Point shear wave ultrasound elastography with Esaote compared to real-time 2D shear wave elastography with supersonic imagine for the quantification of liver stiffness

Evaluation of Hepatosteatosis-Induced Increase in Fibrosity by Two-Dimensional Shear Wave Elastography in Children with Obesity and Comparison with Healthy Peers

OBJECTIVE

The increase in the prevalence of obesity, nonalcoholic fatty liver disease (NAFLD), and related comorbidities in children creates a social and financial burden. In our study, we aimed to evaluate liver findings together with anthropometric and laboratory data with twodimensional shear wave elastography (2D-SWE), one of the SWE types, which is a noninvasive method for assessing tissue stiffness in children with obesity, and to obtain quantitative data that can be used in early diagnosis and follow-up.

MATERIALS AND METHODS

In our single-center, observational cross-sectional study, liver gray scale findings, 2D-SWE findings, anthropometric measurements, and laboratory values of 48 children with obesity and 50 healthy children aged between 5 and 18 years, both between groups and in prepubertal and pubertal subgroups, are compared.

RESULTS

A significant difference was found in the liver stiffness indicator kilopascal (kPA) values and between aspartate aminotransferase values in the prepubertal period and alanine aminotransferase values in the pubertal period (P < .001). No significant difference was found between insulin, HOMA-IR, waist circumference, waist/height ratio, and kPA.

CONCLUSION

Two-dimensional shear wave elastography can be easily applied in the pediatric population as a practical, noninvasive, reproducible, and highly compatible technique. In this regard, 2D-SWE may be useful in the early diagnosis and follow-up of hepatosteatosis and fibrosis in children with obesity and NAFLD-risky cases.

Comparison between Two-Dimensional and Point Shear Wave Elastography Techniques in Evaluating Liver Fibrosis Using Histological Staging as the Reference Standard: A Prospective Pilot Study

Evaluation of hepatic fibrosis is essential to prevent liver-related morbidity and mortality. Although various types of ultrasound shear wave elastography (SWE) have been used and validated, there are limited studies on the relatively newer technique, two-dimensional SWE (2D-SWE). Therefore, this study aimed to compare the diagnostic performances of 2D-SWE and point SWE (p-SWE) for evaluating liver fibrosis using histology as the reference standard. To measure liver stiffness (LS) values, 87 patients underwent 2D-SWE and p-SWE using the same machine. Technical failures and unreliable measurements were also evaluated. The diagnostic performances of 2D-SWE and p-SWE were compared using area under the receiver operating characteristic (AUROC) curve analysis. No technical failures were observed in either method; however, unreliable measurements were less frequent in 2D-SWE (1/87 [1.1%]) than in p-SWE (8/87 [9.2%]) (p < 0.001). The AUROC of the LS values of 2D-SWE were significantly higher than those of p-SWE for diagnosing significant fibrosis (0.965 vs. 0.872, p = 0.022) and cirrhosis (0.994 vs. 0.886, p = 0.042). In conclusion, 2D-SWE is more reliable and accurate than p-SWE for diagnosing hepatic fibrosis.

Correlation Between QElaXto Techniques and Supersonic Imagine for Liver Stiffness Quantification in Chronic Liver Disease

OBJECTIVES

Intersystem variability in liver stiffness (LS) quantification with ultrasound shear wave elastography (SWE) precludes direct comparison of results obtained with different equipment. The aim of this study was to investigate the agreement between point-SWE and 2-dimensional-SWE with Esaote-MyLab 9 (p-QElaXto and 2D-QElaXto, respectively) and 2D-SWE with SuperSonic Imagine (SSI) in order to assess specific LS thresholds for fibrosis staging with QElaXto techniques, using SSI as a reference standard.

METHODS

A total of 235 compensated chronic liver disease (CLD) patients without comorbidities potentially affecting LS were enrolled in the study. Among them, 101 patients underwent also liver biopsy. Agreement between the equipment was assessed with Pearson coefficient and Bland-Altman analysis, while cut-off values were calculated with receiver operating characteristics analysis.

