Acoustic guide pad: a simple innovation that dramatically reduces the risk of misdiagnosis in respiratory muscle ultrasound examinations.

Recently, Journal of Ultrasound in Medicine published an article entitled “Two-dimensional shear wave elastography: utility in differentiating gallbladder cancer from chronic cholecystitis (2023;42:1577–1585) by Soundararajan et al.”1 I read this article with great interest and commend the authors on this prospective study that compared shear wave (SW) values between gallbladder cancer (n = 46) and chronic cholecystitis (n = 51) as a screening modality before final decision making in patients with gallbladder (GB) wall thickening. The authors concluded that the mean SW value was significantly higher in gallbladder cancer patients (34 ± 17.77 kPa) than that of chronic cholecystitis patients (12.27 ± 4.13 kPa). We would like to bring forward few concerns regarding the study. First, the data regarding intra- and interobserver variability have not been provided. This becomes very important as SW values in gallbladder wall show a large instability in measurement. Recently, SW elastography has gained preferential use because of its low cost and easy manipulation of the instrument.2 Among all ultrasound (US)-based elastographies, two-dimensional (2D) SW elastography is currently the most frequently used for hepatic fibrosis quantification; this is due to its ability to sample a large area in the liver, changing the sampling area quickly under B-mode observation and displaying a color mapping of SW values over the B-mode image. The current 2DSW elastography method uses emission of multiple acoustic push-pulses to generate SWs from multiple lines in the tissue. As the SWs propagate, they cause tissue displacement, and this very minimal displacement is tracked by conventional pulse-echo US beams.3 The two-dimensional shear wave elastography (2DSWE) has been reported as useful for predicting tissue characterization. However, like conventional US beams, SWs refract and reflect at the interface between different tissues. As a result, when examining the gallbladder by 2DSWE, propagating SWs are expected to refract at the liver/gallbladder interface (Figure 1). There is another problem. Measurement of SW values is made on the assumption that the tracking US pulses propagate at regular intervals and straight from the transducer through the issue. However, these US pulses refract at the liver/gallbladder interface as well4 (Figure 2). Thus, the SWE results (especially cut-off value of 20 kPa) of the gallbladder wall must be interpreted with caution. Second, there were no cases of surgically resected gallbladder cancer in this study group. However, they authors emphasized the fact that the mean SW value of the uninvolved gallbladder regions in patients with gallbladder cancer was significantly higher than that of chronic cholecystitis, and concluded that the rest of the gallbladder wall, though it appears uninvolved on B-mode, could have microscopic infiltration or metaplastic tissue. We cannot agree with this opinion, because we must consider many other possibilities, including severe fibrosis, or degeneration, and others (all these factors are expected to increase SW values). Third, all their chronic cholecystitis cases were probably complicated by acute change (for this, symptomatic), thus did not reflect a wide spectrum of chronic cholecystitis (eg, xanthogranulomatous cholecystitis). We hope you find our feedback to be useful and we are interested to hear about the authors' opinion regarding our questions. However, the authors should be congratulated, since many of these suggestions give us important hints about how we perform 2DSWE for patients with gallbladder disease.

The aim of this study was to investigate the diagnostic performance of two-dimensional (2D) shear wave elastography (SWE) in the assessment of salivary gland involvement in primary Sjögren's syndrome (pSS). Fifty-three patients with pSS and 30 healthy volunteers were included. The echogenicity of all submandibular and parotid glands was evaluated with B-mode ultrasound, and their elasticity was assessed with 2D SWE. The mean and standard deviation of the shear wave speed and elasticity modes on 2D SWE were calculated. The mean shear wave speed and elasticity mode values for the submandibular and parotid glands were significantly higher in the patients with pSS (P < .05). The mean elasticity of the shear wave speed mode was best able to differentiate the parotid glands of patients with pSS from those of healthy volunteers at a cutoff value of 2.48 m/s, whereas the mean elasticity of the elasticity mode was best able to differentiate the submandibular glands of patients with pSS from those of healthy volunteers at a cutoff value of 21 kPa. Two-dimensional SWE is an effective technique for assessment of the parenchyma of the salivary glands in patients with pSS and predicts interstitial fibrosis and the severity of histologic damage.

