Ultrasound elastography in liver. Diagn Interv Imaging. 2013;94:515-534. [PMID: 23623211 DOI: 10.1016/j.diii.2013.02.005]

Advancing Acoustic Droplet Vaporization for Tissue Characterization Using Quantitative Ultrasound and Transfer Learning

Acoustic droplet vaporization (ADV) is an emerging technique with expanding applications in biomedical ultrasound. ADV-generated bubbles can function as microscale probes that provide insights into the mechanical properties of their surrounding microenvironment. This study investigated the acoustic and imaging characteristics of phase-shift nanodroplets in fibrin-based, tissue-mimicking hydrogels using passive cavitation detection and active imaging techniques, including B-mode and contrast-enhanced ultrasound. The findings demonstrated that the backscattered signal intensities and pronounced nonlinear acoustic responses, including subharmonic and higher harmonic frequencies, of ADV-generated bubbles correlated inversely with fibrin density. Additionally, we quantified the mean echo intensity, bubble cloud area, and second-order texture features of the generated ADV bubbles across varying fibrin densities. ADV bubbles in softer hydrogels displayed significantly higher mean echo intensities, larger bubble cloud areas, and more heterogeneous textures. In contrast, texture uniformity, characterized by variance, homogeneity, and energy, correlated directly with fibrin density. Furthermore, we incorporated transfer learning with convolutional neural networks, adapting AlexNet into two specialized models for differentiating fibrin hydrogels. The integration of deep learning techniques with ADV offers great potential, paving the way for future advancements in biomedical diagnostics.

Impact of sexual activity on bulbocavernosus muscle stiffness assessed by shear wave elastography in women

PURPOSE

The bulbocavernosus muscle (BCM) is a vital component of the pelvic floor muscles, significantly contributing to women's sexual function. Shear wave elastography (SWE) is an innovative, non-invasive imaging technique offering quantitative insights into tissue stiffness, yet its application in evaluating BCM stiffness remains unexplored. This study investigates the stiffness of the BCM in women with different sexual activity histories using SWE.

METHODS

This cross-sectional study was conducted at a tertiary hospital in China between April and September 2024. Sixty-two women aged 18 to 40 were assigned to two groups: the sexually active group (SAG) and the sexually inactive group (SIG). BCM stiffness was measured at rest and during maximal voluntary contraction (MVC). The correlations between BCM stiffness and the Female Sexual Function Index (FSFI) scores were also examined.

RESULTS

Women in the SAG exhibited significantly higher BCM stiffness during MVC compared to those in the SIG, and BCM stiffness during MVC was moderately correlated with the orgasm domain of the FSFI. There were no significant differences in BCM stiffness at rest between the two groups.

CONCLUSION

Sexual activity may positively influence BCM stiffness, which could lead to improved pelvic floor muscle function and potentially enhance sexual health. A moderate correlation between BCM stiffness during MVC and the orgasm domain of the FSFI, suggesting a possible biomechanical association between BCM function and sexual function. Further research is needed to confirm this relationship and explore its clinical implications.

Correlation of shear wave elastography with histopathological grade, tumor stage, and microvessel density in bladder cancer

PURPOSE

To evaluate the pathological correlation and prognostic significance of tissue stiffness measured by shear wave elastography (SWE) in bladder cancer.

MATERIALS AND METHODS

Patients with microscopic or macroscopic hematuria diagnosed with bladder tumors were included. SWE measurements were performed using a Samsung Medison RS80A Prestige ultrasonography device, with ten valid measurements taken for each tumor. Tumor specimens were collected via transurethral resection (transurethral resection of the bladder tumor) for histopathological analysis. Microvessel density (MVD) was assessed by immunohistochemical staining with anti-CD34 antibody using the hot-spot method. Correlations between tissue stiffness, MVD and tumor stage and grade were analyzed, and receiver operating characteristic (ROC) analysis determined the optimal SWE cutoff for differentiating tumor characteristics.

RESULTS

A total of 65 bladder urothelial carcinoma patients were included in the study (43 high-grade, 22 low-grade). SWE and MVD were significantly higher in the high-grade group (p=0.001, p=0.002, respectively). ROC analysis showed SWE could differentiate tumor grades (area under ROC curve=0.837, p<0.001), with a cut-off of 4.25 kPa (74% sensitivity, 86% specificity). Stiffness was also higher in recurrence (p=0.007). A strong positive correlation between SWE and MVD was found (rho=0.767, p<0.001). SWE may be a reliable, non-invasive tool for assessing tumor grade and recurrence risk.

CONCLUSIONS

SWE may be a reliable, non-invasive preoperative marker for bladder cancer, aiding in tumor characterization and clinical decision-making.

Deep denoising approach to improve shear wave phase velocity map reconstruction in ultrasound elastography

BACKGROUND

Measurement noise often leads to inaccurate shear wave phase velocity estimation in ultrasound shear wave elastography. Filtering techniques are commonly used for denoising the shear wavefields. However, these filters are often not sufficient, especially in fatty tissues where the signal-to-noise ratio (SNR) can be very low.

PURPOSE

The purpose of this study is to develop a deep learning approach for denoising shear wavefields in ultrasound shear wave elastography. This may lead to improved reconstruction of shear wave phase velocity image maps.

METHODS

The study addresses noise by transforming particle velocity data into a time-frequency representation. A neural network with encoder and decoder convolutional blocks effectively decomposes the input and extracts the signal of interest, improving the SNR in high-noise scenarios. The network is trained on simulated phantoms with elasticity values ranging from 3  to 60 kPa. A total of 1 85 570 samples with 80%-20 % $\%$ split were used for training and validation. The approach is tested on experimental phantom and ex-vivo goat liver tissue data. Performance was compared with the traditional filtering methods such as bandpass, median, and wavelet filtering. Kruskal-Wallis one-way analysis of variance was performed to check statistical significance. Multiple comparisons were performed using the Mann-Whitney U test and Holm-Bonferroni adjustment ofp - values $p-{\rm values}$ .

RESULTS

The results are evaluated using SNR and the percentage of pixels that can be reconstructed in the phase velocity maps. The SNR levels in experimental data improved from -2 to 9.9 dB levels to 15.6 to 30.3 dB levels. Kruskal-Wallis one-way analysis showed statistical significance (p < 0.05 $p<0.05$ ). Multiple comparisons with p-value corrections also showed statistically significant improvement when compared to the bandpass and wavelet filtering scheme (p < 0.05 $p<0.05$ ). Smoother phase velocity maps were reconstructed after denoising. The coefficient of variation is less than5 % $5\%$ in CIRS phantom and less than18 % $18\%$ in ex-vivo goat liver tissue.

CONCLUSIONS

The proposed approach demonstrates improvement in shear wave phase velocity image map reconstruction and holds promise that deep learning methods can be effectively utilized to extract true shear wave signal from measured noisy data.

Reduced plasma levels of GM-CSF is a common feature of Schistosoma mansoni-infected school-aged children

Background

Currently available schistosomiasis diagnostic and monitoring tools are limited, and the development of novel technologies is necessary to enhance disease diagnostic and surveillance by supporting elimination efforts. Novel disease-specific biomarkers can facilitate the development of these technologies. Through the comparison of parasite burden and host factors, we assessed whether host plasma cytokines could be used as robust biomarkers for intestinal schistosomiasis and associated pathology in school-aged children (SAC) living in endemic areas.

Methods

Levels of host plasma cytokines were measured in SAC from a low-to-moderate burden region five months deworming with praziquantel, using Luminex assay for exploration analysis and ELISA for validation.

Results

The concentration of GM-CSF, IL-2, and VEGF in plasma was significantly lower in schistosome-infected compared to non-infected children, as determined by Luminex assay. Further evaluation by ELISA revealed a negative correlation between GM-CSF plasma levels, but not those of IL-2 or VEGF, and S. mansoni egg burdens in infected individuals. Common coinfections in the study area such as geohelminths, hepatitis or malaria failed to alter plasma GM-CSF levels arguing in favor of a potential specific effect of S. mansoni infection on this cytokine. Receiver operating characteristic analysis confirmed GM-CSF as an acceptable predictive marker of S. mansoni infection, with an area under the curve (AUC) of 75%. Finally, the adjunct use of plasmatic GM-CSF thresholds for screening S. mansoni at-risk children and identify S. mansoni-infected ones increased the sensitivity of a single Kato-Katz test by averagely 15%.

Conclusions

Our findings highlight the potential of using plasma GM-CSF levels to biomark S. mansoni infection and improve the sensitivity of single Kato-Katz based diagnostic for low- to-moderate burden infections.

Comparison of Two-Dimensional Shear Wave Elastography Between Two Different Instruments for Hepatocellular Carcinoma Patients

OBJECTIVES

This study aimed to investigate and compare 2-dimensional shear wave elastography (2D-SWE) measurements and influencing factors among 2 different devices and to evaluate the ability and influencing factors of these measurements to assess liver fibrosis.

METHODS

From October 2022 to September 2023, 290 hepatocellular carcinoma (HCC) patients and 30 healthy volunteers were prospectively included. The 2D-SWE measurements were performed using AixPlorer V (SEmean) and APLIO i900 (CEmean). This study compared 2D-SWE measurements between instruments for evaluating the liver fibrosis stage and analyzed the potential influencing factors.

