Explorative study using ultrasound time-harmonic elastography for stiffness-based quantification of skeletal muscle function

Time-harmonic elastography (THE) is an emerging ultrasound imaging technique that allows full-field mapping of the stiffness of deep biological tissues. THE's unique ability to rapidly capture stiffness in multiple tissues has never been applied for imaging skeletal muscle. Therefore, we addressed the lack of data on temporal changes in skeletal muscle stiffness while simultaneously covering stiffness of different muscles. Acquiring repeated THE scans every five seconds we quantified shear-wave speed (SWS) as a marker of stiffness of the long head (LHB) and short head (SHB) of biceps brachii and of the brachialis muscle (B) in ten healthy volunteers. SWS was continuously acquired during a 3-min isometric preloading phase, a 3-min loading phase with different weights (4, 8, and 12 kg), and a 9-min postloading phase. In addition, we analyzed temporal SWS standard deviation (SD) as a marker of muscle contraction regulation. Our results (median [min, max]) showed both SWS at preloading (LHB: 1.04 [0.94, 1.12] m/s, SHB: 0.86 [0.78, 0.94] m/s, B: 0.96 [0.87, 1.09] m/s, p < 0.001) and the increase in SWS with loading weight to be muscle-specific (LHB: 0.010 [0.002, 0.019] m/s/kg, SHB: 0.022 [0.017, 0.042] m/s/kg, B: 0.039 [0.019, 0.062] m/s/kg, p < 0.001). Additionally, SWS during loading increased continuously over time by 0.022 [0.004, 0.051] m/s/min (p < 0.01). Using an exponential decay model, we found an average relaxation time of 27 seconds during postloading. Analogously, SWS SD at preloading was also muscle-specific (LHB: 0.018 [0.011, 0.029] m/s, SHB: 0.021 [0.015, 0.027] m/s, B: 0.024 [0.018, 0.037] m/s, p < 0.05) and increased by 0.005 [0.003, 0.008] m/s/kg (p < 0.01) with loading. SWS SD did not change over loading time and decreased immediately in the postloading phase. Taken together, THE of skeletal muscle is a promising imaging technique for in vivo quantification of stiffness and stiffness changes in multiple muscle groups within seconds. Both the magnitude of stiffness changes and their temporal variation during isometric exercise may reflect the functional status of skeletal muscle and provide additional information to the morphological measures obtained by conventional imaging modalities.

Combining 99mTc-GSA single-photon emission-computed tomography and Gd-EOB-DTPA-enhanced magnetic resonance imaging for staging liver fibrosis

Preoperative assessment of the degree of liver fibrosis is important to determine treatment strategies. In this study, galactosyl human serum albumin single-photon emission-computed tomography and ethoxybenzyl (EOB) contrast-enhanced magnetic resonance imaging (MRI) were used to assess the changes in hepatocyte function after liver fibrosis, and the standardized uptake value (SUV) was combined with gadolinium EOB-diethylenetriaminepentaacetic acid to evaluate its added value for liver fibrosis staging. A total of 484 patients diagnosed with hepatocellular carcinoma who underwent liver resection between January 2010 and August 2018 were included. Resected liver specimens were classified based on pathological findings into nonfibrotic and fibrotic groups (stratified according to the Ludwig scale). Galactosyl human serum albumin-single-photon emission-computed tomography and EOB contrast-enhanced MRI examinations were performed, and the mean SUVs (SUVmean) and contrast enhancement indices (CEIs) were obtained. The diagnostic value of the acquired SUV and CEIs for fibrosis was assessed by calculating the area under the receiver operating characteristic curve (AUC). In the receiver operating characteristic analysis, SUV + CEI showed the highest AUC in both fibrosis groups. In particular, in the comparison between fibrosis groups, SUV + CEI showed significantly higher AUCs than SUV and CEI alone in discriminating between fibrosis (F3 and 4) and no or mild fibrosis (F0 and 2) (AUC: 0.879, vs SUV [P = 0.008], vs. CEI [P = 0.023]), suggesting that the combination of SUV + CEI has greater diagnostic performance than the individual indices. Combining the SUV and CEI provides high accuracy for grading liver fibrosis, especially in differentiating between grades F0 and 2 and F3-4. SUV and gadolinium EOB-diethylenetriaminepentaacetic acid-enhanced MRI can be noninvasive diagnostic methods to guide the selection of clinical treatment options for patients with liver diseases.

