inversely with MELD and Child Pugh scores. Reduced renal stiffness, but not PI or RI, was associated with the presence of hepatorenal syndrome (p<0.001). Reduced renal stiffness was associated with an increased risk of death due to complications of liver cirrhosis within 3 years (p<0.01).

CONCLUSION

Point-shear wave elastography and duplex sonography correlate with progression of liver cirrhosis, but only shear wave elastography represents a valuable prognostic tool for hepatorenal syndrome and mortality in patients with liver cirrhosis.

[Imaging in chronic inflammatory bowel disease]

In patients with chronic inflammatory bowel disease (IBD), endoscopic techniques (including capsule techniques and balloon enteroscopy for the small intestine), ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) are primarily used as often complementary imaging techniques. Radiation exposure needs to be kept in mind when using CT and conventional X‑ray-techniques. Therefore, most importantly, ultrasound and MRI have changed the routine diagnostics of intestinal diseases. US, CT and MRI not only assess the lumen but, similarly importantly, also the wall and the surrounding structures of the gastrointestinal tract. Furthermore, functional processes can be visualized and provide important information about passage and perfusion, which is mainly true for real-time ultrasound. CT and MRI are usually carried out with the use of contrast agents as contrast-enhanced CT (CECT) and contrast-enhanced MRI (CEMRI). Ultrasound is performed conventionally or with intravascular (CEUS) and/or extravascular intracavitary contrast agent application (icCEUS). This article provides an overview of the current significance of the mentioned imaging procedures in patients with IBD and discusses the typical indications.

Short- and Mid-Term Results Using a 448 Kilohertz Radiofrequency Stimulation on the Elasticity Plantar Fascia Measured by Quantitative Ultrasound Elastography on Active Healthy Subjects: An Open Controlled Clinical Trial with Three Months of Follow-Up

Background: This study is an open clinical trial that included 3 months of follow-up. Methods: This study aimed to show the changes that occur in the viscoelastic properties of the PF measured by SEL after the six applications of a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) in active, healthy subjects, immediately before the CRMR intervention (T0), during the two-week CRMR intervention program (T1), after the CRMR intervention program (T2), two weeks after the CRMR intervention program (T3), one month after the CRMR intervention program (T4), and three months after the CRMR intervention program (T5). Results: Our results showed that the effects of CRMR on the plantar fascia elasticity may last up to one month in a healthy population after a 3-week treatment program when compared to controls, specifically following the medial process of the calcaneal tuberosity (points 1 and 2). However, there were no changes when analyzing points 3 and 4. These findings are a first step towards understanding the duration of the CRMR effects in the elastic properties of the tissue and therefore how long the benefit may last. Conclusions: This study showed that changes in the plantar fascia elasticity measured by SEL have been found after a CRMR intervention protocol, similarly to other structures reported in the literature, such as the patellar tendon or supraspinatus tendon.

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.

Ultrasound elastography in dogs: Physical principles and application in intestinal evaluation

Ultrasound elastography provides diagnostic information based on tissue elasticity. There is a lack of specific studies on the application of elastography in canine intestinal assessment. Therefore, we reviewed comparative medicine studies and those referring to the literature listed in the databases. Static and dynamic elastography techniques are widely applied in human intestinal diseases, especially Chron's disease, but few studies have investigated the application of these modalities in canine enteropathies. This case raises questions about the use of new diagnostic imaging techniques in veterinary gastroenterology and highlights the need for further research. Hence, this study aimed to review the literature on the physical principles of elastography and its clinical application in the intestinal evaluation of dogs.

A Polyvinyl Alcohol (PVA)-Based Phantom for Prostate Cancer Detection Using Multiparametric Ultrasound: A Validation Study

Multiparametric ultrasound (mpUS) enhances prostate cancer (PCa) diagnosis by using multiple imaging modalities. Tissue-mimicking materials (TMM) phantoms, favoured over animal models for ethical and consistency reasons, were created using polyvinyl alcohol (PVA) with varying molecular weights (Mw).

METHODS

Four PVA samples, varying in Mw with constant concertation, were mixed with glycerol, silicon carbide (SiC), and aluminium oxide (Al2O3). Phantoms with varying depth and inclusion sizes were created and tested using shear-wave elastography (SWE). An mpUS phantom was developed to mimic prostate tissue, including isoechoic and hypoechoic inclusions and vessels. The phantom was scanned using supersonic ultrasound, strain elastography, and Doppler ultrasound. Validation was performed using radical prostatectomy data and shear-wave elastography.