RESULTS

The 2D-SWE measurements obtained by the 2 instruments were significantly different (P < .001), but the differences were significant only for patients with stage F4 liver fibrosis (P < .001) and not for volunteers or patients with stage F0-F3 liver fibrosis (all P > .050). Multivariate linear regression analysis revealed that the factors independently influencing the SEmean were alanine aminotransferase (ALT) (P = .034) and liver fibrosis stage (P < .001), while fibrosis stage (P = .028) was the only factor influencing the CEmean.

CONCLUSIONS

Although 2D-SWE from the 2 different instruments was capable of detecting liver fibrosis, it yielded varying results in HCC patients. These discrepancies were predominantly observed in patients with F4 liver fibrosis but not in healthy adults or patients with F0-F3 liver fibrosis. One potential contributing factor to the differences between instruments could be ALT levels.

Two-dimensional shear wave elastography for assessing liver, spleen, and kidneys in healthy newborns

Aim

The aim of the study was to obtain two-dimensional shear wave elastography measurements of the liver, spleen and kidneys in healthy full-term newborns, as well as to assess its feasibility in this age group.

Materials and methods

We performed two-dimensional shear wave elastography of the liver, spleen and kidneys using a linear transducer at least 60 minutes after food intake in a group of 58 healthy, full-term, spontaneously breathing newborns. A series of 5 measurements using 5-mm-diameter regions of interest were performed, with the results expressed in m/s and kPa. Exam feasibility was assessed using the IQR/Median ratio as ≤30% for kPa, and ≤15% for m/s. Descriptive statistics, Shapiro-Wilk W, Levene's, Mann-Whitney U tests and Spearman correlation analysis were used for statistical assessment.

Results

The feasibility of the exam was 68.97% for the right liver lobe, 67.24% for the left lobe, 91.07% for the spleen, 89.29% for the right kidney, 85.71% for the left kidney. Mean results: right liver lobe: 1.43 m/s, SD ±0.11, 6.04 kPa, SD ±0.97, left liver lobe: 1.41 m/s, SD ±0.12, 5.86 kPa, SD ±1.02, spleen: 2.36 m/s, SD ±0.21, 16.99 kPa, SD ±3.21, right kidney: 1.92 m/s, SD ±0.18, 11.34 kPa, SD ±3.21, left kidney: 1.88 m/s, SD ±0.16, 10.81 kPa, SD ±1.80. The splenic-hepatic elastography index for m/s and kPa results was as follows: mean 1.65, SD ±0.20, mean 2.82, SD ±0.73, respectively. No differences were found between the right vs left lobe of the liver, or the right vs left kidney; there was no correlation between the measurements and gender or food intake interval >60 minutes. A positive correlation was found between the results for the right and left lobe of the liver and age, and the results for the left lobe of the liver and body weight.

Conclusions

Two-dimensional shear wave elastography of the liver, spleen and kidneys can be successfully performed in healthy neonates. We obtained reliable mean shear wave elastography values for the examined organs.

[Status Quo of Surgical Navigation]

Surgical navigation, also referred to as computer-assisted or image-guided surgery, is a technique that employs a variety of methods - such as 3D imaging, tracking systems, specialised software, and robotics to support surgeons during surgical interventions. These emerging technologies aim not only to enhance the accuracy and precision of surgical procedures, but also to enable less invasive approaches, with the objective of reducing complications and improving operative outcomes for patients. By harnessing the integration of emerging digital technologies, surgical navigation holds the promise of assisting complex procedures across various medical disciplines. In recent years, the field of surgical navigation has witnessed significant advances. Abdominal surgical navigation, particularly endoscopy, laparoscopic, and robot-assisted surgery, is currently undergoing a phase of rapid evolution. Emphases include image-guided navigation, instrument tracking, and the potential integration of augmented and mixed reality (AR, MR). This article will comprehensively delve into the latest developments in surgical navigation, spanning state-of-the-art intraoperative technologies like hyperspectral and fluorescent imaging, to the integration of preoperative radiological imaging within the intraoperative setting.

SELFNet: Denoising Shear Wave Elastography Using Spatial-temporal Fourier Feature Networks

OBJECTIVE

Ultrasound-based shear wave elastography offers estimation of tissue stiffness through analysis of the propagation of a shear wave induced by a stimulus. Displacement or velocity fields during the process can contain noise as a result of the limited number of acquisitions. With advances in physics-informed deep learning, neural networks can approximate a physics field by minimizing the residuals of governing physics equations.

METHODS

In this research, we introduce a shear wave elastography Fourier feature network (SELFNet) using spatial-temporal random Fourier features within a physics-informed neural network framework to estimate and denoise particle displacement signals. The network uses a sparse mapping to increase robustness and incorporates the governing equations for regularization while simultaneously learning the mapping of the shear modulus. The method was evaluated in datasets from tissue-mimicking phantom of lesions and ex vivo tissue.

RESULTS

The findings indicate that SELFNet is capable of smoothing out the noise in phantom lesions with different stiffness and sizes, outperforming a reference Gaussian filtering method by 17% in relative ℓ2 error, 45% in reconstruction root-mean-square error. Furthermore, the ablation study suggested that SELFNet can prevent over-fitting through the Fourier feature mapping module. An ex vivo study confirmed its applicability to different types of tissue.

CONCLUSION

The implementation of SELFNet shows promise for shear wave elastography with limited acquisitions. In this context, subject to successful translation, it has the potential to be extended to clinical applications, such as the diagnosis of cancer or liver disease.

Non-Invasive Ultrasound Diagnostic Techniques for Steatotic Liver Disease and Focal Liver Lesions: 2D, Colour Doppler, 3D, Two-Dimensional Shear Wave Elastography (2D-SWE), and Ultrasound-Guided Attenuation Parameter (UGAP)

We conducted a comprehensive literature review to evaluate the efficacy of combining two-dimensional shear wave elastography (2D-SWE) and ultrasound-guided attenuation parameter (UGAP) in assessing the risk of progressive metabolic dysfunction-associated steatohepatitis (MASH). This narrative review explores the applications of liver ultrasound in diagnosing metabolic liver diseases, focusing on recent advancements in diagnostic techniques for steatotic liver disease (SLD). Liver ultrasound can detect a spectrum of SLD manifestations, from metabolic dysfunction-associated liver disease (MASLD) to fibrosis and cirrhosis. It is also possible to identify inflammation, hepatitis, hepatocellular carcinoma (HCC), and various other liver lesions. Innovative ultrasound applications, including elastography and UGAP, can significantly enhance the diagnostic capabilities of ultrasound in accurately interpreting liver diseases. Understanding the pathogenesis of liver diseases requires a thorough analysis of their etiology and progression in order to develop sound diagnostic and therapeutic approaches. Chronic liver diseases (CLD) vary in origin, with MASLD affecting approximately 20-25% of the general population. The insidious progression of CLD from inflammation to fibrosis and cirrhosis underscores the need for effective early detection methods. This review aims to highlight the evolving role of non-invasive ultrasound-based diagnostic tests in the early detection and staging of liver diseases. By synthesizing current evidence, we aim to provide an updated perspective on the utility of advanced ultrasound techniques in redefining the diagnostic landscape for metabolic liver diseases.

Assessment of the liver with two-dimensional shear wave elastography following COVID-19 infection: A pilot study

Introduction/Purpose

The coronavirus disease (COVID-19) is a widely spread viral infectious disease, which can impact multiple organs, including the liver. Elevated liver enzymes have been reported in COVID-19 patients; however, potential changes in liver stiffness following the viral infection remain uncertain. The main aim of this pilot study was to determine if there is a significant difference in liver stiffness between individuals who have never been infected with COVID-19 and those who had been infected with COVID-19 <6 months, experiencing only mild symptoms. The secondary aim was to compare the liver stiffness between participants infected with COVID-19 depending on the elapsed time since infection.

Methods

Two-dimensional shear wave elastography (2D-SWE) was performed prospectively on 68 participants. Thirty-four participants had been infected with COVID-19 (all for <6 months) (COVID-19 group), and another 34 had never been infected with COVID-19 (control group). The mean 2D-SWE measurements of both the COVID-19 group and the control group were compared using an independent t-test. The mean 2D-SWE measurements of the COVID-19 subgroups A (<2 months), B (2 to <4 months) and C (4 to <6 months) were compared using a one-way ANOVA test (P < 0.05).

Results

The (mean ± standard deviation) liver stiffness (kPa) of the COVID-19 group (5.26 ± 1.63 kPa) was significantly higher than the control group (4.30 ± 0.96 kPa) (P = 0.005). There was no significant difference in liver stiffness among subgroups A (5.20 ± 1.79 kPa), B (4.70 ± 1.53 kPa) and C (5.96 ± 1.48 kPa) (P = 0.143) respectively.

Discussion

The mean liver stiffness of 4.30  ±  0.96k Pa in the control group showed a high probability of being normal as per guidelines. Conversely, the mean liver stiffness of 5.26  ±  1.63 kPa in the COVID-19 group exhibited a statistically significant increase compared to the control group. However, compensated advanced chronic liver disease was ruled out without other known clinical signs, as per guidelines.