RESULTS

Correlation between 2D-QElaXto and p-QElaXto with SSI resulted very good (r = 0.898 and r = 0.866), especially in precirrhotic stages, with a mean difference between LS values of -1.3 kPa for 2D-QElaXto and -0.6 kPa for p-QElaXto compared with SSI. Cut-off thresholds for diagnosing fibrosis ≥F2, ≥F3, and F4 in non-HBV-related CLD were, respectively, 5.5, 8.0, and 10.6 kPa for 2D-QElaXto and 6.1, 8.1, and 11.7 kPa for p-QElaXto. All three SWE techniques were effective in differentiating significant fibrosis ≥F2 from mild or absent fibrosis in the subgroup of patients submitted to biopsy and showed good feasibility.

CONCLUSIONS

Correlation between QElaXto techniques and SSI in LS measurements is very good. Our study identifies for the first time cut-off thresholds for fibrosis staging in non-HBV-related CLD using two QElaXto techniques.

Measuring and Modelling Nonlinear Elasticity of Ex Vivo Mouse Muscles

Elastography is a noninvasive imaging technique that provides information on soft tissue stiffness. Young's modulus is typically used to characterize soft tissues' response to the applied force, as soft tissues are often considered linear elastic, isotropic, and quasi-incompressible materials. This approximation is reasonable for small strains, but soft tissues undergo large deformations also for small values of force and exhibit nonlinear elastic behavior. Outside the linear regime, the elastic modulus is dependent on the strain level and is different for any kind of tissue. The aim of this study was to characterize, ex vivo, the mechanical response of two different mice muscles to an external force. A system for transverse force-controlled uniaxial compression enabled obtaining the stress-strain (σ-ε) curve of the samples. The strain-dependent Young's modulus (SYM) model was adopted to reproduce muscle compression behavior and to predict the elastic modulus for large deformations. After that, a recursive linear model was employed to identify the initial linear region of the σ-ε curve. Results showed that both muscle types exhibited a strain hardening effect and that the SYM model provided good fitting of the entire σ-ε curves. The application of the recursive linear model allowed capturing the initial linear region in which the approximation of these tissues as linear elastic materials is reasonable. The residual analysis displayed that even if the SYM model better summarizes the muscle behavior on the entire region, the linear model is more precise when considering only the initial part of the σ-ε curve.

A Cross-Machine Comparison of Shear-Wave Speed Measurements Using 2D Shear-Wave Elastography in the Normal Female Breast

Quantitative measures of radiation-induced breast stiffness are required to support clinical studies of novel breast radiotherapy regimens and exploration of personalised therapy, however, variation between shear-wave elastography (SWE) machines may limit the usefulness of shear-wave speed (cs) for this purpose. Mean cs measured in four healthy volunteers’ breasts and a phantom using 2D-SWE machines Acuson S2000 (Siemens Medical Solutions) and Aixplorer (Supersonic Imagine) were compared. Shear-wave speed was measured in the skin region, subcutaneous adipose tissue and parenchyma. cs estimates were on average 2.3% greater when using the Aixplorer compared to S2000 in vitro. In vivo, cs estimates were on average 43.7%, 36.3% and 49.9% significantly greater (p << 0.01) when using the Aixplorer compared to S2000, for skin region, subcutaneous adipose tissue and parenchyma, respectively. In conclusion, despite relatively small differences between machines observed in vitro, large differences in absolute measures of shear wave speed measured were observed in vivo, which may prevent pooling of cross-machine data in clinical studies of the breast.

Association of shear-wave elastography with clinical outcomes post-liver transplantation

PURPOSE

Two-dimensional shear-wave elastography (2D-SWE) assessment of liver stiffness has the advantage of being obtained during conventional ultrasound. Liver-stiffness values on 2D-SWE for grafted livers are unknown, as are their potential link to post-transplantation morbidity. This study was undertaken to determine liver-stiffness values on 2D-SWE for grafted livers without complications, and examine relationships between liver-stiffness values on 2D-SWE and early post-operative arterial or biliary complications.

METHODS

In our facility, all liver-transplant recipients are entered in a comprehensive surgical database, where donor, procedure and recipient characteristics are described. All patients underwent systematic 2D-SWE assessment. Potential relationships were analyzed between liver-stiffness findings and donor, procedure and recipient characteristics, and follow-up events, including death, arterial or biliary complications, graft removal and allograft-dysfunction scores.

