Principles and clinical application of ultrasound elastography for diffuse liver disease

Viscoelasticity in 3D Cell Culture and Regenerative Medicine: Measurement Techniques and Biological Relevance

The field of mechanobiology is gaining prominence due to recent findings that show cells sense and respond to the mechanical properties of their environment through a process called mechanotransduction. The mechanical properties of cells, cell organelles, and the extracellular matrix are understood to be viscoelastic. Various technologies have been researched and developed for measuring the viscoelasticity of biological materials, which may provide insight into both the cellular mechanisms and the biological functions of mechanotransduction. Here, we explain the concept of viscoelasticity and introduce the major techniques that have been used to measure the viscoelasticity of various soft materials in different length- and timescale frames. The topology of the material undergoing testing, the geometry of the probe, the magnitude of the exerted stress, and the resulting deformation should be carefully considered to choose a proper technique for each application. Lastly, we discuss several applications of viscoelasticity in 3D cell culture and tissue models for regenerative medicine, including organoids, organ-on-a-chip systems, engineered tissue constructs, and tunable viscoelastic hydrogels for 3D bioprinting and cell-based therapies.

MRI T2 mapping and shear wave elastography for identifying main pain generator in delayed-onset muscle soreness: muscle or fascia?

INTRODUCTION

The main generator of delayed onset muscle soreness (DOMS) is still unknown. This study aimed to clarify the main generator of DOMS.

METHODS

Twelve participants performed eccentric exercise (EE) on lower legs. MRI and ultrasound were used to assess changes of calf muscle and deep fascia before and after EE. These results were then compared to the muscle pain level.

RESULTS

Compared to baseline, muscle pain peaked at 24-48 h after EE (downstairs 22.25 ± 6.196, 57.917 ± 9.298, F = 291.168, p < 0.01; resting 5.833 ± 1.899, 5.083 ± 2.429, F = 51.678, p < 0.01). Shear wave speed (SWE) of the deep fascia and T2 values of the gastrocnemius muscle and deep fascia all increased and peaked at 48 h after EE (1.960 ± 0.130, F = 22.293; 50.237 ± 2.963, F = 73.172; 66.328 ± 2.968, F = 231.719, respectively, p < 0.01). These measurements were positively correlated with DOMS (downstairs: r = 0.46, 0.76, 0.87, respectively, p < 0.001; resting: r = 0.42, 0.70, 0.77, respectively, p < 0.001). There was a significant positive correlation between SWE and T2 values of deep fascia (r = 0.54, p < 0.01).

CONCLUSION

DOMS is a common result of muscle and fascia injuries. Deep fascia edema and stiffness play a crucial role in DOMS, which can be effectively evaluated MR-T2 and SWE.

CRITICAL RELEVANCE STATEMENT

Delayed-onset muscle soreness is a common result of muscle and deep fascia injuries, in which the edema and stiffness of the deep fascia play a crucial role. Both MRI and shear wave elastography can be effectively used to evaluate soft tissue injuries.

KEY POINTS

• The deep fascia is the major pain generator of delayed-onset muscle soreness. • There is a significant correlation between fascia injury and delayed-onset muscle soreness. • MRI and shear wave elastography are preferred methods for assessing fascia injuries.

Automated classification of liver fibrosis stages using ultrasound imaging

BACKGROUND

Ultrasound imaging is the most frequently performed for the patients with chronic hepatitis or liver cirrhosis. However, ultrasound imaging is highly operator dependent and interpretation of ultrasound images is subjective, thus well-trained radiologist is required for evaluation. Automated classification of liver fibrosis could alleviate the shortage of skilled radiologist especially in low-to-middle income countries. The purposed of this study is to evaluate deep convolutional neural networks (DCNNs) for classifying the degree of liver fibrosis according to the METAVIR score using US images.

METHODS

We used ultrasound (US) images from two tertiary university hospitals. A total of 7920 US images from 933 patients were used for training/validation of DCNNs. All patient were underwent liver biopsy or hepatectomy, and liver fibrosis was categorized based on pathology results using the METAVIR score. Five well-established DCNNs (VGGNet, ResNet, DenseNet, EfficientNet and ViT) was implemented to predict the METAVIR score. The performance of DCNNs for five-level (F0/F1/F2/F3/F4) classification was evaluated through area under the receiver operating characteristic curve (AUC) with 95% confidential interval, accuracy, sensitivity, specificity, positive and negative likelihood ratio.

RESULTS

Similar mean AUC values were achieved for five models; VGGNet (0.96), ResNet (0.96), DenseNet (0.95), EfficientNet (0.96), and ViT (0.95). The same mean accuracy (0.94) and specificity values (0.96) were yielded for all models. In terms of sensitivity, EffcientNet achieved highest mean value (0.85) while the other models produced slightly lower values range from 0.82 to 0.84.

CONCLUSION

In this study, we demonstrated that DCNNs can classify the staging of liver fibrosis according to METAVIR score with high performance using conventional B-mode images. Among them, EfficientNET that have fewer parameters and computation cost produced highest performance. From the results, we believe that DCNNs based classification of liver fibrosis may allow fast and accurate diagnosis of liver fibrosis without needs of additional equipment for add-on test and may be powerful tool for supporting radiologists in clinical practice.

Diagnostic role of gray-scale and shear-wave elastography in pediatric patients with undescended testes: a prospective controlled study

Aim

Ultrasound elastography is a simple non-invasive method for measuring tissue elasticity in relation to tissue fibrosis. The aim of this study was to compare echogenicity, volume and shear wave velocities of undescended vs normally descended testes.

Material and methods

Sixty-six boys with undescended testes were included in this study. The median age range was 35.5 (10-118) months old. The cases included in this prospective study consisted of 66 patients with non-operated undescended testes, with 51 of them being affected unilaterally and 15 affected bilaterally, as diagnosed by physical examination. The control group consisted of 31 healthy boys without any particular health problems. This prospective study was performed by gray-scale ultrasonography and shear wave elastography in boys with undescended testes and healthy testes. The testicular volumes were established by ultrasound measurement, the echogenicity and shear wave elastography values were measured in boys with unilateral and bilateral undescended testes, and the results were compared with healthy boys' testes and their contralateral testes. The stiffness values were recorded for speed (m/s) and elasticity (kPa), and the stiffness values of undescended testes were compared with the healthy control group.

Results

Echogenicity values were lower in the bilateral undescended testes group than in the healthy group, and the healthy group's echogenicity was normal (p <0.001). The ROC curve was used to identify a cut-off shear wave elastography value for predicting decreased testicular echogenicity by using average shear wave elastography values. The area under the curve for the undescended testes was 0.78 (95% CI: 0.70-0.85, sensitivity 83.7%, specificity 68.7%, p <0.001), with an average shear wave elastography value of 2.32 (m/s) for above the cut-off point indicates. This was found to be significantly associated with reduced echogenicity on gray-scale ultrasonography, suggesting that it may be correlated with fibrosis developing in patients with undescended testes.

Conclusion

The study provides interesting findings in that it proposes an alternative non-invasive method for the assessment of testicular tissue in undescended testes. We used shear wave elastography to compare the stiffness of normal testes in both heathy patients and in the contralateral healthy testes of boys with undescended testes, with the values obtained for the undescended testes reflecting the level of fibrosis of the parenchyma. Another outcome of this study was observed in patients with unilateral undescended testes, where the normally descended testes showed increased shear wave elastography values, which could be an early indication of parenchymal change.

Reliability and Validity of Shore Hardness in Plantar Soft Tissue Biomechanics

Shore hardness (SH) is a cost-effective and easy-to-use method to assess soft tissue biomechanics. Its use for the plantar soft tissue could enhance the clinical management of conditions such as diabetic foot complications, but its validity and reliability remain unclear. Twenty healthy adults were recruited for this study. Validity and reliability were assessed across six different plantar sites. The validity was assessed against shear wave (SW) elastography (the gold standard). SH was measured by two examiners to assess inter-rater reliability. Testing was repeated following a test/retest study design to assess intra-rater reliability. SH was significantly correlated with SW speed measured in the skin or in the microchamber layer of the first metatarsal head (MetHead), third MetHead and rearfoot. Intraclass correlation coefficients and Bland-Altman plots of limits of agreement indicated satisfactory levels of reliability for these sites. No significant correlation between SH and SW elastography was found for the hallux, 5th MetHead or midfoot. Reliability for these sites was also compromised. SH is a valid and reliable measurement for plantar soft tissue biomechanics in the first MetHead, the third MetHead and the rearfoot. Our results do not support the use of SH for the hallux, 5th MetHead or midfoot.

A comparison of transient elastography with acoustic radiation force impulse elastography for the assessment of liver health in patients with chronic hepatitis C: Baseline results from the TRACER study

Background

Liver stiffness measurements can be used to assess liver fibrosis and can be acquired by transient elastography using FibroScan® and with Acoustic Radiation Force Impulse imaging. The study aimed to establish liver stiffness measurement scores using FibroScan® and Acoustic Radiation Force Impulse in a chronic hepatitis C cohort and to explore the correlation and agreement between the scores and the factors influencing agreement.