Conclusion

A statistically significant increase in liver stiffness value was observed in the post-COVID-19 infection group compared to the group who had never been infected. This highlights the potential for short-term impact on liver stiffness associated with COVID-19 infection. However, it is unclear if these changes in liver stiffness are associated with liver injury. Further study is warranted to investigate the effects of COVID-19 infection and its long-term impact on the liver.

A Precision Medicine Guided Approach to the Utilization of Biomarkers in MASLD

The new nomenclature of metabolic dysfunction-associated steatotic liver disease (MASLD) emphasizes a positive diagnosis based on cardiometabolic risk factors. This definition is not only less stigmatizing but also allows for subclassification and stratification, thereby addressing the heterogeneity of what was historically referred to as nonalcoholic fatty liver disease. The heterogeneity within this spectrum is influenced by several factors which include but are not limited to demographic/dietary factors, the amount of alcohol use and drinking patterns, metabolic status, gut microbiome, genetic predisposition together with epigenetic factors. The net effect of this dynamic and intricate system-level interaction is reflected in the phenotypic presentation of MASLD. Therefore, the application of precision medicine in this scenario aims at complex phenotyping with consequent individual risk prediction, development of individualized preventive strategies, and improvements in the clinical trial designs. In this review, we aim to highlight the importance of precision medicine approaches in MASLD, including the use of novel biomarkers of disease, and its subsequent utilization in future study designs.

Quantitative ultrasonography reveals skeletal muscle abnormalities in carriers of DMD pathogenic variants

INTRODUCTION/AIMS

Carriers of DMD pathogenic variants may become symptomatic and develop muscle-related manifestations. Despite that, few studies have attempted to characterize changes in the muscles of these carriers using imaging tools, particularly muscle ultrasound (MUS). The aim of this study was to compare lower limb MUS findings in carriers of DMD pathogenic variants (cDMD) vs healthy controls.

METHODS

Twenty-eight women (15 cDMD and 13 controls) underwent clinical evaluation and MUS. We collected information about muscle-related symptoms and assessed muscle strength. MUS was performed by a single physician (blind to the genetic status of subjects). The following muscles were assessed: rectus femoris, sartorius, tibialis anterior, and medial gastrocnemius. For each site, we computed data on muscle thickness, cross-sectional area, sound attenuation index, and elastography. Between-group comparisons were assessed using nonparametric tests and p-values <.05 were deemed significant.

RESULTS

None of the subjects had objective muscle weakness, but exercise intolerance/fatigue was reported by four cDMDs and only one control. Regarding MUS, sound attenuation indices were significantly higher among carriers for all muscles tested. Longitudinal and axial deep echo intensities for the rectus femoris and tibialis anterior were also higher in the cDMD group compared with controls. No significant between-group differences were noted for elastography values, muscle area, or mean echo intensities.

DISCUSSION

cDMD have skeletal muscle abnormalities that can be detected using quantitative MUS. Further studies are needed to determine whether such abnormalities are related to muscle symptoms in these patients.

Safety and effectiveness of direct-acting antiviral drugs in the treatment of hepatitis C in patients with inflammatory bowel disease

BACKGROUND AND AIMS

Hepatitis C virus (HCV) management in Inflammatory Bowel Disease (IBD) is uncertain. The ECCO guidelines 2021 recommended HCV treatment but warn about the risk of IBD reactivation. We aimed to evaluate 1) the effectiveness and safety of direct-acting antivirals (DAAs) in IBD; 2) the interaction of DAAs with IBD drugs.

METHODS

Multicentre study of IBD patients and HCV treated with DAAs. Variables related to liver diseases and IBD, as well as adverse events (AEs) and drug interactions, were recorded. McNemar's test was used to assess differences in the proportion of active IBD during the study period.

RESULTS

We included 79 patients with IBD and HCV treated with DAAs from 25,998 IBD patients of the ENEIDA registry. Thirty-one (39.2 %) received immunomodulators/biologics. There were no significant differences in the percentage of active IBD at the beginning (n = 11, 13.9 %) or at the 12-week follow-up after DAAs (n = 15, 19 %) (p = 0.424). Sustained viral response occurred in 96.2 % (n = 76). A total of 8 (10.1 %) AEs occurred and these were unrelated to activity, type of IBD, liver fibrosis, immunosuppressants/biologics, and DAAs.

CONCLUSIONS

We demonstrate a high efficacy and safety of DAAs in patients with IBD and HCV irrespective of activity and treatment of IBD.

The Influence of Mobility Training on the Myofascial Structures of the Back and Extremities

BACKGROUND

The subject of the study was the effect of a multicomponent program (Mobility Routine) on muscular and fascial stiffness, flexibility, subjective well-being, and body perception.

METHODS

The assumption was that high physical stress affects myofascial structures and joint range of motion. The assessment of myofascial stiffness employed a Shear Wave Elastography. The joint flexibility, pressure pain threshold, and subjective experiences with regard to tension, pain, and general discomfort were documented.

RESULTS

In the CT group, a greater increase in stiffness was measured in fewer measurement areas compared to the MR group. MR demonstrated superior gains in flexibility compared to CT. Both groups experienced significant reductions in pain, tension, and discomfort. In conclusion, repetitive motion patterns akin to CT lead to increased myofascial stiffness, whereas MR yields more balanced stiffness development, compensates for asymmetries, and improves body awareness.

CONCLUSIONS

Hence, this study highlights the advantages of mobility training over Crosstrainer exercises and provides valuable insights for the recommendation of training regimens aiming at the enhancement of musculoskeletal functionality and overall well-being.

LiMAx test and ultrasound elastography to measure biomarkers of declining liver function in patients with liver fibrosis: A correlation analysis

BACKGROUND

Monitoring liver changes is crucial in the management of liver fibrosis. Current diagnostic methods include liver function tests such as the Liver Maximum Capacity (LiMAx) test and measurements of liver stiffness. While the LiMAx test quantifies liver function through 13C-methacetin metabolism, ultrasound (US) elastography noninvasively assesses liver stiffness. The relationship between the findings of these methods in patients with liver fibrosis is not fullyunderstood.

OBJECTIVE

This study evaluated the correlation between LiMAx measurements of liver function and US elastography-based liver stiffness measurements to better understand the interplay between functional and structural liver parameters in fibrotic liver disease. Additionally, the relationship between body mass index (BMI) and these parameters isevaluated.

METHODS

This retrospective study analysed data from 97 patients who underwent both LiMAx testing and real-time elastography, resulting in a total data set of 108 examinations. The correlations between the results of the LiMAx test and elastography and their relationships with body mass index (BMI) were analysed.

RESULTS

There was a significant negative correlation (r = -0.25, p < 0.05) between LiMAx test values and liver stiffness measurements. BMI was significantly negatively correlated with LiMAx values (r = -0.29, p < 0.001) but not significantly correlated with liver stiffness values.

CONCLUSIONS

This retrospective study confirms the results of previous studies showing a notable but weak association between liver function and liver stiffness. Our results highlight the potential value of both tests as complementary tools for the evaluation of liver health, reinforcing the necessity for a multimodal approach to liver assessment.

Enabling strain imaging in realistic Eulerian ultrasound simulation methods

Cardiovascular strain imaging is continually improving due to ongoing advances in ultrasound acquisition and data processing techniques. The phantoms used for validation of new methods are often burdensome to make and lack flexibility to vary mechanical and acoustic properties. Simulations of US imaging provide an alternative with the required flexibility and ground truth strain data. However, the current Lagrangian US strain imaging models cannot simulate heterogeneous speed of sound distributions and higher-order scattering, which limits the realism of the simulations. More realistic Eulerian modelling techniques exist but have so far not been used for strain imaging. In this research, a novel sampling scheme was developed based on a band-limited interpolation of the medium, which enables accurate strain simulation in Eulerian methods. The scheme was validated in k-Wave using various numerical phantoms and by a comparison with Field II. The method allows for simulations with a large range in strain values and was accurate with errors smaller than -60 dB. Furthermore, an excellent agreement with the Fourier theory of US scattering was found. The ability to perform simulations with heterogeneous speed of sound distributions was demonstrated using a pulsating artery model. The developed sampling scheme contributes to more realistic strain imaging simulations, in which the effect of heterogenous acoustic properties can be taken into account.

Liver and kidney ultrasound elastography in children and young adults with hypertension or chronic kidney disease

BACKGROUND

Ultrasound elastography is a research method increasingly used to measure tissue elasticity. The aim of the study was to assess its usability in pediatric patients with either chronic kidney disease (CKD) or hypertension.

METHODS

A total of 46 patients with CKD (group 1), 50 patients with hypertension (group 2), and 33 healthy participants as the control group were included. In all, we performed studies assessing their cardiovascular risk along with liver and kidney elastography.

