Shear-wave elastography to predict hepatocellular carcinoma after hepatitis C virus eradication: A systematic review and meta-analysis.

BACKGROUND: Direct-acting antiviral agents (DAAs) are highly effective treatment for chronic hepatitis C (CHC) with a significant rate of sustained virologic response (SVR). The achievement of SVR is crucial to prevent additional liver damage and slow down fibrosis progression. The assessment of fibrosis degree can be performed with transient elastography, magnetic resonance elastography or shear-wave elastography (SWE). Liver elastography could function as a predictor for hepatocellular carcinoma (HCC) in CHC patients treated with DAAs. AIM: To explore the predictive value of SWE for HCC development after complete clearance of hepatitis C virus (HCV). METHODS: A comprehensive literature search of clinical studies was performed to identify the ability of SWE to predict HCC occurrence after HCV clearance. In accordance with the study protocol, a qualitative and quantitative analysis of the evidence was planned. RESULTS: At baseline and after 12 wk of follow-up, a trend was shown towards greater liver stiffness (LS) in those who go on to develop HCC compared to those who do not [baseline LS standardized mean difference (SMD): 1.15, 95% confidence interval (95%CI): 020-2.50; LS SMD after 12 wk: 0.83, 95%CI: 0.33-1.98]. The absence of a statistically significant difference between the mean LS in those who developed HCC or not may be related to the inability to correct for confounding factors and the absence of raw source data. There was a statistically significant LS SMD at 24 wk of follow-up between patients who developed HCC vs not (0.64; 95%CI: 0.04-1.24). CONCLUSION: SWE could be a promising tool for prediction of HCC occurrence in patients treated with DAAs. Further studies with larger cohorts and standardized timing of elastographic evaluation are needed to confirm these data.

Investigation of correlation between shear wave elastography and lymphangiogenesis in invasive breast cancer and diagnosis of axillary lymph node metastasis.

BACKGROUND: Accurate evaluation of axillary lymph node metastasis (LNM) in breast cancer is very important. A large number of hyperplastic and dilated lymphangiogenesis cases can usually be found in the pericancerous tissue of breast cancer to promote the occurrence of tumor metastasis.Shear wave elastography (SWE) can be used as an important means for evaluating pericancerous stiffness. We determined the stiffness of the pericancerous by SWE to diagnose LNM and lymphangiogenesis in invasive breast cancer (IBC). METHODS: Patients with clinical T1-T2 stage IBC who received surgical treatment in our hospital from June 2020 to December 2020 were retrospectively enrolled. A total of 299 patients were eventually included in the preliminary study, which included an investigation of clinicopathological features, ultrasonic characteristics, and SWE parameters. Multivariable logistic regression analysis was used to establish diagnostic model and evaluated its diagnostic performance of LNM. The correlation among SWE values, collagen volume fraction (CVF), and microlymphatic density (MLD) in primary breast cancer lesions was analyzed in another 97 patients. RESULTS: The logistic regression model is Logit(P)=-1.878 + 0.992*LVI-2.010*posterior feature enhancement + 1.230*posterior feature shadowing + 0.102*posterior feature combined pattern + 0.009*Emax. The optimum cutoff value of the logistic regression model was 0.365, and the AUC (95% CI) was 0.697 (0.636-0.758); the sensitivity (70.7 vs. 54.3), positive predictive value (PPV) (54.0 vs. 50.8), negative predictive value (NPV) (76.9 vs. 69.7), and accuracy (65.2 vs. 61.9) were all higher than Emax. There was no correlation between the SWE parameters and MLD in primary breast cancer lesions. CONCLUSIONS: The logistic regression model can help us to determine LNM, thus providing more imaging basis for the selection of preoperative treatment. The SWE parameter of the primary breast cancer lesion cannot reflect the peritumoral lymphangiogenesis, and we still need to find a new ultrasonic imaging method.

Predictors for liver fibrosis in non-alcoholic patients with psoriatic diseases: A multicenter cross sectional-study.