Methods

Patients had liver stiffness measurements acquired with FibroScan® (right lobe of liver) and Acoustic Radiation Force Impulse (right and left lobe of liver). We used Spearman's correlation to explore the relationship between FibroScan® and Acoustic Radiation Force Impulse scores. A Bland-Altman plot was used to evaluate bias between the mean percentage differences of FibroScan® and Acoustic Radiation Force Impulse scores. Univariable and multivariable analyses were used to assess how factors such as body mass index, age and gender influenced the agreement between liver stiffness measurements.

Results

Bland-Altman showed the average (95% CI) percentage difference between FibroScan® and Acoustic Radiation Force Impulse scores was 27.5% (17.8, 37.2), p  < 0.001. There was a negative correlation between the average and percentage difference of the FibroScan® and Acoustic Radiation Force Impulse scores ( r (95% CI) = -0.41 (-0.57, -0.21), p < 0.001), thus showing that percentage difference gets smaller for greater FibroScan® and Acoustic Radiation Force Impulse scores. Body mass index was the biggest influencing factor on differences between FibroScan® and Acoustic Radiation Force Impulse (r = 0.12 (0.01, 0.23), p = 0.05). Acoustic Radiation Force Impulse scores at segment 5/8 and the left lobe showed good correlation (r (95% CI) = 0.83 (0.75, 0.89), p < 0.001).

Conclusion

FibroScan® and Acoustic Radiation Force Impulse had similar predictive values for the assessment of liver stiffness in patients with chronic hepatitis C infection; however, the level of agreement varied across lower and higher scores.

Uncovering the Cardiovascular Threat: A Comprehensive Examination of Liver Fibrosis and Subclinical Atherosclerosis in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as a global epidemic intricately linked to the rising tide of obesity and metabolic syndrome. This comprehensive review delves into the complex web of relationships between NAFLD, liver fibrosis, and subclinical atherosclerosis, shedding light on their interplay, shared risk factors, and clinical implications. NAFLD encompasses a spectrum of liver conditions, from the benign non-alcoholic fatty liver (NAFL) to the more severe non-alcoholic steatohepatitis (NASH), characterized by inflammation and hepatocellular injury. Central to the discussion is the insidious development of liver fibrosis, the ominous harbinger of progressive liver damage, cirrhosis, and hepatocellular carcinoma. The increasing prevalence of NAFLD, now affecting a quarter of the global population, poses a significant public health challenge. Its association with obesity, insulin resistance, and metabolic syndrome highlights the multifactorial nature of this disease. However, NAFLD's repercussions extend beyond the liver. This review unveils a potent connection between NAFLD and subclinical atherosclerosis, the early precursor to cardiovascular disease. Individuals with NAFLD face an elevated risk of atherosclerosis, even without traditional cardiovascular risk factors. The intricate link between these two conditions is illuminated through shared pathophysiological pathways, including systemic inflammation, insulin resistance, and dyslipidemia. Understanding the interplay between liver fibrosis and subclinical atherosclerosis has profound clinical implications. Patients with advanced fibrosis or cirrhosis are not only at risk of liver-related complications but also of cardiovascular events. This necessitates a holistic approach to patient care, with lifestyle modifications and pharmacological interventions simultaneously managing both conditions. Physicians must prioritize early detection and collaborate across disciplines to provide comprehensive care. Looking ahead, the future holds promising avenues of research. Emerging areas include genetics and precision medicine, microbiome research, and epigenetics, which may unveil new therapeutic targets. Innovations in diagnostics and therapeutics, such as non-invasive biomarkers and combination therapies, offer hope for more effective management. Long-term outcomes and survivorship research will provide insights into the lasting impact of interventions. In conclusion, this review underscores the imperative of addressing liver fibrosis and atherosclerosis in the context of NAFLD. It is a call to action for healthcare professionals, researchers, and policymakers to work collaboratively, promote early detection, and advance our understanding of these interconnected conditions. By doing so, we can enhance patient outcomes and chart a course toward a healthier future for those grappling with NAFLD and its intricate web of consequences.

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.

Clinical study of the value of shear wave elastography in evaluating the degree of liver fibrosis in children

OBJECTIVES

To explore the clinical application of shear wave elastography (SWE) in evaluating the degree of liver fibrosis in children.

METHODS

To explore the value of SWE in assessing liver fibrosis in children, the correlation between elastography values and the METAVIR grade of liver fibrosis in children with biliary system or liver diseases was studied. Children with significant liver enlargement were enrolled, and the fibrosis grade was analyzed to explore the value of SWE in assessing the degree of liver fibrosis in the presence of significant liver enlargement.

RESULTS

A total of 160 children with bile system or liver diseases were recruited. The areas under the receiver operating characteristic curve (AUROCs) for liver biopsy from stage F1 to F4 were 0.990, 0.923, 0.819, and 0.884. According to the degree of liver fibrosis at liver biopsy, there was a high correlation between the SWE value and the degree of liver fibrosis (correlation coefficient 0.74). There was no significant correlation between the Young's modulus value of the liver and the degree of liver fibrosis (correlation coefficient 0.16).

CONCLUSIONS

Supersonic SWE can generally accurately evaluate the degree of liver fibrosis in children with liver disease. However, When the liver is significantly enlarged, SWE can only evaluate liver stiffness based on Young's modulus values, and the degree of liver fibrosis must still be determined by pathologic biopsy.

Exosomes and ultrasound: The future of theranostic applications

Biomaterials and pertaining formulations have been very successful in various diagnostic and therapeutic applications because of its ability to overcome pharmacological limitations. Some of them have gained significant focus in the recent decade for their theranostic properties. Exosomes can be grouped as biomaterials, since they consist of various biological micro/macromolecules and possess all the properties of a stable biomaterial with size in nano range. Significant research has gone into isolation and exploitation of exosomes as potential theranostic agent. However, the limitations in terms of yield, efficacy, and target specificity are continuously being addressed. On the other hand, several nano/microformulations are responsive to physical or chemical alterations and were successfully stimulated by tweaking the physical characteristics of the surrounding environment they are in. Some of them are termed as photodynamic, sonodynamic or thermodynamic therapeutic systems. In this regard, ultrasound and acoustic systems were extensively studied for its ability towards altering the properties of the systems to which they were applied on. In this review, we have detailed about the diagnostic and therapeutic applications of exosomes and ultrasound separately, consisting of their conventional applications, drawbacks, and developments for addressing the challenges. The information were categorized into various sections that provide complete overview of the isolation strategies and theranostic applications of exosomes in various diseases. Then the ultrasound-based disease diagnosis and therapy were elaborated, with special interest towards the use of ultrasound in enhancing the efficacy of nanomedicines and nanodrug delivery systems, Finally, we discussed about the ability of ultrasound in enhancing the diagnostic and therapeutic properties of exosomes, which could be the future of theranostics.

Assessment of ultrasound shear wave elastography within muscles using different region of interest sizes, manufacturers, probes and acquisition angles: an ex vivo study

BACKGROUND

The application of shear wave elastography (SWE) in assessment of the musculoskeletal system is affected by various factors. This study aimed to explore the influence of machines, probes, region of interest (ROI) sizes, and the acquisition angles on muscle shear wave speed (SWS).

METHODS

The SWS of ex vivo isolated muscles were acquired using 3 different machines (Aixplorer system, SuperSonic Imagine; Acuson S3000, Siemens Healthcare; Resona 7, Mindray) and 2 linear probes (Aixplorer system, SL 10-2 and SL 15-4). Also, 4 different ROI sizes (diameter 1-10 mm) and 9 different acquisition angles (0-40°) were tested. The SWS acquired under different conditions were compared, and the intra-class correlation coefficients (ICC) were used to evaluate reproducibility.

RESULTS

There was a significant difference in SWS acquired using the 3 different machines (P<0.001) or with 9 different angles (P=0.008). There was no significant difference in SWS acquired using 2 probes (P=0.053) or 4 different ROI sizes (P=0.874, 0.778, and 0.865 for 3 operators, respectively). All machines produced substantial intra-system reproducibility (ICC, 0.61-0.80). Both probes demonstrated an almost perfect degree of intra-system agreement (ICC, >0.80), and nearly all ROI sizes demonstrated an almost perfect degree of intra- and inter-operator agreement (ICC, >0.80). The measurement reliability was higher when the acquisition angles were no more than 20°.

CONCLUSIONS

The 3 machines had different SWS values. Attention should be paid when comparing SWS results using different machines. For the Aixplorer system, the ROI size had no effect on the SWS values. Angles larger than 25° will lead to SWS measurements with greater variability compared to smaller angles (≤20°).

Diagnostic Accuracy of Shear-Wave Elastography for Breast Lesion Characterization in Women: A Systematic Review and Meta-Analysis

PURPOSE

The aim of this study was to assess the diagnostic accuracy of 2-D shear-wave elastography (SWE) for differentiating benign and malignant breast lesions in women with abnormal findings on mammography.

METHODS

Included in this review are studies of diagnostic accuracy published before June 2021 using 2-D SWE to evaluate female breast lesions. Included studies were required to include at least 50 lesions, report quantitative shear-wave speed (SWS) thresholds, and include a reference standard of either biopsy or 2-year stability. Included studies used the mean, maximum, minimum, or SD of SWS for classification. A systematic search of PubMed, Scopus, Embase, Ovid-MEDLINE, the Cochrane Library, and Web of Science was performed. Bias and applicability of the studies were assessed using Quality Assessment of Diagnostic Accuracy Studies 2. A hierarchical summary receiver operating characteristic model was used to arrive at the summary statistics.