Clinical studies of magnetic resonance elastography from 1995 to 2021: Scientometric and visualization analysis based on CiteSpace

BACKGROUND

To assess the knowledge framework around magnetic resonance elastography (MRE) and to explore MRE research hotspots and emerging trends.

METHODS

The Science Citation Index Expanded of the Web of Science Core Collection was searched on 22 October 2021 for MRE-related studies published between 1995 and 2021. Excel 2016 and CiteSpace V (version 5.8.R3) were used to analyze the downloaded data.

RESULTS

In all, 1,236 articles published by 726 authors from 540 institutions in 40 countries were included in this study. The top 10 authors published 57.6% of all included articles. The 3 most productive countries were the USA (n=631), Germany (n=202), and France (n=134), and the 3 most productive institutions were the Mayo Clinic (n=240), Charité (n=131), and the University of Illinois (n=56). The USA and the Mayo Clinic had the highest betweenness centrality among countries and institutions, respectively, and played an important role in the field of MRE. In this study, the 24,347 distinct references were clustered into 48 categories via reasonable clustering using specific keywords, forming the knowledge framework. Among the 294 co-occurring keywords, "hepatic fibrosis", "stiffness", "skeletal muscle", "acoustic strain wave", "in vivo", and "non-invasive assessment" were research hotspots. "Diagnostic performance", "diagnostic accuracy", "hepatic steatosis", "chronic hepatitis B", "radiation force impulse", "children", and "echo" were frontier topics.

CONCLUSIONS

Scientometric and visualized analysis of MRE can provide information regarding the knowledge framework, research hotspots, frontier areas, and emerging trends in this field.

Evaluation of Different Types of Breast Lesions With Apparent Diffusion Coefficient and Shear Wave Elastography Values: Comparison of Shear Wave Elastography and Apparent Diffusion Coefficient in Breast Lesions

Objective:

The aim of this study was to compare the stiffness of different histological types of breast lesions by obtaining shear wave elastography (SWE) and apparent diffusion coefficient (ADC) values, and to determine the contribution of these two methods to the diagnosis.

Materials and Methods:

In total, 70 patients with biopsy-proven breast lesions were included in the study. The mean SWE values of breast lesions were recorded and ADC values of these lesions were calculated. Receiver operating characteristic (ROC) curve analyses and the diagnostic accuracies of SWE-ADC values were determined.

Results:

The mean SWE values were 45.47 ± 25.11 kPa and 3.51 ± 1.04 m/s in benign group, and 161.11 ± 219.34 kPa and 5.96 ± 1.06 m/s in malignant group, respectively. The mean ADC values were 1.38 ± 0.32 (×10–3 mm2/s) in benign group and 0.96 ± 0.22 (×10–3 mm2/s) in malignant group, respectively. When the diagnostic performances of both imaging modalities on mass stiffness are evaluated, statistically significant negative correlations were found between SWE lesion values and ADC lesion values.

Conclusion:

Evaluation of tissue elasticity has recently been used frequently in the diagnosis of breast diseases. SWE-ADC values, which are negatively correlated in the diagnosis of breast masses, may prove to be a powerful alternative diagnostic tool that can be used interchangeably, as appropriate.

Liver stiffness measurement as a quantitative method for liver fibrosis in children with non-alcoholic fatty liver disease: A meta-analysis

AIM

This study assessed the diagnostic performance of liver stiffness measurement (LSM) in detecting liver fibrosis in paediatric patients with non-alcoholic fatty liver disease (NAFLD) through meta-analysis.

METHODS

Online database searches of PubMed, EMBASE, the Cochrane Library and the Web of Science were conducted for studies that evaluated the performance of LSM for diagnosing liver fibrosis in paediatric patients with NAFLD until 1 January 2021. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool was used to assess the quality of the included studies. Three measures were used to assess the performance of LSM for detecting liver fibrosis in paediatric patients with NAFLD, including the summary sensitivities and specificities, the summary area under the receiver operating characteristic curves and the summary diagnostic odds ratios.

