pSWE Measurements Research Articles

Feasibility of Point Shear Wave Elastography for Evaluating Renal Cortical Thickness: A Prospective Study.

Chronic Kidney Disease [CKD] affects individuals of different age groups worldwide. Moreover, CKD is associated with several risk factors, including obesity, lifestyle, and hypertension, which are common in the Middle East. Ultrasonography is the examination of choice for CKD. In recent years, Shear Wave Elastography [SWE] has developed through the continued development of ultrasound and received substantial attention ;therefore, it can be used to measure tissue stiffness. The study aimed to use point Shear Wave Elastography [p-SWE] to determine the correlation between diabetes and cortical renal thickness in detecting pathologies. This study was performed at the King Abdul-Aziz University Hospital. We examined 61 patients who underwent SWE. The patients were classified into two groups based on the presence or absence of type 2 Diabetes Mellitus [DM]. The results showed that there was a significant correlation between cortical stiffness and DM duration [p<0.005]. In addition, there was a negative correlation between cortical stiffness and cortical thickness [p=0.147] in patients with DM. Moreover, the eGFR decreased with an increase in cortical stiffness [p=0.499]. The cortical thickness in patients with and without DM was 0.750 ± 0.2 kPa and 0.788 ± 0.4 kPa, respectively. The kidney stiffness in patients with DM and control patients was 8.5 ± 8.6 cm and 14.0 ± 25.16 cm, respectively. This study showed that kidney p-SWE measurements were reliable. Therefore, further studies assessing kidney stiffness in patients with and without people with diabetes are recommended.

Image-guided point-shear-wave elastography: a valid and reliable technique for liver fibrotic staging.

Despite progressive implementation of image-guided point-shear wave elastography (pSWE) in guidelines as an alternative to transient elastography for the staging of fibrotic liver disease, pSWE is not widely adopted in clinical workflow. More information on reliability and validity of pSWE systems is needed. Therefore, we performed a phantom study to evaluate the validity and reliability of pSWE with ultrasound systems. Validity and reliability of pSWE measurements from three ultrasound systems were evaluated. Measurements were performed on an elasticity phantom with reference elasticities of 7 ± 1 (low) (median ± interquartile range (IQR)), 14 ± 2 (medium) and 26 ± 3 (high) kPa. Measurements were repeated in tenfold for each reference at 2, 3 and 4 cm depth. Results were considered valid when median elasticity ± IQR was between the uncertainty limits (IQR) for each reference elasticity value andreliable when IQR/median < 0.30. pSWE with the systems provided valid results for all reference elasticities and focal depths, except for overestimation of high reference elasticity at 2 and 4 cm depth for one system (41.5 ± 4.3 and 39.0 ± 1.2 kPa, respectively). Measurements were reliable with a maximum IQR/median of 0.13, well below the guideline of IQR/median < 0.30. The results support the use of pSWE as an alternative to invasive or non-image guided noninvasive techniques for liver fibrotic staging. pSWE with ultrasound systems from different vendors is valid and reliable and can therefore be implemented to optimize clinical workflow by performing imaging and elastography simultaneously.

Investigating the Correlation between Liver Ultrasound pSWE and Portal Vein Hemodynamics: Preliminary Findings

Introduction:: Portal vein size and hemodynamics can be altered in patients with portal hypertension. Elastography for liver stiffness has been proposed as a potential predictor of portal hypertension. However, the relationship between liver stiffness measured using point shear wave elastography (pSWE) and portal vein diameter and Doppler parameters remains unclear. Therefore, this observational study aimed to investigate the correlation between liver ultrasound pSWE and portal vein hemodynamics in healthy participants. Methods:: Twenty-five healthy men with no underlying medical conditions and who were not on regular medications were enrolled in the study. Liver stiffness, portal vein diameter, and Doppler parameters were measured using ultrasound EPIQ Elite with a curved-array transducer (C5-1 MHz) equipped with pSWE and Doppler imaging. Real-time pSWE measurements were taken from the liver. Portal vein diameter and Doppler parameters were measured in a longitudinal view of the extra-hepatic segment. Spearman correlation was used to assess the association between liver pSWE and portal vein diameter as well as Doppler parameters, with a significance level set at &lt; 0.05. Results:: There was no significant correlation between liver stiffness and portal vein diameter (p = 0.67) or Doppler parameters, including peak systolic velocity (p = 0.89), end-diastolic velocity (p = 0.65), and resistive index (p = 0.86). Conclusion:: Our findings suggest no direct correlation between liver stiffness measured using pSWE and portal vein hemodynamics in healthy adults. Further studies are warranted to investigate the relationship between liver pSWE and the hemodynamics of portal veins in patients with liver diseases.