RESULTS

Eighty-seven prospective and retrospective studies were included, encompassing 17,810 women (mean age 42.3 ± 10.4 years) with 19,043 lesions (7,623 malignant). Summary sensitivities and specificities, respectively, were 0.86 (95% confidence interval [CI], 0.83-0.88) and 0.87 (95% CI, 0.84-0.88) for mean SWS, 0.83 (95% CI, 0.80-0.85) and 0.88 (95% CI, 0.86-0.90) for the maximum, 0.86 (95% CI, 0.74-0.93) and 0.81 (95% CI, 0.69-0.89) for the minimum, and 0.82 (95% CI, 0.77-0.86) and 0.88 (95% CI, 0.85-0.91) for the SD. Alternatively, the areas under the receiver operating characteristic curve were 0.93 (95% CI, 0.91-0.94), 0.92 (95% CI, 0.90-0.94), 0.90 (95% CI, 0.82-0.96), and 0.92 (95% CI, 0.88-0.94), respectively.

CONCLUSIONS

This review demonstrates the discriminative power of SWE in the diagnosis of breast cancer. Using the resulting likelihood ratios, SWE may prove beneficial in downgrading BI-RADS® 4a or upgrading BI-RADS 3 lesions. However, current society guidelines do not provide definitive recommendations regarding the use of SWE and its counterpart strain elastography (SE). Comparison with our results suggests that SE alone or a combination of SE and SWE may provide better diagnostic performance than SWE alone and serve as an adjunct to current diagnostic techniques.

The significance of dual-mode elastography in the diagnosis of breast lesions by physicians with different levels of experience

BACKGROUND

This study aimed to assess the diagnostic value of dual-mode elastography for benign and malignant breast lesions and determine whether this technique can improve the diagnostic ability of physicians with different levels of experience.

METHODS

One hundred and eighty-three breast lesions were analyzed retrospectively, and the following values were calculated for the lesions with various shells: shear modulus (G), Young's modulus (E), shear wave velocity (Cs), and strain ratio (SR). A random forest algorithm was used to select the optimal modes for elastography. A receiver operating characteristic curve was used to assess the diagnostic efficacy for benign and malignant breast lesions. Sensitivity and specificity values were calculated to evaluate any improvements in the diagnostic efficacy of physicians with different levels of experience (junior, intermediate-level, and senior) in the evaluation of malignant breast lesions using dual-mode elastography.

RESULTS

The best-performing mode of shear wave elastography (SWE) in the diagnosis of breast lesions was the A'min 1.0 (Cs) mode (minimum shear wave velocity of the area of interest and 1.0 mm around the area of interest), and the best-performing mode of strain elastography (SE) was the B/A' 0.5 (ratio of fat to the elasticity of the area of interest and 0.5 mm around the area of interest). When the two methods were used in series, results showed high specificity (98%), positive likelihood ratio (PLR) (21.2), and positive predictive value (PPV) (95%). Series means that if SE and SWE were malignant, the result in series was malignant, and that if either SE or SWE was benign, the result in series was benign. When the methods were used in parallel, the results showed high sensitivity (91%), negative likelihood ratio (NLR) (0.15), and negative predictive value (NPV) (89%). Parallel means that if SE and SWE were benign, the result in parallel was benign, and that if either SE or SWE was malignant, the result in parallel was malignant. When conventional ultrasound was combined with dual-mode elastography, the intermediate-level and junior physicians' diagnoses of breast lesions showed a higher sensitivity, specificity, and area under the curve than conventional ultrasound diagnosis alone.

CONCLUSIONS

Dual-mode elastography is effective in the diagnosis of breast lesions. The sensitivity and specificity values in this study show that diagnoses made by junior and intermediate-level physicians improve when dual-mode elastography is used, although diagnoses made by senior physicians do not improve significantly.

Diagnostic Performance of 2-D Shear Wave Elastography on the Evaluation of Hepatic Fibrosis with Emphasis on Impact of the Different Region-of-Interest Methods

The purpose of this study was to evaluate the impact of the different region-of-interest (ROI) methods of 2-D shear wave elastography (2-D SWE) on hepatic fibrosis diagnosis. In this retrospective study, 83 patients who underwent 2-D SWE with three ROI methods (a circle ROI, a box ROI and multiple ROIs in an elastogram) and transient elastography (TE) were included. Liver stiffness (LS) was measured five times with each ROI method. These LS values were compared, and their correlation with those obtained from TE was evaluated. The LS values obtained using the three different ROI methods differed statistically (p < 0.001). However, the LS values obtained using each ROI method of 2-D SWE were highly correlated with those obtained using TE (r > 0.7, p < 0.001). All three ROI methods of 2-D SWE had high areas under the receiver operating characteristic curve in diagnosing significant fibrosis and cirrhosis (0.841, 0.820 and 0.840, respectively; 0.962, 0.946 and 0.945, respectively). There were no significant differences in area under the receiver operating characteristic curve among the ROI methods of 2-D SWE. Regardless of the ROI method, 2-D SWE had high performance in diagnosing hepatic fibrosis.

Effect of Q-Box size on liver stiffness measurement by two-dimensional shear wave elastography

PURPOSE

To investigate the effect of the Q-Box size on liver stiffness (LS) measurement by two-dimensional shear wave elastography (2D SWE).

METHODS

Ninety-eight patients with chronic liver disease were enrolled. Each patient was continuously measured five times. The Q-Box diameter was adjusted to 10, 20, and 30 mm each time. The liver stiffness values (LSVs) at different diameters were compared in the following groups: LSVs ≤6.2 kPa, 6.2 kPa < LSVs ≤11 kPa, LSVs >11 kPa. The reliability and repeatability of LS measurement at different diameters were evaluated.

RESULTS

The differences in LSVs at different Q-Box diameters were statistically significant only when LSV ≤6.2 kPa (p = 0.004). There were no statistically significant differences in standard deviation (SD), SD/median, coefficient of variation (CV), and interquartile range (IQR)/median at different Q-Box diameters (p > 0.05). There were statistical differences in minimum LSVs and percentage of minimum LSVs ≤0.2 kPa as well as in stability index (SI) and percentage of SI <90% at different Q-Box diameters (p < 0.05). The intraclass correlation coefficients (ICCs) were up to 0.98 at Q-Box diameters of 10, 20, and 30 mm.

CONCLUSIONS

Our study showed that Q-Box size may lead to significant differences in LSVs, especially when LSVs ≤6.2 kPa. The Q-Box size had a large effect on the reliability of a single LS measurement but did not affect the repeatability of multiple measurements.

Prognostic value of liver stiffness measurement in patients with hepatocellular carcinoma (HCC) treated by radiofrequency ablation: a meta-analysis

BACKGROUND

In patients with stage 0-A (as per Milan criteria) hepatocellular carcinoma (HCC) image-guided ablation is less invasive and requires shorter hospitalization than resection, but long-term prognosis is poorer. This meta-analysis was conducted to investigate whether liver stiffness measurement (LSM) could be used to predict prognosis in HCC patients after tumor ablation.

METHODS

A literature search was conducted for all studies published till July 2020 in PubMed, Web of Science, Cochrane Library and EMBASE. Studies were included if they investigated the association between pretreatment LSM and prognosis in HCC patients treated with ablation. Subgroup analysis, meta-regression, publication bias assessment and sensitivity were conducted.

RESULTS

Eight studies (with a total of 1276 HCC patients) were included in this meta-analysis. All patients were treated with radiofrequency ablation. Pooled results showed that high pretreatment LSM were associated with poor overall survival (OS) (hazard ratio [HR] = 4.31, 95% confidence interval [CI]: 2.27-8.20, p < .001) and recurrence-free survival (RFS), regardless of whether LSM was considered as a categorical variable (HR = 2.63, 95% CI = 1.63-4.22, p < .001) or as a continuous variable (HR = 1.02, 95% CI = 1.01-1.04, p = .003). Among studies treating LSM value as a categorical variable, liver stiffness measured using acoustic radio force impulse (ARFI) or transient elastography (TE) was significantly associated with RFS, but not liver stiffness measured using two-dimensional shear wave elastography (SWE).

CONCLUSIONS

High baseline LSM value appears to be associated with poor prognosis in HCC patients treated with radiofrequency ablation.

Liver Fibrosis Assessment

Early diagnosis of hepatic fibrosis (HF) is pivotal for management to cease progression to cirrhosis and hepatocellular carcinoma. HF is the telltale sign of chronic liver disease, and confirmed by liver biopsy, which is an invasive technique and inclined to sampling errors. The morphologic parameters of cirrhosis are assessed on conventional imaging such as on ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Newer imaging modalities such as magnetic resonance elastography and US elastography are reliable and accurate. More research studies on novel imaging modalities such as MRI with diffusion weighted imaging, enhancement by hepatobiliary contrast agents, and CT using perfusion are essential for earlier diagnosis, surveillance and accurate management. The purpose of this article is to discuss non-invasive CT, MRI, and US imaging modalities for diagnosis and stratify HF.

Quantification of liver and muscular fat using contrast-enhanced Dual Source Dual Energy Computed Tomography compared to an established multi-echo Dixon MRI sequence

PURPOSE

To investigate the feasibility of liver fat quantification in contrast-enhanced dual source dual energy computed tomography (DECT) using multi-echo Dixon magnetic resonance imaging (MRI) as reference standard.