RESULTS

Liver-stiffness values on 2D-SWE of 337 ultrasound examinations from 165 liver-transplant recipients were collected retrospectively. Median time from transplantation to 2D-SWE examination was 149 days, with median follow-up at 36 months. The mean±SD stiffness value for grafts without complications was 7.3±2.3kPa; it was significantly higher during the first 90 days (8.2±2.5kPa) post-transplant than after 1year (7.0±2.4kPa) (P=0.01). Patients with biliary complications during the first-year post-transplantation had significantly higher mean liver-stiffness values on 2D-SWE than those without, respectively: 9.8±7.0 vs 7.5±1.8kPa (P=0.01).

CONCLUSIONS

Post-transplantation patients without complications had stiffer livers than the general population, with higher values during the first 90 days after surgery. Liver-stiffness values on 2D-SWE were significantly higher for patients with biliary, but not arterial, complications.

Comparison of Sound Touch Elastography, Sound Touch Quantify, and 4 Serum Fibrosis Indexes for the Diagnosis of Liver Fibrosis in Patients With Chronic Hepatitis B

ABSTRACT

The aim of this research was to compare the use of shear wave elastography (sound touch elastography [STE] and sound touch quantify [STQ]) and serum liver fibrosis indexes in the evaluation and staging of chronic hepatitis B (CHB) liver fibrosis. Sound touch elastography is a form of 2-dimensional shear wave elastography, and STQ is a form of point shear wave elastography. Between June 2018 and March 2019, 122 patients with CHB were assessed using STE and STQ. Serum liver biomarkers tests were undertaken, and liver biopsy was performed, and these were used to assign a pathological stage based on the Scheuer scoring system. A receiver operating characteristic curve was used to analyze the diagnostic value of noninvasive methods for evaluating and staging liver fibrosis. The cutoff values of STE for liver fibrosis stages S2 to S4 were 8.85, 9.97, and 10.29 kPa, respectively, and the areas under the receiver operating characteristic (AUCs) curve were 0.703, 0.821, and 0.900, respectively. The cutoff values of STQ for liver fibrosis stages S2 to S4 were 11.31, 13.81, and 20.60 kPa, respectively, and the AUCs were 0.674, 0.807, and 0.893, respectively. The AUCs of STE and STQ in diagnosing fibrosis stage were significantly higher than those of liver serum biomarkers (P < 0.05). The AUCs for the ability of the aspartate transaminase-to-platelet ratio index, the fibrosis index based on the 4 factors, the King score, and the Forns index to diagnose S2 fibrosis were 0.502, 0.624, 0.542, and 0.616, respectively, and the AUCs for their ability to diagnose S4 fibrosis were 0.856, 0.861, 0.883, and 0.823, respectively. Both STE and STQ are noninvasive methods for the assessment of liver fibrosis in CHB patients, with better diagnostic performances than those of 4 serum fibrosis indexes.

Comparison of point and two-dimensional shear wave elastography of the spleen in healthy subjects

BACKGROUND

Few systematic comparative studies of the different methods of physical elastography of the spleen are currently available.

AIM

To compare point shear wave and two-dimensional elastography of the spleen considering the anatomical location (upper, hilar, and lower pole).

METHODS

As part of a prospective clinical study, healthy volunteers were examined for splenic elasticity using four different ultrasound devices between May 2015 and April 2017. The devices used for point shear wave elastography were from Siemens (S 3000) and Philips (Epiq 7), and those used for two-dimensional shear wave elastography were from GE (Logiq E9) and Toshiba (Aplio 500). In addition, two different software versions (5.0 and 6.0) were evaluated for the Toshiba ultrasound device (Aplio 500). The study consisted of three arms: A, B, and C.

RESULTS

In study arm A, 200 subjects were evaluated (78 males and 122 females, mean age 27.9 ± 8.1 years). In study arm B, 113 subjects were evaluated (38 men and 75 women, mean age 26.0 ± 6.3 years). In study arm C, 44 subjects were enrolled. A significant correlation of the shear wave velocities at the upper third of the spleen (r = 0.33088, P < 0.0001) was demonstrated only for the Philips Epiq 7 device compared to the Siemens Acuson S 3000. In comparisons of the other ultrasound devices (GE, Siemens, Toshiba), no comparable results could be obtained for any anatomical position of the spleen. The influencing factors age, gender, and body mass index did not show a clear correlation with the measured shear wave velocities.

CONCLUSION

The absolute values of the shear wave elastography measurements of the spleen and the two different elastography methods are not comparable between different manufacturers or models.

