Clinical relevance of shear wave elastography compared with transient elastography and other markers of liver fibrosis.

BACKGROUND: Early and accurate non-invasive diagnosis of liver fibrosis is important for reducing the burden of cirrhosis and related complications. AIM: This cross-sectional study compares shear wave elastography (SWE), transient elastography (TE) and clinical markers of chronic liver disease in patients with various liver disorders. METHODS: Liver ultrasound with SWE was performed on 421 adult patients, 227 of whom also had TE. Patient age, gender, body mass index (BMI), liver disease aetiology and laboratory results were recorded. Associations between SWE, TE and other tests for liver fibrosis and chronic liver disease severity were sought. Advanced liver fibrosis was defined as liver stiffness measurement (LSM) equivalent to ≥F3 using Metavir staging. RESULTS: Patients were predominantly male (68%), with mean (standard deviation) age 54 (13) years, BMI 28 (6) kg/m2 and serum alanine aminotransferase (ALT) 39 (27) U/L. Liver disorders were predominantly non-alcoholic fatty liver disease (NAFLD), chronic hepatitis B (CHB), chronic hepatitis C (CHC) and alcohol-related liver disease. The median (interquartile range) LSM was 10 (6-20) kPa with SWE and 9.2 (6-21) kPa with TE. Advanced liver fibrosis was associated with older age, higher BMI, model for end-stage liver disease score, aspartate aminotransferase (AST), AST/ALT ratio, AST to platelet ratio index, fibrosis-4 index and Hepascore. SWE and TE LSM were positively correlated, particularly for NAFLD and CHC. SWE LSM predicted ultrasound and endoscopy-diagnosed portal hypertension and oesophageal varices. CONCLUSIONS: Across various liver diseases, SWE is at least comparable with TE and other non-invasive tests of liver fibrosis. SWE is accurate for predicting liver-related portal hypertension.

Shear Wave Elastography of the Maternal Cervix: A Comparison of Transvaginal and Transabdominal Ultrasound Approaches.

OBJECTIVES: This work aimed to compare the use of shear wave elastography on the maternal cervix with transvaginal (TV) and transabdominal (TA) ultrasound approaches to assess differences in shear wave speeds (SWSs) obtained for possible clinical use. METHODS: In both TV and TA ultrasound approaches, SWS measurements were attempted at the anterior and posterior portions of the internal and external cervical os on 38 gravid participants. RESULTS: A larger number of SWS measurements were obtained at the anterior portion of the cervix by both approaches. The numbers of reliable measurements of the SWS obtained at the anterior and posterior portions of the internal and external os were 99, 65, 103, and 77 in the TA approach and 93, 53, 110, and 87 in the TV approach, respectively. The mean difference in -the SWS obtained between the TV and TA ultrasound approaches was statistically significant at the anterior and posterior portions of the internal os, with differences of 0.67 and 0.52 m/s (P < .05). Differences were not significant at the external os both anteriorly and posteriorly, with differences of 0.15 and - 0.07 m/s (P > .05). CONCLUSIONS: Both TA and TV ultrasound approaches may be used to obtain SWSs in the maternal cervix. This study has shown that SWSs obtained by each approach need to be considered independently, as the TV approach produced significantly greater SWSs at the internal os compared to the TA approach, but the values were similar at the external os.

Shear Wave Elastography on the Uterine Cervix: Technical Development for the Transvaginal Approach.

OBJECTIVES: This research aimed to identify biological and technical confounders in the nonpregnant cervix when applying shear wave elastography with an endovaginal transducer. METHODS: Cervical speed measurements were obtained at the internal and external os in the anterior and posterior portions of the cervix using a transvaginal approach in 69 nongravid patients. RESULTS: Reliable measurements were obtained at the external os and internal os, anteriorly and posteriorly, in 63, 55, 55, and 26 patients, respectively. The mean speed obtained at the external os, anteriorly and posteriorly, was 2.52 ± 0.49 m/s and 2.87 ± 0.63 m/s, respectively, and at the internal os, anteriorly and posteriorly, 3.29 ± 0.79 m/s and 4.10 ± 1.11 m/s, respectively. The difference in speed between all regions was statistically significant (P < .05). CONCLUSION: Ultrasound-induced artifacts appear to affect the transmission of the elastographic main pulse, with cervical position contributing to suboptimal shear wave production in the posterior cervix. Reliable shear wave propagation can be achieved in the anterior cervix in most patients.

