Elastography: modality-specific approaches, clinical applications, and research horizons

The place of B-mode ultrasonography, shear-wave elastography, and superb microvascular imaging in the diagnosis of De Quervain tenosynovitis

PURPOSE

Superb microvascular imaging (SMI) and Shear wave elastography (SWE) are newly developed ultrasonographic diagnostic tools used to support the diagnosis of De Quervain tenosynovitis (DQT). The aim of this study was to examine the capacity to differentiate between the wrist with DQT and the healthy wrist, as well as the potential for predicting the disease's severity using B-mode ultrasonography, SWE, and SMI.

METHODS

A total of 19 cases with unilateral clinical DQT were included in the prospective study. The wrists of these cases without DQT clinic constituted the control group.

RESULTS

The SWE parameters of m/s and kPa cutoff values were ≤5.225 and ≤ 77.65, respectively, in the wrists with DQT compared to the wrists not diagnosed with DQT (p < 0.001). Regarding SMI findings no microvascularity was determined in the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon sheaths of the wrists without DQT, and a significant increase was observed in the degree of microvascularity as the clinical severity of DQT increased.

CONCLUSION

SWE results can differentiate between the presence and absence of DQT. SMI grading of the APL and EPB tendon sheaths may be helpful to the clinician in deciding the clinical severity of DQT.

Evaluation of Achilles Tendon Stiffness as Measured by Shear Wave Elastography in Female College Athletes Compared With Nonathletes

BACKGROUND

We sought to utilize a noninvasive technology to assess the effects of activity on Achilles tendon stiffness and define baseline Achilles tendon stiffness in female college athletes compared with nonathletes using tendon shear wave velocity as a marker for tendon stiffness.

HYPOTHESIS

Training status and exercise may affect Achilles tendon stiffness.

STUDY DESIGN

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 32 college-age female athletes were prospectively enrolled (n = 17 varsity athletes and n = 15 nonathletes). Demographic characteristics, activity level, and previous injuries were recorded. Sonographic shear wave elastography (SWE) was used to assess Achilles tendon shear wave velocity bilaterally for all subjects, both at baseline and after 2 minutes of exercise. Student t tests were used to compare the mean elastography measurements between participants stratified by athlete status and pre/postexercise stimulus. Analysis of variance (ANOVA) was used to compare the mean proximal, middle, and distal Achilles tendon elastography measurements.

RESULTS

As seen by a greater mean shear wave velocity (8.60 ± 1.58 m/s vs 8.25 ± 1.89 m/s; P = 0.02), athletes had stiffer tendons than nonathletes. Exercise stimulus decreased average tendon shear wave velocity (8.57 ± 1.74 m/s vs 8.28 ± 1.72 m/s; P = 0.05). Tendon shear wave velocity was greatest proximally and least distally with significant differences between each region (P < 0.001). In addition, there was a significant 2-way interaction between weekly training status and foot dominance (P = 0.01). Post hoc analysis showed that this result was due to differences in tendon shear wave velocity between the dominant and nondominant lower extremity in nonathletes (7.73 ± 2.00 m/s vs 8.76 ± 1.62 m/s; P < 0.001).

CONCLUSION

Female varsity collegiate athletes have higher baseline Achilles tendon stiffness as measured by SWE compared with nonathletes. Mean tendon stiffness varies based on Achilles measurement location. SWE is a quick, cost-effective, and noninvasive imaging modality that can be used to evaluate tendon stiffness and elasticity.

CLINICAL RELEVANCE

SWE is an efficient and noninvasive imaging modality that can evaluate dynamic tendon stiffness and elasticity. SWE may be helpful to assess injuries in female college athletes and may play a role in risk stratification or clinical follow-up. In theory, SWE could be used to identify athletes with increased elasticity as a marker for potential risk for rupture in this population.

Acoustic radiation force impulse shear wave elastography quantifies upper limb muscle in patients with Duchenne muscular dystrophy

We investigated whether the upper limb muscle stiffness quantified by the acoustic radiation force impulse shear wave elastography (ARFI/SWE) is a potential biomarker for age-related muscle alteration and functional decline in patients with Duchenne muscular dystrophy (DMD). 37 patients with DMD and 30 typically developing controls (TDC) were grouped by age (3-8, 9-11, and 12-18 years). ARFI/SWE measured the biceps and deltoid muscle's shear wave velocities (SWVs). Performance of Upper Limb Module (PUL 1.2 module) assessed muscle function in DMD patients. Mann Whitney test compared muscle SWVs between DMD and TDC, stratified by three age groups. We used analysis of variance with Bonferroni correction to compare muscle SWVs between DMD and TDC and correlated muscle SWVs with PUL results in the DMD group. Results showed that the SWVs of biceps differentiated DMD patients from TDC across age groups. Younger DMD patients (3-8 years) exhibited higher SWVs (p = 0.013), but older DMD patients (12-18 years) showed lower SWVS (p = 0.028) than same-aged TDC. DMD patients had decreasing biceps SWVs with age (p < 0.001), with no such age effect in TDC. The SWVs of deltoid and biceps positively correlated with PUL scores (r = 0.527 ∼ 0.897, P < 0.05) and negatively correlated with PUL timed measures (r = -0.425 ∼ -0.542, P < 0.05) in DMD patients. Our findings suggest that ARFI/SWE quantifying the SWVs in upper limb muscle could be a potential biomarker to differentiate DMD from TDC across ages and that DMD patients showed age-related muscle alteration and limb functional decline.

Ultrasound-Based Technologies for the Evaluation of Testicles in the Dog: Keystones and Breakthroughs

Ultrasonography is a valuable diagnostic tool extensively used in the andrology of human and domestic animals, including dogs. This review aims to provide an overview of various technologies based on ultrasound, from the basic B-Mode ultrasonography to the more recent advancements, such as contrast-enhanced ultrasonography (CEUS) and ultrasound elastography (UEl), all of which are utilized in the evaluation of canine testicles. The review outlines the principles behind each of these technologies and discusses their application in assessing normal and abnormal testicular conditions. B-mode canine testicular ultrasonography primarily focuses on detecting focal lesions but has limitations in terms of objectivity. Other technologies, including Doppler ultrasonography, B-Flow, and CEUS, allow for the characterization of vascular patterns, which could be further measured using specific applications like spectral Doppler or quantitative CEUS. Additionally, ultrasound elastography enables the assessment of parenchyma stiffness both qualitatively and quantitatively. These ultrasound-based technologies play a crucial role in andrology by providing valuable information for evaluating testicular function and integrity, aiding in the identification of pathological conditions that may impact the health and quality of life of male dogs.

Regional assessments of supraspinatus muscle stiffness in normal adults using shear wave elastography

Objectives

To provide normal references for regional shear wave elastography assessments of supraspinatus muscle in a population.

Methods

Shear wave elastography images of supraspinatus muscles were evaluated on 100 shoulders of 50 normal adults in a fixed position with 30° shoulder abduction both at rest and contraction. Shear wave velocity values and activity values of intramuscular tendon, anterior superficial, anterior deep, posterior superficial, posterior deep, and central subregions were measured. The possible differences in hand dominance, sexes, stratified age groups, and internal muscular-component subregions were discussed.

Results

The results showed that shear wave velocity values at rest and activity values differed significantly among supraspinatus muscular-component subregions. Shear wave velocity values at rest were normally highest in posterior deep and lowest in central subregions, whereas activity values were highest in central subregions. The results also showed evaluation of the intramuscular tendon using shear wave elastography to be practicable. The differences in shear wave velocity values at rest between the dominant and nondominant sides were not significant in each subregion, while the values at rest of the majority of subregions were significantly greater in males than in females. Stratified by age groups of 10 years, the shear wave velocity values at rest of some subregions tended to increase with age, with uncorrelations possibly related to insufficient sample sizes and different intensities of limb activities.

Conclusions

This study suggested that regional assessments of supraspinatus stiffness using shear wave elastography are feasible, with further research supporting that it can provide information on the surgery, training, and rehabilitation of rotator cuff tears.

Diagnostic Considerations in Compressive Neuropathies

Peripheral nerve compression of the upper extremity is a common pathology often necessitating surgical intervention, much is known, but much more is left to understand. For the more common pathologies, carpal tunnel syndrome, cubital tunnel syndrome, and ulnar tunnel syndrome, research and clinical efforts directed toward standardization and reduction of resource use have been attempted with varied success. Diagnosis of many of these syndromes is largely based on a proper history and physical examination. Electrodiagnostic studies continue to have value, but proportionally less than previous decades. In addition, emerging technologies, including magnetic resonance neurography, novel ultrasound evaluation techniques, and ultrasound-guided diagnostic injections, are beginning to demonstrate their ability to add value to the diagnostic algorithm, particularly when less common compressive neuropathies are present and/or the diagnosis is in question.