RESULTS

Our final data included seven studies with a total of 436 paediatric patients with NAFLD for meta-analysis. The overall prevalence of mild fibrosis, significant fibrosis, advanced fibrosis and cirrhosis was 66.3, 31.5, 14.9 and 1.2%, respectively. The summary sensitivity, specificity and area under the receiver operating characteristic values of LSM were 80, 92 and 0.94 for the prediction of mild fibrosis; 91, 97 and 0.98 for the prediction of significant fibrosis; and 89, 93 and 0.96 for the prediction of advanced fibrosis, respectively.

CONCLUSION

Liver stiffness measurement exhibited good diagnostic performance in predicting liver fibrosis and can be used as a non-invasive tool in the management of paediatric patients with non-alcoholic fatty liver disease.

Noninvasive Detection of Intracranial Hypertension by Novel Ultrasound Time-Harmonic Elastography

OBJECTIVE

A method for measuring intracranial pressure (ICP) noninvasively has long been sought after in neurology and neurosurgery. Treatment failure in individuals presenting with unspecific symptoms such as headache, gait disturbance, or visual impairment occurring in response to increased ICP can lead to irreversible brain injury, progressive disability, and death. Guidelines for diagnostic ICP measurement recommend intracranial placement of pressure tip catheters or lumbar puncture (LP) despite their invasiveness and possible complications. As ICP fluctuations are closely associated with changes in brain stiffness, ultrasound elastography could be a valid method to detect ICP noninvasively and with short examination times.

MATERIALS AND METHODS

In this pilot study, we have investigated the use of time-harmonic shear waves, introduced into the brain by an external shaker, and measured in real-time by transtemporal ultrasound, for deducing a noninvasive imaging marker sensitive to elevated ICP. To this end, we developed cerebral ultrasound time-harmonic elastography for the noninvasive quantification of shear wave speed (SWS) as a surrogate marker of cerebral stiffness in a short examination time of a few minutes.

RESULTS

We found that SWS in patients enrolled for LP with confirmed intracranial hypertension was 1.81 ± 0.10 m/s, distinguishing them from healthy volunteers with excellent diagnostic accuracy (1.55 ± 0.08 m/s; P < 0.001; area under the curve, 0.99). Interestingly, values in symptomatic patients decreased to normal stiffness immediately after LP (1.56 ± 0.06 m/s, P < 0.001). Moreover, invasively measured opening pressure correlated with SWS measured before LP and liquid volume drained through the spinal tap with the SWS difference between the 2 measurements.

CONCLUSIONS

Collectively, our results suggest a tight link between cerebral stiffness and ICP and demonstrate that intracranial hypertension can be detected noninvasively within short examination times, opening avenues for diagnostic applications of cerebral ultrasound time-harmonic elastography in neurology and emergency medicine.

Aptamer-Assisted Protein Orientation on Silver Magnetic Nanoparticles: Application to Sensitive Leukocyte Cell-Derived Chemotaxin 2 Surface Plasmon Resonance Sensors

Leukocyte cell-derived chemotaxin 2 (LECT2) has been proved to be a potential biomarker for the diagnosis of liver fibrosis. In this work, a sensitive surface plasmon resonance (SPR) assay for LECT2 analysis was developed. Tyrosine kinase with immune globulin-like and epidermal growth factor-like domains 1 (Tie1) is an orphan receptor of LECT2 with a C-terminal Fc tag, which is far away from the LECT2 binding sites. The Fc aptamer was intentionally used to capture the Tie1 through its Fc tag, connecting with Fe₃O₄-coated silver magnetic nanoparticles (Ag@MNPs) and ensuring the LECT2 binding site to be outward. Attributed to the orientation nature of the captured protein, Ag@MNPs were able to enhance the SPR signal. A sensitive LECT2 sensor was successfully fabricated with a detection limit of 10.93 pg/mL. The results showed that the immobilization method improved the binding efficiency of Tie1 protein. This strategy could be extended to attach antibodies or recombinant Fc label proteins to Fc aptamer-based nanoparticles.

Performance of Imaging Techniques in Non-invasive Diagnosis of Non-alcoholic Fatty Liver Disease in Children: A Systematic Review and Meta-Analysis

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in children. With the continuous emergence of various non-invasive diagnostic methods, imaging techniques have always been considered as potential alternative methods to liver biopsy. This study aimed to evaluate the diagnostic performance of imaging techniques so as to search for the most promising technology.