Comparison of 2-D Shear Wave Elastography and Point Shear Wave Elastography for Assessing Liver Fibrosis

Progressive liver fibrosis may result in cirrhosis, portal hypertension and increased risk of hepatocellular carcinoma. We performed a meta-analysis to compare liver fibrosis staging in chronic liver disease patients using 2-D shear wave elastography (2-D SWE) and point shear wave elastography (pSWE). The PubMed, Web of Science and Cochrane Library databases were searched until May 31, 2020 for studies evaluating the diagnostic performance of 2-D SWE and pSWE in assessing liver fibrosis. Pooled sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratios and area under receiver operating characteristic curve were estimated using the bivariate random effects model. As a result, 71 studies with 11,345 patients were included in the analysis. The pooled sensitivities of 2-D SWE and pSWE significantly differed for the detection of significant fibrosis (F ≥ 2; 0.84 vs. 0.76, p < 0.001) and advanced fibrosis (F ≥ 3; 0.90 vs. 0.83, p = 0.003), but not for detection of cirrhosis (F = 4; 0.89 vs. 0.85, p = 0.090). The pooled specificities of 2-D SWE and pSWE did not significantly differ for detection of F ≥ 2 (0.81 vs. 0.79, p = 0.753), F ≥ 3 (0.87 vs. 0.83, p = 0.163) or F = 4 (0.87 vs. 0.84, p = 0.294). Both 2-D SWE and pSWE have high sensitivity and specificity for detecting each stage of liver fibrosis. Two-dimensional SWE has higher sensitivity than pSWE for detection of significant fibrosis and advanced fibrosis.

The Relevance of Noninvasive Tools To Assess Fibrosis in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a growing cause of chronic liver diseases worldwide, involving about 25% of people. NAFLD incorporates a large spectrum of pathological conditions, from simple steatosis to non-alcoholic steatohepatitis (NASH), cirrhosis and its complications include hepatic decompensation and hepatocellular carcinoma (HCC). This progression occurs, over many years, in an asymptomatic way, until advanced fibrosis appears. Thus, the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis are key issues. To date, the histological assessment of fibrosis with liver biopsy is the gold standard, but obviously, invasiveness is the greater threshold. In addition, rare but potentially life-threatening complications, poor acceptability, sampling variability and cost maybe restrict its use. Furthermore, due to the epidemic of NAFLD worldwide and several limitations of liver biopsy evaluation, noninvasive assessment tools to detect fibrosis in NAFLD patients are needed.

Comparative Study Between the Diagnostic Performance of Point and 2-D Shear-Wave Elastography for the Non-invasive Assessment of Liver Fibrosis in Patients With Chronic Hepatitis C Using Transient Elastography as Reference

The study compared the diagnostic performance of two shear-wave elastography techniques, elastography point quantification (ElastPQ) and 2-D shear-wave elastography by General Electric (2-D-SWE.GE), for the non-invasive assessment of liver fibrosis in a cohort of patients with chronic hepatitis C virus (HCV) infection, using transient elastography (TE) as the reference method. There was no significant difference between the feasibility rates of TE, ElastPQ and 2-D-SWE.GE (p = 0.507). A good correlation was found between the liver stiffness (LS) values obtained using the two elastographic methods (r = 0.78). The mean LS values obtained using the ElastPQ technique were significantly higher than those obtained using 2-D-SWE.GE (12.1 ± 7.3 kPa vs. 10.4 ± 4.0 kPa, p < 0.0001). Pairwise comparisons of receiver operator characteristics curves between 2-D-SWE.GE and ElastPQ have shown that there are no significant differences in their performance for staging F ≥ 2 fibrosis (p = 0.89), F ≥ 3 fibrosis (p = 0.76) and F = 4 fibrosis (p = 0.86) in patients with chronic HCV infection.

Normative values of pancreas stiffness by shear wave elastography in healthy children and adolescents

PURPOSE

To define normal pancreas elasticity and velocity values with shear wave elastography (SWE) in healthy children and assess associations with gender, age, and body mass index (BMI).