Chronic obstructive pulmonary disease (COPD) is associated with an increased risk of sarcopenia, which contributes to disease progression and poor clinical outcomes. Ultrasound offers a noninvasive and effective way to assess muscle structure and function. This study aimed to evaluate the diagnostic utility of two-dimensional ultrasound (2D-US) and shear wave elastography (SWE) for detecting sarcopenia in COPD patients. In this prospective, single-center study, 76 COPD patients were enrolled and classified into sarcopenia and non-sarcopenia groups based on diagnostic criteria. All participants underwent 2D-US to assess the thickness of the diaphragm (DTei), intercostal muscles (ICMTei), rectus abdominis (RAT), rectus femoris (RFT), and biceps brachii (BBT); as well as the cross-sectional area of the rectus femoris (RF-CSA), and biceps brachii (BB-CSA). Additionally, respiratory muscle function parameters, including diaphragm thickening fraction (DTF), diaphragm excursion (DE), and intercostal muscle thickening fraction (ICMTF), were also measured. Where feasible, SWE was performed on 42 patients to measure the shear wave velocity (SWV) of each muscle. Multivariable logistic regression identified independent predictors of sarcopenia, and diagnostic performance was evaluated using ROC curve analysis. Between April and July 2025, 76 COPD patients were enrolled in the study assess ultrasound screening sarcopenia in COPD patients, and 30 healthy subjects were recruited in the reproducibility study. In the repeatability assessment, the ICC values for all parameters ranged from 0.851 to 0.994. In the sarcopenia screening study, significant differences were observed between groups for multiple parameters, including DTei, DE, RFT, RF-CSA, BB-CSA, D-SWV, ICM-SWV, RA-SWV, and BB-SWV (all p < 0.05). Logistic regression identified ICMTF (OR = 6.738), BBT (OR = 6.231), DTF (OR = 3.505), DE (OR = 0.312), RF-CSA (OR = 0.127), and BB-CSA (OR = 0.009) as independent predictors of sarcopenia (AUC = 0.956). After including SWE parameters, RA-SWV (OR = 19.171), BB-SWV (OR = 4.837), RF-CSA (OR = 0.263), DTei (OR = 0.197), and ICM-SWV (OR = 0.165) were identified as additional predictors, improving diagnostic accuracy (AUC = 0.961). Combining morphological and elasticity-based ultrasound parameters provides a reliable, non-invasive method for diagnosing sarcopenia in COPD patients. This approach may help guide early interventions and personalized management strategies.

To study the utility of 2D shear wave elastography (SWE) and ascertain cut-off values of shear wave elasticity (SWe) to differentiate benign and malignant thickening of the gallbladder wall. This study was a prospective study of patients with symptomatic gallstone disease (GSD, n=51) and gallbladder cancer (GBC, n=46) and controls without any biliary disease (n=46). All the participants underwent 2D USG and SWE of the gallbladder. Grey-scale ultrasound and SWE were done in the different regions in the gallbladder. The median age of the patients with GSD was 49 years (interquartile range [IQR]: 33-55), GBC was 55 years (IQR: 46-65), and controls was 37 years (IQR: 27-48.25). In patients with GBC, asymmetrical mural thickening was the predominant imaging pattern (n=24, 52.2%). The mean SWe of the abnormal area in GBC (34.99 ± 17.77 kPa [n=46]) was significantly higher than that of the uninvolved region (18.27 ± 8.12 kPa [n=35]; P < .01). The mean SWe of the uninvolved region in GBC (18.27 ± 8.12 kPa [n=35]) was also significantly higher (P < .01) than that of GSD (12.27 ± 4.13 kPa [n=51]) and controls (10.52 ± 3.75 kPa [n=46]). On ROC analysis, AUC of 0.927, at a cut-off of 20 kPa, sensitivity was 91.3%, specificity was 83.5%, positive likelihood ratio was 5.54, and negative likelihood ratio was 0.10 to diagnose GBC. The 2D SWE is a reliable adjunctive tool to grey-scale USG in differentiating the malignant from benign gallbladder wall and may help to pick up early malignancy in GSD.