RESULTS

Liver elastography parameters were increased compared to those in the control group (1.49 m/s, p = 0.007, in group 1 and 1.52 m/s, p < 0.001, in group 2, vs. 1.41 m/s among controls). Kidney elastography parameters were significantly higher in group 2 (1.9 m/s, p = 0.001, and 1.9 m/s, p = 0.003, in each kidney) when compared to group 1 (1.79 m/s and 1.81 m/s). Additionally, all participants were divided according to overweight/obesity and normal weight status, where both liver (1.53 m/s vs. 1.45 m/s, p < 0.001) and kidney parameters (1.96 m/s and 1.92 m/s vs. 1.81 m/s and 1.84 m/s, p = 0.002) were significantly higher in the group of overweight/obese subjects.

CONCLUSIONS

Ultrasound elastography of the liver and kidney is feasible in pediatric patients with either CKD or hypertension, showing increased liver stiffness parameters in both groups, further aggravated by obesity. In obese patients with CKD, kidney stiffness also increased indicating a negative effect of clustering cardiovascular risk factors leading to decreased kidney elasticity. Further research is warranted. A higher resolution version of the Graphical abstract is available as Supplementary information.

Sono-Elastography: An Ultrasound Quantitative Non-Invasive Measurement to Guide Bacterial Pneumonia Diagnosis in Children

Lung ultrasound (LUS) is, at present, a standard technique for the diagnosis of acute lower respiratory tract infections (ALRTI) and other lung pathologies. Its protocolised use has replaced chest radiography and has led to a drastic reduction in radiation exposure in children. Despite its undeniable usefulness, there are situations in which certain quantitative measurements could provide additional data to differentiate the etiology of some pulmonary processes and thus adapt the treatment. Our research group hypothesises that several lung processes such pneumonia may lead to altered lung tissue stiffness, which could be quantified with new diagnostic tests such as lung sono-elastography (SE). An exhaustive review of the literature has been carried out, concluding that the role of SE for the study of pulmonary processes is currently scarce and poorly studied, particularly in pediatrics. The aim of this review is to provide an overview of the technical aspects of SE and to explore its potential usefulness as a non-invasive diagnostic technique for ALRTI in children by implementing an institutional image acquisition protocol.

A scoping review of current and emerging techniques for evaluation of peripheral nerve health, degeneration and regeneration: part 2, non-invasive imaging

Peripheral neuroregenerative research and therapeutic options are expanding exponentially. With this expansion comes an increasing need to reliably evaluate and quantify nerve health. Valid and responsive measures of the nerve status are essential for both clinical and research purposes for diagnosis, longitudinal follow-up, and monitoring the impact of any intervention. Furthermore, novel biomarkers can elucidate regenerative mechanisms and open new avenues for research. Without such measures, clinical decision-making is impaired, and research becomes more costly, time-consuming, and sometimes infeasible. Part 1 of this two-part scoping review focused on neurophysiology. In part 2, we identify and critically examine many current and emerging non-invasive imaging techniques that have the potential to evaluate peripheral nerve health, particularly from the perspective of regenerative therapies and research.

Elastography of the Liver in Wilson's Disease

Staging of liver fibrosis is of special significance in Wilson's disease as it determines the patient's prognosis and treatment. Histopathological examination is a standard method for fibrosis assessment; however, non-invasive methods like transient elastography and share wave elastography are believed to be reliable and repetitive and are expected to replace liver biopsy in Wilson's disease. This article presents a short description of available elastography techniques and the results of the most recent studies on elastography of the liver in patients with Wilson's disease.

Axial stress determines the velocity of shear wave propagation in passive but not active muscles in vivo

Ultrasound shear wave elastography can be used to characterize mechanical properties of unstressed tissue by measuring shear wave velocity (SWV), which increases with increasing tissue stiffness. Measurements of SWV have often been assumed to be directly related to the stiffness of muscle. Some have also used measures of SWV to estimate stress, since muscle stiffness and stress covary during active contractions, but few have considered the direct influence of muscle stress on SWV. Rather, it is often assumed that stress alters the material properties of muscle, and in turn, shear wave propagation. The objective of this study was to determine how well the theoretical dependency of SWV on stress can account for measured changes of SWV in passive and active muscles. Data were collected from six isoflurane-anesthetized cats; three soleus muscles and three medial gastrocnemius muscles. Muscle stress and stiffness were measured directly along with SWV. Measurements were made across a range of passively and actively generated stresses, obtained by varying muscle length and activation, which was controlled by stimulating the sciatic nerve. Our results show that SWV depends primarily on the stress in a passively stretched muscle. In contrast, the SWV in active muscle is higher than would be predicted by considering only stress, presumably due to activation-dependent changes in muscle stiffness. Our results demonstrate that while SWV is sensitive to changes in muscle stress and activation, there is not a unique relationship between SWV and either of these quantities when considered in isolation.NEW & NOTEWORTHY Ultrasound shear wave elastography may be an inexpensive way to measure muscle stress in passive muscle. Here, using a cat model we directly measured shear wave velocity (SWV), muscle stress, and muscle stiffness. Our results show that SWV depends primarily on the stress in a passively stretched muscle. In contrast, the SWV in active muscle is higher than would be predicted by considering only stress, presumably due to activation-dependent changes in muscle stiffness.

Ex vivo bovine liver nonlinear viscoelastic properties: MR elastography and rheological measurements

INTRODUCTION

Knowledge of the nonlinear viscoelastic properties of the liver is important, but the complex tissue behavior outside the linear viscoelastic regime has impeded their characterization, particularly in vivo. Combining static compression with magnetic resonance (MR) elastography has the potential to be a useful imaging method for assessing large deformation mechanical properties of soft tissues in vivo. However, this remains to be verified. Therefore this study aims first to determine whether MR elastography can measure the nonlinear mechanical properties of ex vivo bovine liver tissue under varying levels of uniform and focal preloads (up to 30%), and second to compare MR elastography-derived complex shear modulus with standard rheological measurements.

METHOD

Nine fresh bovine livers were collected from a local abattoir, and experiments were conducted within 12hr of death. Two cubic samples (∼10 × 10 × 10 cm³) were dissected from each liver and imaged using MR elastography (60 Hz) under 4 levels of uniform and focal preload (1, 10, 20, and 30% of sample width) to investigate the relationship between MR elastography-derived complex shear modulus (G∗) and the maximum principal Right Cauchy Green Strain (C₁₁). Three tissue samples from each of the same 9 livers underwent oscillatory rheometry under the same 4 preloads (1, 10, 20, and 30% strain). MR elastography-derived complex shear modulus (G∗) from the uniform preload was validated against rheometry by fitting the frequency dependence of G∗ with a power-law and extrapolating rheometry-derived G∗ to 60 Hz.

RESULTS

MR elastography-derived G∗ increased with increasing compressive large deformation strain, and followed a power-law curve (G∗ = 1.73 × C₁₁^-0.38, R² = 0.96). Similarly, rheometry-derived G∗ at 1 Hz, increasing from 0.66 ± 1.03 kPa (1% strain) to 1.84 ± 1.65 kPa (30% strain, RM one-way ANOVA, P < 0.001), and the frequency dependence of G∗ followed a power-law with the exponent decreasing from 0.13 to 0.06 with increasing preload. MR elastography-derived G∗ was 1.4-3.1 times higher than the extrapolated rheometry-derived G∗ at 60 Hz, but the strain dependence was consistent between rheometry and MR elastography measurements.

CONCLUSIONS

This study demonstrates that MR elastography can detect changes in ex vivo bovine liver complex shear modulus due to either uniform or focal preload and therefore can be a useful technique to characterize nonlinear viscoelastic properties of soft tissue, provided that strains applied to the tissue can be quantified. Although MR elastography could reliably characterize the strain dependence of the ex vivo bovine liver, MR elastography overestimated the complex shear modulus of the tissue compared to rheological measurements, particularly at lower preload (<10%). That is likely to be important in clinical hepatic MR elastography diagnosis studies if preload is not carefully considered. A limitation is the absence of overlapping frequency between rheometry and MR elastography for formal validation.

Effect of contrast-enhanced ultrasound (CEUS) on liver stiffness measurements obtained by transient and shear-wave elastography

BACKGROUND

Since liver fibrosis is one of the most accurate predictors of prognosis in hepatopatic patients, its accurate assessment and staging is a major public health issue. Transient elastography (TE) (Fibroscan, Echosens, Paris, France) and shear wave elastography (SWE) represent the gold standard techniques among non-invasive methods to assess liver fibrosis. Contrast-enhanced ultrasound (CEUS) is increasingly used to diagnose the nature of liver lesions and is often performed together with TE and SWE. In this study we evaluated the effect of CEUS on liver stiffness measurements obtained by TE and SWE.

METHODS

A retrospective analysis of ultrasound (US) exams performed by an expert operator was carried out. TE and SWE were performed 30 seconds before and after the execution of CEUS. Statistical analysis was carried out using the statistical software R. Kolmogorov-Smirnov analysis was performed to test the normality of continuous variables. The pre- and post-CEUS liver stiffness values were compared using the Wilcoxon's Test.

RESULTS

Ninety-six patients were enrolled. While the measurements were comparable when performed with TE, those obtained by SWE decreased by 6% after administration of the contrast agent (P=0.0005). Fibrosis stage deviated between pre- and post-CEUS in 16 (17%) patients with Fibroscan and 22 (23%) patients with SWE. Among the latter, in 9 cases (10%) a deviation from absent-low (F0-F2) to high-fibrosis (F3, F4), or vice versa, occurred.