Modern Imaging Techniques in the Study and Disease Diagnosis of the Mammary Glands of Animals

The study of the structure and function of the animals' mammary glands is of key importance, as it reveals pathological processes at their onset, thus contributing to their immediate treatment. The most frequently studied mammary diseases are mastitis in cows and ewes and mammary tumours in dogs and cats. Various imaging techniques such as computed tomography, positron emission tomography, magnetic resonance imaging, and ultrasonographic techniques (Doppler, contrast-enchanced, three-dimensional and elastography) are available and can be applied in research or clinical practice in order to evaluate possible abnormalities in mammary glands, as well as to assist in the differential diagnosis. In this review, the above imaging technologies are described, and the perspectives of each method are highlighted. It is inferred that ultrasonographic modalities are the most frequently used imaging techniques for the diagnosis of clinical or subclinical mastitis and treatment guidance on a farm. In companion animals, a combination of imaging techniques should be applied for a more accurate diagnosis of mammary tumours. In any case, the confirmation of the diagnosis is provided by laboratory techniques.

Relationship between Muscle-Tendon Stiffness and Drop Jump Performance in Young Male Basketball Players during Developmental Stages

BACKGROUND

The relationship between stiffness and drop jump performance in athletes in various stages of development has yet to be fully investigated. The first aim of this study was to investigate the association between the stiffness of the patellar and quadriceps tendon (PT, QT), gastrocnemius-Achilles tendon unit (GAT), and rectus femoris (RF) using drop jump (DJ) performance in young basketball players. The second aim was to investigate possible variations in the stiffness levels of those tissues in different developmental stages.

METHODS

The stiffness levels of the GAT, PT, QT, and RF were measured in both limbs in 73 male basketball players aged 12 to 18 years. The reactive strength index (RSI), contact time (CT) and jump height (JH) during 30 and 40 cm DJs were also measured.

RESULTS

Pearson correlation coefficients showed a significant association between DJ performance and PT, QT, GAT, and RF dynamic stiffness. Moreover, the youngest subjects were found to have lower stiffness values than the older ones.

CONCLUSIONS

Tissue stiffness can affect athletic performance by modifying the stretch-shortening cycle in young basketball players. Stiffness of muscles and tendons increases during the maturation process. Further investigations could shed light on the effect of training on the stiffness of muscles and tendons.

Shear wave elastography imaging in a porcine tendinopathy model

OBJECTIVE

To quantify the effect of structural damage in an ex vivo animal tendinopathy model using shear wave elastography (SWE).

MATERIALS AND METHODS

Sixteen porcine flexor tendons were injected with a 0.05 mL bolus of 1.5% collagenase solution to induce focal structural damage without surfacing tears. Control tendons were injected with saline (n = 16). Eight tendons from each group were incubated at 37 °C for 3.5 h while the remaining 8 from each group were incubated for 7 h. Tendons were mechanically stretched to 0% and 1% strain. Simultaneously, SWE was acquired proximal to, at, and distal to the injection site using a clinical ultrasound scanner.

RESULTS

There were significant differences in SWS (saline > collagenase) at 1% strain and 7-h incubation for all three locations (PROX p = 0.0031, ROI p = 0.001, DIST p = 0.0043). There were also significant differences at 0% strain and 7 h, but only at (p = 0.0005), and distal to (p = 0.0035), the injection site. No statistically significant differences were observed for 3.5-h incubation, at 0% or 1% strain.

CONCLUSIONS

Collagenase-mediated structural damage does appear to convey decreased tissue elasticity on SWE when ex vivo tendons are incubated for 7 h. These findings suggest that SWE may be a useful tool for predicting ultimate tissue strength in tendinopathic tissues. Pull-to-failure testing should be performed in the future and are expected to show that tendons with decreased SWS, and, therefore, decreased elasticity, rupture at lower pulls forces.

Multiple Optical Elastography Techniques Reveal the Regulation of Corneal Stiffness by Collagen XII

Purpose

Collagen XII plays a role in regulating the structure and mechanical properties of the cornea. In this work, several optical elastography techniques were used to investigate the effect of collagen XII deficiency on the stiffness of the murine cornea.

Methods

A three-prong optical elastography approach was used to investigate the mechanical properties of the cornea. Brillouin microscopy, air-coupled ultrasonic optical coherence elastography (OCE) and heartbeat OCE were used to assess the mechanical properties of wild type (WT) and collagen XII-deficient (Col12a1-/-) murine corneas. The Brillouin frequency shift, elastic wave speed, and compressive strain were all measured as a function of intraocular pressure (IOP).

Results

All three optical elastography modalities measured a significantly decreased stiffness in the Col12a1-/- compared to the WT (P < 0.01 for all three modalities). The optical coherence elastography techniques showed that mean stiffness increased as a function of IOP; however, Brillouin microscopy showed no discernable trend in Brillouin frequency shift as a function of IOP.

Conclusions

Our approach suggests that the absence of collagen XII significantly softens the cornea. Although both optical coherence elastography techniques showed an expected increase in corneal stiffness as a function of IOP, Brillouin microscopy did not show such a relationship, suggesting that the Brillouin longitudinal modulus may not be affected by changes in IOP. Future work will focus on multimodal biomechanical models, evaluating the effects of other collagen types on corneal stiffness, and in vivo measurements.

Role of Shear-Wave Elastography in Achilles Tendon in Psoriatic Arthritis and Its Correlation with Disease Severity Score, Psoriasis Area and Severity Index

Purpose  The aim of this study was to compare accuracy of shear-wave elastography (SWE) with gray scale (GS) ultrasound and power Doppler (pD) for diagnosing Achilles tendinopathy in psoriatic patients with and without arthritis and correlation with achillodynia and disease severity score, psoriasis area and severity index (PASI).

Methods  A total of 100 Achilles tendons were evaluated where 56% were cases of psoriatic arthritis with achillodynia; 44% were controls of psoriasis without arthritis in this prospective study. Evaluation was done with GS, pD, SWE at proximal, mid, and distal third of the tendon. Qualitative (color maps) and quantitative data, elastic modulus, kilopascal (kPa), were generated. Pearson's correlation was done to see association between kPa, PASI and clinical symptoms, achillodynia, scored using visual analog scale (VAS).

Results  Significant negative correlation was seen between duration of arthritis, VAS and PASI with SWE values with r  = −0.34, −0.47, and −0.41, respectively. SWE could identify abnormal tendons in 71/100 (71%) in the overall study, 53/56 (94.6%) in cases, and 18/44 (40.9%) in control. The statistical significance was set at p  ≤ 0.05. In comparison, conventional ultrasound, GS, and pD together could identify 13/56 (23.21%) in cases and no abnormal tendon was identified in the control group.

Conclusion  SWE is a reliable, noninvasive, and valuable tool to detect early tendinopathy and monitor progression of disease.

Shear wave elastography of the common fibular nerve at the fibular head

ABSTRACT

The aim of this work is to study the sonoelastographic features of the common fibular nerve in healthy adult subjects.This is an observational cross-sectional study. Shear wave elastography was used to evaluate the common fibular nerve. Crosssectional area and stiffness were measured in kilopascal (kPa) and meters/second (m/s).The study included 82 common fibular nerves in 41 healthy adult subjects. The mean cross-sectional area of the common fibular nerve at the fibular head was 8.7 mm2. Positive correlation was noted between stiffness measurements between short and long axes by both methods. The mean stiffness of the common fibular nerve in the short axis was 22.5 kPa, and in the long axis (LA) was 35.4 kPa. Positive correlation was noted between height and stiffness measured by both methods in both axes by kPa. In m/s, the mean stiffness of the common fibular in the short axis was 2.6 m/s, and while in the LA was 3.4 m/s. Height showed positive correlation with both axes for stiff measurements in m\s. Weight showed positive correlation with stiffness measurements by m/s in the LA.The results obtained in our study could be a reference point for evaluating stiffness of the common fibular nerve in research involving different pathologies.