METHODS

We searched English and Chinese databases. English databases included Cochran library, Embase, PubMed, and Web of Science, while Chinese databases included the Wanfang database and China National Knowledge Internet.

RESULTS

Finally, 11 articles were included (12 studies, one of which included studies on both fibrosis and steatosis). Further, 26.2% of the participants had mild steatosis, 34.1% had moderate steatosis, and 34.9% had severe steatosis. Also, 64.0% had any fibrosis, 29.1% had significant fibrosis, 13.8% had advanced fibrosis, and 2.8% had cirrhosis. Irrespective of the grade of fibrosis, transient elastography (TE) had higher sensitivity (97-100%), whereas magnetic resonance elastography (MRE) had the lowest sensitivity (58-63%). The pooled sensitivity and specificity of imaging techniques in diagnosing steatosis were 89% (95% CI, 71-96) and 89% (95% CI, 72-96), and AUROC 0.95 (95% CI, 93-97), multifrequency magnetic resonance elastography-hepatic fat fraction (mMRE-HFF) had the highest sensitivity (87%, 95% CI 77-97), ultrasonography (US) had the lowest specificity (96%, 95% CI 92-98%).

CONCLUSION

Imaging techniques have a good diagnostic performance for children with NAFLD, especially the diagnosis of liver fibrosis based on ultrasound or magnetic resonance elastography. Compared with different imaging techniques, TE has the best performance in diagnosing significant fibrosis. Liver stiffness measurement (LSM) is expected to become a biological indicator for routine screening, dynamic monitoring of disease changes, and prognostic evaluation.

Diagnostic accuracy of fibrosis tests in children with non-alcoholic fatty liver disease: A systematic review

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in children. Even at young age, it can progress to liver fibrosis. Given the drawbacks of liver biopsy, there is a need for non-invasive methods to accurately stage liver fibrosis in this age group. In this systematic review, we evaluate the diagnostic accuracy of non-invasive methods for staging liver fibrosis in children with NAFLD.

METHODS

We searched MEDLINE, Embase, Web of Science and the Cochrane Library, for studies that evaluated the performance of a blood-based biomarker, prediction score or imaging technique in staging liver fibrosis in children with NAFLD, using liver biopsy as the reference standard.

RESULTS

Twenty studies with a total of 1787 NAFLD subjects were included, which evaluated three prediction scores, five simple biomarkers, two combined biomarkers and six imaging techniques. Most studies lacked validation. Substantial heterogeneity of studies and limited available study data precluded a meta-analysis of the few fibrosis tests evaluated in more than one study. The most consistent accuracy data were found for transient elastography by FibroScan®, ELF test and ultrasound elastography, with an area under the receiver operating characteristics curve varying between 0.92 and 1.00 for detecting significant fibrosis.

CONCLUSION

Due to the lack of validation, the accuracy and clinical utility of non-invasive fibrosis tests in children with NAFLD remains uncertain. As studies have solely been performed in tertiary care settings, accuracy data cannot directly be translated to screening populations.

How histopathologic changes in pediatric nonalcoholic fatty liver disease influence in vivo liver stiffness

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents. About 30% of patients with NAFLD progress to the more severe condition of nonalcoholic steatohepatitis (NASH), which is typically diagnosed using liver biopsy. Liver stiffness (LS) quantified by elastography is a promising imaging marker for the noninvasive assessment of NAFLD and NASH in pediatric patients. However, the link between LS and specific histopathologic features used for clinical staging of NAFLD is not well defined. Furthermore, LS data reported in the literature can vary greatly due to the use of different measurement techniques. Uniquely, time-harmonic elastography (THE) based on ultrasound and magnetic resonance elastography (MRE) use the same mechanical stimulation, allowing us to compare LS in biopsy-proven NAFLD previously determined by THE and MRE in 67 and 50 adolescents, respectively. In the present work, we analyzed the influence of seven distinct histopathologic features on LS, including septal infiltration, bridging fibrosis, pericellular fibrosis, hepatocellular ballooning, portal inflammation, lobular inflammation, and steatosis. LS was highly correlated with periportal and lobular fibrosis as well as hepatocellular ballooning while no independent association was found for inflammation and steatosis. Based on this analysis, we propose a composite elastography score (CES) which includes the four key histopathologic features identified as mechanically relevant. Interestingly, CES-relevant histopathologic features were associated with zonal distribution patterns of pediatric NAFLD. Mechano-structural changes associated with NAFLD progression can be histopathologically staged using the CES, which is easily determined noninvasively based on LS measured by time-harmonic elastography.