CONCLUSIONS

Our study, the first to assess the effects of CEUS on US elastography, shows that the contrast agent (Sonovue, Bracco Suisse SA, Cadempino, Switzerland) does not significantly affect liver stiffness measurements obtained by TE, whereas the accuracy decreases when performed by SWE.

Spontaneous Seroclearance Is Associated with Lower Liver Fibrosis in Treatment-Naïve Chronic Hepatitis B Patients

BACKGROUND

Chronic hepatitis B virus (HBV) is a major public health concern. Transient elastrography (TE) is a reliable method in assessing hepatic fibrosis in patients with liver disease. We assess the potential clinical associations between HBsAg seroclearance and the severity of liver fibrosis.

METHODS

We retrospectively performed a matched analysis of 23 consecutive HBsAg seroclearance patients who underwent TE between March 2008 and August 2021 from a community practice at a 1:3 ratio based on clinic visit date. Baseline laboratory and clinical data were collected. Fisher's exact test and Chi-square test for proportions, and Wilcoxon rank-sum test for median were performed.

RESULTS

Twenty-three cases and 69 controls were identified. Median follow up (interquartile range) for the cases and controls was 24,314 (1402) and 2332 (1587) days (p  =  0.15), respectively. All patients were Asian. Median age of cases was higher than controls (64 vs 52, p < 0.01, respectively). While most comorbidities were similar, diabetes and hyperlipidemia were more prevalent in cases. Baseline HBV DNA was detectable in 78% of cases and 97% of controls (p < 0.01). More cases had baseline HBsAg titers below 1000 IU/mL than controls (81% vs 8.7%, p < 0.01). Other baseline laboratory values were similar. Few cases had a fibrosis score greater than 1, while control had over a quarter of patients with a fibrosis score of 2 or 3.

CONCLUSION

Spontaneous HBsAg seroclearance remains rare in patients with chronic HBV infection. It is associated with low baseline HBsAg, and lower level of liver fibrosis as detected by TE.

Second-Order Ultrasound Elastography With L1-Norm Spatial Regularization

Time delay estimation (TDE) between two radio-frequency (RF) frames is one of the major steps of quasi-static ultrasound elastography, which detects tissue pathology by estimating its mechanical properties. Regularized optimization-based techniques, a prominent class of TDE algorithms, optimize a nonlinear energy functional consisting of data constancy and spatial continuity constraints to obtain the displacement and strain maps between the time-series frames under consideration. The existing optimization-based TDE methods often consider the L2 -norm of displacement derivatives to construct the regularizer. However, such a formulation over-penalizes the displacement irregularity and poses two major issues to the estimated strain field. First, the boundaries between different tissues are blurred. Second, the visual contrast between the target and the background is suboptimal. To resolve these issues, herein, we propose a novel TDE algorithm where instead of L2 -, L1 -norms of both first- and second-order displacement derivatives are taken into account to devise the continuity functional. We handle the non-differentiability of L1 -norm by smoothing the absolute value function's sharp corner and optimize the resulting cost function in an iterative manner. We call our technique Second-Order Ultrasound eLastography (SOUL) with the L1 -norm spatial regularization ( L1 -SOUL). In terms of both sharpness and visual contrast, L1 -SOUL substantially outperforms GLobal Ultrasound Elastography (GLUE), tOtal Variation rEgulaRization and WINDow-based time delay estimation (OVERWIND), and SOUL, three recently published TDE algorithms in all validation experiments performed in this study. In cases of simulated, phantom, and in vivo datasets, respectively, L1 -SOUL achieves 67.8%, 46.81%, and 117.35% improvements of contrast-to-noise ratio (CNR) over SOUL. The L1 -SOUL code can be downloaded from http://code.sonography.ai.

Effects of Confounding Factors on Liver Stiffness in Two-Dimensional Shear Wave Elastography in Beagle Dogs

Background

Two-dimensional shear wave elastography (2D-SWE) is a powerful technique that can non-invasively measure liver stiffness to assess hepatic fibrosis.

Purpose

This study aimed to identify the effects of confounding factors, including anesthesia, breathing, and scanning approach, on liver stiffness when performing 2D-SWE in dogs.

Materials and Methods

Nine healthy Beagle dogs were included in this study. Hepatic 2D-SWE was performed, and liver stiffness was compared between conscious and anesthetized states, free-breathing and breath-holding conditions, and intercostal and subcostal approaches. For the anesthetized state, the breath-holding condition was subdivided into seven phases, which included forced-expiration (5 and 10 mL/kg), end-expiration (0 cm H₂O), and forced-inspiration (5, 10, 15, and 20 cm H₂O), and liver stiffness was compared among these phases. Changes in liver stiffness were compared between intercostal and subcostal approaches according to breathing phases.

Results

No significant difference was observed in liver stiffness between the conscious and anesthetized states or between the free-breathing and breath-holding conditions. No significant difference was noted in liver stiffness among the breathing phases, except for forced-inspiration with high airway pressure (15 and 20 cm H₂O in the intercostal approach and 10, 15, and 20 cm H₂O in the subcostal approach), which was associated with significantly higher liver stiffness (p < 0.05). Liver stiffness was significantly higher in the subcostal approach than in the intercostal approach (p < 0.05). Changes in liver stiffness were significantly higher in the subcostal approach than in the intercostal approach in all forced-inspiratory phases (p < 0.05).

Conclusion

In conclusion, when performing 2D-SWE in dogs, liver stiffness is unaffected by anesthesia and free-breathing. To avoid inadvertent increases in liver stiffness, the deep inspiratory phase and subcostal approach are not recommended. Thus, liver stiffness should be interpreted considering these confounding factors.

Artificial intelligence in the diagnosis of cirrhosis and portal hypertension

Clinically significant portal hypertension is associated with an increased risk of developing gastroesophageal varices and hepatic decompensation. Hepatic venous pressure gradient measurement and esophagogastroduodenoscopy are the gold-standard methods for assessing clinically significant portal hypertension and gastroesophageal varices, respectively. However, invasiveness, cost, and feasibility limit their widespread use, especially if repeated and serial evaluations are required to assess the efficacy of pharmacotherapy. Artificial intelligence describes a range of techniques that allow machines to perform tasks typically thought to require human reasoning and problem-solving skills. Artificial intelligence has made great strides in the field of medicine, and is also involved in portal hypertension diagnosis. Artificial intelligence tools will potentially transform our practice by leveraging massive amounts of data to personalize care to the right patient, in the right amount, at the right time. This review focuses on the recent advances in artificial intelligence for the noninvasive diagnosis of portal hypertension and gastroesophageal varices and monitoring of risk assessment of its complications in clinical practice.

Ultrasound Elastography in Ocular and Periocular Tissues: A Review

Ultrasound elastography has become available in everyday practice, allowing direct measurement of tissue elasticity with important and expanding clinical applications. Several studies that have evaluated pathological and non-pathological tissues have demonstrated that ultrasound elastography can actually improve the diagnostic accuracy of the underlying disease process by detecting differences in their elasticity. Ocular and periocular tissues can also be characterized by their elastic properties. In this context, a comprehensive review of literature on ultrasound elastography as well as its current applications in Ophthalmology is presented.

Application of ultrasound elastography for monitoring the effects of TβR1 shRNA therapy on hepatic fibrosis in a rat model

BACKGROUND

To investigate the application of ultrasound elastography in monitoring the effects of the transforming growth factor (TGF)-β1 signaling pathway-targeted combination therapy for hepatic fibrosis.

METHODS

1. Short hairpin RNA (shRNA) constructs targeted towards TβR1 were designed, synthesized, and packaged using an adeno-associated virus (AAV), and the effective target shRNA was selected based on transfection results. 2. Fifty rats were randomly allocated (n = 10 per group) to the (A) control group, (B) model group, (C) 0-week therapy group, (D) 4-week therapy group, and (E) combination therapy group. At weeks 2, 4, 6, 8, 10, and 12, acoustic radiation force impulse (ARFI) elastography was used to measure the liver stiffness, inner diameter of the portal vein diameter, and blood velocity; radio frequency ultrasound imaging was used to measure the abdominal aortic elasticity parameter and pulse wave velocity (PWV) of the rats. 3. At week 12, portal vein puncture was performed to measure the portal venous pressure, and rat liver specimens were obtained for the pathological measurement of the degree of hepatic fibrosis.

RESULTS

1. An shRNA interference sequence targeted towards TβR1 was successfully designed, screened, and packaged using an AAV, and small-animal imaging results indicated expression of the specific shRNA in the liver. 2. At week 12, the ultrasound elastography results were significantly different between the experimental groups and the control group (p < 0.01); among the experimental groups, differences were significant between the therapy groups and the model group (p < 0.01). For groups C and E, the therapeutic effects on hepatic fibrosis in rats were significant, with the pathological results indicating a significant reduction in the degree of hepatic fibrosis (p < 0.01). The therapeutic effectiveness of group D was less than that of group C (p < 0.05). Significant differences existed between the portal venous pressure of the experimental groups and of the control group (p < 0.01). For the abdominal aortic elasticity parameter measured by radio frequency ultrasound imaging, differences existed between the values obtained from the experimental groups and from that of the control group (p < 0.05), while statistically significant differences were not found among the various experimental groups. 3. Continuous ultrasound examination results indicated that the elasticity value of group A was significantly different from those of the other groups after 2 weeks of model establishment (p < 0.01); after 6 weeks, the elasticity values of groups C and E were significantly different compared with those of groups B and D (p < 0.01). For the abdominal aortic elasticity parameter and pulse wave velocity (PWV), there were no significant differences among the various groups (p > 0.05).