METHODS

This prospective study included a total of 100 cases (male: 50; female: 50), aged 3-17 years. Preschool, school, and adolescent periods of 3-6 years (n = 27), 7-12 years (n = 30), and 13-17 years (n = 43), respectively, were created in addition to two groups representing prepubertal and postpubertal periods of 3-10 years (n = 50) and 11-18 years (n = 50), respectively. Demographic data regarding the gender, age, height, body weight, and BMI were recorded. Pancreatic head, corpus, and tail SWE measurements were performed with a convex transducer (3.5-5 MHz). Correlations and comparisons were made for stiffness values between groups. Statistical analyses used Mann-Whitney U, Kruskal-Wallis, and Spearman's correlation tests.

RESULTS

Medians (25-75th percentage) of age and BMI were 7 (4.25-10) years and 15 (13-17) years and 17.47 (14.94-19.23) kg/m² and 21.22 (17.41-24) kg/m² in the two age groups, respectively. The median (interquartile range) elasticity and velocity values for the head, corpus, and tail sections of the pancreas were measured as 9.35 (2.9) kPa and 1.76 (0.26) m/s; 9.3 (2.5) kPa and 1.74 (0.21) m/s; and 8.75 (2) kPa and 1.69 (0.15) m/s, respectively. No significant differences were identified for stiffness values between gender and pancreatic section. Pancreatic stiffness values were significantly different among two (p = 0.001) and three (p = 0.028) age groups, and presented mild positive correlations with age (r: 0.23, p: 0.002), height (r: 0.18, p: 0.01), body weight (r: 0.38, p: 0.003), and BMI (r: 0.37, p: 0.045).

CONCLUSION

Normal elasticity and velocity values were defined for the pancreas with SWE in children. Pancreatic stiffness does not significantly change among pancreas parts, but it increases with the transition from childhood to adolescence.

Technical Performance of Two-Dimensional Shear Wave Elastography for Measuring Liver Stiffness: A Systematic Review and Meta-Analysis

Objective

To assess the technical performance of two-dimensional shear wave elastography (2D-SWE) for measuring liver stiffness.

Materials and Methods

The Ovid-MEDLINE and EMBASE databases were searched for studies reporting the technical performance of 2D-SWE, including concerns with technical failures, unreliable measurements, interobserver reliability, and/or intraobserver reliability, published until June 30, 2018. The pooled proportion of technical failure and unreliable measurements was calculated using meta-analytic pooling via the random-effects model and inverse variance method for calculating weights. Subgroup analyses were performed to explore potential causes of heterogeneity. The pooled intraclass correlation coefficients (ICCs) for interobserver and intraobserver reliability were calculated using the Hedges-Olkin method with Fisher's Z transformation of the correlation coefficient.

Results

The search yielded 34 articles. From 20 2D-SWE studies including 6196 patients, the pooled proportion of technical failure was 2.3% (95% confidence interval [CI], 1.3–3.9%). The pooled proportion of unreliable measurements from 20 studies including 6961 patients was 7.5% (95% CI, 4.7–11.7%). In the subgroup analyses, studies conducting more than three measurements showed fewer unreliable measurements than did those with three measurements or less, but no intergroup difference was found in technical failure. The pooled ICCs for interobserver reliability (from 10 studies including 517 patients) and intraobserver reliability (from 7 studies including 679 patients) were 0.87 (95% CI, 0.82–0.90) and 0.93 (95% CI, 0.89–0.95), respectively, suggesting good to excellent reliability.

Conclusion

2D-SWE shows good technical performance for assessing liver stiffness, with high technical success and reliability. Future studies should establish the quality criteria and optimal number of measurements.

Multi-parameter ultrasound based on the logistic regression model in the differential diagnosis of hepatocellular adenoma and focal nodular hyperplasia

BACKGROUND

Focal nodular hyperplasia (FNH) has very low potential risk, and a tendency to spontaneously resolve. Hepatocellular adenoma (HCA) has a certain malignant tendency, and its prognosis is significantly different from FNH. Accurate identification of HCA and FNH is critical for clinical treatment.

AIM

To analyze the value of multi-parameter ultrasound index based on logistic regression for the differential diagnosis of HCA and FNH.

METHODS

Thirty-one patients with HCA were included in the HCA group. Fifty patients with FNH were included in the FNH group. The clinical data were collected and recorded in the two groups. Conventional ultrasound, shear wave elastography, and contrast-enhanced ultrasound were performed, and the lesion location, lesion echo, Young’s modulus (YM) value, YM ratio, and changes of time intense curve (TIC) were recorded. Multivariate logistic regression analysis was used to screen the indicators that can be used for the differential diagnosis of HCA and FNH. A ROC curve was established for the potential indicators to analyze the accuracy of the differential diagnosis of HCA and FNH. The value of the combined indicators for distinguishing HCA and FNH were explored.