Reliability Indicators for 2-Dimensional Shear Wave Elastography.

Ultrasound (US) shear wave technology providers have either point shear wave elastography (SWE) or 2-dimensional SWE available on their US systems. With 2-dimensional SWE, larger regions of interest can be interrogated, with both the main acoustic radiation pulses and the resultant shear waves potentially being affected by US artifacts. Some providers assist the operator with elastographic maps indicating the reliability or precision of the shear wave propagation. This Technical Innovation explores the importance of the consideration of the precision maps and standard deviation output available on some devices and the implications for conversion of shear wave speed to pressure.

Hepatic steatosis: Qualitative and quantitative sonographic assessment in comparison to histology.

Introduction: Globally, B-mode ultrasound is the most common modality used for the diagnosis of hepatic steatosis. We aimed to assess the correlation between qualitative liver ultrasound parameters, attenuation imaging (ATI) and histopathology-diagnosed steatosis grade obtained from liver biopsy. Our secondary aim was to examine the interobserver variability of qualitative ultrasound features. Methods: A retrospective cohort study was performed which included adult patients (age ≥ 18 years) who had same-day liver ultrasound, ATI and liver biopsy for grading hepatic steatosis severity between 2018 and 2022. The qualitative US features for hepatic steatosis were independently scored by three radiologists and interobserver variability was examined. Histologic steatosis grade, ATI and qualitative ultrasound parameters were compared. Results: Ninety patients were included; 67% female with a median age of 54 (IQR 39-65) years. The radiologist's overall impression had the highest correlation (very strongly correlated) with histologic steatosis grade (r = 0.82, P < 0.001). ATI coefficient and all qualitative ultrasound B-mode features except for liver echotexture and focal fat sparing were strongly correlated with histologic steatosis grade (r ≥ 0.70, P < 0.001). Most qualitative ultrasound features had good agreement between observers (Kappa statistic 0.61-1.0, P < 0.001), (Kendall coefficient 0.92, P < 0.001). Conclusion: The examined qualitative ultrasound parameters and ATI had good-excellent performance for diagnosing clinically significant hepatic steatosis; however, the radiologist's overall impression had the best correlation with histologic steatosis grade. Our findings suggest an ongoing role for qualitative liver ultrasound assessment of hepatic steatosis despite the emergence of newer quantitative measures.

Hepatic steatosis: Ultrasound assessment using attenuation imaging (ATI) with liver biopsy correlation.

INTRODUCTION: Hepatic steatosis duration and severity are risk factors for liver fibrosis and cardiometabolic disease. We assessed the diagnostic accuracy of attenuation imaging (ATI), compared with histologic hepatosteatosis grading in adults with varied suspected liver pathologies. METHODS: Liver biopsy was performed on 76 patients (51 women, 25 men) with non-malignant diffuse parenchymal liver disease, within 4 weeks of multiparametric liver ultrasound including attenuation imaging (ATI). Skin-liver capsule distance (SCD) and body mass index (BMI) were measured. Histologic steatosis was graded none (S0), mild (S1), moderate (S2) or severe (S3). We compared histology and sonographic parameters. RESULTS: The median patient age was 50.5 (range 18-83) years and BMI 28.9 kg/m2 (interquartile range 24.0-33.3). The distribution of histologic steatosis grade was S0 (44%), S1(17%), S2(30%) and S3(9%). Median ATI value for each biopsy steatosis grade was 0.60 (IQR: 0.52-0.65), 0.65 (IQR: 0.6-0.71), 0.83 (IQR: 0.74-0.90) and 0.90 (IQR: 0.82-1.01) dB/cm/MHz for S0, S1, S2 and S3, respectively. The AUC of ATI for detection of any steatosis (S1-S3) and moderate to severe steatosis (S2-S3) was 0.85 (95% CI: 0.75-0.91) and 0.91 (95% CI: 0.83-0.99) with cut-offs of 0.55 and 0.62 dB/cm/MHz. ATI threshold of 0.74 dB/cm/MHz was able to discriminate between S0-S1 and S2-3 with accuracy, CI and kappa statistic of 0.8889, 0.65-0.98 and 0.7534. CONCLUSION: We found a good correlation between ATI and steatosis grade. The most accurate discrimination was between none to mild (S0-1) and moderate to severe (S2-3) steatosis.

Crohn's disease activity: quantitative contrast-enhanced ultrasound assessment.