CONCLUSION

CCl4-induced hepatic fibrosis can be treated through shRNA silencing of TβR1. Ultrasound ARFI elastography is superior to external force-assisted elastography as it can reflect the degree of fibrosis in moderate to severe hepatic fibrosis and the variations in the degree of fibrosis after treatment. Portal venous pressure was positively correlated with the degree of fibrosis; with early combination therapy, both the degree of fibrosis and portal venous pressure could be effectively reduced.

Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

Changes in biomechanical properties of biological soft tissues are often associated with physiological dysfunctions. Since biological soft tissues are hydrated, viscoelasticity is likely suitable to represent its solid-like behavior using elasticity and fluid-like behavior using viscosity. Shear wave elastography is a non-invasive imaging technology invented for clinical applications that has shown promise to characterize various tissue viscoelasticity. It is based on measuring and analyzing velocities and attenuations of propagated shear waves. In this review, principles and technical developments of shear wave elastography for viscoelasticity characterization from organ to cellular levels are presented, and different imaging modalities used to track shear wave propagation are described. At a macroscopic scale, techniques for inducing shear waves using an external mechanical vibration, an acoustic radiation pressure or a Lorentz force are reviewed along with imaging approaches proposed to track shear wave propagation, namely ultrasound, magnetic resonance, optical, and photoacoustic means. Then, approaches for theoretical modeling and tracking of shear waves are detailed. Following it, some examples of applications to characterize the viscoelasticity of various organs are given. At a microscopic scale, a novel cellular shear wave elastography method using an external vibration and optical microscopy is illustrated. Finally, current limitations and future directions in shear wave elastography are presented.

Using shear wave elasticity in normal terminal ileum of a healthy southwest Chinese population: a pilot study of reference elasticity ranges

Background

Elastography has not been widely applied to the gastrointestinal tract. The bowel wall's normal elasticity values are still unknown and are necessary for studies of gastrointestinal diseases. This study explores the feasibility of using shear wave elastography (SWE) to measure the terminal ileum wall stiffness in healthy subjects and establish the corresponding normal ranges of elasticity values.

Methods

This observational study recruited 139 healthy adult volunteers from April to July 2020. All examinations were performed in the anterior terminal ileum wall. Shear wave velocity (SWV) and Young's modulus (E) values were measured in the midline on longitudinal sections and replicated different operators' obtained data. Also, bowel wall thickness (BWT) and depth were recorded. Subgroups were classified according to the volunteers' gender, age, body mass index (BMI), BWT, and depth. The intra-class correlation coefficient was calculated to analyze inter- and intra-operator consistency, and independent t-tests and one-way analysis of variance were used to explore the differences in variables.

Results

The inter- and intra-operator agreements were good to excellent by different operators and in the replicated measurements (intra-operator consistency: 0.963; inter-operator consistency: 0.842). In all volunteers, the mean SWV was 1.08±0.25 m/s, the mean E value was 3.84±1.84 kPa, and the median BWT was 2 mm. SWV and E did not show significant differences according to gender (P=0.589), age (P=0.738), BMI (P=0.678), depth (P=0.375), or BWT (P=0.410). BWT did not show significant differences according to age (P=0.142), BMI (P=0.863), or depth (P=0.368).

Conclusions

SWE can be used in terminal ileum wall stiffness measurements with good reliability, and the SWE values do not appear to vary significantly according to different physiological factors. The corresponding elasticity ranges of the terminal ileum in normal adults were acquired.

Real-Time Tissue Elastography to Evaluate Hepatic Hypoxic-Ischemic Injury Caused by Brain Death

ABSTRACT

This study aimed to explore the potential of real-time tissue elastography (RTE) in evaluating hepatic hypoxic-ischemic injury caused by brain death. We performed RTE and biopsy for 50 donated liver. Hematoxylin-eosin staining was used to observe hepatocyte acidophilic change. Liver grafts were divided into 2 groups, one nonacidophilic change (n = 7) and the other with acidophilic change (n = 43). Correlation and difference analysis were performed for hematoxylin-eosin staining results and RTE parameters. The result indicated that 4 of the 11 RTE parameters, namely, the area of low strain within the region of interest (%AREA), contrast (CONT), inverse difference moment (IDM), and correlation (CORR) were related to hepatocytes acidophilic change (r = 0.284, P = 0.046; r = 0.349, P = 0.013; r = -0.444, P = 0.001; r = -0.381, P = 0.00). Whereas %AREA and CONT of the nonacidophilic change group were lower than that of the acidophilic change group (P < 0.05), IDM and CORR in nonacidophilic change group were higher than that of the acidophilic change group (P < 0.05); the remaining parameters were not statistically different between 2 groups (P > 0.05). Analysis of receiver operating characteristic curve indicated that the area under the curve of %AREA, CONT, IDM, and CORR were 0.75, 0.79, 0.81, and 0.77, respectively. Based on this, we concluded that the quantitative analysis parameters of RTE could preliminary assess hepatic hypoxic-ischemic injury caused by brain death.

Evaluation of liver fibrosis and cirrhosis on the basis of quantitative T1 mapping: Are acute inflammation, age and liver volume confounding factors?

PURPOSE

To evaluate potential confounding factors in the quantitative assessment of liver fibrosis and cirrhosis using T1 relaxation times.

METHODS

The study population is based on a radiology-information-system database search for abdominal MRI performed from July 2018 to April 2019 at our institution. After applying exclusion criteria 200 (59 ± 16 yrs) remaining patients were retrospectively included. 93 patients were defined as liver-healthy, 40 patients without known fibrosis or cirrhosis, and 67 subjects had a clinically or biopsy-proven liver fibrosis or cirrhosis. T1 mapping was performed using a slice based look-locker approach. A ROI based analysis of the left and the right liver was performed. Fat fraction, R2*, liver volume, laboratory parameters, sex, and age were evaluated as potential confounding factors.

RESULTS

T1 values were significantly lower in healthy subjects without known fibrotic changes (1.5 T MRI: 575 ± 56 ms; 3 T MRI: 857 ± 128 ms) compared to patients with acute liver disease (1.5 T MRI: 657 ± 73 ms, p < 0.0001; 3 T MRI: 952 ± 37 ms, p = 0.028) or known fibrosis or cirrhosis (1.5 T MRI: 644 ± 83 ms, p < 0.0001; 3 T MRI: 995 ± 150 ms, p = 0.018). T1 values correlated moderately with the Child-Pugh stage at 1.5 T (p = 0.01, ρ = 0.35).

CONCLUSION

T1 mapping is a capable predictor for detection of liver fibrosis and cirrhosis. Especially age is not a confounding factor and, hence, age-independent thresholds can be defined. Acute liver diseases are confounding factors and should be ruled out before employing T1-relaxometry based thresholds to screen for patients with liver fibrosis or cirrhosis.

Virtual Source Synthetic Aperture for Accurate Lateral Displacement Estimation in Ultrasound Elastography

Ultrasound elastography (USE) is an emerging noninvasive imaging technique in which pathological alterations can be visualized by revealing the mechanical properties of the tissue. Estimating tissue displacement in all directions is required to accurately estimate the mechanical properties. Despite capabilities of elastography techniques in estimating displacement in both axial and lateral directions, estimation of axial displacement is more accurate than lateral direction due to higher sampling frequency, higher resolution, and having a carrier signal propagating in the axial direction. Among different ultrasound imaging techniques, synthetic aperture (SA) has better lateral resolution than others, but it is not commonly used for USE due to its limitation in imaging depth of field. Virtual source synthetic aperture (VSSA) imaging is a technique to implement SA beamforming on the focused transmitted data to overcome the limitation of SA in depth of field while maintaining the same lateral resolution as SA. Besides lateral resolution, VSSA has the capability of increasing sampling frequency in the lateral direction without interpolation. In this article, we utilize VSSA to perform beamforming to enable higher resolution and sampling frequency in the lateral direction. The beamformed data are then processed using our recently published elastography technique, OVERWIND. Simulation and experimental results show substantial improvement in the estimation of lateral displacements.

Ultrasound Shear Wave Elastography and Transient Optical Coherence Elastography: Side-by-Side Comparison of Repeatability and Accuracy

Objective: We compare the repeatability and accuracy of ultrasound shear wave elastography (USE) and transient optical coherence elastography (OCE). Methods: Elastic wave speed in gelatin phantoms and chicken breast was measured with USE and OCE and compared with uniaxial mechanical compression testing. Intra- and Inter-repeatability were analyzed using Bland-Altman plots and intraclass correlation coefficients (ICC). Results: OCE and USE differed from uniaxial testing by a mean absolute percent error of 8.92% and 16.9%, respectively, across eight phantoms of varying stiffness. Upper and lower limits of agreement for intrasample repeatability for USE and OCE were ±0.075 m/s and −0.14 m/s and 0.13 m/s, respectively. OCE and USE both had ICCs of 0.9991. In chicken breast, ICC for USE was 0.9385 and for OCE was 0.9924. Conclusion: OCE and USE can detect small speed changes and give comparable measurements. These measurements correspond well with uniaxial testing.