The gap between overweight and obesity status in children - (STROBE-compliant article)

Overweight might represent only the early stage of obesity or it might act as a trigger of self-awareness turning into an ideal chance for preventing further obesity development.The aim of this study was to assess the differences between overweight and obese children in terms of anthropometric, low-grade systemic inflammation, liver impairment and atherosclerotic risk.We performed a study on 132 children aged between 5 and 18 years, divided according to the BMI into 2 groups: group 1 to 76 obese children, and group 2 to 56 overweight children, assessing anthropometric, laboratory and elastography parameters.We obtained significantly higher values of anthropometric parameters in obese children versus overweight ones. We found higher levels of leukocytes, lymphocytes, AST, ALT, and E median (P = .0345, P = .0103, P < .0001, P = .0008 and P < .0001) in the obese group as compared to the overweight one. BMI was positively correlated with neutrophils, NLR, ESR, glycemia, anthropometric parameters, and E median (P = .0007/<.0001/.0018/.0044/<.0001/<.0001/<.0001/<.0001/<.0001/.0204); and negatively with lymphocytes and HDL-cholesterol (r = -0.2747/-0.2181, P = .0116/.0120).Our study underlined significant differences between overweight and obese children in terms of inflammatory status and liver impairment suggesting that the risk is directly related to the increase in BMI.

Changes in Liver Mechanical Properties and Water Diffusivity During Normal Pregnancy Are Driven by Cellular Hypertrophy

During pregnancy, the body’s hyperestrogenic state alters hepatic metabolism and synthesis. While biochemical changes related to liver function during normal pregnancy are well understood, pregnancy-associated alterations in biophysical properties of the liver remain elusive. In this study, we investigated 26 ex vivo fresh liver specimens harvested from pregnant and non-pregnant rats by diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE) in a 0.5-Tesla compact magnetic resonance imaging (MRI) scanner. Water diffusivity and viscoelastic parameters were compared with histological data and blood markers. We found livers from pregnant rats to have (i) significantly enlarged hepatocytes (26 ± 15%, p < 0.001), (ii) increased liver stiffness (12 ± 15%, p = 0.012), (iii) decreased viscosity (−23 ± 14%, p < 0.001), and (iv) increased water diffusivity (12 ± 11%, p < 0.001). In conclusion, increased stiffness and reduced viscosity of the liver during pregnancy are mainly attributable to hepatocyte enlargement. Hypertrophy of liver cells imposes fewer restrictions on intracellular water mobility, resulting in a higher hepatic water diffusion coefficient. Collectively, MRE and DWI have the potential to inform on structural liver changes associated with pregnancy in a clinical context.

MR elastography: Principles, guidelines, and terminology

Magnetic resonance elastography (MRE) is a phase contrast-based MRI technique that can measure displacement due to propagating mechanical waves, from which material properties such as shear modulus can be calculated. Magnetic resonance elastography can be thought of as quantitative, noninvasive palpation. It is increasing in clinical importance, has become widespread in the diagnosis and staging of liver fibrosis, and additional clinical applications are being explored. However, publications have reported MRE results using many different parameters, acquisition techniques, processing methods, and varied nomenclature. The diversity of terminology can lead to confusion (particularly among clinicians) about the meaning of and interpretation of MRE results. This paper was written by the MRE Guidelines Committee, a group formalized at the first meeting of the ISMRM MRE Study Group, to clarify and move toward standardization of MRE nomenclature. The purpose of this paper is to (1) explain MRE terminology and concepts to those not familiar with them, (2) define "good practices" for practitioners of MRE, and (3) identify opportunities to standardize terminology, to avoid confusion.

Performance of a Noninvasive Time-Harmonic Elastography Technique for Liver Fibrosis Evaluation Using Vibration Controlled Transient Elastography as Reference Method

AIM

This study aimed to evaluate the diagnosis performance of time-harmonic elastography (THE) technique in real life in assessing liver fibrosis, considering vibration-controlled transient elastography (VCTE) as a reference method.