Two-dimensional Shear Wave Elastography with Propagation Maps for the Assessment of Liver Fibrosis and Clinically Significant Portal Hypertension in Patients with Chronic Liver Disease: A Prospective Study

Two-dimensional (2-D) shear wave elastography is a new sonographic elastography method for noninvasive measurement of liver stiffness. The aim of this study was to establish reference values of normal liver stiffness on 2-D shear wave elastography in children. Two-dimensional shear wave elastography values were measured in 202 children with no liver disease from the neonatal period to puberty, who were divided into 4 age groups: newborns and infants, preschoolers, elementary school children and adolescents. We investigated the effects of age, depth of elastography measurement, transducer, number of measurements per child, liver size and Doppler parameters of hepatic blood flow on liver elasticity values. The mean normal liver elasticity value in the study population was: 4.29±0.59 kilopascals (kPa). In neonates and infants, mean liver elasticity value was 4.63 (± 0.6) kPa, in preschoolers and elementary school children, 4.05 (± 0.57) kPa and 4.15 (± 0.52) kPa, respectively, and in adolescents, 4.39 (± 0.55) kPa. Values in neonates and infants as well as adolescents were significantly higher than in preschoolers and elementary school children (Kruskal-Wallis, P<0.001; Mann-Whitney U tests, P<0.05). There was no significant association between liver elasticity values and size of the right lobe or Doppler parameters of hepatic blood flow. Different depths and the number of elastography measurements had no effect on liver elasticity values. Two-dimensional shear wave elastography is achievable in a wide range of age in children. We established the reference values of normal liver stiffness on 2-D shear wave elastography in children.

There has been great interest in the development of non-invasive techniques for the diagnosis of liver fibrosis in chronic liver diseases, including ultrasound elastographic methods. Some of these methods have already been adequately studied for the non-invasive assessment of diffuse liver diseases. Others, however, such as two-dimensional Shear Wave Elastography (SWE), of more recent appearance, have yet to be validated and some aspects are for the moment incompletely elucidated. This review discusses some of the aspects related to two-dimensional SWE: the examination technique, the examination performance indicators, intra and interobserver agreement and clinical applications. Recommendations for a high-quality examination technique are formulated.

PurposeThis study aimed to evaluate the intra-observer agreement of ultrasound elastography according to region-of-interest (ROI) size in surgically confirmed epidermal cysts.MethodsThis retrospective study included 201 surgically confirmed epidermal cysts that underwent two consecutive strain elastography and shear wave elastography (SWE) examinations. Circular ROIs were drawn in the lesion and adjacent fat to obtain the strain ratio, shear wave (SW) velocity, and SW elasticity. Lesions were stratified by ROI diameter into <2 mm (group 1) and ≥2 mm (group 2). For each parameter, the absolute intra-observer differences, intraclass correlation coefficients (ICCs), Bland-Altman bias, 95% limits of agreement (LoAs), and correlations with the ROI-to-lesion-diameter ratio (ROI ratio) were calculated.ResultsThe ICCs for SW velocity were good in group 2 and moderate in group 1, whereas the ICCs for strain ratio and SW elasticity were moderate in both groups. The mean difference in strain ratio correlated positively with the ROI ratio, but not with absolute ROI diameter, whereas mean differences in SW velocity and SW elasticity correlated negatively with both ROI diameter and ROI ratio. Group 2 demonstrated significantly smaller mean differences in SW velocity and SW elasticity than group 1 (velocity, 1.20±2.12 vs. 1.17±1.32 m/s, P=0.005; elasticity, 79.5±97.9 vs. 49.2±65.5 kPa, P=0.030). Bland-Altman analysis confirmed narrower LoAs in group 2 for all three parameters.ConclusionAn ROI diameter ≥2 mm reduced measurement differences in SWE of epidermal cysts, whereas a large ROI ratio increased measurement variability in strain ratio, supporting technique-specific ROI optimization.