Multisample Ultrasound Point Shear Wave Elastography of the Liver: Repeatability and Agreement With Conventional Point Shear Wave Elastography.

To characterize the technical performance of a multisample ultrasound point shear wave elastography (pSWE) technique that allows 15 individual measurements of liver stiffness in a single acquisition. In 56 overweight and obese adults, research ultrasound examinations were performed using conventional pSWE and multisample pSWE (Sequoia; Siemens Healthineers). Five independent measurements were acquired with the conventional technique over five consecutive breath holds (5C1 and DAX transducers). A single multisample acquisition (DAX transducer) of up to 15 unique measurements was acquired during a single breath hold. All imaging was performed before (baseline) and after a "coffee break" (repeat). Median liver stiffness measurements between techniques and between baseline and repeat imaging were compared using Pearson correlation (r) and intra-class correlation (ICC) coefficients. Mean participant age was 33.7 ± 11.4 years; 40 participants were female. There was high correlation between conventional pSWE measurements obtained using the 5C1 and DAX transducers at baseline (r = .75 [95% CI: 0.61-0.85], P < .0001) and repeat (r = .88 [95% CI: 0.78-0.92], P < .0001). There was moderate agreement between conventional pSWE measurements obtained using the 5C1 and DAX transducers at baseline (ICC = 0.69 [95% CI: 0.52-0.81]), and good agreement at repeat (ICC = 0.81 [95% CI: 0.65-0.90]). There was moderate correlation (r = .59 [95% CI: 0.39-0.74], P < .0001) and moderate agreement (ICC = 0.58 [95% CI: 0.38-0.73]) between baseline conventional and multisample pSWE measurements acquired using the DAX transducer; there was high correlation (r = .73 [95% CI: 0.57-0.83], P < .0001) and moderate agreement (ICC = 0.72 [95% CI: 0.56-0.82] between techniques at repeat. There was moderate correlation (r = .65 [95% CI: 0.46-0.78], P < .0001) and moderate agreement (ICC = 0.64 [95% CI: 0.45-0.77]) between baseline and repeat multisample pSWE measurements. Multisample pSWE, allowing up to 15 measurements in a single breath hold, showed moderate to high correlation and moderate agreement with conventional pSWE.

Point Shear Wave Elastography in Diagnosis and Follow-Up of Salivary Gland Affection after Head and Neck Cancer Treatment.

Therapies of head and neck squamous cell carcinoma (HNSCC), particularly irradiation and chemotherapy (C/RT), can affect salivary glands to some extent. Recent studies suggest that point shear wave elastography (pSWE) is well suited for the diagnosis and rating of homogenous damage to parenchymatous organs. The purpose of this study was to assess the value of this sonographic modality as a tool for the evaluation both of salivary gland affection after HNSCC therapy and the effect of a salivary replacement therapy based on liposomes. A total of 69 HNSCC patients were included in this study. All patients had finished cancer treatment and attended regular follow-up. pSWE values of ipsi- and contralateral parotid (PG) and submandibular glands (SMG) were obtained in a standardized manner and compared to those of a healthy control (HC) group. After a two months treatment with a liposomal saliva replacement therapy pSWE quantification was performed again. Ipsi- and contralateral salivary glands suffer under standard HNSCC tumor therapy. Here, the ipsilateral parotid gland (PG) is primarily affected. Therefore, a sequence of manifestation (surgery &lt; surgery plus adjuvant C/RT &lt; primary C/RT) is comprehensible, evaluated by pSWE measurements. The examination of all glands and statistical analysis of the values compared to controls resulted in an pSWE cutoff value for affected glandular tissue of &gt;2 m/s. Using a liposomal saliva replacement therapy, pSWE values of the ipsilateral PG can be improved, although the level of HC could not be restored.