METHOD

Patients who underwent MRI of the liver including a multi-echo Dixon sequence for estimation of proton density fat fraction in 2017 as well as contrast-enhanced DECT imaging of the abdomen were included in this retrospective, monocentric IRB approved study. Furthermore, patients with a hepatic fat amount >5% who were examined in 2018 with MRI and DECT were included. The final study group consisted of 81 patients with 90 pairs of examinations. Analysis of parameter maps was performed manually using congruent regions of interest which were placed in the liver parenchyma, in the erector spinae muscles, and psoas major muscles.

RESULTS

Mean patient age was 61 ± 13 years. Median time between MRI and DECT was 48 days. MRI liver fat quantification resulted in a median of 3.8% (IQR: 2.2-8.2%) compared to 1.8% (IQR: 0-6.3%) in DECT (p < 0.001), with a Spearman correlation of 0.73. Bland-Altman analysis resulted in a systematic underestimation of liver fat in DECT, with a mean difference of -1.7%. Fat quantification in the erector spinae muscles (p = 0.257) and the psoas major muscles (p = 0.208) was not significantly different in DECT compared to MRI.

CONCLUSIONS

Liver and muscular fat quantification in portal-venous phase DECT is feasible with good to excellent correlation compared to a multi-echo Dixon MRI sequence analysis. While there is an underestimation of the liver fat content in DECT, there are no significant differences between DECT and MRI fat quantification of the erector spinae and psoas major muscles.

The evaluation of the use of 2D shear-wave ultrasound elastography in differentiation of clinically insignificant and significant liver fibrosis in pediatric age group

OBJECTIVE

To determine the accuracy of 2D shear-wave elastography (2D-SWE) in pediatric age group patients in differentiating clinically insignificant and significant liver fibrosis using METAVIR fibrosis scoring system as the gold standard.

INTRODUCTION

Liver biopsy has long been the gold standard in liver fibrosis diagnosis. However, due to probable complications and sampling variabilities, the need for more accurate and non-invasive techniques has increased. 2D-SWE is a non-invasive technique used in the evaluation of liver stiffness and utilized more and more in routine clinical practice with recent advances and researches.

MATERIALS AND METHODS

In this retrospective single-center study, we included 46 pediatric age group patients who had a liver parenchymal biopsy and 2D-SWE evaluation regardless of etiology. For 2D-SWE, the LOGIQ E9 system (GE Medical Systems, Wisconsin, USA) and, for histopathological evaluation, METAVIR fibrosis scoring system were utilized. Patients were further subgrouped as clinically insignificant (METAVIR Score F0-1) and significant (METAVIR Score F2-4). The Kolmogorov-Smirnov and Mann-Whitney U tests were employed for statistical analysis. The diagnostic accuracy of 2D-SWE was assessed, and cutoff values were set by ROC curve analysis.

RESULTS

kPa values were statistically different between clinically significant and insignificant fibrosis patient groups (p < 0.001). kPa value of 8.92 was designated as the best cutoff value according to the Youden Index.

CONCLUSION

2D-SWE is one of the non-invasive techniques in the evaluation of liver fibrosis. Our findings suggest that 2D-SWE accurately differentiate clinically insignificant and significant liver fibrosis.

Microscope-Based Automated Quantification of Liver Fibrosis in Mice Using a Deep Learning Algorithm

In preclinical studies that involve animal models for hepatic fibrosis, accurate quantification of the fibrosis is of utmost importance. The use of digital image analysis based on deep learning artificial intelligence (AI) algorithms can facilitate accurate evaluation of liver fibrosis in these models. In the present study, we compared the quantitative evaluation of collagen proportionate area in the carbon tetrachloride model of liver fibrosis in the mouse by a newly developed AI algorithm to the semiquantitative assessment of liver fibrosis performed by a board-certified toxicologic pathologist. We found an excellent correlation between the 2 methods of assessment, most evident in the higher magnification (×40) as compared to the lower magnification (×10). These findings strengthen the confidence of using digital tools in the toxicologic pathology field as an adjunct to an expert toxicologic pathologist.

Sonographic evaluation of the portal vein diameter in patients with chronic liver disease in northeastern Nigeria

INTRODUCTION

Chronic liver disease is a public health burden worldwide. Portal hypertension is a major portosystemic abnormality in chronic liver disease. This study aimed to determine the main, right, and the left portal vein diameter in patients with chronic liver disease.

MATERIALS AND METHODS

A cross-sectional study was carried out at the Abubakar Tafawa Balewa University Teaching Hospital, Bauchi, northeastern Nigeria from December 2018 to September 2019. Ethical clearance was obtained from the institutional review board. A total of 200 subjects were recruited comprising 100 patients with chronic liver disease and 100 age-matched controls, aged 18 years and above. A transabdominal ultrasound scan was carried out measuring the main, right, and left portal vein diameter while lying supine and/or in the right anterior oblique position after overnight fasting, or 6 hours before the scan. Data analysis was done using SPSS version 22.0. Descriptive statistics (mean, standard deviation) and Pearson's correlation were used.

RESULTS

There were 106(53%) males and 94(47%) females, aged between 18 and 73 years with a mean age of 46.79 ± 15.43. The main, right, and left portal vein diameter in patients with chronic liver disease was 14.51 ± 0.78 mm, 6.83 ± 0.81 mm, and 6.26 ± 0.74 mm, which were higher than those of their control. The portal vein diameter positively correlated (weak) with age and respiratory phases among participants (P < 0.05).

CONCLUSION

This study found the main, right, and left portal vein diameter among patients with chronic liver disease to be larger than those of the controls. Ultrasonography is a reliable diagnostic tool in evaluating portosystemic pathologies.

Texture Analysis of Gray-Scale Ultrasound Images for Staging of Hepatic Fibrosis

Purpose

Materials and Methods

Results

Conclusion

Combination of shear-wave elastography with ultrasonography for detection of breast cancer and reduction of unnecessary biopsies: a systematic review and meta-analysis

Purpose

This study was undertaken to compare the diagnostic performance and biopsy reduction rate of combined shear-wave elastography (SWE) and B-mode ultrasonography (US) versus B-mode US alone for breast lesions and to determine the most discriminatory parameter in SWE.

Methods

A systematic review and meta-analysis were conducted. The resources for the study were obtained from MEDLINE, Embase, Cochrane Library, and KoreaMed on August 17, 2018. The quality of the articles was evaluated using the Scottish Intercollegiate Guidelines Network (SIGN) tool.

Results

Twenty-five articles with 5,147 breast lesions were selected. The meta-analysis showed pooled sensitivities of 0.94 and 0.97 (P=0.087), pooled specificities of 0.85 and 0.61 (P=0.009), and area under the receiver operating characteristic curve (AUC) of 0.96 and 0.96 (P=0.095) for combined SWE and B-mode US versus B-mode US alone. When SWE was combined with B-mode US, the Breast Imaging Reporting and Data System category changed from 4 to 3 in 71.3% of the tests, decreasing the frequency of unnecessary biopsies by 41.1%. All four parameters of SWE (the color grade of lesion stiffness, maximum elasticity, mean elasticity, and color grade of lesion stiffness/homogeneity of the lesion) improved the specificity when they were added to B-mode US. The AUC for each SWE parameter was 0.99, 0.96, 0.96, and 0.93, respectively.

Conclusion

Adding SWE to B-mode US not only provides additional diagnostic information for differentiating between benign and malignant breast lesions, but also decreases the likelihood of unnecessary biopsies.

Role of shear wave sono-elastography (SWE) in characterization of hepatic focal lesions

Background

Focal liver lesions are considered a major problem during abdominal examinations. Shear wave sono-elastography (SWE) has been demonstrated to be helpful in assessment of liver fibrosis degree.

The purpose of this study was to evaluate the role of SWE in characterization of benign and malignant hepatic focal lesions.

Results

Seventy-five (75) patients with variable focal liver lesions (52 malignant and 23 benign) were analyzed by SWE. The stiffness values of surrounding hepatic parenchyma were also measured as a reference for readings of the focal lesion stiffness values. Final diagnosis was achieved by core needle biopsy (in 1 benign and 38 malignant cases) and contrast enhanced CT and MRI (in all cases).

Cholangiocarcinoma (CCC) was the stiffest malignant lesion with median stiffness value (35.9 kPa). Focal nodular hyperplasia (FNH) was the stiffest benign lesion (26.7 kPa).

The median stiffness value of malignant focal lesions (20.22 kPa) was significantly higher than that of benign focal lesions (10.68 kPa) (P value < 0.001).

ROC curve of SWE median stiffness values for differentiation of benign from malignant hepatic focal lesions had AUC = 0.834, and using cut of value 14.165 kPa, yielding 98.1% sensitivity, 78.3% specificity, and 92% accuracy.

Conclusion

SWE has high accuracy in differentiating benign form malignant liver focal lesions with promising results in individual characterization of some malignant (HCC and CCC) and benign hepatic focal lesion (FNH from other benign lesions).