RESULTS

The acoustic properties varied with enhancers like glycerol and Al2O3. Low Mw PVA samples had a speed of sound ranging from 1547.50 ± 2 to 1553.70 ± 2.2 m/s and attenuation of 0.61 ± 0.062 to 0.63 ± 0.05 dB/cm/MHz. High Mw PVA samples ranged from 1555 ± 2.82 to 1566 ± 4.5 m/s and 0.71 ± 0.02 to 0.73 ± 0.046 dB/cm/MHz. Young's modulus ranged from 11 ± 2 to 82.3 ± 0.5 kPa across 1 to 10 freeze-thaw cycles. Inclusion size, depth, and interaction statistically affect the SWE measurements with p-value = 0.056327, p-value = 8.0039 × 10-8, and p-value = 0.057089, respectively. SWE showed isoechoic inclusions, prostate tissue, and surrounding tissue only. The Doppler velocity was measured in three different inner diameters.

CONCLUSION

PVA mixed with enhancer materials creates an mpUS phantom with properties that mimic normal and abnormal prostate tissue, blood vessels, and soft tissue, facilitating advanced diagnostic training and validation.

The Role of Endoscopic Ultrasound-Guided Shear Wave Elastography in Pancreatic Diseases

Elastography is a non-invasive imaging modality that has been developed for the evaluation of the stiffness of various organs. It is categorized into two main types: strain elastography and shear wave elastography. While strain elastography offers valuable information on the mechanical properties of the organ being studied, it is limited by the qualitative nature of its measurements and its reliance on operator skills. On the other hand, shear wave elastography overcomes these limitations as it provides a quantitative assessment of tissue stiffness, offers more reproducibility, and is less operator-dependent. Endoscopic ultrasound-guided shear wave elastography (EUS-SWE) is an emerging technique that overcomes the limitations of transabdominal ultrasound in the evaluation of the pancreas. A growing body of literature has demonstrated its safety and feasibility in the evaluation of pancreatic parenchyma. This article provides a comprehensive review of the current state of the literature on EUS-SWE, including its technical aspects, clinical applications in the evaluation of various pancreatic conditions, technological limitations, and future directions.

Strain Elastography Evaluation of Patellar Tendons in Dogs after TPLO/TTA for Cranial Cruciate Ligament Rupture, Qualitative and Semiquantitative Evaluation Compared with Healthy Subjects

Strain elastography (SE) evaluates tissue stiffness, providing qualitative and semiquantitative evaluation, with a strain ratio (SR) > 1 indicating that the target lesion is stiffer than the reference tissue. The patellar tendon has been described as soft in healthy dogs and hard in dogs with cranial cruciate ligament rupture, but SR usefulness has not been assessed. Dogs were divided into healthy (G1) and at least 1 month after surgery (G2) groups. Thickness was recorded, and a B-mode score of 0-3 was determined based on the abnormality's severity. SE was qualitatively performed with a score of 1-4, and EI was recorded on the whole ligament and in proximal, intermediate and distal areas; SR was collected with the fat pad and cutis/subcutis. G1 was significantly thinner, with a lower score than G2 and a more elastic pattern. EI for G1 was significantly lower than G2 for the whole tendon and the single portions, and EI for the distal portion was significantly lower than the proximal and intermediate one in G2. SR was <1 in G1 and >1 in G2 for both the fat pad and cutis/subcutis. These data suggest that after surgery, the tendon may become non-uniformly stiffer. The cutis/subcutis appears to be a more reliable reference tissue than the infrapatellar fat pad.

Ultrasound elastography: a brief clinical history of an evolving technique

The history of the emerging elastographic technique is presented. Ultrasound imaging of elasticity and tissue strain has gained clinical acceptance as an established technique useful in routine daily clinical practice.

Examination of the masseter muscle in patients with hemifacial microsomia using high-frequency ultrasound and shear wave elastography

BACKGROUND

This study aimed to prospectively investigate the reference values for masseter muscle thickness and hardness using ultrasonography and shear wave elastography, respectively, in patients with hemifacial microsomia (HFM).

METHODS

We enrolled 51 patients, aged 5-20 years, with HFM including 31 males and 20 females. The upper-lower, left-right, and anterior-posterior diameters of 102 masseter muscles and stiffness of 98 masseter muscles were determined by examining the unaffected and affected sides of each participant's face.

RESULTS

The upper-lower, left-right, and anterior-posterior diameters of the masseter muscle were significantly smaller at rest (4.26 ± 0.83, 2.94 ± 0.75, and- 0.80 ± 0.25 cm, respectively) and during contraction (3.95 ± 0.78, 2.71 ± 0.78, and 0.87 ± 0.29 cm, respectively) in the affected side than those in the healthy side (5.45 ± 0.66, 3.87 ± 0.49, and 0.97 ± 0.20 cm, respectively, at rest and 4.99 ± 0.45, 3.49 ± 0.53, and 1.07 ± 0.23 cm, respectively, during contraction, p < 0.05). In the resting state, the hardness of the masseter muscle on the affected side (0.77 ± 0.66 m/s) was significantly greater than that on the healthy side (0.42 ± 0.41 m/s; p < 0.05). The magnitude of changes in the upper-lower, left-right, and anterior-posterior diameters of the biting muscle in the occlusal state were significantly smaller on the affected side (-0.30 ± 0.27, -0.23 ± 0.17, and 0.08 ± 0.08 cm, respectively) than those in the healthy side (-0.47 ± 0.38, -0.37 ± 0.25, and 0.10 ± 0.12 cm, respectively, p < 0.05).