OBJECTIVES: To determine whether quantitative parameters from contrast-enhanced ultrasound examination (CE-US) of the bowel wall correlate with endoscopic inflammatory activity in Crohn's disease and to assess its utility in the follow-up of patients on treatment. METHODS: This was a prospective study of 30 patients with Crohn's disease requiring colonoscopy or flexible sigmoidoscopy. The Crohn's disease activity index (CDAI), serum C-reactive protein (CRP) and Crohn's disease endoscopic index of severity (CDEIS) were calculated. CE-US was performed within 7 days of endoscopy using intravenous perflutren lipid microsphere and repeated a median of 45.5 days following treatment. Time-intensity curves of bowel wall enhancement were generated to derive the area under the curve (AUC), time to peak intensity (TTP) and peak intensity (PI). RESULTS: In separate multivariate regression models, the AUC, TTP and PI showed no significant association with endoscopic activity whilst controlling for CDAI and CRP. However, the reductions in CDAI and CRP following treatment were mirrored by significant reductions in TTP (P = 0.05). CONCLUSIONS: CE-US does not appear to predict for Crohn's disease endoscopic activity independent of simple parameters such as CDAI and CRP. However, it may be useful in the serial assessment of patients on treatment.

Correlation between hepatorenal index and attenuation imaging for assessing hepatic steatosis.

Introduction: Hepatic steatosis screening is required to assess high-risk populations, identify those for intervention, monitor response and prevent disease progression and complications. Liver biopsy and magnetic resonance imaging proton density fat fraction are current gold standards, but are limited by biopsy risk factors, patient tolerance and cost. Non-invasive, cost-effective, semi-quantitative and quantitative ultrasound assessment exists. The aim of this study was to assess the correlation between the semi-quantitative hepatorenal index (HRI) to assess hepatic steatosis using the quantitative attenuation imaging (ATI) as a reference standard, in adults with varied suspected liver pathologies. Methods: Data were collected prospectively between April 2019 and March 2020 at a tertiary institution on any patient >18 years referred to US assessment of suspected liver pathology. The only exclusion criteria were absent or invalid HRI or ATI measurements. Three hundred fifty eight patients were included. Results: There was a significant weak positive correlation between HRI and ATI (r = 0.351, P < 0.001) and between HRI steatosis grade (SG) and ATI SG (r = 0.329, P < 0.001), using previously established cut-off values. With ATI as the reference standard, there was no significant correlation between HRI and hepatic steatosis within steatosis grades, nor for no (SG = 0) or any (SG > 0) hepatic steatosis. Conclusions: Our study in a typical heterogeneous clinical population suggests the semi-quantitative HRI is of limited use in hepatic steatosis imaging. As HRI is the objective measure of the subjective brightness (B)-mode assessment, this imaging feature may not be as reliable as previously thought. Quantitative ATI may be the preferred non-invasive technique for hepatic steatosis assessment.

Use of shear wave elastography on the maternal cervix to recognise cervical insufficiency using a transabdominal ultrasound approach.

INTRODUCTION: The ramifications of preterm birth on society and the role of cervical length in identifying cervical insufficiency are well known. The main goal of this work was to apply shear wave elastography to the maternal cervix to assess the stiffness of the cervix and identify cervical insufficiency, using a transabdominal ultrasound approach. METHODS: Measurements of shear wave speed were obtained using a transabdominal ultrasound approach, at the anterior and posterior portions of the internal and external cervical os on 504 participants. A total of 455 participants were contacted following the expected date of birth of the fetus and birth details were obtained. RESULTS: The anterior and posterior portions of the internal os showed a significant correlation between shear wave speed and time until delivery of the fetus for women who gave birth spontaneously, with R 2 Linear being 0.024 (P = 0.012) and 0.017 (P = 0.05) respectively, and these correlations increased for the group of participants that were scanned between the 18th and end of the 20th week of pregnancy to R 2 Linear = 0.043 (P = 0.001) and 0.021 (P = 0.040) respectively. A ratio of internal os/external os anteriorly also showed a correlation of R 2 Linear = 0.030 (P = 0.009). CONCLUSION: A transabdominal ultrasound technique has identified a reduction in shear wave speeds at the internal os in the mid-trimester, in women who had a subsequent preterm birth.

A Novel, Reliable Protocol to Objectively Assess Scar Stiffness Using Shear Wave Elastography.