Ultrasound Shear Wave Elastography for Evaluation of Diaphragm Stiffness in Patients with Stable COPD: A Pilot Trial

OBJECTIVES

Skeletal muscle dysfunction is one of the most common comorbidities in chronic obstructive pulmonary disease (COPD). The occurrence of respiratory failure in COPD is common and leads to the patient's death. The diaphragm is the most important muscle in the respiratory system and plays a key role in the onset of respiratory failure. This study explores the feasibility of ultrasound shear wave elastography (SWE) to measure diaphragmatic stiffness and evaluates its changes in COPD patients.

METHODS

In total, 77 participants (43 patients with stable COPD and 34 healthy controls) were enrolled. All subjects underwent complete diaphragmatic ultrasound SWE measurements and pulmonary function tests. The diaphragmatic stiffness was indicated via diaphragmatic shear wave velocity (SWV) at functional residual capacity (FRC). A trained operator performed the ultrasound SWE examinations of the first 15 healthy controls thrice to assess the reliability of diaphragmatic SWE.

RESULTS

A good to excellent reliability was found in diaphragmatic SWV at FRC (ICC = 0.93, 95%CI 0.82-0.98). As compared to the control group, the diaphragmatic SWV at FRC was considerably high in the COPD group (median 2.5 m/s versus 2.1 m/s, P = .008). Diaphragmatic SWV at FRC was linked to forced expiratory volume in one second (r = -0.30, P = .009), forced vital capacity (r = -0.33, P = .003), modified Medical Research Council score (r = 0.30, P = .001), and COPD assessment test score (r = 0.48, P < .001).

CONCLUSIONS

Ultrasound SWE may be employed as an effective tool for quantitative evaluation of diaphragm stiffness and can help in personalized management of COPD, such as treatment guidance and follow-up monitoring.

The role of real-time elastosonography in the diagnosis of quadriceps fat pad edema

BACKGROUND

Quadriceps fat pad edema (QFPE) is one of the causes of anterior knee pain. Real-time elastosonography (RTE) has been increasingly used in musculoskeletal disorders.

PURPOSE

To evaluate the role of RTE in the diagnosis of QFPE.

MATERIAL AND METHODS

A total of 23 patients with QFPE on magnetic resonance imaging (MRI) (study group) were prospectively compared with 29 patients with normal MRI findings (control group) using RTE. On MRI, the thickness of the quadriceps fat pad (QFP), and on RTE, strain ratio (SR) of QFP were measured and compared between the two groups.

RESULTS

The study group contained 23 patients (12 men, 11 women; mean age = 41.6 ± 7.0 years) and the control group contained 29 patients (14 men, 15 women; mean age = 42.3 ± 6.1 years). No significant differences were found in terms of mean age and sex between the two groups (P = 0.70, P = 0.78, respectively). The median thicknesses of the QFPs were 8.10 mm and 6.75 mm in the study and control groups, respectively (P < 0.001). The median SR values of the study group and control group were found to be 63.20 and 6.24, respectively. The SR values were significantly higher in patients with QFPE (P < 0.001).

CONCLUSION

RTE may be an effective imaging method for evaluating QFPE.

Quantifying Lower Limb Muscle Stiffness as Ambulation Function Declines in Duchenne Muscular Dystrophy with Acoustic Radiation Force Impulse Shear Wave Elastography

Duchenne muscular dystrophy (DMD) is a progressive muscular disease, but validated imaging tools to quantify muscle microstructure alteration as mobility declines are lacking. We aimed to determine the feasibility of using acoustic radiation force impulse shear-wave elastography (ARFI/SWE) in the quantitative assessment of lower limb muscle stiffness in DMD patients. Shear wave velocities (SWVs) of lower limbs were measured in 39 DMD patients and 36 healthy controls aged 3-20 y. Mean SWV values of the controls and of the DMD patients at different ambulatory stages were compared using analysis of variance with Bonferroni correction. The DMD group had increased lower limb muscle stiffness compared with controls. Stiffness of the tibialis anterior and medial gastrocnemius muscle decreased from ambulatory to early non-ambulatory stages, whereas stiffness of the rectus femoris muscle increased from ambulatory to late non-ambulatory stages. We describe how SWV changes in lower limb muscles have the potential to predict ambulatory decline in DMD.

Tissue predictability of elastography is low in collagenase induced deep digital flexor tendinopathy

Elastography is an emerging imaging modality for characterizing tendon injury in horses, but its ability to differentiate tissue deformability relative to treatment group and biochemical properties using a prospective, experimental study design remain unknown. Objectives of the current study were to (a) to investigate differences in glycosaminoglycan, DNA, and soluble collagen levels in mesenchymal stem cell (MSC) treated limbs compared to untreated control limbs utilizing a collagenase model of tendinopathy; (b) compare elastographic features between treatment groups; and (c) determine tissue-level predictive capabilities of elastography in relation to biochemical outcomes. Bone marrow was collected for MSC culture and expansion. Tendinopathy of both forelimb deep digital flexor tendons (DDFTs) was induced with collagenase under ultrasonographic guidance. One randomly assigned limb was treated with intra-lesional MSC injection with the opposite limb serving as an untreated control. Horses were placed into a controlled exercise program with elastographic evaluations performed baseline (0) and 14, 60, 90, and 214 days post-treatment. Postmortem biochemical analysis was performed. MSC-treated limbs demonstrated significantly less (42%) glycosaminoglycan (P = .006). Significant differences in elastographic region of interest (ROI) percent hardness, ROI color histogram, and subjective lesion stiffness were appreciated between treatment groups at various study time points. Elastographic outcome parameters were weak predictors of biochemical tissue analysis, with all R² values ≤ 0.50. Within this range of differences in glycosaminoglycan content between treatment groups, elastography outcomes did not predict biochemical differences. Tissue-specific differences between DDFTs treated with MSCs compared to controls were apparent biochemically, but not predicted by elastography.

In Achilles Tendon Disorders, Will Sonoelastography Add to Grey-Scale Ultrasound? Using MRI as Gold Standard

Background The aim of this study was to verify the findings of color-coded sonoelastography in Achilles tendon disorders against ultrasonographic and MR imaging findings, describing the elastographic patterns and correlating their diagnostic ability to magnetic resonance imaging (MRI) as a gold standard. Results Our study showed that sonoelastography appeared to be highly sensitive to ultrasonographically detected changes, with 100% sensitivity, 16.6% specificity, 73% positive predictive value, and 100% negative predictive value, making it a good negative test to exclude suspected tendinopathy in equivocal cases. MRI examination was used as a gold standard. Elastographic grades showed moderate agreement to those of MRI ( κ = 0.44, p < 0.001), while elastography had overall sensitivity of 87.5%, 100% specificity, and 90% accuracy in differentiating normal and pathological tendons. Conclusion We concluded that sonoelastography is a sensitive method in the diagnosis of Achilles tendon pathologies detected by ultrasound examination and it can be well correlated to MRI with high specificity for pathological tendons.

Skeletal Muscle and Childhood Cancer: Where are we now and where we go from here

Skeletal muscle (muscle) is essential for physical health and for metabolic integrity, with sarcopenia (progressive muscle mass loss and weakness), a pre-curser of aging and chronic disease. Loss of lean mass and muscle quality (force generation per unit of muscle) in the general population are associated with fatigue, weakness, and slowed walking speed, eventually interfering with the ability to maintain physical independence, and impacting participation in social roles and quality of life. Muscle mass and strength impairments are also documented during childhood cancer treatment, which often persist into adult survivorship, and contribute to an aging phenotype in this vulnerable population. Although several treatment exposures appear to confer increased risk for loss of mass and strength that persists after therapy, the pathophysiology responsible for poor muscle quantity and quality is not well understood in the childhood cancer survivor population. This is partly due to limited access to both pediatric and adult survivor muscle tissue samples, and to difficulties surrounding non-invasive investigative approaches for muscle assessment. Because muscle accounts for just under half of the body's mass, and is essential for movement, metabolism and metabolic health, understanding mechanisms of injury responsible for both initial and persistent dysfunction is important, and will provide a foundation for intervention. The purpose of this review is to provide an overview of the available evidence describing associations between childhood cancer, its treatment, and muscle outcomes, identifying gaps in current knowledge.

Shear wave elastography of the radial nerve in healthy subjects

Objective

This study was performed to examine the sonoelastographic features of the radial nerve in healthy subjects.

Methods

In this observational cross-sectional study, shear wave elastography was used to evaluate the radial nerve. The cross-sectional area and stiffness were measured.

Results

The study included 37 nerves in 20 healthy adult subjects. The mean cross-sectional area of the radial nerve at the arm was 6.1 mm². The mean stiffness of the radial nerve in the short axis was 30.3 kPa, and that in the long axis was 34.9 kPa. The elasticity measurements were significantly different between the long axis and short axis.