US Elastography in Hepatic Fibrosis-Radiology In Training

A 72-year-old woman with an elevated body mass index and moderate alcohol intake was seen in the gastroenterology clinic. The patient had a past history of abnormal liver function tests and previous biopsy-proven steatosis with early fibrosis. She was reevaluated, following an initial loss to follow-up, by using US elastography to assess for fibrosis progression. The utility of US elastography in the noninvasive diagnosis and longitudinal monitoring of hepatic fibrosis is discussed. An overview of available technologies, including transient elastography and shear-wave elastography, is provided. ^©RSNA, 2021 Online supplemental material is available for this article.

Biomarkers of cholestasis

Cholestasis is a major pathological manifestation, often resulting in detrimental liver conditions, which occurs in a variety of indications collectively termed cholestatic liver diseases. The frequent asymptomatic character and complexity of cholestasis, together with the lack of a straightforward biomarker, hampers early detection and treatment of the condition. The 'omics' era, however, has resulted in a plethora of cholestatic indicators, yet a single clinically applicable biomarker for a given cholestatic disease remains missing. The criteria to fulfil as an ideal biomarker as well as the challenging molecular pathways in cholestatic liver diseases advocate for a scenario in which multiple biomarkers, originating from different domains, will be assessed concomitantly. This review gives an overview of classical clinical and novel molecular biomarkers in cholestasis, focusing on their benefits and drawbacks.

What's New in Hepatic Steatosis

Hepatic steatosis can lead to liver cancer, cirrhosis, and portal hypertension. There are two main types, non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease. The detection and quantification of hepatic steatosis with lifestyle changes can slow the evolution from NAFLD to steatohepatitis. Currently, the gold standard for the quantification of fat in the liver is biopsy, has some limitations. Hepatic steatosis is frequently detected during cross sectional imaging. Ultrasound (US), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI) provide noninvasive assessment of liver parenchyma and can detect fat infiltration in the liver. However, the non-invasive quantification of hepatic steatosis by imaging has been challenging. Recent MRI techniques show great promise in the detection and quantification of liver fat. The aim of this article is to review the utilization of non-invasive imaging modalities for the detection and quantification of hepatic steatosis, to evaluate their advantages and limitations.

Liver manifestations in a cohort of 39 patients with congenital disorders of glycosylation: pin-pointing the characteristics of liver injury and proposing recommendations for follow-up

Background

The congenital disorders of glycosylation (CDG) are a heterogeneous group of rare metabolic diseases with multi-system involvement. The liver phenotype of CDG varies not only according to the specific disorder, but also from patient to patient. In this study, we sought to identify common patterns of liver injury among patients with a broad spectrum of CDG, and to provide recommendations for follow-up in clinical practice.

Methods

Patients were enrolled in the Frontiers in Congenital Disorders of Glycosylation natural history study. We analyzed clinical history, molecular genetics, serum markers of liver injury, liver ultrasonography and transient elastography, liver histopathology (when available), and clinical scores of 39 patients with 16 different CDG types (PMM2-CDG, n = 19), with a median age of 7 years (range: 10 months to 65 years). For patients with disorders which are treatable by specific interventions, we have added a description of liver parameters on treatment.

Results

Our principal findings are (1) there is a clear pattern in the evolution of the hepatocellular injury markers alanine aminotransferase and aspartate aminotransferase according to age, especially in PMM2-CDG patients but also in other CDG-I, and that the cholangiocellular injury marker gamma-glutamyltransferase is not elevated in most patients, pointing to an exclusive hepatocellular origin of injury; (2) there is a dissociation between liver ultrasound and transient elastography regarding signs of liver fibrosis; (3) histopathological findings in liver tissue of PMM2-CDG patients include cytoplasmic glycogen deposits; and (4) most CDG types show more than one type of liver injury.

Conclusions

Based on these findings, we recommend that all CDG patients have regular systematic, comprehensive screening for liver disease, including physical examination (for hepatomegaly and signs of liver failure), laboratory tests (serum alanine aminotransferase and aspartate aminotransferase), liver ultrasound (for steatosis and liver tumors), and liver elastography (for fibrosis).

Transient elastography correlated to four different histological fibrosis scores in children with liver disease

Currently, liver histology is the gold standard for the detection of liver fibrosis. In recent years, new methods such as transient elastography (TE) have been introduced into clinical practice, which allow a non-invasive assessment of liver fibrosis. The aim of the present study was to investigate the predictive value of TE for higher grade fibrosis and whether there is any relevance which histologic score is used for matching. For this purpose, we compared TE with 4 different histologic scores in pediatric patients with hepatopathies. Furthermore, we also determined the aspartate aminotransferase-to-platelet ratio (APRI) score, another non-invasive method, to investigate whether it is equally informative. Therefore, liver fibrosis in 75 children was evaluated by liver biopsy, TE and laboratory values. Liver biopsies were evaluated using four common histological scoring systems (Desmet, Metavir, Ishak and Chevalier's semi-quantitative scoring system). The median age of the patients was 12.3 years. TE showed a good correlation to the degree of fibrosis severity independent of the histological scoring system used. The accuracy of the TE to distinguish between no/minimal fibrosis and severe fibrosis/cirrhosis was good (p = 0.001, AUC-ROCs > 0.81). The optimal cut-off value for the prediction of severe fibrosis was 10.6 kPa. In contrast, the APRI score in our collective showed no correlation to fibrosis.Conclusion: TE shows a good correlation to the histological findings in children with hepatopathy, independent of the used histological scoring system. What is Known: • The current gold standard for detecting liver fibrosis is liver biopsy. Novel non-invasive ultrasound-based methods are introduced to clinical diagnostics. • Most histological scores have been developed and evaluated in adult populations and for only one specific liver disease. What is New: • Transient elastography (TE) in children showed a good correlation to fibrosis severity irrespective of the utilized histological scoring system. • The aspartate aminotransferase-to-platelet ratio (APRI) showed no correlation with different stages of liver fibrosis in children.

The Use of Two-Dimensional Shear Wave Elastography in People with Obesity for the Assessment of Liver Fibrosis in Non-Alcoholic Fatty Liver Disease

Obesity is associated with significant comorbidities, including non-alcoholic fatty liver disease (NAFLD). Given its potential to progress to advanced liver disease, monitoring the extent and progress of liver fibrosis and assessing its fibrosis stage are essential. Although liver biopsy is considered to be the gold standard for liver fibrosis staging, it is an invasive procedure with risk of complications. Considering the rising prevalence of obesity and NAFLD globally, developing non-invasive diagnostic methods is a priority. Transient elastography (TE) is increasingly being used to assess the severity of liver disease. However, in the presence of severe obesity, the increased thickness of subcutaneous adipose tissue and changes in anatomy may affect its diagnostic accuracy. Two-dimensional shear wave elastography (2D-SWE) assesses the liver stiffness in real time along with simultaneous anatomic B-mode ultrasound imaging and allows selection of the region of interest. This would suggest that 2D-SWE has several advantages over TE in patients with severe obesity. The purpose of this review is to examine the current literature addressing the use of 2D-SWE in the assessment of liver fibrosis in patients with NAFLD. This review also examines the evidence on the use of 2D-SWE in patients with obesity and NAFLD and compares it to TE as a novel and non-invasive method of assessing liver fibrosis.

Deep learning networks on chronic liver disease assessment with fine-tuning of shear wave elastography image sequences

Chronic liver disease (CLD) is currently one of the major causes of death worldwide. If not treated, it may lead to cirrhosis, hepatic carcinoma and death. Ultrasound (US) shear wave elastography (SWE) is a relatively new, popular, non-invasive technique among radiologists. Although many studies have been published validating the SWE technique either in a clinical setting, or by applying machine learning on SWE elastograms, minimal work has been done on comparing the performance of popular pre-trained deep learning networks on CLD assessment. Currently available literature reports suggest technical advancements on specific deep learning structures, with specific inputs and usually on a limited CLD fibrosis stage class group, with limited comparison on competitive deep learning schemes fed with different input types. The aim of the present study is to compare some popular deep learning pre-trained networks using temporally stable and full elastograms, with or without augmentation as well as propose suitable deep learning schemes for CLD diagnosis and progress assessment. 200 liver biopsy validated patients with CLD, underwent US SWE examination. Four images from the same liver area were saved to extract elastograms and processed to exclude areas that were temporally unstable. Then, full and temporally stable masked elastograms for each patient were separately fed into GoogLeNet, AlexNet, VGG16, ResNet50 and DenseNet201 with and without augmentation. The networks were tested for differentiation of CLD stages in seven classification schemes over 30 repetitions using liver biopsy as the reference. All networks achieved maximum mean accuracies ranging from 87.2%-97.4% and area under the receiver operating characteristic curves (AUCs) ranging from 0.979-0.990 while the radiologists had AUCs ranging from 0.800-0.870. ResNet50 and DenseNet201 had better average performance than the other networks. The use of the temporal stability mask led to improved performance on about 50% of inputs and network combinations while augmentation led to lower performance for all networks. These findings can provide potential networks with higher accuracy and better setting in the CLD diagnosis and progress assessment. A larger data set would help identify the best network and settings for CLD assessment in clinical practice.