Systematic Review of Instrumented Measures of Skeletal Muscle Mechanical Properties: Evidence for the Application of Shear Wave Elastography with Children

The aim of this review was to identify instrumented devices that quantify skeletal muscle mechanical properties and to evaluate their potential clinical utility and clinimetric evidence with respect to children. Four databases were searched to identify articles reporting original clinimetric data for devices measuring muscle stiffness or elastic modulus, along a muscle's main fibre direction. Clinimetric evidence was rated using the Consensus-Based Standard for the Selection of Measurement Instruments (COSMIN) checklist. Sixty-five articles provided clinimetric data for two devices meeting our criteria: the Aixplorer and the Acuson. Both are shear wave elastography devices that determine the shear modulus of muscle tissue. The Aixplorer had strong construct validity and reliability, and the Acuson, moderate construct validity and reliability. Both devices have sound clinical utility with non-invasive application at various joint positions and data acquisition in real time, minimizing fatigue. Further research is warranted to evaluate utility for children with specific disorders of abnormal muscle structure or function.

Two-Dimensional-Shear Wave Elastography with a Propagation Map: Prospective Evaluation of Liver Fibrosis Using Histopathology as the Reference Standard

Objective

The aim of this study was to prospectively evaluate whether liver stiffness (LS) assessments, obtained by two-dimensional (2D)-shear wave elastography (SWE) with a propagation map, can evaluate liver fibrosis stage using histopathology as the reference standard.

Materials and Methods

We prospectively enrolled 123 patients who had undergone percutaneous liver biopsy from two tertiary referral hospitals. All patients underwent 2D-SWE examination prior to biopsy, and LS values (kilopascal [kPa]) were obtained. On histopathologic examination, fibrosis stage (F0–F4) and necroinflammatory activity grade (A0–A4) were assessed. Multivariate linear regression analysis was performed to determine the significant factors affecting the LS value. The diagnostic performance of the LS value for staging fibrosis was assessed using receiver operating characteristic (ROC) analysis, and the optimal cut-off value was determined by the Youden index.

Results

Reliable measurements of LS values were obtained in 114 patients (92.7%, 114/123). LS values obtained from 2D-SWE with the propagation map positively correlated with the progression of liver fibrosis reported from histopathology (p < 0.001). According to the multivariate linear regression analysis, fibrosis stage was the only factor significantly associated with LS (p < 0.001). The area under the ROC curve of LS from 2D-SWE with the propagation map was 0.773, 0.865, 0.946, and 0.950 for detecting F ≥ 1, F ≥ 2, F ≥ 3, and F = 4, respectively. The optimal cut-off LS values were 5.4, 7.8, 9.4, and 12.2 kPa for F ≥ 1, F ≥ 2, F ≥ 3, and F = 4, respectively. The corresponding sensitivity and specificity of the LS value for detecting cirrhosis were 90.9% and 88.4%, respectively.

Conclusion

The LS value obtained from 2D-SWE with a propagation map provides excellent diagnostic performance in evaluating liver fibrosis stage, determined by histopathology.

Toward Quantitative and Operator-independent Quasi-static Ultrasound Elastography: An Ex Vivo Feasibility Study

It is known that the elasticity of liver reduces progressively in the case of diffuse liver disease. Currently, the diagnosis of diffuse liver disease requires a biopsy, which is an invasive procedure. In this paper, we evaluate and report a noninvasive method that can be used to quantify liver stiffness using quasi-static ultrasound elastography approach. Quasi-static elastography is popular in clinical applications where the qualitative assessment of relative tissue stiffness is enough, whereas its potential is relatively underutilized in liver imaging due to lack of local stiffness contrast in the case of diffuse liver disease. Recently, we demonstrated an approach of using a calibrated reference layer to produce quantitative modulus elastograms of the target tissue in simulations and phantom experiments. In a separate work, we reported the development of a compact handheld device to reduce inter- and intraoperator variability in freehand elastography. In this work, we have integrated the reference layer with a handheld controlled compression device and evaluate it for quantitative liver stiffness imaging application. The performance of this technique was assessed on ex vivo goat liver samples. The Young's modulus values obtained from indentation measurements of liver samples acted as the ground truth for comparison. The results from this work demonstrate that by combining the handheld device along with reference layer, the estimated Young's modulus value approaches the ground truth with less error compared with that obtained using freehand compression (8% vs. 15%). The results suggest that the intra- and interoperator reproducibility of the liver elasticity also improved when using the handheld device. Elastography with a handheld compression device and reference layer is a reliable and simple technique to provide a quantitative measure of elasticity.

Test-retest repeatability of ultrasonographic shear wave elastography in a rat liver fibrosis model: toward a quantitative biomarker for preclinical trials

PURPOSE

This study evaluated the test-retest repeatability and measurement variability of ultrasonographic shear wave elastography (SWE) for liver stiffness in a rat liver fibrosis model.

METHODS

In 31 Sprague-Dawley rats divided into three groups (high-dose, low-dose, and control), liver fibrosis was induced by intraperitoneal administration of thioacetamide for 8 weeks. A dedicated radiographer performed SWE to measure liver stiffness in kilopascals in two sessions at a 3-day interval. We calculated correlations between liver stiffness and histopathologic results, measurement variability in each session using coefficients of variation (CoVs) and interquartile/median (IQR/M), and test-retest repeatability between both sessions using the repeatability coefficient.

RESULTS

Different levels of liver fibrosis in each group were successfully induced in the animal model. The mean liver stiffness values were 8.88±1.48 kPa in the control group, 11.62±1.70 kPa in the low-dose group, and 11.91±1.73 kPa in the high-dose group. The correlation between collagen areas and liver stiffness values was moderate (r=0.6). In all groups, the second session yielded lower CoVs (i.e., more reliable results) for liver stiffness than the first session, suggesting a training effect for the operator. The mean IQR/M values were also lower in the second session than in the first session, which had four outliers (0.21 vs. 0.12, P<0.001). The test-retest repeatability coefficient was 3.75 kPa and decreased to 2.82 kPa after removing the four outliers.

CONCLUSION

The use of ultrasonographic SWE was confirmed to be feasible and repeatable for evaluating liver fibrosis in preclinical trials. Operator training might reduce variability in liver stiffness measurements.

Impact of respiratory motion on liver stiffness measurements according to different shear wave elastography techniques and region of interest methods: a phantom study

Purpose

This study quantified the impact of respiratory motion on liver stiffness measurements according to different shear wave elastography (SWE) techniques and region of interest (ROI) methods, using liver fibrosis phantoms.

Methods

Three operators measured stiffness values in four phantoms with different stiffness on a moving platform with two SWE techniques (point-SWE [pSWE] and 2-dimensional SWE [2D-SWE]), three types of motion (static mode and moving mode at low and high speeds), and four ROI methods in 2D-SWE (circle, point, box, and multiple). The circular ROI method was used to compare the two SWE techniques. The occurrence of technical failure and unreliable measurements, stiffness values, and measurement time were evaluated.

Results

Technical failure was observed only in moving mode for pSWE and 2D-SWE (n=1 for both). Unreliable measurements were also only observed in moving mode and were significantly less common in 2D-SWE (n=1) than in pSWE (n=12) (P<0.001). No statistically significant differences in the technical failure rate or stiffness values were noted between the static and moving modes for both SWE techniques. The technical failure and unreliable measurement rates were not significantly different among the ROI methods for 2D-SWE. Stiffness values did not differ significantly according to the ROI method used in any moving mode. However, the multiple ROI method had significantly shorter measurement times than the circular ROI method for all moving modes.

Conclusion

2D-SWE may be preferable for evaluating liver fibrosis in patients with poor breath-hold. Furthermore, 2D-SWE with multiple ROIs enables rapid measurements, without affecting liver stiffness values.

Does Operator Experience and the Q-Box Diameter Affect the Repeatability of Liver Stiffness Measurements Obtained by 2-Dimensional Shear Wave Elastography?

OBJECTIVES

The purpose of this research was to evaluate whether operator experience and the quantitative analysis system (Q-Box; SuperSonic Imagine, Aix-en-Provence, France) diameter affect the repeatability of liver stiffness measurements.

METHODS

We enrolled 417 outpatients. All measurements were performed by 2 operators, including an expert and a novice. Each patient was continuously measured 3 times by the 2 operators. The Q-Box diameter was adjusted to 10, 20, and 30 mm each time, and the mean elasticity values were recorded. Intraobserver repeatability was evaluated by the intraclass correlation coefficient (ICC). Interobserver repeatability was evaluated by the ICC, coefficient of variation (CV), and Bland-Altman plots.

RESULTS

The study group included 241 male and 176 female patients. The expert operator had higher ICCs than the novice operator at each Q-Box diameter. The overall interobserver agreement was excellent, and the results showed that compared to other groups, the ICC was the lowest and the CV was the largest for the 30-mm-diameter group. The ICC and CV values were similar between the 10- and 20 mm-diameter groups. The Bland-Altman plots showed that the mean difference was -0.2 kPa for the 10-, 20-, and 30 mm-diameter groups. However, the limits of agreement were the largest in the 30-mm-diameter group and were similar between the 10- and 20-mm-diameter groups.

CONCLUSIONS

The repeatability of liver stiffness measurements is affected not only by experience but also by the Q-Box diameter.