Effect of Depth on Ultrasound Point Shear Wave Elastography in an Elasticity Phantom

Background: Phantom studies are widely used to assess variability in measurements. This study aimed to assess the reliability and accuracy of point Shear Wave elastography (pSWE) measurements of an elasticity phantom. Methods: Measurements were obtained by an experienced certified clinical sonographer at three different depth levels in kPa, using a curvilinear 5-1MHz transducer of the EPIQ7 ultrasound imaging system. Results: A total of 180 pSWE measurements were obtained at three different depth levels (three cm, five cm, and seven cm) of the phantom background. The mean CV of pSWE was low at all depths (3 cm: 8.8%; 5 cm: 7%; 7 cm: 7.2%). There was a significant difference between measurements at depths of 3 cm vs. 7 cm (MD: −0.85, 95% CI −1.5, −0.11, p = 0.024) and measurements at depths 5 cm vs. 7 cm (MD: −1.1, 95% CI −1.7, −0.47, p = 0.001). An overestimation of mean pSWE measurements at a depth of 7 cm was noted compared to the manufacturer’s value (2.7%, p = 0.006). Conclusions: Superficial phantom SWE measurements in this study had low variability compared to deep measurement. pSWE measurements at deep levels can be overestimated.

Evaluation of ultrasound point shear wave elastography reliability in an elasticity phantom.

PurposeTo date, limited studies have specifically addressed the reliability of ultrasound point shear-wave elastography (pSWE). Therefore, the aim of the present study was to assess the reproducibility of ultrasound pSWE within and between operators using two ultrasound scanners.MethodsiU22 and EPIQ7 ultrasound scanners were used to assess the reliability of pSWE measurements of four inclusions [L I (8 kPa), L II (14 kPa), L III (48 kPa), and L IV (80 kPa)] at a depth of 3.5 cm in an elasticity phantom using a curvilinear 5-1 MHz transducer. The intra-operator, inter-operator, and inter-scanner reproducibility of pSWE was assessed using intraclass correlation coefficients (ICCs). Bland-Altman plots were used to establish bias and limits of agreement (LoA) between measurements. The accuracy of pSWE from manufacturer values was determined using the one-sample t-test.ResultsIntra-operator agreement was excellent, with an ICC >0.90. The bias in measurements for operator A was -0.36±3.13 kPa (LoA, -6.47 to 5.75), and for operator B it was 1.97±6.29 kPa (LoA, -10.25 to 14.21). Inter-operator agreement was excellent, with an ICC of 0.95. The bias in measurements between operators was -0.42±5.00 kPa (LoA, -10.24 to 9.38). The inter-scanner agreement between EPIQ7 and iU22 was excellent, with an ICC of 0.96. The bias in measurements between scanners was 1.74±4.44 kPa (LoA, -6.95 to 10.45). There was significant overestimation for L I (17.75%) and L II (31.14%) and underestimation for L III (-15.28%) and L VI (-98.00%) relative to the manufacturer-reported values.ConclusionPhantom ultrasound pSWE was reproducible within and between operators, and between Philips ultrasound scanners; further studies using different ultrasound systems and transducers are required.

Determining the effects of excess weight on renal cortical stiffness in children and adolescents with point Shear Wave Elastography.

To determine the early effects of excess weight on renal cortical stiffness in children and adolescents using point shear wave elastography (pSWE). One hundred and forty-six overweight and obese children (43.2% male; mean age, 12.6±2.9 years: range 4.3-18) and 48 lean children (27.1% male: mean age, 12.4±3.4: range 4.8-18.9) were included in the study and control group, respectively. pSWE measurements of the two kidneys were performed. The mean value of shear wave velocity was compared between groups. The mean shear wave velocity was 2.79±0.53 m/s for the control subjects and 3.09±0.59 m/s for the overweight-obese subjects. The differences between the two groups were sta-tistically significant (p=0.001). There was no correlation between shear wave velocity and age or depth. A positive correlation was found between shear wave velocity and body mass index, body mass index-standard deviation score. Renal cortical stiffness was higher in children with excess weight than in lean children. This study is the first attempt at applying pSWE to investigate the early adverse effects of excess weight.

Analysis of Point Shear Wave Elastography and Biochemical Markers for the Detection of Liver Fibrosis.