Conclusion

The elastic modulus of the radial nerve was studied in healthy subjects and can serve as a reference for future assessment of different radial nerve pathologies.

Estimation of Accuracy of B-Mode Sonography and Elastography in Differentiation of Benign and Malignant Lymph Nodes With Cytology as Reference Standard: A Prospective Study

Purpose: To prospectively estimate the reliability of B-mode ultrasonography and sonoelastography in differentiating benign and malignant cervical lymph nodes with cytological findings as to the reference standard.

Materials and Methods: A total of 50 patients referred for sonography for enlarged cervical lymph nodes were included in the study. They were subjected initially to B-mode ultrasonography and sonoelastography and later underwent fine-needle aspiration cytology (FNAC) in the same sitting. Sensitivity, specificity, and accuracy were compared.

Results: Out of 50 cases, 33 were males, and 17 were females. On B-mode ultrasonography, 15 enlarged cervical lymph nodes were benign-looking and 35 were malignant-looking. When studied on elastography, 12 were benign-looking and 38 showed features of malignancy. However, when studied histopathologically, 18 were benign and 32 were malignant. The sensitivity, specificity, and diagnostic accuracy were compared, and the results were better in sonoelastography than B-mode ultrasonography. When both B-mode and sonoelastography were combined, an increase in the sensitivity for differentiation was achieved. However, a decrease in specificity was noted when both modalities were combined in our study, probably due to a significant number of patients with tuberculous cervical lymphadenopathy.

Conclusion: In countries like India, where granulomatous infection like tuberculosis is prevalent, the combination of sonoelastography with B-mode ultrasonography has decreased specificity in the differentiation of benign and malignant cervical lymph nodes, and histopathology is always needed for the final confirmation of diagnosis. The decreased specificity on elastography is attributed to simultaneous coexisting inflammation and fibrosis in chronic granulomatous lymphadenopathy.

Heartbeat optical coherence elastography: corneal biomechanics in vivo

SIGNIFICANCE

Mechanical assessment of the cornea can provide important structural and functional information regarding its health. Current clinically available tools are limited in their efficacy at measuring corneal mechanical properties. Elastography allows for the direct estimation of mechanical properties of tissues in vivo but is generally performed using external excitation force.

AIM

To show that heartbeat optical coherence elastography (Hb-OCE) can be used to assess the mechanical properties of the cornea in vivo.

APPROACH

Hb-OCE was utilized to detect Hb-induced deformations in the rabbit cornea in vivo without the need for external excitation. Furthermore, we demonstrate how this technique can distinguish corneal stiffness between untreated (UT) and crosslinked (CXL) tissue.

RESULTS

Our results demonstrate that stiffness changes in the cornea can be detected using only the Hb-induced deformations in the cornea. Additionally, we demonstrate a statistically significant difference in strain between the UT and CXL corneas.

CONCLUSIONS

Hb-OCE may be an effective tool for assessing the mechanical properties of the cornea in vivo without the need for external excitation. This tool may be effective for clinical assessment of corneal mechanical properties because it only requires optical coherence tomography imaging and data processing.

Shear wave elastography of the ulnar nerve at the forearm

The study included 38 ulnar nerves in 20 healthy subjects. High-resolution ultrasound and Shear wave elastography were used to evaluate the ulnar nerve at the mid forearm. The mean cross-sectional area of the ulnar nerve was 7.1 mm2. The mean shear elastic modulus of the nerve in the short axis was 27.4 kPa. The mean shear elastic modulus of the nerve in long axis was 24.7 kPa. No statistical relation could be noted between elasticity measurements in long and short axes. The ulnar nerve elastic modulus also showed no correlation with CSA neither in the long axis nor short axis. Age, height, weight, and body mass index showed no correlation with the ulnar elastic modulus in short or long axes. The elastic modulus of the ulnar nerve has been determined in healthy subjects and can serve as a reference for future assessment of compressive neuropathies of the ulnar nerve.

Quantitative Musculoskeletal Ultrasound

Ultrasound (US) imaging plays a crucial role in the assessment of musculoskeletal (MSK) disorders. Several quantitative tools are offered by US systems and add information to conventional US imaging. This article reviews the quantitative US imaging tools currently available in MSK radiology, specifically focusing on the evaluation of elasticity with shear-wave elastography, perfusion with contrast-enhanced US and noncontrast superb microvascular imaging, and bone and muscle mass with quantitative US methods. Some of them are well established and already of clinical value, such as elasticity and contrast-enhanced perfusion assessment in muscles and tendons. MSK radiologists should be aware of the potential of quantitative US tools and take advantage of their use in everyday practice, both for clinical and research purposes.

Novel Muscle Imaging in Inflammatory Rheumatic Diseases-A Focus on Ultrasound Shear Wave Elastography and Quantitative MRI

In recent years, imaging has played an increasing role in the clinical management of patients with rheumatic diseases with respect to aiding diagnosis, guiding therapy and monitoring disease progression. These roles have been underpinned by research which has enhanced our understanding of disease pathogenesis and pathophysiology of rheumatology conditions, in addition to their key role in outcome measurement in clinical trials. However, compared to joints, imaging research of muscles is less established, despite the fact that muscle symptoms are very common and debilitating in many rheumatic diseases. Recently, it has been shown that even though patients with rheumatoid arthritis may achieve clinical remission, defined by asymptomatic joints, many remain affected by lingering constitutional systemic symptoms like fatigue, tiredness, weakness and myalgia, which may be attributed to changes in the muscles. Recent improvements in imaging technology, coupled with an increasing clinical interest, has started to ignite new interest in the area. This perspective discusses the rationale for using imaging, particularly ultrasound and MRI, for investigating muscle pathology involved in common inflammatory rheumatic diseases. The muscles associated with rheumatic diseases can be affected in many ways, including myositis-an inflammatory muscle condition, and myopathy secondary to medications, such as glucocorticoids. In addition to non-invasive visual assessment of muscles in these conditions, novel imaging techniques like shear wave elastography and quantitative MRI can provide further useful information regarding the physiological and biomechanical status of the muscle.

Evaluation of Postoperative Changes in Patellar and Quadriceps Tendons after Total Knee Arthroplasty-A Comprehensive Analysis by Shear Wave Elastography, Power Doppler and B-mode Ultrasound

RATIONALE AND OBJECTIVES

Up to now, the diagnosis of tendinopathies is based on conventional B-mode-ultrasound (B-US), Power Doppler-ultrasound (PD-US), and magnetic resonance imaging. In the past decade, Shear Wave Elastography (SWE) has been introduced in tendon imaging, for example in athletes or patients suffering from tendinopathy. SWE allows real-time quantification of tissue stiffness, and, by this, the assessment of the mechanical properties of a tendon and its changes during acute disease and tendon healing. So far there are no ultrasound-based studies that have evaluated postoperative tendon changes, anatomical and mechanical properties and tendon healing of the patellar, and quadriceps tendon following Total Knee Arthroplasty (TKA). The purpose of this prospective study was two-fold: first to analyze morphologic, vascular, and mechanical properties of patellar and quadriceps tendons in patients following TKA; and, second to evaluate possible changes thereof and their visibility in the course of time.

MATERIALS AND METHODS

Observational cross-sectional, IRB-approved study in 63 postoperative patients with a total of 76 total knee arthroplasties (50 unilateral, 13 bilateral) and 50 nonoperated knees for comparison, resulting in 152 postoperative patellar- and quadriceps and 100 nonoperated patellar- and quadriceps-tendons for comparative analysis. For further examination, we divided the 63 patients into two groups according to the duration since surgery (group A < 24 months; group B > 24 months). All patients completed a standardized questionnaire, furthermore the Knee Society score and the Knee Society function score. The amount of experienced pain was assessed using the ordinal numeric rating scale and the presence of anterior knee pain was examined. Subsequently every participant underwent a standardized multimodal ultrasound protocol consisting of B-US, PD-US, and SWE of the left and right patellar and quadriceps tendons.