PurposeThis study evaluated epidermal cyst elasticity using multiple parameters of strain elastography (SE) and shear wave elastography (SWE) and assessed the reproducibility of each parameter.MethodsThis retrospective study included 73 patients with epidermal cysts who underwent SE and SWE. SE scores were classified as 1-4 according to elasticity. The strain ratio was evaluated using the elasticity ratio of lesions and adjacent subcutaneous fat tissue. For SWE, the shear wave velocity (m/s), elasticity (kPa) according to the Young modulus, velocity ratio, and elasticity ratio were evaluated. All values were measured twice. The reproducibility of SE and SWE measurements was assessed. The relationships among SE and SWE measurements were evaluated.ResultsThe strain ratio on SE images showed good reproducibility (intra-class correlation coefficient [ICC]=0.789), and SE scores showed substantial reproducibility (kappa=0.753 and kappa=0.758 for readers 1 and 2, respectively). Moderate reproducibility was found for shear wave velocity and elasticity (ICC=0.750 and ICC=0.648, respectively), as well as for the shear wave velocity of the reference tissue and velocity ratio (ICC=0.747 and ICC=0.713, respectively). All SE scores were positively correlated with the strain ratio (P<0.001). The strain ratio in the second SE session was significantly correlated with the elasticity ratio and velocity ratio in the first SWE session (r=0.245, P=0.037; r=0.243, P=0.038, respectively). Other variables were not correlated.ConclusionSE and SWE parameters of epidermal cysts showed moderate to good reproducibility. The strain ratio on SE showed good reproducibility and could provide relatively objective and consistent measurements of epidermal cyst elasticity.

Two-dimensional (2D) shear wave elastography (SWE) can measure the elasticity of skeletal muscle, tendons, and ligaments. Three-dimensional (3D) SWE has been used to detect breast cancer but has not been applied to the musculoskeletal system. This study aimed to investigate whether 3D SWE could be used in skeletal muscles in vivo. The study enrolled 20 healthy volunteers at Beijing Chaoyang Hospital from August to October 2016. Two-dimensional and 3D SWE scans were used to measure the Young modulus of the flexor carpi radialis in the relaxed state. Longitudinal and transverse scanning was performed. Data were analyzed by a 1-way analysis of variance/least significant difference post hoc test, a paired t test, and Bland-Altman plots. The participants included 10 male and 10 female volunteers with a mean age ± SD of 25 ± 5 years. The Young modulus did not differ between 3D and 2D SWE for the sagittal plane (longitudinal scanning, 34.9 ± 5.7 versus 32.7 ± 5.2 kPa; P = .096) or transverse plane (transverse scanning, 9.1 ± 2.1 versus 9.2 ± 1.6 kPa; P = .877). The Young modulus did not differ between sagittal, transverse, and coronal planes for 3D SWE longitudinal scanning (34.9 ± 5.7, 34.3 ± 5.8, and 34.8 ± 5.9 kPa, respectively; P = .936) or 3D SWE transverse scanning (9.1 ± 2.0, 9.1 ± 2.1, and 8.8 ± 2.1 kPa; P = .838). However, the Young modulus for each individual plane (sagittal, transverse, or coronal) differed significantly between longitudinal and transverse scanning (P < .001). Both 2D SWE and 3D SWE are suitable techniques for clinical use, depending on the examiner's experience/preference. However, 3D SWE provides a multiplanar/multislice view that better illustrates the spatial characteristics of muscle tissue. Three-dimensional SWE may be a new method for fully visualizing the musculoskeletal system.