The aim of this research was to investigate the use of shear wave elastography as a novel tool to quantify and visualize scar stiffness after a burn. Increased scar stiffness is indicative of pathologic scarring which is associated with persistent pain, chronic itch and restricted range of movement. Fifty-five participants with a total of 96 scars and 69 contralateral normal skin sites were evaluated. A unique protocol was developed to enable imaging of the raised and uneven burn scars. Intra-rater and inter-rater reliability was excellent (intra-class correlation coefficient >0.97), and test-retest reliability was good (intra-class correlation coefficient >0.85). Shear wave elastography was able to differentiate between normal skin, pathologic scars and non-pathologic scars, with preliminary cutoff values identified. Significant correlations were found between shear wave velocity and subjective clinical scar assessment (r = 0.66). Shear wave elastography was able to provide unique information associated with pathologic scarring and shows promise as a clinical assessment and research tool.

Objective quantification of burn scar stiffness using shear-wave elastography: Initial evidence of validity.

Shear-wave elastography (SWE) is an ultrasound based technology that can provide reliable measurements (velocity) of scar stiffness. The aim of this research was to evaluate the concurrent validity of using both the measured velocity and the calculated difference in velocity between scars and matched controls, in addition to evaluating potential patient factors that may influence the interpretation of the measurements. METHODS: A cross-sectional study of 32 participants, with 48 burn scars and 48 matched contralateral control sites were evaluated with SWE, the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS) tactile sub-scores. RESULTS: Spearman's rho demonstrated high correlations (r > 0.7) between the measured scar velocity and both the POSAS and VSS pliability sub-scores, whereas moderate correlations (r > 0.6) were found with the calculated difference in velocity. Regression analysis indicated that the association of increased velocity in scars, varied by length of time after burn injury and gender. Body location and Fitzpatrick skin type also demonstrated significant associations with velocity, whereas age did not. CONCLUSION: SWE shows potential as a novel tool to quantify burn scar stiffness, however patient factors need to be considered when interpreting results. Further research is recommended on a larger variety of scars to support the findings.

Shear wave elastography of the maternal cervix: A transabdominal technique.

INTRODUCTION: Reduced cervical length as seen on transvaginal ultrasound is a strong indicator of spontaneous preterm birth in the high-risk population. In low-risk women the appropriate method to assess this risk is still debatable. Ultrasound elastography has been used to assess cervical strength. This research aimed to assess the accuracy of shear wave speeds (SWS) obtained deep to echo free fluid-filled structures, and the use of two-dimensional shear wave on the maternal cervix using a transabdominal ultrasound approach. METHOD: Agreement of SWS measurements obtained through fluid and directly onto an ultrasound phantom was assessed for accuracy. Speed measurements were obtained in the anterior and posterior portions of the internal and external cervical os on 50 gravid participants in the mid-trimester of pregnancy. RESULTS: No difference in SWS was obtained in the phantom with either direct contact or through the saline water-bath (P > 0.05). In 50 participants, measurements were obtainable at the external os anterior and posterior in 49 and 38 participants, respectively, and in 47 and 42 participants for internal os anterior and posterior. The mean speed obtained at the external os anterior and posterior was 2.01 ± 0.51 and 2.38 ± 0.47 m/s, respectively, and at the internal os anterior and posterior, 2.49 ± 0.50 and 2.58 ± 0.41 m/s. CONCLUSION: Shear wave speed measurements can be obtained in the maternal cervix using a transabdominal approach with a moderately full maternal bladder in most patients, with a larger number of shear wave measurements obtained in the anterior cervix compared to posterior.

Sonographic twinkle artefact in renal calculus detection: Impact of scanning factors in a phantom model.

INTRODUCTION: A common clinical use of the twinkle artefact is to detect and confirm renal calcification on ultrasound. There is however variable demonstration of this artefact using newer generation ultrasound machines. The purpose of this study was to assess the impact of altering multiple scanning factors on ultrasound machines from four major manufacturers on the demonstration of the twinkle artefact. Two custom-made phantoms and five-point Likert-like Scale were utilised. METHODS: These phantoms contained a range of urinary calculi varying in size, composition, surface contour and depth. The calculi were serially imaged with each ultrasound machine, using manufacturers presets and varying just one imaging factor or parameter at a time. The documented twinkle artefact in the images were subsequently analysed, together with the imaging preset and factor changes that had been made. RESULTS: Those factors that had the greatest effect in order of impact were colour write priority, colour gain, transducer type, depth of calculus, acoustic power and size of calculus. Variability was also demonstrated between manufacturers. CONCLUSION: By isolating the effect of scanning factor changes, their importance and contribution to appearances in the ultrasound image can be assessed. Image interpretation in the clinical setting requires an understanding of the underlying physics, particularly in the evaluation of artefacts associated with renal calculi.