RESULTS

Using the different US-modalities, operated patellar, and quadriceps tendons (n = 152) were significantly more frequent classified as pathological (B-US) (p < 0.001), the mean Ohberg score was significantly higher (PD-US) (p < 0.001), and the tendons were significantly softer (SWE) than their nonoperated counterparts (n = 100). Mean SWE-value of postoperative patellar tendons was 45.66 ± 14.84 kPa versus 60.08 ± 19.13 kPa in nonoperated knees (p < 0.001). Mean SWE-value of postoperative quadriceps tendons was 35.73 ± 15.66 kPa versus 52.69 ± 16.20 kPa in nonoperated knees (p < 0.001). Comparing the two postoperative groups (group A and B), we recognized a significant decrease of pathologically classified patellar and quadriceps tendons (B-US and PD-US) in group B. The early postoperatively reduced SWE values slightly increased during the course of time.

CONCLUSION

After TKA, patellar, and quadriceps tendons show significant measurable alterations in B-US, PD-US, and SWE. Especially a significant decrease of tendon stiffness in operated knees, as assessed by SWE, might be a surrogate marker for changed mechanical properties. These alterations improve, the longer ago the surgery was. The quantitative information obtained by SWE could be of particular interest in follow-up and therapy monitoring after TKA. Knowledge about tendon stiffness and it's varieties in different population groups (e.g. athletes, elderly, postoperative patients) is crucial to sonographically rate a tendon as "healthy" or "diseased."

Heartbeat OCE: corneal biomechanical response to simulated heartbeat pulsation measured by optical coherence elastography

SIGNIFICANCE

It is generally agreed that the corneal mechanical properties are strongly linked to many eye diseases and could be used to assess disease progression and response to therapies. Elastography is the most notable method of assessing corneal mechanical properties, but it generally requires some type of external excitation to induce a measurable displacement in the tissue.

AIM

We present Heartbeat Optical Coherence Elastography (Hb-OCE), a truly passive method that can measure the elasticity of the cornea based on intrinsic corneal displacements induced by the heartbeat.

APPROACH

Hb-OCE measurements were performed in untreated and UV-A/riboflavin cross-linked porcine corneas ex vivo, and a distinct difference in strain was detected. Furthermore, a partially cross-linked cornea was also assessed, and the treated and untreated areas were similarly distinguished.

RESULTS

Our results suggest that Hb-OCE can spatially map displacements in the cornea induced by small fluctuations in intraocular pressure, similar to what is induced by the heartbeat.

CONCLUSIONS

The described technique opens the possibility for completely passive and noncontact in vivo assessment of corneal stiffness.

Postoperative diagnostic potentials of median nerve strain and applied pressure measurement after carpal tunnel release

Bakground

The objective of this study is to investigate the prognostic values of median nerve strain and applied pressure measurement for the assessment of clinical recovery after carpal tunnel release.

Methods

Forty-five wrists, from 45 idiopathic carpal tunnel syndrome patients who treated with open carpal tunnel release, were evaluated by ultrasound. Median nerve strain, pressure applied to the skin, and ratio of pressure-strain were measured at the proximal part of the carpal tunnel. In addition, distal latencies in the motor and sensory nerve conductions studies and cross-sectional area of median nerve were measured. The parameters were compared before and after the open carpal tunnel release. According to patient recovery, the receiver operating characteristic curves were generated to evaluate the prognostic values of the parameters. The areas under the receiver operating characteristic curves were compared among parameters.

Results

There was a significant increase in the median nerve strain, and significant decreases in the pressure applied to the skin and ratio of pressure-strain after carpal tunnel release (P < 0.01). There were significant decreases in the distal latencies and the cross-sectional area after carpal tunnel release (P < 0.01). The areas under the curves were 0.689, 0.773, 0.811, 0.668, 0.637, and 0.562 for the pressure, strain, pressure-strain ratio, motor latency, sensory latency, and area, respectively.

Conclusions

The results suggest that elasticity of the median nerve and pressure around the nerve recover quickly after carpal tunnel release. Pressure-strain ratio was the most reliable parameter to reflect clinical recovery. The measurement of strain and applied pressure can be useful indicators to evaluate effectiveness of the carpal tunnel release.

Trial registration

Registered as NCT04027998 at ClinicalTrials.gov. Retrospectively registered on July 22, 2019.

Structural, biomechanical and hemodynamic assessment of the bladder wall in healthy subjects

AIM

The aim of this study was to apply and evaluate three ultrasound methods to measure the bladder wall in a healthy population using high-resolution applications and to establish reference points and baselines for future research into lower urinary tract diseases, specifically to understand how lower urinary tract disorders affect the bladder wall and to find objective, non-invasive diagnostic tests.

METHODS

The study was conducted on 116 healthy volunteers aged 19-79 years old with approximately 10 participants in each decade group.

RESULTS

The following bladder parameters were recorded and measured using a GE LOGIQ E9 XDclear 2.0 ultrasound machine (GE Healthcare, Wauwatosa, WI, USA):Full bladder wall thickness (BWT) and each of three bladder wall layers thickness (BWLT) - serosa, detrusor and mucosa;Shear Wave Velocity (SWV) in m/s, using 2D Shear Wave Elastography (2D-SWE); andBladder wall blood circulation (Resistive Index, RI), using Duplex Doppler ultrasound.All of the above measurements were recorded at three different urine filling volumes: V0 (20-50 mL), V2 (180-200 mL) and V4 (380-400 mL) with ten repeats for each measured parameter. As expected, BWT and BWLT correlated inversely with increasing bladder volume. While there are no large differences in the healthy bladders of men compared with women, or with age, some small, but statistically significant, differences revealed. BWT at V0 is greater in men, as is the detrusor thickness at VO, but there are no differences at other volumes or for other layers. There is a small, but statistically significant thickening of BWT and detrusor layer and increase in SWV with age in men at V0. SWE showed increase in SWV measured at 400 mL bladder volume across all gender and age groups. There was no change in bladder wall vessels RI with age, between gender groups or increasing bladder volume.

CONCLUSION

We used three ultrasound applications to obtain bladder wall reference data in healthy individuals and investigated the relationships between BWT, BWLT, SWV, RI and gender, age at three bladder volumes, for further studies into identifying and diagnosing different urinary bladder disorders. With further research, ultrasound could be used as a diagnostic test to differentiate bladder pathology in clinical practice.

Strain Ratio Measurements of Patellar and Achilles Tendons With Different Reference Regions in Healthy Volunteers

Strain ratio measurements of tendons vary because of the reference tissue selection. The main purpose of this study is to highlight, in detail, the numeric variability attributable to the use of various reference materials on strain ratio measurements of patellar and Achilles tendons. Measurements were performed at the proximal, middle and distal thirds of the patellar and Achilles tendons on the dominant site of healthy volunteers. A total of 3 references were used: the Hoffa's fat pad for the patellar tendon, the Kager's fat pad for the Achilles tendon, subcutaneous tissue and Aquaflex gel pads (Parker Laboratories, Fairfield, NJ, USA) for both tendons. Although the same methods were used by the same physician for each tendon site on repeated measurements, strain ratio values had numeric variability with various reference materials in each measurement. Therefore, comparison of numeric strain ratio results of various studies with various reference materials could confuse the clinical interpretations of these numeric data, and, using a reference material with standard stiffness like Aquaflex ultrasound gel pads, should be considered by verifying these results with further studies.

Assessing colitis ex vivo using optical coherence elastography in a murine model

BACKGROUND

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that causes regions of ulceration within the interior of the colon. UC is estimated to afflict hundreds of thousands of people in the United States alone. In addition to traditional colonoscopy, ultrasonic techniques can detect colitis, but have limited spatial resolution, which frequently results in underdiagnoses. Nevertheless, clinical diagnosis of colitis is still generally performed via colonoscopy. Optical techniques such as confocal microscopy and optical coherence tomography (OCT) have been proposed to detect UC with higher resolution. However, UC can potentially alter tissue biomechanical properties, providing additional contrast for earlier and potentially more accurate detection. Although clinically available elastography techniques have been immensely useful, they do not have the resolution for imaging small tissues, such as in small mammalian disease models. However, OCT-based elastography, optical coherence elastography (OCE), is well-suited for imaging the biomechanical properties of small mammal colon tissue.

METHODS

In this work, we induced elastic waves in ex vivo mouse colon tissue using a focused air-pulse. The elastic waves were detected using a phase-stabilized swept source OCE system, and the wave velocity was translated into stiffness. Measurements were taken at six positions for each sample to assess regional sample elasticity. Additional contrast between the control and diseased tissue was detected by analyzing the dispersion of the elastic wave and tissue optical properties obtained from the OCT structural image.