Objective: To determine test–re-test reproducibility of the Timed Up & Go (TUG) test, 30-second repetition maximum (repmax) of functional exercises, 6-Minute Walk Test (6MWT) and High-level Mobility Assessment Tool (HiMAT) in children with Acquired Brain Injury (ABI). Secondarily, to assess the accuracy between hand-timed and video-timed scores for the TUG test and HiMAT.Methods: Thirty children at least 1 year post-ABI (mean age at assessment = 11 years 11 months, SD = 2 years 4 months; 14 males; Gross Motor Function Classification Scale I = 17, II = 13) were assessed twice. Intra-class correlation coefficients (ICC), standard error of measurement and minimum detectable change (MDC) were determined. The Bland-Altman method and 95% limits of agreement (LOA) were used to assess the agreement between hand and video-timed TUG test and HiMAT scores.Results: Test–re-test reproducibility was acceptable for the TUG test (ICC = 0.92; MDC = 1.2s); repmax of functional exercises (ICC = 0.84–0.98; MDC = 4–8 reps); 6MWT (ICC = 0.90; MDC = 69.38 m) and HiMAT (ICC = 0.98; MDC = 6). Comparison of hand and video scores for the TUG test and HiMAT demonstrated a mean difference of 0.23 (LOA = –0.3–0.7) and –0.07 (LOA = –1.99–1.85), respectively.Conclusions Test–re-test reproducibility of lower limb activity capacity measures in children with ABI are acceptable. The MDC scores provide a useful reference to interpret treatment effectiveness. Video timing was more accurate than hand-timing for the TUG test.

<h3>Introduction and objectives</h3> Chronic Obstructive Pulmonary Disease (COPD) is a small airway disease associated with ventilation heterogeneity. The Lung Clearance Index (LCI) is a potential early marker of lung damage and has been demonstrated to be repeatable within visit for patients with stable COPD. We sought to evaluate the feasibility and repeatability of the LCI between visits among subjects with stable COPD. <h3>Methods</h3> The LCI was measured by performing an inert Multiple Breath Washout using a modified photoacoustic Innocor device with 2% Sulphur Hexafluoride (SF₆) on subjects with stable COPD, GOLD Stage II-IV alongside phase 3 slope analyses. The LCI_SF6 was repeated (in triplicate) at weeks one and eight in accordance to ERS/ATS standards. Repeatability data was analysed using a combination of Intraclass Correlation Coefficients (ICC) and Bland-Altman plots. Phase 3 slopes were analysed using a custom MATLAB algorithm. <h3>Results</h3> 20 patients were initially recruited, 18 of which were suitable for analysis (16 male, mean [SD] age 70 [6.5], FEV1%predicted 51 [15.4], LCI 11.104 [2.372]). The between visit repeatability (ICC) was: FRC_LCI 0.919, LCI_SF6 0.881, S_cond 0.517, S_acin 0.801. The Bland Altman plot did not reveal any systematic bias. <h3>Conclusions</h3> The LCI_SF6 is feasible and repeatable between visits over an eight week period in patients with stable COPD. This demonstrates high ICC's in the FRC_LCI, LCI_SF6 and the S_acin. The repeatability of the S_cond was considered moderate.

Reliability of shear wave elastography for cervical and lumbar fascia stiffness and thickness in healthy and chronic neck and low back pain subjects.