Background and Objectives: This work focuses on the possibility of using the point shear wave elastography (pSWE) method for detecting biochemical markers in diffuse liver diseases. Additionally, this study addresses the issue of the influence of ultrasound factors on the pSWE quality indicators of the obtained measurements. Materials and Methods: A pSWE examination was performed on 139 patients (69 female and 70 male) diagnosed with diffuse liver disease. The average age for all patients was 50.7 ± 15.0 years (female: 52.7 ± 15.2 years; male: 48.8 ± 14.6 years). Of these 139 patients, 65 met the inclusion criteria regarding biochemical parameters. The pSWE quality indicators were related to abnormalities found in B-mode ultrasound. Results: A strong positive correlation was found between the results of the pSWE and all biochemical indexes analysed, with the exception of age/platelet count (PLT), for which an average correlation was obtained. The greatest correlation was observed between the elastography and King’s Score index. There was no correlation observed between elastography and any of the analysed parameters or biochemical indexes considered. The pSWE measurements were impaired by factors such as thick soft tissue, uneven hepatic surface, hepatomegaly and female gender. No statistically significant difference in pSWE quality indicators parameters was found between disease entities. Conclusions: pSWE seems to be a complementary method for detecting biochemical indexes, but its results can be influenced by numerous factors.

Magnetic resonance elastography vs. point shear wave ultrasound elastography for the assessment of renal allograft dysfunction

PurposeTo investigate the utility of magnetic resonance elastography (MRE) vs. ultrasound (US) point shear wave elastography (pSWE) for the assessment of chronic renal allograft dysfunction, prediction of outcome and determine the correlation with Banff pathology scores. MethodsIn this IRB approved prospective study, 27 enrolled patients with functional (n = 15) and chronic dysfunctional (n = 12) renal allografts underwent same day 2D MRE and pSWE. Histogram parameters [including mean, median, standard deviation, kurtosis and skewness] of the magnitude of the complex shear modulus (MRE) and median Young’s modulus (pSWE) were measured in the cortex (MRE and pSWE) and combined corticomedullary regions (MRE). Histopathology was available for 16 patients (4 functional, 12 dysfunctional). ResultsMRE and pSWE stiffness were not significantly different between functional and dysfunctional groups (p range 0.139-0.347). The skewness of MRE corticomedullary stiffness was significantly lower (p = 0.04) in patients with chronic dysfunction and correlated significantly with Banff histopathologic scores (range r=-0.518–0.567, p = 0.035–0.040). MRE cortical and corticomedullary mean stiffness showed strong performance in predicting graft loss/relist (AUC 0.958, p = 0.011 for both). Reliable pSWE measurements were obtained in 13 patients (48 %). pSWE stiffness did not correlate with Banff scores and did not predict outcome. ConclusionsThe skewness of MRE corticomedullary stiffness is sensitive to changes in chronic allograft dysfunction, while mean/median MRE renal stiffness and median US stiffness did not differentiate patients with stable function vs those with chronic renal allograft dysfunction. MRE corticomedullary mean stiffness appears to be a predictor of graft loss/relist. pSWE was not found to be a useful method for assessing renal allografts.

Stiffness and Anisotropy Effect on Shear Wave Elastography: A Phantom and in Vivo Renal Study

Tissue elasticity is related to the pathologic state of kidneys and can be measured using shear wave elastography (SWE). However, SWE quantification has not been rigorously validated. The aim of this study was to evaluate the accuracy of SWE-measured stiffness and the effect of tissue anisotropy on SWE measurements. Point SWE (pSWE), 2-D SWE and dynamic mechanical analysis (DMA) were used to measure stiffness and evaluate the effect of tissue anisotropy on the measurements. SWE and DMA were performed on phantoms of different gelatin concentrations. In the tissue anisotropy study, SWE and DMA were performed on the outer cortex of sheep kidneys. In the in vivo study, 15 patients with different levels of interstitial fibrosis were recruited for pSWE measurements. Another 10 healthy volunteers were recruited for tissue anisotropy studies. SWE imaging revealed a non-linear increase with gelatin concentration. There was a significant correlation between pSWE and 2-D SWE, leading to the establishment of a linear regression equation between the two SWE ultrasound measurements. In the anisotropy study, the median difference in stiffness between shear waves oriented at 0° and 90° towards the pyramid axis was significant. In the in vivo study, there was a strong positive linear correlation between pSWE and the percentage of interstitial fibrosis. There was a significant difference in the Young's modulus (YM) between severities of fibrosis. The mean YM values were lower in control patients than in patients with mild, moderate and severe fibrosis. YM values were also significantly higher when shear waves were oriented at 0° toward the pyramid axis. Tissue stiffness and anisotropy affects SWE measurements. These factors should be recognized before applying SWE for the interpretation of measured values.