RESULTS

The results show distinct differences (P<0.05) in the stiffness between control and colitis disease samples, with a Young's modulus of 11.8±8.0 and 5.1±1.5 kPa, respectively. The OCT signal standard deviations for control and diseased samples were 5.8±0.3 and 5.5±0.2 dB, respectively. The slope of the OCT signal spatial frequency decay in the control samples was 92.7±10.0 and 87.3±4.7 dB∙µm in the colitis samples. The slope of the linearly fitted dispersion curve in the control samples was 1.5 mm, and 0.8 mm in the colitis samples.

CONCLUSIONS

Our results show that OCE can be utilized to distinguish tissue based on stiffness and optical properties. Our estimates of tissue stiffness suggest that the healthy colon tissue was stiffer than diseased tissue. Furthermore, structural analysis of the tissue indicates a distinct difference in tissue optical properties between the healthy and UC-like diseased tissue.

Reliability of ultrasound strain elastography in the assessment of the quadriceps and patellar tendon in healthy adults

Objective

To report the intra- and inter-operator reliability of ultrasound strain elastography measures in the assessment of quadriceps and patellar tendons.

Materials and methods

Forty tendons were investigated of 20 healthy volunteers. Five anatomical sites were examined and analysed by three operators of differing levels of experience. Ultrasound was performed over two measures, employing three sonoelastography measurement techniques using a GE S8 with linear probe (L6-15 MHz). The percentage of exact agreement, Cohen's kappa and ICC_2,1 were performed to assess intra- and inter-operator reliability.

Results

The patellar tendon is more reliably measured across all techniques compared to the quadriceps tendon, particularly the distal region. Colour scoring was the most reliable method of sonoelastography. Colour scoring intra- and inter-operator reliability was better for patella tendon sites across all operators (60-95% agreement range), and greatest for experienced operators. Elasticity index intra-operator reliability was greatest for the most experienced operator compared with the least (ICC range 0.35-0.72 and ICC 0.17-0.60). Elasticity ratio intra-operator reliability of the patella tendon was fair-excellent for the experienced operator (ICC range 0.43-0.91), excluding the mid patellar region (ICC 0.13). Poor-fair inter-operator reliability was observed for elasticity ratio (ICC range 0.0-0.54) and elasticity index (ICC range 0.0-0.57).

Conclusions

Strain elastography of the patellar tendon is more reliable than the quadriceps tendon. Intra- and inter-operator reliability was better when undertaken by more experienced operators. Colour scoring was more reliable than elasticity ratio and index methods. Poor-fair intra- and inter-operator reliability of the elasticity ratio and elasticity index was observed.

Ulnar nerve instability in the cubital tunnel of asymptomatic volunteers

PURPOSE

Ulnar nerve instability (UNI) in the cubital tunnel is defined as ulnar nerve subluxation or dislocation. It is a common disorder that may be noted in patients with neuropathy or in the asymptomatic. Our prospective, single-site study utilized high-resolution ultrasonography (US) to evaluate the ulnar nerve for cross-sectional area (CSA) and measures of shear-wave elastography (SWE). Mechanical algometry was obtained from the ulnar nerve in the cubital tunnel to assess pressure pain threshold (PPT).

METHODS

Forty-two asymptomatic subjects (n = 84 elbows) (25 males, 17 females) aged 22-40 were evaluated. Two chiropractic radiologists, both with 4 years of ultrasound experience performed the evaluation. Ulnar nerves in the cubital tunnel were sampled bilaterally in three different elbow positions utilizing US, SWE, and algometry. Descriptive statistics, two-way ANOVA, and rater reliability were utilized for data analysis with p ≤ 0.05.

RESULTS

Fifty-six percent of our subjects demonstrated UNI. There was a significant increase in CSA in subjects with UNI (subluxation: 0.066 mm² ± 0.024, p = 0.027; dislocation: 0.067 mm² ± 0.024, p = 0.003) compared to controls (0.057 mm² ± 0.017) in all three elbow positions. There were no significant group differences in SWE or algometry. Inter- and intra-observer agreements for CSA of the ulnar nerves within the cubital tunnel were assessed using intraclass correlation coefficient (ICC) and demonstrated moderate (ICC 0.54) and excellent (ICC 0.94) reliability.

CONCLUSIONS

Most of the asymptomatic volunteers demonstrated UNI. There was a significant increase in CSA associated with UNI implicating it as a risk factor for ulnar neuropathy in the cubital tunnel. There were no significant changes in ulnar nerve SWE and PPT. Intra-rater agreement was excellent for the CSA assessment of the ulnar nerve in the cubital tunnel. High-resolution US could be utilized to assess UNI and monitor for progression to ulnar neuropathy.

Real-time ultrasound elastography evaluation of achilles tendon properties in patients with mild hemiplegic stroke after rehabilitation training

OBJECTIVE

This study aims to evaluate the Achilles tendon's properties after rehabilitation training in patients with stroke using real-time ultrasound elastography.

METHODS

A total of 24 patients with mild hemiplegic stroke in the past 6 to 12 months and unilateral lower limb movement disorder were prospectively enrolled. All patients accepted 9-week rehabilitation training with the same schema. The 2-dimensional elastography and real-time elastography findings in the impaired and contralateral normal Achilles tendon were measured at pretraining and at 3, 6, and 9 weeks after training, which included tendon length, thickness, elasticity score (grade 1-3), and strain ratio of fat to tendon. The functional properties, which include the 10-meter walk test and timed up-and-go scores, were evaluated before and after the 9-week training.

RESULTS

The impaired Achilles tendon had a longer length (P = .002), lower frequency of grade 1 (P = .012), and lower strain ratio (P = .009) than the contralateral tendon before training. The impaired tendons at the third, sixth, and ninth weeks after training were compared to ones before training, respectively, which revealed shorter length, increased frequency of grade 1, and increased strain ratio. The first statistically significant changes in the length were observed at the sixth week, while such changes in elasticity score and strain ratio were observed at the ninth week.

CONCLUSIONS

Two-dimensional elastography and real-time elastography can provide valuable imaging markers for quantitatively evaluating the Achilles tendon's properties after rehabilitation training in patients with stroke.

Assessing the elastic properties of skeletal muscle and tendon using shearwave ultrasound elastography and MyotonPRO

The purposes of this study were to compare Young’s modulus values determined by shear wave ultrasound elastography (SWUE) with stiffness index obtained using a hand-held MyotonPRO device on the resting stiffness of gastrocnemius muscle belly and Achilles tendon; and to examine the test-retest reliability of those stiffness measurement using hand-held MyotonPRO. Twenty healthy volunteers participated in the study. The measurement values of muscle and tendon was determined in dominant legs. Each marker point was assessed using MyotonPRO and SWUE, respectively. Intra-operator reliability of MyotonPRO was established in 10 of the subjects. The correlation coefficients between the values of muscle and tendon stiffness indices determined by MyotonPRO and SWUE were calculated. Significant correlations were found for muscle and tendon stiffness and Young’s modulus ranged from 0.463 to 0.544 (all P < 0.05). The intra-operator reliability ranged from good to excellent (ICC_(3,1) = 0.787~0.928). These results suggest that the resting stiffness of gastrocnemius muscle belly and Achilles tendon measured by MyotonPRO is related to the Young’s modulus of those quantified by SWUE. The MyotonPRO shows good intra-operator repeatability. Therefore, the present study shows that MyotonPRO can be used to assess mechanical properties of gastrocnemius muscle belly and Achilles tendon with a resting condition.

Soft tissue elastography via shearing interferometry

Early detection of cancer can significantly increase the survival chances of patients. Palpation is a traditional method in order to detect cancer; however, in minimally invasive surgery the surgeon is deprived of the sense of touch. We demonstrate how shearing elastography can recover elastic parameters and furthermore can be used to localize stiffness imhomogenities even if hidden underneath the surface. Furthermore, the influence of size and depth of the stiffness imhomogenities on the detection accuracy and localization is investigated.

Diagnostic Performance of Superb Microvascular Imaging and Other Sonographic Modalities in the Assessment of Lateral Epicondylosis

OBJECTIVES

The aim of this study was to compare the diagnostic performance of different sonographic modalities for diagnosing lateral epicondylosis.

METHODS

A total of 50 symptomatic and 50 asymptomatic common extensor tendons in 44 patients with lateral epicondylosis, and 25 healthy participants were prospectively examined by B-mode sonography, color Doppler imaging, power Doppler imaging, Superb Microvascular Imaging (SMI; Toshiba Medical Systems Corporation, Tokyo, Japan), and strain elastography. We evaluated blood flow in common extensor tendons by using a grading system with color Doppler imaging, power Doppler imaging, and SMI. The diagnostic performance of the modalities was compared.