RESULTS

Multivariate logistic regression analysis showed that lesion echo (P = 0.000), YM value (P = 0.000) and TIC decreasing slope (P = 0.000) were the potential indicators identifying HCA and FNH. In the ROC curve analysis, the accuracy of the YM value distinguishing HCA and FNH was the highest (AUC = 0.891), which was significantly higher than the AUC of the lesion echo and the TIC decreasing slope (P < 0.05). The accuracy of the combined diagnosis was the highest (AUC = 0.938), which was significantly higher than the AUC of the indicators diagnosing HCA individually (P < 0.05). This sensitivity was 91.23%, and the specificity was 83.33%.

CONCLUSION

The combination of lesion echo, YM value and TIC decreasing slope can accurately differentiate between HCA and FNH.

Preliminary analysis of ultrasound elastography imaging-based thermometry on non-perfused ex vivo swine liver

AIMS

Real-time monitoring of tissue temperature during percutaneous tumor ablation improves treatment efficacy, leading clinicians in adjustment of treatment settings. This study aims at assessing feasibility of ultrasound thermometry during laser ablation of biological tissue using a specific ultrasound imaging techniques based on elastography acoustic radiation force impulse (ARFI).

METHODS

ARFI uses high-intensity focused ultrasound pulses to generate 'radiation force' in tissue; this provokes tissue displacements trackable using correlation-based ultrasound methods: the sensitivity of shear waves velocity is able to detect temperature changes. Experiments were carried out using a Nd:YAG laser (power: 5 W) in three non-perfused ex vivo pig livers. In each organ, a thermocouple was placed close to the applicator tip (distance range 1.5-2.5 cm) used to record a reference temperature. Positioning of laser applicator and thermocouple was eco-guided. The organ was scanned by an echography system equipped with ARFI; propagation velocity was measured in a region of interest of 1 × 0.5 cm located close to thermocouple, to investigate influence of tissue temperature on shear waves velocity.

RESULTS

Shear wave velocity has a very low sensitivity to temperature up to 55-60 °C, and in all cases, velocity is < 5 m s^-1; for temperature > 55-60 °C, velocity shows a steep increment. The system measures a value "over limit", meaning a velocity > 5 m s^-1.

CONCLUSIONS

Ultrasound thermometry during laser ablation of biological tissue based on elastography shows an abrupt output change at temperatures > 55-60 °C. This issue can have a relevant clinical impact, considering tumor necrosis when temperature crosses 55 °C to define the boundary of damaged volume.

Multiparametric ultrasound: evaluation of greyscale, shear wave elastography and contrast-enhanced ultrasound for prostate cancer detection and localization in correlation to radical prostatectomy specimens

BACKGROUND

The diagnostic pathway for prostate cancer (PCa) is advancing towards an imaging-driven approach. Multiparametric magnetic resonance imaging, although increasingly used, has not shown sufficient accuracy to replace biopsy for now. The introduction of new ultrasound (US) modalities, such as quantitative contrast-enhanced US (CEUS) and shear wave elastography (SWE), shows promise but is not evidenced by sufficient high quality studies, especially for the combination of different US modalities. The primary objective of this study is to determine the individual and complementary diagnostic performance of greyscale US (GS), SWE, CEUS and their combination, multiparametric ultrasound (mpUS), for the detection and localization of PCa by comparison with corresponding histopathology.

METHODS/DESIGN

In this prospective clinical trial, US imaging consisting of GS, SWE and CEUS with quantitative mapping on 3 prostate imaging planes (base, mid and apex) will be performed in 50 patients with biopsy-proven PCa before planned radical prostatectomy using a clinical ultrasound scanner. All US imaging will be evaluated by US readers, scoring the four quadrants of each imaging plane for the likelihood of significant PCa based on a 1 to 5 Likert Scale. Following resection, PCa tumour foci will be identified, graded and attributed to the imaging-derived quadrants in each prostate plane for all prostatectomy specimens. Primary outcome measure will be the sensitivity, specificity, negative predictive value and positive predictive value of each US modality and mpUS to detect and localize significant PCa evaluated for different Likert Scale thresholds using receiver operating characteristics curve analyses.