MATERIAL AND METHOD

We prospectively evaluated outpatients from the gastroenterology department. Liver stiffness (LS) was measured by the THE system by dedicated operators, and by VCTE by experienced operators. The diagnostic accuracy of THE in staging liver fibrosis was assessed. We also performed an intra- and interobserver reproducibility sub-analysis on a sub-group of 27 subjects, where liver stiffness measurements (LSM) were performed by a novice, an elastography expert, and an ultrasound expert.

RESULTS

Of the 165 patients, using VCTE cut-off values, 49.6% were F0-F1, 15.7% were F2, 6.6% were F3, and 28.1% were F4. A direct, significant and strong correlation (r = 0.82) was observed between LSM assessed by VCTE and THE, p < 0.0001. The cut-off for ruling out liver cirrhosis (LC) by THE on our study group was <1.61 m/s (7.77 kPa)-AUROC = 0.90 [95% CI (0.82-0.93)], Se = 90.7%, Sp = 66.6%, PPV = 55.7%, NPV = 93.9%. The cut-off for ruling in LC by THE was >1.83 m/s (10 kPa)-AUROC = 0.90 [95% CI (0.82-0.93)], p < 0.0001, Se = 65.1%, Sp = 96.7%, PPV = 90.3%, NPV = 85.7%. The overall agreement between examiners was excellent: 0.94 (95% CI: 0.89-0.97); still, the ICCs were higher for the more experienced elastography examiner: 0.92 (95% CI: 0.82-0.96) vs. 0.94 (95% CI: 0.87-0.97) vs. 0.97 (95% CI: 0.95-0.99).

CONCLUSIONS

THE is a feasible and reproducible elastography technique that can accurately rule in and rule out advanced liver disease.

Updates in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in childhood. There is an increase in disease prevalence and diagnoses as it is difficult to diagnose the problem. There are currently no effective medications. Management of NAFLD is a challenge for primary care clinicians and subspecialists. This paper provides guidelines for disease screening, diagnosis, management, and algorithm for subspecialty referral.

Pre-operative Detection of Liver Fibrosis in Hepatocellular Carcinoma Patients Using 2D Shear Wave Elastography: Where to Measure?

The aim of this study was to pre-operatively investigate the diagnostic performance of 2D shear wave elastography (2D-SWE) for staging liver fibrosis and inflammation in patients with hepatocellular carcinoma (HCC) who then undergo surgery and to determine the optimal locations for measurement. In total, 106 patients were enrolled in this prospective study from March 2017 to May 2018. Two-dimensional SWE was used to measure liver stiffness (LS) in each patient 0-1, 1-2 and 2-5 cm from the tumor border (groups 1, 2 and 3, respectively). Spearman's correlation was used to evaluate the relationships between LS and hepatic fibrosis and between LS and inflammation. Receiver operating characteristic curve (ROC) analysis was used to evaluate the diagnostic accuracy of 2D-SWE. The technical success rate of SWE in tissue distant from the tumor (group 3) was significantly higher than that in peri-tumoral tissue (groups 1 and 2) (p < 0.001). Moreover, the area under the ROC for diagnosing cirrhosis (F4) and severe inflammation (A3) was higher for group 3 than for groups 1 and 2. Our results suggest that 2D-SWE is a helpful approach to assessment of hepatic fibrosis in HCC patients before hepatic resection. We found that to achieve a superior success rate and preferable diagnosis accuracy for patients with HCC, LS measurement should be performed 2-5 cm from the tumor margin.

The assessment of liver fibrosis in children with obesity on two methods: transient and two dimensional shear wave elastography

The aim of this study was to assess the liver stiffness values in children with obesity versus healthy children on 2D-SWE and TE taking into account different laboratory parameters. We performed a case-control study on 287 children aged between 3 to 18 years, admitted in a Romanian Pediatric Tertiary Hospital, which we divided according to the body mass index (BMI) into two groups: the study group-77 children with obesity, and control group-210 children with normal weight. All children underwent anamnesis, clinical exam, laboratory parameters, ultrasound exam, and elastography. Children with obesity presented higher values of platelets, AST, ALT, and AAR as compared to control group (p = 0.0005/p = 0.0065/p < 0.0001/p < 0.0001). We found no significant differences for APRI between the two groups (p = 0.9827), although the values were higher in children with obesity. Significantly higher values of liver stiffness in children with obesity on both 2D-SWE and TE (p = 0.0314/p < 0.0001) were obtained. Similarly, the velocity values measured by 2D-SWE were also significantly higher in the study group (p < 0.0001). Our findings revealed significantly higher levels of platelets, transaminases, AAR, and liver stiffness values on both TE and 2D-SWE in children with obesity. 2D-SWE and TE might represent useful non-invasive methods for predicting liver impairment associated to pediatric obesity.