RESULTS

When a cutoff value of hypoechogenicity was used for the mean strain ratio, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy rates were 92.0%, 94%.0, 93.9%, 92.2%, and 93.0%, respectively. When a cutoff point of grade 1 was used, the sensitivity, specificity, PPV, NPV, and accuracy rates were 26.0%, 10.0%, 10.0%, 57.5%, and 63.0, for color Doppler imaging; 40.0%, 10.0%, 10.0%, 62.5%, and 70.0% for power Doppler imaging; and 84.0%, 94.0%, 93.0%, 85.5%, and 89.0% for SMI. When a cutoff value of 3.94 was used for the mean strain ratio, the sensitivity, specificity, PPV, NPV, and accuracy rates were 78.0%, 92.0%, 90.7%, 80.7%, and 85.0%, respectively. A statistically significant correlation was detected between SMI, strain elastography, and visual analog scale scores (P < .001).

CONCLUSIONS

The combination of SMI and B-mode sonography was found to have excellent diagnostic performance for lateral epicondylosis. Neovascularzation in patients' tendons with lateral epicondylosis was identified much better with SMI compared to color or power Doppler imaging.

Ultrasound elastography in tendon pathology: state of the art

Elastography assesses the biomechanical and structural properties of tissues by measuring their stiffness. Despite promising results, elastography has not yet earned its place in the daily practice of musculoskeletal radiologists. The purpose of this article is to present and examine the data available to date on ultrasound elastography of the tendons through a review of the literature to provide musculoskeletal radiologists with an overview that may help them better understand and use elastography routinely. The most common techniques in ultrasound elastography are described. Then, the aspects of the physiologic and pathologic tendon are presented and discussed. One must make this technique one's own to better apprehend its contribution to the musculoskeletal imaging field, while bearing in mind that further research will be required before admitting elastography as a reliable and validated tool able to optimize our daily clinical practice.

Shear-Wave Elastography: Basic Physics and Musculoskeletal Applications

In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue's elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system. ^©RSNA, 2017.

Shear wave elastography findings of de Quervain tenosynovitis

OBJECTIVE

Our aim was to evaluate the feasibility of using shear wave elastography (SWE) to assess first extensor compartment tendons rigidity and its alterations with tenosynovitis.

MATERIALS AND METHODS

We performed B-mode ultrasound and SWE to total number of 80 participants. All participants were evaluated clinically to call the diagnosis of de Quervain tenosynovitis or to rule out the diagnosis. We composed 2 groups. Group 1 included 40 healthy volunteers (33 females and 7 male participants with ages ranging from 24 to 60 years, median age was 37.5 years) and group 2 had 40 de Quervain patients (32 females and 8 male patients with ages ranging from 25 to 51 years, median age was 34 years). SWE measurements were repeated 3 times and arithmetic average was used for the final SWE value.

RESULTS

The median SWE value of healthy group (group 1) was 72kPa and the de Quervain patient group (group 2) was 29kPa. Two groups demonstrated statistically significant difference (p<0.001). The ROC curve analysis was performed and the SWE value of 40.5kPA was calculated as a cut-off value for the diagnosis of de Quervain tenosynovitis with 95% specificity and 85% sensitivity.

CONCLUSION

SWE modality can provide useful data regarding de Quervain tenosynovitis.

Measurement of Median Nerve Strain and Applied Pressure for the Diagnosis of Carpal Tunnel Syndrome

The objective of this study was to evaluate the diagnostic utility of strain and applied-pressure measurements of the median nerve in carpal tunnel syndrome (CTS). Thirty-five wrists of 23 idiopathic CTS patients and 30 wrists of 15 normal patients were examined. Median nerve strain, pressure to the skin and the pressure/strain ratio were measured at the proximal carpal tunnel level. Parameters were compared between CTS patients and controls. The areas under the receiver operating characteristic curves (AUCs) were compared for the parameters. Median nerve strain was significantly lower in the patients than in the controls (p < 0.01). Pressure and pressure/strain ratio were significantly higher in the patients than in the controls (p < 0.05: pressure, p < 0.01: ratio). The AUCs were 0.926, 0.681 and 0.937 for strain, pressure and pressure/strain ratio, respectively. Pressure/strain ratio is useful for evaluating the condition of the median nerve with respect to the hardness of the surrounding structures in CTS.

Evaluation of Inferior Turbinate Stroma with Ultrasound Elastography in Allergic Rhinitis Patients

Background:

Diagnosis of allergic rhinitis is primarily based on history, physical examination and allergy testing. A technique that noninvasively evaluates the soft tissue changes in the nasal mucosa of allergic rhinitis patients has not been defined.

Aims:

To assess nasal mucosal changes and measure the submucosal fibrosis in allergic rhinitis patients with sonoelastography.

Study Design:

Case control study.

Methods:

Eighty-eight turbinates of 44 patients were included in the study. There were 23 prick test positive allergic rhinitis patients. The control group constituted 21 patients. The rhinitis quality of life questionnaire and the visual analogue scale were applied to the allergic rhinitis patients. A higher visual analogue scale score indicated more severe allergic rhinitis symptoms. Sonoelastographic measurements were made from the lateral nasal wall. The propagation speed of sound waves was recorded in m/s. The presence of asthma and the type of allergic rhinitis (seasonal or perennial) was noted.

Results:

Ten patients had seasonal allergic rhinitis and thirteen patients had perennial allergic rhinitis. Six patients (26.1%) had accompanying asthma along with allergic rhinitis. The median visual analogue scale score was 7 (3-9) in allergic rhinitis patients. The median symptom duration was 7 (1-24) months. The median quality of life questionnaire score was 3.39 (1.68-5.43) points. The median sonoelastography scores of allergic rhinitis patients and healthy subjects were 2.38 m/s (0.9-4.47) and 2.42 m/s (1.62-3.50), respectively. Sonoelastographic measurements of seasonal and perennial allergic rhinitis patients did not differ significantly (p>0.05). The presence of asthma did not have a significant impact on the elastography measurements (p>0.05). However, regression analysis revealed a significant inverse correlation (coefficients: B=0.005, standard error=0.097, beta 0=0.008) between the visual analogue scale and sonoelastography scores (p<0.05).

Conclusion:

Sonoelastography was not suitable as a diagnostic tool in allergic rhinitis. Reduced sonoelastography scores were measured in more symptomatic patients. Higher visual analogue scale scores could be an indicator of disease severity.

Serial Changes of Tendon Histomorphology and Strain Elastography After Induced Achilles Tendinopathy in Rabbits: An In Vivo Study

OBJECTIVES

The purpose of this study was to investigate and compare the serial changes of morphology and strain in the early process of Achilles tendinopathy in a rabbit model.

METHODS

A total of 10 New Zealand white rabbits underwent ligation of one of their Achilles tendons to induce ischemic injury. Both inflamed and contralateral Achilles tendons were serially evaluated with 3 follow-ups: the first on days 3 to 5, the second on days 9 to 13, and the third and last follow-up on days 15 to 20 after surgery. During each examination, tendon thickness was measured and red, green, and blue pixel intensities of the elastogram were analyzed using color histogram analysis software. Differences between the inflamed and control group were compared.

RESULTS

The mean thickness of the inflamed tendons increased during consecutive follow-ups and was significantly larger than that of control tendons (P < .01). The mean red pixel intensity ratio of the inflamed tendons was also serially increased and was higher than that in the control tendons, indicating softening. However, the difference was significant only in the second and third follow-ups (P < .01).

CONCLUSIONS

Tendon thickening and softening developed during the early process of Achilles tendinopathy in a rabbit model. Tendon softening may present later than thickening.

Elastographic Findings of Achilles Tendons in Asymptomatic Professional Male Volleyball Players

OBJECTIVES

Elastography is a new sonographic technique that evaluates the elasticity of different tissues such as the Achilles tendon. In this study, we aimed to investigate the elastographic findings of Achilles tendons in professional athletes in comparison with healthy volunteers.

METHODS

Twenty-one professional male volleyball players with no history of Achilles trauma were included in this study. Twenty-one healthy male volunteers with similar ages and body mass indices were selected as control participants. All participants underwent sonographic and elastographic evaluations of the Achilles tendons to evaluate Achilles tendon thickness and stiffness.