CONCLUSIONS

The knowledge of these values allows for better understanding of the disease characteristics of HFM, which may be used for its diagnosis, treatment, and prognosis. Patients experiencing different severity levels exhibited significant differences in the morphology and function of the masseter muscle on the affected-side (p < 0.05).

EVIDENCE LEVEL

Level III.

Contrast-enhanced ultrasound in renal cystic lesions: an update

This narrative review aims to describe the current status of contrast-enhanced ultrasound (CEUS) in characterizing renal cystic lesion. The imaging techniques usually performed for their evaluation are ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) with different criteria of application based on the individual case and the purpose of the examination. Generally, US, as a non-ionizing examination, is the first imaging modality performed and therefore the one that incidentally detects cystic lesions. CT is the most performed imaging modality for cystic lesion assessment before MRI evaluation. It provides better characterization and management and has been introduced into the Bosniak classification. In this context, CEUS is making its way for its characteristics and represents the emerging technique in this field. With these premises, the authors analyze the role of CEUS in the evaluation of renal cysts, starting with an explanation of the technique, describe its main advantages and limitations, and end with a discussion of its application in the Bosniak classification and management, following the current major guidelines.

Utilization of Texture Analysis in Differentiating Benign and Malignant Breast Masses: Comparison of Grayscale Ultrasound, Shear Wave Elastography, and Radiomic Features

OBJECTIVE

This study aims to determine which qualitative and quantitative US features are independently associated with malignancy, including those derived from grayscale imaging morphology, shear wave elastography (SWE), and texture analysis.

METHODS

This single-center retrospective study was approved by the institutional research ethics board. Consecutive breast US studies performed between January and December 2020 were included. Images were acquired using a Canon Aplio i800 US unit (Canon Medical Systems, Inc., CA) and i18LX5 wideband linear matrix transducer. Grayscale US features, SWE mean, and median elasticity were obtained. Single representative grayscale images were analyzed using dedicated software (LIFEx, version 6.30). First-order and gray-level co-occurrence matrix second-order texture features were extracted. Multivariate logistic regression was performed to assess for predictors of malignancy (STATA v16.1).

RESULTS

One hundred forty-seven cases with complete SWE data were selected for analysis (mean age 54.3, range 21-92). The following variables were found to be independently associated with malignancy: age (P <.001), family history (P = .013), irregular mass shape (P = .024), and stiffness on SWE (mean SWE ≥40 kPa; P <.001). Remaining variables (including texture features) were not found to be independently associated with malignancy (P >.05).

CONCLUSION

US texture analysis features were not associated with malignancy independent of other qualitative and quantitative US characteristics currently utilized in clinical practice. This suggests texture analysis may not be warranted when differentiating benign and malignant breast masses on US. In contrast, irregular mass shape on grayscale imaging and increased stiffness on SWE were found to be independent predictors of malignancy.

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.

Clinical, Safety, and Engineering Perspectives on Wearable Ultrasound Technology: A Review

Wearable ultrasound has the potential to become a disruptive technology enabling new applications not only in traditional clinical settings, but also in settings where ultrasound is not currently used. Understanding the basic engineering principles and limitations of wearable ultrasound is critical for clinicians, scientists, and engineers to advance potential applications and translate the technology from bench to bedside. Wearable ultrasound devices, especially monitoring devices, have the potential to apply acoustic energy to the body for far longer durations than conventional diagnostic ultrasound systems. Thus, bioeffects associated with prolonged acoustic exposure as well as skin health need to be carefully considered for wearable ultrasound devices. This article reviews emerging clinical applications, safety considerations, and future engineering and clinical research directions for wearable ultrasound technology.

Application of strain elastography ultrasound to the endometrium of normal women

BACKGROUND

While there is a scarcity of studies utilizing strain elastography (SE) for the endometrium, commonly used gynecologic ultrasound instruments are equipped with built-in elastography modalities, primarily SE. With the objective of facilitating comprehensive examinations for gynecologic patients on a single ultrasound instrument, we undertook this study. Therefore, our aim was to study the value of SE ultrasonography in the assessment of endometrial elasticity in normal women.