Non-invasive structure-function assessment of the liver by 2D time-harmonic elastography and the dynamic Liver MAximum capacity (LiMAx) test

BACKGROUND AND AIM

Accurate assessment of structural and functional characteristics of the liver could improve the diagnosis and the clinical management of patients with chronic liver diseases. However, the structure-function relationship in the progression of chronic liver disease remains elusive. The aim of this study is the combined measurement of liver function by the ¹³ C-methacetin Liver MAximum capacity (LiMAx) test and tissue-structure related stiffness by 2D time-harmonic elastography for the assessment of liver disease progression.

METHODS

LiMAx test and time-harmonic elastography were applied, and the serological scores fibrosis 4 index and aspartate aminotransferase to platelet ratio index were calculated in patients with chronic liver diseases (n = 75) and healthy control subjects (n = 22). In 47 patients who underwent surgery, fibrosis was graded by histological examination of the resected liver tissue.

RESULTS

LiMAx values correlated negatively with liver stiffness (r = -0.747), aminotransferase to platelet ratio index (r = -0.604), and fibrosis 4 (r = -0.573). Median (interquartile range) LiMAx values decreased with fibrosis progression from 395 μg/kg/h (371-460 μg/kg/h) in participants with no fibrosis to 173 μg/kg/h (126-309 μg/kg/h) in patients with severe fibrosis. Median liver stiffness increased progressively with the stage of fibrosis from no fibrosis (1.56 m/s [1.52-1.63 m/s]) to moderate fibrosis (1.60 m/s [1.54-1.67 m/s]) to severe fibrosis (1.85 m/s [1.76-1.92 m/s]).

CONCLUSION

Our findings show that structural changes in the liver due to progressing liver diseases and reflected by increased tissue stiffness correlate with a functional decline of the organ as reflected by a decreased metabolic capacity of the liver.

Future of breast elastography

Both strain elastography and shear wave elastography have been shown to have high sensitivity and specificity for characterizing breast lesions as benign or malignant. Training is important for both strain and shear wave elastography. The unique feature of benign lesions measuring smaller on elastography than B-mode imaging and malignant lesions appearing larger on elastography is an important feature for characterization of breast masses. There are several artifacts which can contain diagnostic information or alert to technique problems. Both strain and shear wave elastography continue to have improvements and new techniques will soon be available for clinical use that may provide additional diagnostic information. This paper reviews the present state of breast elastography and discusses future techniques that are not yet in clinical practice.

In vivo time-harmonic ultrasound elastography of the human brain detects acute cerebral stiffness changes induced by intracranial pressure variations

Cerebral stiffness (CS) reflects the biophysical environment in which neurons grow and function. While long-term CS changes can occur in the course of chronic neurological disorders and aging, little is known about acute variations of CS induced by intracranial pressure variations. Current gold standard methods for CS and intracranial pressure such as magnetic resonance elastography and direct pressure recordings are either expensive and slow or invasive. The study objective was to develop a real-time method for in vivo CS measurement and to demonstrate its sensitivity to physiological aging and intracranial pressure variations induced by the Valsalva maneuver in healthy volunteers. We used trans-temporal ultrasound time-harmonic elastography (THE) with external shear-wave stimulation by continuous and superimposed vibrations in the frequency range from 27 to 56 Hz. Multifrequency wave inversion generated maps of shear wave speed (SWS) as a surrogate maker of CS. On average, cerebral SWS was 1.56 ± 0.08 m/s with a tendency to reduce with age (R = -0.76, p < 0.0001) while Valsalva maneuver induced an immediate stiffening of the brain as reflected by a 10.8 ± 2.5% increase (p < 0.0001) in SWS. Our results suggest that CS is tightly linked to intracranial pressure and might be used in the future as non-invasive surrogate marker for intracranial pressure, which otherwise requires invasive measurements.