Assessment of liver fibrosis using 2-dimensional shear wave elastography: a prospective study of intra- and inter-observer repeatability and comparison with point shear wave elastography

PurposeThe purpose of this study was to prospectively investigate the intra- and inter-observer repeatability of a new 2-dimensional (2D) shear wave elastography (SWE) technique (S-Shearwave Imaging) for assessing liver fibrosis in chronic liver disease patients, and to compare liver stiffness measurements (LSMs) made using 2D-SWE with those made using point SWE (pSWE).MethodsThis prospective study received institutional review board approval and informed consent was obtained from all patients. Fifty-three chronic liver disease patients were randomly allocated to group 1 (for intra-observer repeatability [n=33]) or group 2 (for inter-observer repeatability [n=20]). In group 1, two 2D-SWE sessions and one pSWE sessions were performed by one radiologist. In group 2, one 2D-SWE session and one pSWE session were performed by the aforementioned radiologist, and a second 2D-SWE session was performed by another radiologist. The intraclass correlation coefficient (ICC) was used to assess intra- and inter-observer reliability. LSMs obtained using 2D-SWE and pSWE were compared and correlated using the paired t test and Pearson correlation coefficient, respectively.ResultsLSMs made using 2D-SWE demonstrated excellent intra- and inter-observer repeatability (ICC, 0.997 [95% confidence interval, 0.994 to 0.999]) and 0.995 [0.988 to 0.998], respectively). LSMs made using 2D-SWE were significantly different from those made using pSWE (2.1±0.6 m/sec vs. 1.9±0.6 m/sec, P<0.001), although a significant correlation existed between the 2D-SWE and pSWE LSMs (rho=0.836, P<0.001).ConclusionS-Shearwave Imaging demonstrated excellent intra- and inter-observer repeatability, and a strong correlation with pSWE measurements of liver stiffness. However, because of the significant difference between LSMs obtained using 2D-SWE and pSWE, these methods should not be used interchangeably.

High Prevalence of Hepatic Fibrosis, Measured by Elastography, in a Population-Based Study of Mexican Americans

Hepatic fibrosis is a primary risk factor for cirrhosis and hepatocellular carcinoma, which affect a disproportionate number of Hispanics in the United States. We aimed to determine the prevalence of significant fibrosis, measured by point shear-wave elastography (pSWE), and determine characteristics of hepatic fibrosis and simple steatosis in a population-based study of Mexican American Hispanics in south Texas. Liver stiffness was measured by pSWE, performed by 2 separate operators, for 406 participants in the Cameron County Hispanic Cohort from 2015 through 2017. Significant fibrosis (F2-F4) was defined as median stiffness > 1.34 m/s. Steatosis was determined by ultrasound. All participants underwent a clinical examination that included a comprehensive laboratory analysis and standardized interview about their medical and social history. We calculated weighted prevalence of fibrosis and determined clinical and demographic associations with significant fibrosis (with or without steatosis) and simple steatosis with no/minimal fibrosis using multinomial logistic regression. Fifty-nine participants were excluded due to unreliable pSWE findings or inconclusive ultrasound results, for a final analysis of 347 participants. The prevalence of significant fibrosis was 13.8%; most of these participants (37/42, 88.1%) had no evidence of viral hepatitis or heavy drinking. Levels of liver enzymes were associated with fibrosis and simple steatosis. Indicators of metabolic health (insulin resistance, triglycerides, and cholesterol) were significantly associated with simple steatosis. Fibrosis, but not simple steatosis, was significantly associated with of antibodies against HCV in plasma (odds ratio, 18.9; P = .0138) and non-significantly associated with reduced platelet count (odds ratio, 0.8 per 50x103/μL; 95% CI, 0.5-1.1). Multivariable analyses, as well as sensitivity analyses removing F4 fibrosis and viral or alcoholic etiologies, confirmed our results. We estimated the prevalence of fibrosis in a large population of Mexican American Hispanics using pSWE measurements. We found Mexican American Hispanics to have a higher prevalence of fibrosis compared to European and Asian populations, primarily attributable to metabolic disease.

Point shear wave elastography (pSWE) using Acoustic Radiation Force Impulse (ARFI) imaging: a feasibility study and norm values for renal parenchymal stiffness in healthy children and adolescents.