1 Pulmonologist. Pulmonary Circulation Group/Pulmonary Function and Exercise Physiology Section, Department of Pulmonology, Universidade Federal de Sao Paulo/Escola Paulista de Medicina – UNIFESP/EPM, Federal University of Sao Paulo/Paulista School of Medicine – Sao Paulo, Brazil Why is it so important that pulmonologists are familiar with respiratory muscle assessment? Respiratory muscle weakness is associated with increased respiratory workload and reduced or interrupted (central or peripheral) neural stimulation. In healthy individuals (in whom central respiratory drive is normal), the respiratory muscle strength required in order to drive the respiratory system must be greater than the sum of the work imposed by the lungs, rib cage, and airways.(1) An imbalance between the respiratory workload and respiratory muscle strength results in progressive respiratory muscle weakness, which can progress to alveolar hypoventilation and respiratory failure depending on its severity. In most cases, the inspiratory muscles (the most important of which is the diaphragm) are affected first, because of their active role in breathing.(2) Several diseases, particularly neuromuscular diseases, can affect the respiratory muscles. However, systemic inflammation (autoimmune rheumatic diseases), heart failure, and pulmonary impairment, observed in obstructive diseases with lung hyperinflation, in restrictive diseases, and in cases of rib cage deformities, can also adversely affect the respiratory muscles.(3) Therefore, respiratory muscle assessment can be one of the steps in the investigation of dyspnea of unknown cause or in the investigation of the clinical and functional dissociation in patients with chronic respiratory failure. In the initial evaluation of respiratory muscle strength, easily applied and widely available methods should be prioritized, overall evaluation of respiratory muscles being given priority over a more specific respiratory muscle assessment. Therefore, MIP and MEP measurements play a central role in the diagnostic evaluation of respiratory muscle strength. Values of MIP and MEP within the normal range rule out respiratory muscle weakness. However, low MIP and MEP values do not unequivocally confirm the presence of respiratory muscle weakness, because they might be related to technical problems or underexertion; therefore, further investigation is required in order to confirm the diagnosis. Steier et al.(4) showed that the use of MIP and MEP alone in the evaluation of patients with neuromuscular disease or patients with dyspnea of unknown cause can lead to overdiagnosis of respiratory muscle weakness, whereas a combination of methods reduces false-positive results by 30%. In the current issue of the Brazilian Journal of Pulmonology, Caruso et al.(5) present the various methods of respiratory muscle assessment. The division of the methods into volitional and nonvolitional respiratory muscle tests and their progressive sequencing (ranging from simple, noninvasive tests to tests that are more complex) facilitate the understanding of the tests and aid in choosing the test that is most suitable for the suspected diagnosis. It is of note that the authors addressed the increased use of diaphragmatic ultrasound in determining inspiratory muscle weakness. The advantage of ultrasound is that it requires equipment that is widely available, although it requires an operator who is familiar with the technique. Ultrasound can be used in order to evaluate diaphragmatic structure and function and can be performed in an outpatient or hospital setting.(5) However, certain diseases require methods that are more complex for an accurate diagnosis, including electrical or magnetic phrenic nerve stimulation and (surface or needle) electromyography, the latter being able to evaluate the diaphragm and different inspiratory and expiratory muscles separately.(2) It should be noted that respiratory muscle assessment can be performed in the pediatric population. However, volitional respiratory muscle testing is not feasible in infancy and early childhood in particular. Therefore, invasive techniques such as sniff transdiaphragmatic pressure during crying spells and sniff nasal inspiratory pressure are required and can be performed in children over 4 years of age.(6) Despite being outside the scope of the study by Caruso et al.,(5) tests such as pulmonary function

To investigate the correlation of fetal lung maturity (FLM) and its stiffness obtained by two-dimensional shear wave elastography (2D-SWE) in rabbits. In 50 fetal rabbits (23-30 days gestation), lung and liver elasticity were measured by 2D-SWE. After cesarean section, dipalmitoylphosphatidylcholine (DPPC) concentration in alveolar lavage fluid and lung interstitial ratio were assessed. Partial correlation analysis was then performed to examine the correlation of fetal lung elasticity/lung-to-liver elasticity (LLE) ratio with DPPC content and with interstitial ratio, respectively. Fetal lung and liver 2D-SWE measurements showed good consistency. Fetal lung elasticity and LLE ratio were strongly negatively correlated with DPPC (r = -0.866 [95% CI -0.928, -0.757] and -0.840 [-0.914, -0.714], P < 0.001) and slightly reduced after controlling for interstitial ratio (r = -0.727 [-0.848, -0.534] and -0.672 [-0.815, -0.453], P < 0.001). Conversely, strong positive correlations with the interstitial ratio (r = 0.757 [0.580, 0.865] and 0.763 [0.590, 0.869], P < 0.001) decreased to moderate levels after adjusting for DPPC (r = 0.446 [0.151, 0.667] and 0.471 [0.183, 0.685], P < 0.01). 2D-SWE may serve as a useful non-invasive tool for predicting FLM in rabbits, providing a basis for further studies on human FLM. Key Message: Two-dimensional shear wave elastography (2-DSWE) correlates strongly with surfactant content in fetal lungs, offering a potential non-invasive biomarker of functional lung maturity to address the clinical need for predicting neonatal respiratory readiness. Novelty: We provide the first quantitative evidence that 2D-SWE values reflect biochemical (surfactant) more closely than structural maturation, redefining its role in perinatal assessment. Significance & Impact: 2D-SWE may serve as a novel, non-invasive ultrasound modality for assessing fetal lung maturity. These preclinical findings suggest that it might potentially aid in RDS risk assessment, potentially laying a certain foundation for future clinical research.