DISCUSSION

In the evaluation of new PCa imaging modalities, a structured comparison with gold standard radical prostatectomy specimens is essential as first step. This trial is the first to combine the most promising ultrasound modalities into mpUS. It complies with the IDEAL stage 2b recommendations and will be an important step towards the evaluation of mpUS as a possible option for accurate detection and localization of PCa.

TRIAL REGISTRATION

The study protocol for multiparametric ultrasound was prospectively registered on Clinicaltrials.gov on 14 March 2017 with the registry name 'Multiparametric Ultrasound-Study for the Detection of Prostate Cancer' and trial registration number NCT03091231.

The role of imaging in prediction of post-hepatectomy liver failure

Post-hepatectomy liver failure (PHLF) is not only a leading cause of mortality but also a leading cause of life-threatening complications in patients undergoing liver resection. The ability to accurately detect the emergence of PHLF represents a crucially important step. Currently, PHLF can be predicted by a comprehensive evaluation of biological, clinical, and anatomical parameters. With the development of new technologies, imaging methods including elastography, diffusion-weighted magnetic resonance imaging, and gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid-enhanced MRI play a more significant role in the pre-operative prediction and assessment of PHLF. In this review, we summarize the mainstream studies, with the aim of evaluating the role of imaging and improving the clinical value of existing scoring systems for predicting PHLF.

Evaluation of parotid glands in healthy children and adolescents using shear wave elastography and superb microvascular imaging

OBJECTIVES

We aim to determine parotid gland elasticity values from healthy children and adolescents using shear wave elastography (SWE). We also define the degree of vascularity using superb microvascular imaging (SMI), power Doppler (PD), and color Doppler (CD) and compare SMI with CD and PD.

MATERIALS AND METHODS

A total of 100 cases, comprising 50 girls and 50 boys, with ages ranging from 3 to 17 years were included in this prospective study. SWE, SMI, PD, and CD measurements were taken from both parotid glands, and the relationships with sex, age, and body mass index (BMI) were determined. The SMI was compared with the PD and CD.

RESULTS

The median elasticity values measured with SWE were 8.37 ± 2.09 kPa and 1.68 ± 0.26 m/s on the right and 8.33 ± 2.04 kPa and 1.69 ± 0.26 m/s on the left. There were significant positive correlations present for those aged below and above 10 years and for BMI with elasticity values. The median vascular spot numbers measured using SMI, PD, and CD were 5 ± 1.70, 3.5 ± 1.45, and 2 ± 1.1 on the right and 4 ± 1.7, 4 ± 1.43, and 2 ± 1.05 on the left, respectively. The median values obtained with SMI were significantly higher than the median values obtained with both PD and CD.

CONCLUSION

This study determined the reference SWE, SMI, PD, and CD values for normal parotid glands in healthy children and adolescents. Elasticity values were affected by age and BMI. There was no correlation between vascularity values and age, sex, or BMI. SMI provided more detailed information about vascularity compared with the other methods.

Non-invasive evaluation of stable renal allograft function using point shear-wave elastography

OBJECTIVE

To investigate the feasibility of point shear-wave elastography (SWE) in evaluating patients with stable renal allograft function who underwent protocol biopsies.

METHODS

95 patients with stable renal allograft function that underwent ultrasound-guided biopsies at predefined time points (10 days or 1 year after transplantation) were enrolled. Ultrasound and point SWE examinations were performed immediately before protocol biopsies. Patients were categorized into two groups: subclinical rejection (SCR) and non-SCR. Tissue elasticity (kPa) on SWE was measured in the cortex of all renal allografts.

RESULTS

SCR was pathologically confirmed in 34 patients. Tissue elasticity of the SCR group (31.0 kPa) was significantly greater than that of the non-SCR group (24.5 kPa) (=0.016), while resistive index value did not show a significant difference between the two groups (p = 0.112). Tissue elasticity in renal allografts demonstrated significantly moderate negative correlation with estimated glomerular filtration rate (correlation coefficient = -0.604, p < 0.001). Tissue elasticity was not independent factor for SCR prediction on multivariate analysis.

CONCLUSION

As a non-invasive tool, point SWE appears feasible in distinguishing between patients with SCR and without SCR in stable functioning renal allografts. Moreover, it may demonstrate the functional state of renal allografts. Advances in knowledge: On point SWE, SCR has greater tissue elasticity than non-SCR.