Wisteria floribunda agglutinin-positive human Mac-2-binding protein as a predictive marker of liver fibrosis in human immunodeficiency virus/hepatitis C virus coinfected patients

AIM

In human immunodeficiency virus (HIV) and hepatitis C virus (HCV) coinfected patients, the progression of liver failure is reported to be more aggressive than that in HCV mono-infected patients. Wisteria floribunda agglutinin-positive human Mac-2-binding protein (WFA⁺ -M2BP) is well recognized as a liver fibrosis glycobiomarker with a unique fibrosis-related glycoalteration. We analyzed HIV/HCV coinfected patients' M2BP levels as a possible marker for predicting liver fibrosis.

METHODS

M2BP was measured in 31 HIV/HCV coinfected patients, and we analyzed the correlation between WFA⁺ -M2BP and several markers of fibrosis, liver function, and tumor markers. We compared the WFA⁺ -M2BP levels in HIV/HCV coinfected patients with those of HCV mono-infected patients by performing a propensity score matching analysis.

RESULTS

In the HIV/HCV coinfected patients, the serum level of WFA⁺ -M2BP was well correlated with the markers type IV collagen, hyaluronic acid, and alpha-fetoprotein, but not protein induced by vitamin K absence-II. In the propensity score matching with HCV mono-infected patients, the WFA⁺ -M2BP levels were significantly higher in the HIV/HCV coinfected patients compared with the levels in the HCV mono-infected patients.

CONCLUSION

In conclusion, WFA⁺ -M2BP might be a feasible predictive marker of fibrosis in HIV/HCV coinfected patients.

Comparison of point and 2-dimensional shear wave elastography for the evaluation of liver fibrosis

PURPOSE

This study aimed to assess the technical performance of ElastQ Imaging compared with ElastPQ and to investigate the correlation between liver stiffness (LS) values obtained using these two techniques.

METHODS

This retrospective study included 249 patients who underwent LS measurements using both ElastPQ and ElastQ Imaging equipped on the same machine. The applicability, repeatability (coefficient of variation [CV]), acquisition time, and LS values were compared using the chi-square or Wilcoxon signed-rank tests. In the development group, the correlation between the LS values obtained by the two techniques was assessed with Spearman correlation coefficients and linear regression analysis. In the validation group, the agreement between the estimated and real LS values was evaluated using a Bland-Altman plot.

RESULTS

ElastQ Imaging had higher applicability (94.0% vs. 78.3%, P<0.001) and higher repeatability, with a lower median CV (0.127 vs. 0.164, P<0.001) than did ElastPQ. The median acquisition time of ElastQ Imaging was significantly shorter than that of ElastPQ (45.5 seconds vs. 96.5 seconds, P<0.001). The median LS value obtained using ElastQ Imaging was significantly higher than that obtained using ElastPQ (5.60 kPa vs. 5.23 kPa, P<0.001). The LS values between the two techniques exhibited a strong positive correlation (r=0.851, P<0.001) in the development group. The mean difference and 95% limits of agreement were 0.0 kPa (-3.9 to 3.9 kPa) in the validation group.

CONCLUSION

ElastQ Imaging may be more reliable and faster than ElastPQ, with strongly correlated LS measurements.

Effect of acquisition depth and precompression from probe and couplant on shear wave elastography in soft tissue: an in vitro and in vivo study

BACKGROUND

Shear wave elastography is a promising method to diagnose early musculoskeletal lesions. We aimed to explore the feasible depth and acceptable precompression applied by probe and couplant for soft tissues in the present system.

METHODS

Ex-vivo muscles were evaluated at depths of 0.5-6 cm by 3 operators, using 1-5 mm couplant thickness and 0-3.0 kPa probe pressure. We compared the shear wave speed (SWS) and used intraclass correlation coefficients to assess reproducibility. In vivo skin and subcutaneous superficial fascia from volunteers were tested at depths ranging from 0.1-0.5 cm with 1-20 mm couplant thickness.

RESULTS

The SWS of ex-vivo muscles varied and increased with depth, and could not be acquired at 6 cm because the shear wave failed to be detected. Furthermore, while the SWS of ex-vivo muscles were not affected by the couplant thickness, it was affected by probe pressure. Most cases demonstrated a satisfactory agreement degree of the intraoperator reproducibility (ICC, 0.81-0.95) and a substantial interoperator reproducibility (ICC >0.60). Inter- and intra-operator reproducibility was better at a depth of 0.5-4 cm than at 5 cm. In the in vivo study, when tissues within a 0.2 cm depth were evaluated, the SWS that was acquired using a couplant thickness of >10 mm was different from that acquired using other thicknesses.

CONCLUSIONS

The SWS acquired at a depth of ≤3 cm with a suitable amount of couplant is recommended.

Ultrasound shear wave elastography and liver biopsy to determine liver fibrosis in adult patients

Introduction:

Liver biopsy is considered as the gold standard for diagnosis of chronic liver disease, yet liver biopsy is an invasive method that may be associated with complications. Therefore, non-invasive methods are needed to diagnose fibrosis. This study was conducted to compare liver stiffness measured by Shear-wave Elastography (SWE) to fibrosis in liver biopsy.

Method and Materials:

In this prospective study, 176 adult patients with chronic liver disease of different etiologies were included. All patients were evaluated using SWE and a liver biopsy. The diagnostic accuracy of SWE was evaluated using receiver operating characteristics (ROC) plots based on the degree of fibrosis (METAVIR score). SPSS software version 19 was used for statistical analysis and P < 0.05 considered significant.

Results:

There was a significant correlation between liver stiffness and fibrosis stage (ρ=0.939; P < 0.0001). The ROC curve AUC were 0.871, 0.895 and 0.937 for fibrosis stages F2, F3 and F4 respectively. The cutoff values were 8.6 kPa for F2, 10.7 kPa for F3, and 13.8 kPa for F4, with sensitivity and specificity of 81.76% and 77.01%, 90.20% and 78.40%, 89.53% and 94.38% respectively.

Conclusion:

The results of this study showed that liver SWE is an effective non-invasive method for assessing liver fibrosis in patients with chronic liver disease of different etiologies.

Liver stiffness as a predictor of hepatocellular carcinoma behavior in patients with hepatitis C related liver cirrhosis

BACKGROUND

Risk stratification and prognostication of hepatocellular carcinoma (HCC) help to improve patient outcome. Herein we investigated the role of liver stiffness measurement (LSM) in the prediction of HCC behavior.

METHODS

Totally 121 naïve patients with HCC were included. HCC radiological evaluation and staging were done. LSM was measured using virtual touch quantification. Patients were divided into early to intermediate HCC (BCLC-0, A and B) and late HCC (BCLCC and D). HCC was treated according to the BCLC stage. HCC recurrence-free interval was estimated.

RESULTS

The mean LSM inside the tumor was significantly lower than the peri-tumoral area and the cirrhotic non-cancerous liver parts (P < 0.001). In late HCCs stage, the mean LSM inside the tumor and in the peri-tumoral tissue was lower than the corresponding values in the early to intermediate HCCs stage (P < 0.001). LSM inside the tumor and in the peri-tumoral tissue negatively correlated with serum AFP, tumor vascular invasion, and stage (P < 0.05). The recurrence-free interval was directly correlated to LSM inside the tumor and inversely to LSM in cirrhotic non tumorous liver part. Kaplan-Meier analysis showed that the recurrence-free interval was significantly longer in patients with LSM inside the tumor of ≥1.25 m/s compared to those with LSM inside the tumor of <1.25 m/s.

CONCLUSIONS

LSM can serve as a potential non-invasive predictor for HCC clinical behavior and the recurrence-free interval following loco-regional treatments.

Combined effect of hepatic venous pressure gradient and liver stiffness on long-term mortality in patients with cirrhosis

BACKGROUND/AIMS

Both hepatic venous pressure gradient (HVPG) and liver stiffness (LS) are useful tools for predicting mortality in patients with cirrhosis. We investigated the combined effect of HVPG and LS on long-term mortality in patients with cirrhosis.

METHODS

We retrospectively collected data from 103 patients with cirrhosis, whose HVPG and LS were measured between November 2009 and September 2013. The patients were divided into four groups according to the results of the HVPG and LS measurements. Long-term mortality and the risk factors for mortality were analyzed.

RESULTS

Of the 103 patients, 35 were in group 1 (low HVPG and low LS), 16 in group 2 (high HVPG and low LS), 24 in group 3 (low HVPG and high LS), and 28 in group 4 (high HVPG and high LS). Over a median follow-up of 47.3 months, 18 patients died. The mortality rate of patients in group 4 was significantly higher than in the other three groups (vs. group 1, p = 0.005; vs. group 2, p = 0.049; vs. group 3, p = 0.004), but there were no significant differences in survival between groups 1, 2, and 3. In multivariable analyses, both HVPG and LS were identified as independent risk factors for mortality (hazard ratio [HR], 1.127, p = 0.018; and HR, 1.062, p = 0.009, respectively).

CONCLUSION

In patients with cirrhosis, those with concurrent elevation of HVPG and LS had the highest long-term mortality rates. However, when either HVPG or LS alone was elevated, mortality did not increase significantly.

Ultrasound elastography as a potential diagnostic aid in oral submucous fibrosis

Background

Oral submucous fibrosis (OSMF) is a well-recognized "potentially malignant" disorder. It mostly affects the productive population of young adults and adolescents. The diagnosis of oral submucous fibrosis is primarily clinical and subjective. The only objective diagnostic method for OSMF is tissue biopsy. This study was conducted to find the potential use of ultrasound elastography to objectively quantify the clinical presentation in accordance with severity of the clinical condition in OSMF.