To evaluate the applicability of point shear wave elastography (pSWE) for measuring renal parenchymal stiffnessin healthy children and adolescents and to establish norm values for shear wave speed (SWS) using two ARFI methodsand ultrasound probes. We prospectively investigated 264 children (43.9% males). pSWE(Virtual TouchTM Quantification and Virtual TouchTM Imaging Quantification (VTQ and VTIQ; Siemens, Germany)) wasperformed in the renal cortex of 528 healthy kidneys using a 1-6 MHz convex and a 4-9 MHz linear ultrasound probe inventrolateral and dorsal examinations. Feasibility and reproducibility of pSWE measurements were evaluated. SWS valueswere analysed with regard to age, body dimensions, kidney volume and measuring depth. pSWE measurementswere successful in >95% of subjects using the low and in <60% using the high-frequency probe. Mean SWS values (m/s)differed by method and probe: 2.10±0.43 (VTQ1-6MHz, convex, ventrolateral), 2.30±0.37 (VTQ1-6MHz, convex, dorsal), 1.58±0.44 (VTQ4-9MHz, linear, dorsal) and 1.96±0.27 (VTIQ4-9MHz, linear, dorsal). SWS was positively correlated withage, weight and body height, but independent of sex, BMI, or kidney volume and depth. pSWE (VTQ) is afeasible method to evaluate renal parenchymal stiffness in children of all ages. SWS values are age and weight dependentand differ significantly between high- and low-frequency probes. High-frequency probes and VTIQ should only be used inchildren <10 years.

Intra- and inter-observer variation and accuracy using different shear wave elastography methods to assess circumscribed objects - a phantom study.

The elastic properties of circumscribed tissues (e.g., tendons, lymph nodes, prostates, brain tumors) are of considerableclinical interest. The purpose of this study was thus to compare the Intra-/Inter-observer variation and accuracy in vitro ofpoint shear wave elastography (pSWE) with that of 2D-SWE and to assess 2D-SWE's precision with variable ROI (vROI) incircumscribed objects. Round targets (Elasticity QA Phantom Model 049) were examined for varyingdegrees of stiffness (8, 14, 45, and 80 kPa) and diameters (20/10 mm). Three ultrasound systems and four probes were applied(pSWE: Acuson/S3000 9L4/4C1 and Epiq7 C51, 2D-SWE: Aplio/500 PVT375BT). Three different ROIs were used, namelyfixed ROI (fROI) and variable ROI: rectangular-best-fitted ROI, and round-best-fitted ROI. Each measurement was performedtwice by four observers. A total of 3,604 measurements were conducted. The intra-observer variation of 2D-SWEmeasurements indicated better agreement (Intraclass Correlation Coefficient (ICC) = 0.971; 95% CI=[0.945; 0.985]), thanfor the pSWE measurements (ICC = 0.872; 95% CI=[0.794; 0.92]). With both methods, the shear wave elastography appliedshowed low inter-observer variation: ICC = 0.980; 95% CI=[0.970; 0.987]. However, a significant difference was observedbetween fROI (pSWE) and vROI (2D-SWE) on circumscribed objects in terms of accuracy. The lowest degree of observationerror was detected in situations where the ROI was not "best fitted", but placed within the target of 3mm from the border(target diameter: 20mm; mean relative error = 0.15). When estimating the elastic properties of circumscribedtissues, the different measurement techniques performed by commercial shear wave elastography systems reveal a strong susceptibilityfor observational errors, depending upon the fixed vs. variable ROI of the pSWE vs. 2D-SWE technique.

Reproducibility of 2‐Dimensional Shear Wave Elastography Assessment of the Liver: A Direct Comparison With Point Shear Wave Elastography in Healthy Volunteers