Current Ultrasound Technologies and Instrumentation in the Assessment and Monitoring of COVID-19 Positive Patients

Since the emergence of the COVID-19 pandemic in December of 2019, clinicians and scientists all over the world have faced overwhelming new challenges that not only threaten their own communities and countries but also the world at large. These challenges have been enormous and debilitating, as the infrastructure of many countries, including developing ones, had little or no resources to deal with the crisis. Even in developed countries, such as Italy, health systems have been so inundated by cases that health care facilities became oversaturated and could not accommodate the unexpected influx of patients to be tested. Initially, resources were focused on testing to identify those who were infected. When it became clear that the virus mainly attacks the lungs by causing parenchymal changes in the form of multifocal pneumonia of different levels of severity, imaging became paramount in the assessment of disease severity, progression, and even response to treatment. As a result, there was a need to establish protocols for imaging of the lungs in these patients. In North America, the focus was on chest X-ray and computed tomography (CT) as these are widely available and accessible at most health facilities. However, in Europe and China, this was not the case, and a cost-effective and relatively fast imaging modality was needed to scan a large number of sick patients promptly. Hence, ultrasound (US) found its way into the hands of Chinese and European physicians and has since become an important imaging modality in those locations. US is a highly versatile, portable, and inexpensive imaging modality that has application across a broad spectrum of conditions and, in this way, is ideally suited to assess the lungs of COVID-19 patients in the intensive care unit (ICU). This bedside test can be done with little to no movement of the patients from the unit that keeps them in their isolated rooms, thereby limiting further exposure to other health personnel. This article presents a basic introduction to COVID-19 and the use of the US for lung imaging. It further provides a high-level overview of the existing US technologies that are driving development in current and potential future US imaging systems for lung, with a specific emphasis on portable and 3-D systems.

Comparison of different MyotonPRO probes for skin stiffness evaluation in young women

BACKGROUND

Stiffness of skin is widely used parameter in many research areas, for example cosmetic industry, dermatology or rheumatology for assessing of skin condition as well as changes occurring in skin. In this pioneering study, we conducted measurements of skin stiffness using MyotonPRO -novel tool, which was mainly used to evaluate biomechanical properties of muscles, ligaments and tendons. We expected that MyotonPRO , which shows great reproducibility in previous studies, will also be able to measure skin stiffness.

MATERIALS AND METHODS

Four replaceable probes designed by MyotonPRO (L-shape short and medium arm, standard cylindrical flat-end probe and the same standard probe with disc attachment ) were tested for measurement of skin stiffness in young women (30 healthy females) at three different locations (clavicula, volar forearm and shin).

RESULTS

There was no significant difference between stiffness values obtained with L-shape short and L-shape medium arm probes in all investigated areas. Stiffness values recorded by regular probe and regular probe with disc attachment differ significantly from those collected with L-shape probes. There was also significant difference between values of stiffness obtained by standard with disc attachment and standard probes.

CONCLUSION

Both L-shape probes show a great reliability for skin stiffness assessment. Therefore, MyotonPRO can be considered a reliable device for assessing skin stiffness.

Synthetic aperture with high lateral sampling frequency for ultrasound elastography

Ultrasound elastography is a non-invasive technique for detecting pathological alterations in tissue. It is known that pathological alteration of tissue often has a direct impact on its elastic modulus, which can be revealed using elastography. For estimating elastic modulus, we need to estimate both axial and lateral displacement accurately. Current state of the art elastography techniques provide a substantially less accurate lateral displacement field as compared to the axial displacement field. One of the most important factors in poor lateral estimation is a low sampling frequency in the lateral direction. In this paper, we use synthetic aperture beamforming to benefit from its capability of high sampling frequency in the lateral direction. We compare highly sampled data and focused line per line beam formed data by feeding them to our recently published elastography method, OVERWIND [1]. According to simulation and phantom experiments, not only the lateral displacement estimation is substantially improved, but also the axial displacement estimation is improved.

Hepatocellular Carcinoma and Non-Alcoholic Fatty Liver Disease: A Step Forward for Better Evaluation Using Ultrasound Elastography

Simple Summary

Non-alcoholic fatty liver disease (NAFLD) attracts a lot of attention, due to the increasing prevalence and progression to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Consequently, new non-invasive, cost-effective diagnostic methods are needed. This review aims to explore the diagnostic performance of ultrasound (US) elastography in NAFLD and NAFLD-related HCC, adding a new dimension to the conventional US examination—the liver stiffness quantification. The vibration controlled transient elastography (VCTE), and 2D-Shear wave elastography (2D-SWE) are effective in staging liver fibrosis in NAFLD. VCTE presents the upside of assessing steatosis through the controlled attenuation parameter. Hereby, we critically reviewed the elastography techniques for the quantitative characterization of focal liver lesions (FLLs), focusing on HCC: Point shear wave elastography and 2D-SWE. 2D-SWE presents a great potential to differentiate malignant from benign FLLs, guiding the clinician towards the next diagnostic steps. As a disease-specific surveillance tool, US elastography presents prognostic capability, improving the NAFLD-related HCC monitoring.

Abstract

The increasing prevalence of non-alcoholic fatty liver disease (NAFLD) in the general population prompts for a quick response from physicians. As NAFLD can progress to liver fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC), new non-invasive, rapid, cost-effective diagnostic methods are needed. In this review, we explore the diagnostic performance of ultrasound elastography for non-invasive assessment of NAFLD and NAFLD-related HCC. Elastography provides a new dimension to the conventional ultrasound examination, by adding the liver stiffness quantification in the diagnostic algorithm. Whilst the most efficient elastographic techniques in staging liver fibrosis in NAFLD are vibration controlled transient elastography (VCTE) and 2D-Shear wave elastography (2D-SWE), VCTE presents the upside of assessing steatosis through the controlled attenuation parameter (CAP). Hereby, we have also critically reviewed the most important elastographic techniques for the quantitative characterization of focal liver lesions (FLLs), focusing on HCC: Point shear wave elastography (pSWE) and 2D-SWE. As our paper shows, elastography should not be considered as a substitute for FLL biopsy because of the stiffness values overlap. Furthermore, by using non-invasive, disease-specific surveillance tools, such as US elastography, a subset of the non-cirrhotic NAFLD patients at risk for developing HCC can be detected early, leading to a better outcome. A recent ultrasomics study exemplified the wide potential of 2D-SWE to differentiate benign FLLs from malignant ones, guiding the clinician towards the next steps of diagnosis and contributing to better long-term disease surveillance.

Quantitative ultrasound elastography and serum ferritin level in dogs with liver tumors

Objective:

The objective of this study was to assess the serum ferritin level and quantitate ultrasound elastography as a marker to distinguish dogs with benign and malignant liver tumors.

Materials and Methods:

Twenty-eight dogs were determined the serum ferritin and ultrasound elastography by using fine-needle aspiration biopsy.

Results:

Our results demonstrated that dogs with malignant liver tumors had significantly higher mean serum ferritin concentrations than those with benign liver tumors (p = 0.004). The mean intensity of blue and red colors from elastography was greater in the malignant than those in the benign group, especially for the blue color, meaning that lesions showed more hard tissue. Additionally, histograms of blue color in the malignant tended to be higher than the benign group.

Conclusion:

We suggested that quantitative ultrasound elastography and serum ferritin concentration comprise an alternative and non-invasive diagnostic method that could be used to predict the type of liver tumors in dogs.

Radiomics Improves Cancer Screening and Early Detection

Imaging is a key technology in the early detection of cancers, including X-ray mammography, low-dose CT for lung cancer, or optical imaging for skin, esophageal, or colorectal cancers. Historically, imaging information in early detection schema was assessed qualitatively. However, the last decade has seen increased development of computerized tools that convert images into quantitative mineable data (radiomics), and their subsequent analyses with artificial intelligence (AI). These tools are improving diagnostic accuracy of early lesions to define risk and classify malignant/aggressive from benign/indolent disease. The first section of this review will briefly describe the various imaging modalities and their use as primary or secondary screens in an early detection pipeline. The second section will describe specific use cases to illustrate the breadth of imaging modalities as well as the benefits of quantitative image analytics. These will include optical (skin cancer), X-ray CT (pancreatic and lung cancer), X-ray mammography (breast cancer), multiparametric MRI (breast and prostate cancer), PET (pancreatic cancer), and ultrasound elastography (liver cancer). Finally, we will discuss the inexorable improvements in radiomics to build more robust classifier models and the significant limitations to this development, including access to well-annotated databases, and biological descriptors of the imaged feature data.See all articles in this CEBP Focus section, "NCI Early Detection Research Network: Making Cancer Detection Possible."