Materials and Methods

The study sample consisted of 27 clinically diagnosed and staged participants with OSMF. Transcutaneous ultrasonography was done by a single operator on GE Logiq E9 machine with a 6-15 MHz linear matrix probe. Color-coded scheme was used to qualitatively grade the eight different zones of oral mucosa with the use of stress-strain elastography. The grades ranged from 0 to 5, where 0 represented artifacts and color range from red to blue corresponded to varying degree of increasing tissue stiffness. Clinical stage 1, 2, and 3 corresponded to mouth opening of >30 mm, 20-30 mm, and <20 mm, respectively. The summative elastography score range as follows: 8-10, 11-14, and ≥15 represented the respective degree of tissue stiffness from soft, mild stiff to severe stiff.

Results

The results obtained by Pearson's correlation between the elastographic grading and clinical grading came out to be 0.007, and it was highly significant. The sensitivity and specificity of the diagnostic method were 90.9% and 20%, respectively.

Conclusion

The advantages of ultrasound elastography as a diagnostic tool over the subjective clinical method of diagnosis and staging of OSMF looks promising. Further studies should be conducted with a suitable specific transducer probe and with quantitative diagnostic elastography method.

Radiological Advances in Pancreatic Islet Transplantation

Type 1 diabetes mellitus (T1DM) is characterized by hyperglycemia, owing to the loss of pancreatic β cells in response to an autoimmune reaction leading to a state of absolute insulin deficiency. T1DM treatment is shifting from exogenous insulin replacement therapy toward pancreatic β-cell replacement, to restore physiologically responsive insulin secretion to variations in blood glucose levels. β-cell replacement strategies include human whole pancreas transplantation, islet transplantation with cell encapsulation and bioengineered pancreas. Interventional radiology and imaging modalities including positron emission tomography, single-photon emission computed tomography, magnetic resonance imaging, ultrasonography, and molecular imaging are imperative to enable successful β-cell replacement. Herein, the role of radiological modalities in the treatment of T1DM and its prospective use for noninvasive post-transplantation graft monitoring is discussed.

Bariatric Surgery as an Efficient Treatment for Non-Alcoholic Fatty Liver Disease in a Prospective Study with 1-Year Follow-up : BariScan Study

BACKGROUND

Bariatric surgery gains attention as a potential treatment for non-alcoholic fatty liver disease (NAFLD). The present study aimed to evaluate improvement of NAFLD after the two most common bariatric procedures with validated non-invasive instruments.

MATERIAL AND METHODS

N = 100 patients scheduled for laparoscopic sleeve gastrectomy (LSG) or Roux-en-Y gastric bypass (RYGB) were included. NAFLD was evaluated preoperatively and postoperatively with liver stiffness measurement by transient elastography and laboratory-based fibrosis scores. Clinical data included body mass index (BMI), total weight loss (%TWL), excess weight loss (%EWL), age, gender, comorbidities, and the Edmonton obesity staging system (EOSS).

RESULTS

There were significant improvements of BMI, %TWL, %EWL, and EOSS after bariatric surgery. Liver stiffness was significantly improved from pre- to postoperative (12.9 ± 10.4 vs. 7.1 ± 3.7 kPa, p < 0.001) at median follow-up of 12.5 months. Additionally, there were significant improvements of liver fibrosis scores (aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio 0.8 ± 0.3 vs. 1.1 ± 0.4, p < 0.001; NAFLD fibrosis score - 1.0 ± 1.8 vs. - 1.7 ± 1.3, p < 0.001; APRI score 0.3 ± 0.2 vs. 0.3 ± 0.1, p = 0.009; BARD score 2.3 ± 1.2 vs. 2.8 ± 1.1, p = 0.008) and laboratory parameters (ALT, AST, and GGT). After adjustment for baseline liver stiffness, RYGB showed higher improvements than LSG, and there was no gender difference. Improvement of liver stiffness was not correlated to improvement of BMI, %TWL, %EWL, or EOSS.

CONCLUSIONS

NAFLD seems to be improved by bariatric surgery as measured by validated non-invasive instruments. Furthermore, it appears that RYGB is more effective than LSG. No correlation could be detected between NAFLD and weight loss. The present study highlights the potential of bariatric surgery for successful treatment of NAFLD. Further research is required to understand the exact mechanisms.

Patchy echogenicity of the liver in patients with chronic hepatitis B does not indicate poorer elasticity

PURPOSE

This study was conducted to investigate whether the presence of patchy echogenicity in the liver of patients with chronic hepatitis B (CHB) is predictive of liver stiffness.

METHODS

A total of 200 CHB patients with and without patchy echogenicity of the liver were assigned to two groups, with 100 patients in each group, and 32 of them underwent liver biopsy. Additionally, 80 healthy subjects, 100 inactive HBV carriers, and 100 patients with decompensated hepatic cirrhosis were assigned to the control groups. Laboratory tests and clinical data were collected, and shear wave velocity (SWV) of the liver was measured for all 480 subjects.

RESULTS

The median SWV in patients with a normal liver, inactive hepatitis B virus carriers, CHB patients with and without patchy echogenicity, and decompensated hepatic cirrhosis were 1.07 m/sec, 1.08 m/sec, 1.16 m/sec, 1.16 m/sec, and 2.02 m/sec, respectively; there was no significant difference in SWV values between CHB patients with patchy echogenicity and those without patchy echogenicity. Furthermore, among CHB patients with and without patchy echogenicity, no significant difference in SWV was found according to fibrosis stage.

CONCLUSION

The presence of patchy echogenicity of the liver does not indicate a higher degree of liver stiffness.

Abdominal Wall Thickness Affects Liver Stiffness Measurements by 2-D Shear Wave Elastography in Patients with Chronic Liver Disease

This study was conducted to define the effect of abdominal wall thickness (AWT) and its composition on the level of confidence in liver stiffness (LS) measurements obtained with 2-D shear wave elastography (2-D-SWE) in patients with chronic liver disease. In this retrospective study, a total of 1291 patients who underwent LS measurement by 2-D-SWE were enrolled. The abdominal wall was divided into three layers: layer 1 extended from the skin to the subcutaneous fat layer; layer 2 was the muscle layer; and layer 3 extended from the peritoneum to the liver capsule (including the omental fat layer, if present). We regarded the sums of layers 1-3 and layers 1 and 3 as the AWT and non-muscular layer thickness (NMT). Age/sex/body mass index-adjusted multivariate logistic regression analysis was performed to identify factors influencing the level of confidence of LS measurements. Three hundred eighty-six patients (29.9%) were classified in the unreliable LS group (standard deviation/median LS > 0.1). The fourth quartile of AWT and third and fourth quartiles of NMT/AWT were significantly associated with unreliable LS values (odds ratios = 2.103, 1.753 and 1.695, respectively). In conclusion, high AWT and NMT/AWT ratios reduce the confidence in LS measurements obtained with 2-D-SWE.

Normal Changes and Ranges of Pediatric Testicular Volume and Shear Wave Elasticity

To determine normal ranges for pediatric testicular volume and stiffness values (SV) on ultrasonography (US) and shear wave elastography (SWE) with respect to age and weight, testicular US scans (including SWE) of children (<10 y old) performed from February 2015 to January 2017 were retrospectively reviewed; grossly normal testes or testes with small hydroceles were included. Correlations between age weight, and testicular volume or SV were evaluated. Among a total of 52 boys (1-92 mo, median = 23.5 mo), there were positive correlations between testicular volume and age (R² = 0.451, p < 0.001) and weight (R² = 0.515, p < 0.001). Testicular SV was negatively correlated with age (R² = 0.166, p = 0.051) and weight (R² = 0.372, p = 0.049). Therefore, SV decreases while volume increases with increasing weight in testes of healthy children. Normal ranges for testicular volume and SV in children younger than 10 y are reported.

Pediatric Fontan Associated Liver Disease: Non-invasive Evaluation with Serologic Markers and Acoustic Radiation Force Impulse (ARFI) Elastography

Hepatic fibrosis is a significant complication in adult Fontan patients suggesting development as a function of time since the surgery. Children with Fontan circulation are not routinely assessed for development of liver disease. We aimed to evaluate the effectiveness of serologic biomarkers and acoustic radiation force impulse (ARFI) elastography to detect liver disease in pediatric Fontan patients. Patients ≥ 1 year after Fontan operation prospectively had hepatic US with acoustic radiation force impulse and laboratory testing. Clinical cardiac data (echocardiograms, cardiac catheterizations) were reviewed. Statistical analysis was performed using Pearson's correlation coefficient, Wilcoxon rank-sum test and Kruskal-Wallis test. Forty patients were enrolled with median age of 11 years and median time since Fontan of 6.5 years. Platelet count negatively correlated with years since Fontan (p < 0.000). Thrombocytopenia was noted in 15% of patients with the lowest platelet count of 78 K/cu mm, in a patient >10 years from the Fontan (DORV) operation. Alanine transaminase (ALT, p = 0.034) and aspartate aminotransferase (AST, p = 0.009) were higher in patients with Extracardiac Conduit Fontan and not in other Fontan operations. Heterogeneous echotexture on liver ultrasound correlated with years since Fontan (p = 0.022), however all acoustic radiation force impulse values were elevated (> 1.34 m/s) and did not correlate with age, years since Fontan, labs or imaging. FibroSure values did not correlate with years since Fontan. This suggests that ARFI may be elevated due to passive hepatic congestion, limiting its value in this patient population. Additional testing is necessary to identify reliable noninvasive screening modalities for hepatic fibrosis in Fontan patients. Our study is the largest pediatric study to evaluate ARFI in patients after the Fontan operation and showed increased shear wave speed for all patients with no correlation with time since palliation. Decreasing platelet count may indicate the development of liver fibrosis.