The validity and reliability of using ultrasound elastography to measure cutaneous stiffness, a systematic review.

BACKGROUND: Ultrasound elastography is an imaging technology which can objectively and non-invasively assess tissue stiffness. It is emerging as a useful marker for disease diagnosis, progression and treatment efficacy. OBJECTIVE: To examine current, published research evaluating the use of ultrasound elastography for the measurement of cutaneous or subcutaneous stiffness and to determine the level of validity and reliability, recommended methodologies and limitations. METHODS: MEDLINE, Web of science and Scopus were systematically searched in August 2016 to identify original articles evaluating the use of ultrasound elastography to assess cutaneous stiffness. Relevant studies were then quality evaluated using the Quality Assessment of Diagnostic Accuracy Studies v 2 (QUADAS-2) tool and the Quality Appraisal of Reliability Studies (QAREL). RESULTS: From a total of 688 articles, 14 met the inclusion criteria for full review. Within the 14 studies, elastography was used to evaluate tumors, systemic sclerosis, lymphedema, abscess, and post-radiation neck fibrosis. Only three robust studies demonstrated good interrater reliability, whereas all validity studies had low sample sizes and demonstrated risks of bias. CONCLUSION: Robust evidence supporting the use of ultrasound elastography as a diagnostic tool in cutaneous conditions is low, however, initial indicators support further research to establish the utility of ultrasound elastography in dermatology.

A comparison of ultrasonic measurement techniques for the maternal cervix in the second trimester.

Introduction: The appropriate ultrasound technique to assess the maternal cervical length in women at low risk of preterm birth is yet to be established. This study aimed to determine the accuracy of different ultrasound approaches for measuring the maternal cervix in patients between 17 and 22 weeks gestation. Methods: The prospective study recruited 50 patients who were at a low risk of preterm birth. All measurements were acquired by one operator who was blind to the measurements being acquired in all approaches. The cervical length was registered using the transabdominal approach with a full and empty bladder, the transperineal approach and the transvaginal. The transvaginal approach was used as the reference measurement. Results: The transabdominal full bladder, post void, transperineal and transvaginal measurements were obtainable in 50, 49, 45 and 50 participants respectively. The transabdominal post void measurements showed a bias of -0.06 mm from perfect agreement with transvaginal. The transperineal measurements showed a bias of -0.16 mm. The transabdominal full bladder measurements were positively biased by 14.05 mm (p < 0.05). All transabdominal post void cervical lengths of 30 mm or greater registered a transvaginal cervical length greater than 25 mm in this study. Conclusion: The cervix should not be assessed in the transabdominal approach with a full maternal bladder due to overestimation of cervical length. Transvaginal cervical length can be reproduced accurately by post void transabdominal cervical length in most cases. Transperineal cervical length should be considered if transvaginal cervical length is contraindicated.

Cervical length for predicting preterm birth and a comparison of ultrasonic measurement techniques.

Introduction: Preterm birth is the leading cause of neonatal morbidity and mortality not attributable to congenital anomalies or aneuploidy. It has been shown that a shortened cervix is a powerful indicator of preterm births in women with singleton and twin gestations - the shorter the cervical length, the higher the risk of spontaneous preterm birth. Ultrasound measurements of the cervix are a more accurate way of determining cervical length (CL) than using a digital method. Background: There are three approaches that may be used to perform ultrasound measurements of the cervix; these are the transabdominal (TA), transperineal (TP) and the transvaginal (TV) approach. The TV approach is considered to be the gold standard. In women who are considered to be at a high risk of preterm birth it is now recommended that the cervix is measured at the mid-trimester ultrasound using the TV ultrasound approach. For women considered to be at a historical low risk the TV scan is not recommended, however it has been found that many women who deliver a preterm baby have no known risk factors. Conclusion: There is contradictory evidence in the literature with regard to the correlation between TA, TP and TV measurements. This article provides an overview of these three approaches with a focus on the clinical value for the assessment of the maternal cervix.