RESULTS

We observed thickening in many of the thirds of the Achilles tendons (right proximal, right middle, left middle, and left distal thirds) of athletes in comparison with healthy volunteers. We did not detect any abnormalities according to the sonographic evaluations in both athletes and healthy volunteers. In the elastographic evaluations, we observed softening in the middle thirds of the Achilles tendons of athletes according to the main types (P < .001) and subtypes (P < .001 for right; and P = .002 for left middle third). There was no difference observed in the elastographic evaluations of the proximal and distal thirds.

CONCLUSIONS

On sonography and elastography, we observed thickening and softening in Achilles tendons of athletes in comparison with healthy volunteers who had similar ages and body mass indices. These changes could be associated with early tendon degeneration. Further longitudinal studies may support this consideration.

Muscle elastography: a new imaging technique for multiple sclerosis spasticity measurement

Multiple sclerosis (MS) spasticity is currently evaluated on the basis of neurological examinations such as Ashworth Scale (AS) and 0-10 NRS. Severity of spasticity is difficult to quantify. We investigated the use of real time elastography (RTHE) ultrasounds for evaluating objectively the muscle fibers status in MS spasticity patients and their changes after a new antispasticity treatment. Two studies were performed. In study A, 110 MS patients underwent a neurological evaluation based on the AS and RTHE. The RTHE images were scored with the new 1-5 muscle fibers rigidity imaging scale, here called MEMSs (Muscle Elastography Multiple Sclerosis Score). The correlation between AS and MEMSs was found to be statistically significant. In study B, 55 MS patients treated with THC:CBD oromucosal spray for their resistant spasticity were followed prospectively. MS spasticity was evaluated by the 0-10 NRS scale at baseline and after 4 weeks of treatment. MEMSs' figures were obtained at both timepoints. Responders to THC:CBD oromucosal spray (pre-defined as an improvement ≥20% in their 0-10 NRS spasticity score vs. baseline) were 65% of sample. These patients had a mean 0-10 NRS reduction of 1.87 and a MEMSs reduction of 1.97 (P values <0.0001). The remaining 35% of patients, classified as clinically non-responders, showed still a significant mean reduction in MEMSs (0.8, P = 0.002). Our overall results showed that RTHE, operativized throughout MEMSs, could be an objective gold standard to evaluate MS muscle spasticity as well as the effectiveness of antispasticity therapy.

Assessment of forearm muscle spasticity with sonoelastography in patients with stroke

OBJECTIVE

The aim of the study was to investigate the feasibility of sonoelastography to show muscle stiffness in post-stroke spasticity, and the relationship between sonoelastography findings and clinical spasticity scores in the spastic forearm muscles.

METHODS

This study was carried out in a university rehabilitation centre. 23 patients with stroke with forearm muscle spasticity (≥1+ using the Modified Ashworth scale score and ≥1 using the Tardieu scale) were included. Sonoelastography parameters (elasticity index and elasticity ratio) were measured from the flexor digitorum superficialis, flexor digitorum profundus, flexor carpi radialis and flexor carpi ulnaris muscles on the affected and unaffected sides.

RESULTS

Both elasticity index and elasticity ratio of the wrist and finger flexors on the hemiplegic side were significantly increased compared with those on the healthy side (p < 0.05). The Tardieu angle of finger flexors was negatively correlated with the elasticity index and elasticity ratio measured in the spastic flexor digitorum profundus (r = -0.418 and r = -0.469, respectively). Tardieu angle of finger flexors was negatively correlated with the elasticity index measured in the spastic flexor digitorum superficialis (r = -0.435). There was no correlation between other parameters.

CONCLUSION

Sonoelastography may provide objective assessment of spasticity both in diagnosis and follow-up. To strengthen this prediction, further studies are necessary. Advances in knowledge: The results of this study represent that sonoelastography is a promising evaluation method for forearm muscle spasticity.

Sonoelastography of Musculoskeletal Soft Tissue Masses: A Pilot Study of Quantitative Evaluation

OBJECTIVES

To evaluate quantitative sonoelastography of benign and malignant musculoskeletal soft tissue masses.

METHODS

We conducted a prospective study of 50 patients from a specialist sarcoma center who had extremity soft tissue masses referred for biopsy. After consent, the quantitative shear wave velocity (meters per second) was measured in longitudinal and transverse planes (3 readings in each plane and mean calculated). All masses subsequently underwent biopsy, excision, or both, with the histologic diagnosis taken as the reference standard. At a subsequent sitting, all anonymized B-mode sonograms were scored independently by 2 radiologists as benign or malignant with agreement by consensus if necessary.

RESULTS

Of the 50 masses, 15 were malignant and 35 benign. Nine masses had incomplete velocity readings. Intraclass correlation coefficients for intra-reader reliability of velocity measurements were highly repeatable. There was preliminary evidence that the longitudinal shear wave velocity of malignant masses was on average 30% slower than that of benign masses (P< .10). Longitudinal and transverse shear wave measurements were moderately associated with each other (P = .003). There was no evidence that shear wave velocity varied with patient age, sex, or mass volume. For B-mode assessment of malignancy, sensitivity (Wilson 90% confidence interval) was 73.3% (52.1%, 87.4%), and specificity was 77.1% (63.8%, 86.6%). Interobserver agreement was substantial (κ= 0.86). Four of 15 malignant masses (26.6%) were incorrectly classified as benign on B-mode assessment (all grade 1 liposarcomas).

CONCLUSIONS

These data suggest that shear wave velocity measurement is reproducible and that malignant masses may have slower longitudinal shear wave velocities than benign masses. The sample size of this pilot study precludes adjusted analysis but should form the basis for larger study designs.

Hypospadias anatomy: Elastosonographic evaluation of the normal and hypospadic penis

BACKGROUND

Hypospadias is one of the most common congenital anomalies in childhood. The aim of this study is to apply elastosonography on normal and hypospadic penis to verify the structural differences in tissues composition and stiffness.

MATERIALS AND METHODS

We analyzed medical chart of patients treated at our Institution for hypospadias during the period December 2005 and December 2014 (group 1). Other two groups were enrolled for this study: group 2- patients with hypospadias waiting for surgery and group 3-patients without hypospadias. Inclusion and exclusion criteria were created; all patients underwent penile ultrasound and elastosonography. Elastographic index of elasticity was defined as soft, medium-hard or hard. We assigned the value 1 to soft tissue, 2 and 3 to medium-hard and hard respectively.

RESULTS

During the study period 294 patients were treated for hypospadias. After reviewing medical chart 115 patients were considered for analysis (group 1). 22 patients were enrolled in group 2 and 38 patients were enrolled in group 3. Group 1: 7 proximal hypospadias, 29 penile hypospadias, 79 distal hypospadias. Patients with hypospadias had malformation also at corpus spongiosum and cavernosum respect to controls. Elastography showed a corpus spongiosum stiffness defined as medium-hard or hard in all cases of the pathologic group and soft in all the subjects of the control group (p < 0.05).

CONCLUSIONS

Elastosonography showed how the hypospadia anatomy is deeply altered, even in an anatomical area far from meatal abnormality: corpus spongiosum in hypospadic penis seems to be globally stiffer and less elastic and cavernous corpora are less developed.

Use of Ultrasound Elastography in the Assessment of the Musculoskeletal System

This article presents possible applications of ultrasound elastography in musculoskeletal imaging based on the available literature, as well as the possibility of extending indications for the use of elastography in the future. Ultrasound elastography (EUS) is a new method that shows structural changes in tissues following application of physical stress. Elastography techniques have been widely used to assess muscles and tendons in vitro since the early parts of the twentieth century. Only recently with the advent of new technology and creation of highly specialized ultrasound devices, has elastography gained widespread use in numerous applications.

The authors performed a search of the Medline/PubMed databases for original research and reviewed publications on the application of ultrasound elastography for musculoskeletal imaging.

All publications demonstrate possible uses of ultrasound elastography in examinations of the musculoskeletal system. The most widely studied areas include the muscles, tendons and rheumatic diseases. There are also reports on the employment in vessel imaging.

The main limitation of elastography as a technique is above all the variability of applied pressure during imaging, which is operator-dependent. It would therefore be reasonable to provide clear guidelines on the technique applied, as well as clear indications for performing the test. It is important to develop methods for creating artifact-free, closed-loop, compression-decompression cycles.

The main advantages include cost-effectiveness, short duration of the study, non-invasive nature of the procedure, as well as a potentially broader clinical availability. There are no clear guidelines with regard to indications as well as examination techniques.

Ultrasound elastography is a new and still poorly researched method. We conclude, however, that it can be widely used in the examinations of musculoskeletal system. Therefore, it is necessary to conduct large, multi-center studies to determine the methodology, indications and technique of examination.