Prognostic values of shear wave elastography in adolescent boys with varicocele

INTRODUCTION

Shear wave elastography is an ultrasound technique for non-invasive quantification of tissue stiffness. It was used in assessing testis elasticity in some scrotal abnormalities, such as undescended pediatric testes or adult varicocele testes. In this study, its usefulness in adolescent patients with varicocele was examined.

OBJECTIVE

The aim of this study was to quantify elasticity of testes with the use of elastography and comparison of the results with typical threshold values used in varicocele management in adolescent patients with varicoceles.

STUDY DESIGN

In 30 patients with clinically diagnosed left varicoceles, quantitative 2D shear wave imaging of varicocele testes and contralateral ones were performed.

RESULTS

The relationships between the grade of varicocele and elastography were calculated. The stiffness was 2.5 ± 0.49 kPa in testes with grade I of varicocele, 2.59 ± 0.81 in grade II and 2.80 ± 0.72 kPa in grade III. In contralateral testes, it was respectively grade I 2.39 ± 0.49 kPa, grade II 2.41 ± 0.61 kPa, and grade III 2.42 ± 0.85 kPa. The statistical significance was close to importance in grade III (P = 0.153). There was a statistically significant difference between elastography results in patients with volume difference over 20%. In testes with varicocele, it was 2.77 ± 0.75 kPa and in contralateral testes, 2.37 ± 0.65 kPa (P < 0.05). In patients with testis volume difference between 0 and 20%, elastography results were comparable, and it was 2.45 ± 0.57 kPa in testes with varicocele and 2.44 ± 0.61 kPa in contralateral testes (Table).

DISCUSSION

Ultrasound is currently the most widely used imaging technique for the assessment of varicocele, but its role in the diagnostic algorithm is still controversial. Therefore, many attempts are made to determine the manifestations of testicular damage that precede morphological deterioration, which could increase the importance of imaging techniques in treatment planning.

CONCLUSION

The changes of tissue elasticity due to varicocele seem to confirm the need of surgery in patients with testis volume difference more than 20% and in grade III of varicocele (Table). In case of validation of diffuse testis changes, they could indicate the need for surgery also in other stages.

Diagnostic performance of a point shear wave elastography (pSWE) for hepatic fibrosis in patients with autoimmune liver disease

BACKGROUND & AIMS

Elastography point quantification is a convenient method for measuring liver stiffness. It can be performed simultaneously with conventional ultrasonography. This study aimed to evaluate its diagnostic performance for assessing hepatic fibrosis in patients with autoimmune liver disease (AILD), including autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC).

METHODS

The diagnostic performance of elastography point quantification (ElastPQ) was evaluated and compared with that of serum fibrosis markers, including the aspartate aminotransferase to platelet ratio index (APRI) and fibrosis-4 (FIB-4), using the receiver operating characteristics analysis with histologic evaluation as the reference standard.

RESULTS

In 49 AIH patients, sensitivity and specificity of ElastPQ were 93.6% and 44.4%, respectively, for significant fibrosis (≥ F2, cutoff 4.47 kPa), and 63.6% and 86.8% for cirrhosis (F4, cutoff 9.28 kPa). In 41 PBC patients, they were 81.8% and 73.3%, respectively, for significant fibrosis (≥ F2, cutoff 5.56 kPa), and 100% and 81.6%, respectively, for advanced fibrosis (≥ F3, cutoff 6.04 kPa). The areas under the receiver operating characteristic curves of ElastPQ for significant fibrosis (0.77, 95% CI 0.67-0.86) and cirrhosis (0.81, 95% CI 0.65-0.96) were higher than those of APRI and FIB-4 in AILD patients. According to the multivariable analysis, histological activity, steatosis, and body max index (BMI) were not significant factors that influenced the result of ElastPQ.

CONCLUSIONS

ElastPQ exhibited better diagnostic performance-without the influence of confounding factors-for assessing hepatic fibrosis in AILD patients than serum fibrosis markers.

Towards quantitative quasi-static ultrasound elastography using a reference layer for liver imaging application: A preliminary assessment

Changes in tissue elasticity are generally correlated with pathological phenomena. For example, diffuse liver disease progressively reduces the elasticity of the liver. Quasi-static elastography is popular in clinical applications to visualize regions with different relative stiffness. However, the limitation of this technique is that it provides only qualitative information. To overcome this, we investigate the use of a calibrated reference layer, sandwiched between the transducer and the tissue surface, to quantitatively image the unknown modulus of the examined tissue. The performance of the method was studied through simulations and experiments on agar-gelatin phantoms having Young's modulus within a range appropriate for the liver application. Furthermore, we explored the translational capability of the proposed method to work with existing commercially-available ultrasound scanners having elastography option. The Young's modulus value of the phantom estimated from quantitative elastography in simulation and experiment was compared against the corresponding ground-truth modulus value obtained from COMSOL and Universal Testing Machine (UTM) results, respectively. The results obtained for the compressive elastic modulus of the underlying phantom using quasi-static ultrasound elastography was found to be within 6% and 11% in simulation and experiments, respectively, to the corresponding ground-truth values.

The relationship of spleen stiffness value measured by shear wave elastography with age, gender, and spleen size in healthy volunteers

PURPOSE

The aim of this study is to evaluate spleen stiffness values with shear wave elastography (SWE) quantitatively in healthy adults and investigate the relationship of spleen stiffness with age, gender, and spleen size.

METHODS

This study included 65 healthy individuals. Spleen stiffness measurement was obtained with 2 dimensional (2-D) SWE method from the middle portion of spleen and calculated in kilopascals by taking the average of three valid measurements. Longitudinal and transverse spleen sizes were measured. The relationship of spleen stiffness with age, gender, and spleen size was investigated. The association between spleen size and age and gender was also evaluated.

RESULTS

The mean spleen stiffness value was 13.82 ± 2.91 kPa, and the spleen stiffness was not affected by age, gender, or spleen size. Longitudinal spleen size was significantly lower in females than that in males. Moreover, there was a significant negative correlation between longitudinal spleen size and age (r = 0.247, p = 0.048).

CONCLUSION

Spleen stiffness can be quantitatively measured by 2-D SWE, and the spleen stiffness is not affected by age, gender, and spleen size. The values obtained in this study can be used as normal base values in examination of different spleen pathologies.

NAFLD evaluation: Which is more appropriate, multislice computed tomography or ultrasound real-time shear wave elastography?

OBJECTIVE

This study aims to assess the value of ultrasound real-time shear wave elastography (US-SWE) for evaluation of nonalcoholic fatty liver disease (NAFLD) in a rabbit model compared with multislice computed tomography (MSCT).

MATERIAL AND METHODS

Twenty-six rabbits were fed with high-fat, high-cholesterol diet and six rabbits were fed with a standard diet. All rabbits were performed with MSCT and US-SWE at various time points to measure changes in liver parenchyma. The diagnostic efficiency of US-SWE was analyzed using receiver operating characteristics (ROC) curves compared with MSCT based on the liver pathology.

RESULTS

The statistically significant differences in the areas under the ROC curves between using MSCT and US-SWE modalities were detected to discriminate between normal vs. NAFLD or higher severity pathology. Similarly, for normal or NAFLD vs. borderline or NASH livers, statistically significant differences between using US-SWE and MSCT modalities were also detected for nonalcoholic steatohepatitis (NASH) vs. lower severity pathology.

CONCLUSIONS

MSCT, but not US-SWE, had a better ability to differentiate normal or NAFLD livers from higher severity NAFLD livers. However, the diagnostic efficiency of US-SWE was superior to that of MSCT for differentiating NASH from normal or lower severity NAFLD.

Point Shear Wave Elastography for Grading Liver Fibrosis: Can the Number of Measurements Be Reduced?

The aim of this study was to assess whether the number of liver point shear wave elastography (pSWE) measurements could be reduced compared with the currently recommended 10 valid measurements. Three thousand four hundred one pSWE examinations in patients with liver disease were performed with 10 consecutive valid measurements in liver segment 8. Liver fibrosis grading using published cutoff values were compared retrospectively using the median of 10 versus the first 1-9 measurements with Kendall's τ coefficient. Overall and binary (clinically significant [≥F2] versus non-significant [F0/F1]) fibrosis grading highly correlated when using 5-9 versus 10 valid measurements (τ = 0.96/0.95, p < 0.001). With the use of 5 valid measurements, a change in binary grading was observed in 87 of 3401 (2.6%) exams and only when velocities measured between 1.1 and 1.5 m/s. Therefore, using 5-9 valid measurements in pSWE of the liver results in a small portion of liver fibrosis grading misclassifications compared with use of 10 measurements and could help decrease scanning time, cost and discomfort in sonographers and patients.