Two-dimensional shear wave elastography (2D-SWE) imaging for the noninvasive assessment of tissue stiffness was assessed for reproducibility in healthy volunteers in quantifying liver elasticity, compared with an established point shear wave elastography (p-SWE) technique also known as virtual touch quantification (VTQ) (SIEMENS). Eleven healthy volunteers were examined by four experienced operators on two occasions, separated by two weeks (sessions A and B). Ten 2D-SWE using LOGIQ E9 and p-SWE measurements using VTQ (in meters per second) were consecutively taken from deep portions of liver segments 5 or 6 away from vascular structures, using standard techniques. Inter- and intra-observer agreement was assessed by intraclass coefficient (ICC). A total of 880 2D-SWE and p-SWE velocities were recorded. Mean values from the four operators ranged between 1.188 and 1.196 m/s for 2D-SWE and 1.170 to 1.207 m/s for p-SWE. Interobserver reproducibility was good for both sessions with ICCs of 0.88 and 0.93 (2D-SWE) and 0.87 and 0.93 (p-SWE). The overall intra-operator reproducibility between sessions A and B was good for both p-SWE and 2D-SWE with ICC of 0.87 and 0.83, respectively. For inter- and intra-observer variability, the ICC was more than or equal to 0.71, indicating that the results were reliable. There was a strong and significant correlation between the 2D-SWE and p-SWE measurements (r = 0.87, P = .0006), but their velocities did not agree equally across different velocities. Two-dimensional SWE using LOGIQ E9 is a reliable and reproducible method for measuring elasticity in healthy volunteers and has a similar degree of reliability as p-SWE using VTQ, but absolute measurements from the two techniques should not be used interchangeably.

Effect of Fontan operation on liver stiffness in children with single ventricle physiology.

Assess liver stiffness using ultrasound point shear wave elastography (US P-SWE) in children before and after the Fontan operation. Eighteen children undergoing the Fontan operation were prospectively enrolled. Eight US P-SWE measurements were obtained from the right hepatic lobe before surgery, and at multiple postoperative time points. Temporally related inferior vena cava pressure (IVC) data was collected from medical records, when available. Changes in mean liver shear wave speed (SWS) were assessed using a mixed-effect model with post hoc Tukey correction. Changes in IVC pressure were evaluated using the Wilcoxon signed-rank test. A p value less than 0.05 was considered significant. Mean age at enrolment was 33.5 ± 10.5months. Baseline mean liver SWS was normal at 1.18 ± 0.29m/s, increased to 2.28 ± 0.31m/s at 2.5 ± 1.2days (p < 0.0001) and to 2.22 ± 0.38m/s at 7.5 ± 1.4days (p < 0.0001). Five subjects returned at a mean of 185 ± 28days, and mean liver SWS remained elevated at 2.08 ± 0.24m/s (p < 0.0001). Mean IVC pressure increased from 7.2 ± 2.6mmHg at baseline to 16.44 ± 3.3mmHg at 2.2 ± 0.8days post-surgery (p = 0.004). The Fontan operation immediately and chronically increases liver stiffness and IVC pressure. Our study provides further evidence that congestion is a key driver of Fontan-associated liver disease. • The Fontan operation triggers immediate hepatic congestion and marked liver stiffening. • Congestion, not fibrosis, drives early increased liver stiffness in Fontan patients. • Hepatic congestion persists chronically for months after the Fontan operation. • Congestion confounds shear wave elastography as a post-Fontan liver fibrosis biomarker.

Ultrasound and Point Shear Wave Elastography in Livers of Patients with Primary Sclerosing Cholangitis

Point shear wave elastography (pSWE) is an ultrasound-based method for non-invasive quantification of liver fibrosis. The objective of this study was to explore liver pSWE in patients with primary sclerosing cholangitis (PSC) for assessment of fibrosis. Fifty-five non-transplant patients with PSC (38 males, 17 females; mean age: 46.4 y) were included and compared with 24 matched controls. Median (range) PSC duration was 8.1 (0–33) y. Ultrasonographic scanning followed by liver stiffness measurement by pSWE was performed using a conventional ultrasound system (Philips iU22). Signs of liver fibrosis on B-mode were identified in 21 patients (38%). Splenomegaly was found in 19 patients (35%) and ascites in two patients (4%). Successful pSWE measurements were achieved in the right liver lobe of all individuals and in the left liver lobe of 36 patients (65.5%). PSC patients had significantly higher median shear wave velocity (SWV) than controls in the right liver (median [range] SWV 1.26 [0.73–2.57] m/s vs. 1.09 [0.88–1.25] m/s, p < 0.001). SWV measured in the left liver lobe and spleen did not differ between PSC patients and controls. Our findings indicate that PSC patients have increased median SWV, indicating more fibrosis compared with controls; however, a wide range of SWV values were obtained among PSC patients, possibly reflecting the various stages in disease development.