METHODS

Three hundred and twenty normal women were recruited at our hospitals from November 2021 to December 2022. Each volunteer underwent a transvaginal two-dimensional (2D) and SE ultrasound during either the endometrial proliferative or secretory phase. The 2D ultrasound indices obtained included endometrial thickness, echo type (type A, B, and C), and blood flow grading (grades 0, 1, 2, and 3). SE indices obtained included endometrial strain values, myometrial strain values, and endometrial strain ratios. Differences in endometrial ultrasound indices between different menstrual cycles and different age groups were compared.

RESULTS

Comparison of 2D ultrasound parameters revealed that endometrial thickness in the proliferative phase endometrium group was smaller than that in the secretory phase endometrium group, with a statistically significant difference. Additionally, there was a statistically significant difference in endometrial echo types between the two groups, while the disparity in endometrial blood flow grading was not significant. Regarding SE parameters, the median and mean values of endometrial strain ratio in the proliferative phase endometrium group were smaller than those in the secretory phase endometrium group, showing a statistically significant difference. However, there were no significant differences observed between the two groups in endometrial strain and myometrial strain in the fundus. Furthermore, there were no significant differences in any of the endometrial ultrasound indices among the different age groups.

CONCLUSIONS

SE can reflect changes in endometrial stiffness in different menstrual cycles and is an important tool for assessing endometrial softness.

Impact of ultrasound elastography in evaluating Bethesda category IV thyroid nodules with histopathological correlation

Introduction

Fine needle aspiration (FNA) is the gold standard method recommended in the diagnosis of thyroid nodules. Bethesda IV cytology results are identified in 7-9% of nodules investigated through FNA, with reported malignancy rate in a wide range of 10-40%. The recommended treatment is either surgical or risk additional molecular testing before surgery. However, a large number of nodules belonging to this category (60-80%) are observed to be benign after surgical excision, which can put the patient at risk of unnecessary surgical morbidity. This study aimed to assess the diagnostic performance of conventional ultrasound, the ACR TI-RADS score and elastography in cases of Bethesda IV cytology on FNA.

Methods

We evaluated ninety-seven consecutive cases with Bethesda category IV results on FNA by using conventional B-mode ultrasound, qualitative strain or shear-wave elastography (Hitachi Preirus Machine, Hitachi Inc., Japan and Aixplorer Mach 30 Supersonic Imagine, Aix-en-Provence, France) and all nodules were classified according to the ACR TI-RADS system. Conventional ultrasound was used to categorize the nodules as potentially malignant based on the following features: hypoechogenicity, inhomogeneity, a taller than wide shape, irregular margins, presence of microcalcifications, an interrupted thyroid capsule and suspicious cervical lymph nodes. Elastography classified nodules with increased stiffness as suspicious for malignancy.

Results

We considered pathology results as the gold standard diagnosis, finding that 32 out of 97 nodules were carcinomas (33%) and 65 out of 97 were benign nodules (67%). The benign group included twenty cases of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Finally, we compared ultrasound data with pathology results, which showed that nineteen out of the 32 malignant nodules presented with increased stiffness on elastography (p=0.0002). On conventional ultrasound, we found that microcalcifications (p=0.007), hypoechogenicity and irregular margins (p=0.006) are features which can distinguish between benign and malignant nodules with statistical significance.

Discussion

Integrating elastography as a parameter of the ACR TI-RADS score in the evaluation of Bethesda category IV nodules showed a sensitivity of 90.62% in detecting thyroid cancer cases (p=0.006). We can conclude that elastographic stiffness as an addition to high risk features observed on conventional ultrasound improves the detection of malignant nodules in cases with Bethesda IV cytology.

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.

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.

Ultrasound Elastography: Basic Principles and Examples of Clinical Applications with Artificial Intelligence—A Review

Ultrasound elastography (USE) or elastosonography is an ultrasound-based, non-invasive imaging method for assessing tissue elasticity. The different types of elastosonography are distinguished according to the mechanisms used for estimating tissue elasticity and the type of information they provide. In strain imaging, mechanical stress is applied to the tissue, and the resulting differential strain between different tissues is used to provide a qualitative assessment of elasticity. In shear wave imaging, tissue elasticity is inferred through quantitative parameters, such as shear wave velocity or longitudinal elastic modulus. Shear waves can be produced using a vibrating mechanical device, as in transient elastography (TE), or an acoustic impulse, which can be highly focused, as in point-shear wave elastography (p-SWE), or directed to multiple zones in a two-dimensional area, as in 2D-SWE. A general understanding of the basic principles behind each technique is important for clinicians to improve data acquisition and interpretation. Major clinical applications include chronic liver disease, breast lesions, thyroid nodules, lymph node malignancies, and inflammatory bowel disease. The integration of artificial intelligence tools could potentially overcome some of the main limitations of elastosonography, such as operator dependence and low specificity, allowing for its effective integration into clinical workflow.

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.