Psoriasis has been related to metabolic dysfunction-associated fatty liver disease and, liver fibrosis. This study aimed to evaluate the prevalence of liver fibrosis in psoriasis and identify predictors for fibrosis. This is a cross-sectional study conducted from December 2012 to June 2016 assessing psoriasis and psoriatic arthritis patients attended at four centers in Mexico City. Data regarding history of the skin disease, previous and current medication, and previously diagnosed liver disease was collected. Liver fibrosis was assessed with four different non-invasive methods (FIB4, APRI, NAFLD score and elastography). We compared data based on the presence of fibrosis. Adjusted-logistic regression models were performed to estimate OR and 95% CI. A total of 160 patients were included. The prevalence of significant fibrosis using elastography was 25% (n = 40), and 7.5% (n = 12) for advanced fibrosis. Patients with fibrosis had higher prevalence of obesity (60% vs 30.8%, P = 0.04), type 2 diabetes (40% vs 27.5%, P = 0.003), gamma-glutamyl transpeptidase levels (70.8±84.4 vs. 40.1±39.2, P = 0.002), and lower platelets (210.7±58.9 vs. 242.8±49.7, P = 0.0009). Multivariate analysis showed that body mass index (OR1.11, 95%CI 1.02-1.21), type 2 diabetes (OR 3.44, 95%CI 1.2-9.88), and gamma-glutamyl transpeptidase (OR 1.01, 95%CI1-1.02) were associated with the presence of fibrosis. The use of methotrexate was not associated. Patients with psoriasis are at higher risk of fibrosis. Metabolic dysfunction, rather than solely the use of hepatotoxic drugs, likely plays a major role; it may be beneficial to consider elastography regardless of the treatment used. Metabolic factors should be assessed, and lifestyle modification should be encouraged.

Predictive value of placental real-time shear wave elastography combined with 3-dimensional power Doppler index for preeclampsia.

This study aimed to investigate the value of placental real-time shear wave elastography combined with three-dimensional power Doppler index (3D-PDI) in the prediction of preeclampsia. We conducted a retrospective study selecting 60 pregnant women diagnosed with preeclampsia as the experimental group and 60 normal pregnant women as the control group from January 2021 to December 2022. The elastic modulus values of different regions of the placenta and placental 3D-PDI were detected and compared between the two groups. The ROC curve was used to evaluate the diagnostic value of each parameter, alone or in combination, for preeclampsia. The study findings demonstrated that the elastic modulus values of different regions of the placenta and 3D-PDI of the two groups have statistical significance. The values of SWE, VI, FI, and VFI are different in prediction of preeclampsia, and the combination of various parameters can improve the prediction value. Overall, our study provides a valuable method for the prediction of preeclampsia with the advantages of non-invasiveness, efficiency, and simplicity.

Implementation of a randomized mobile-technology lifestyle program in individuals with nonalcoholic fatty liver disease.

Identifying effective, feasible, low-cost interventions that promote sustainable lifestyle changes in nonalcoholic fatty liver disease (NAFLD) is a key unmet need. The aim of this study was to assess predictors of lifestyle practice patterns of NAFLD patients and evaluate the implementation of a mobile technology-based intervention. We prospectively enrolled adults with NAFLD (diagnosed by imaging or biopsy). Individuals with additional liver diseases or decompensated cirrhosis were excluded. Patient were randomized to usual care or a FitBit based program for 6-months. We obtained anthropometrics, labs, vibration controlled transient elastography (VCTE), health-related quality of life (HRQOL), physical activity, diet and motivation to change data. 70 patients were enrolled, 33% with cirrhosis. Median age was 52.1 years, 47% males, 83% white, body mass index 32.3, liver stiffness 7.6 kPa, controlled attenuation parameter 319 db/m, and 50% had diabetes. Baseline HRQOL was 5.4/7 and independently negatively correlated with level of concern about their disease and positively with physical function. Younger age was independently associated with unhealthy diets whereas diabetes was independently associated with unhealthy diets and higher VCTE kPa. 6-month follow-up data available on 31 patients showed trends in improvement in weight. In a cohort of NAFLD patients, we identified independent correlates of lifestyle behaviors and HRQOL. Implementation of interventions that improve physical function may improve HRQOL in NAFLD. Younger patients and those with diabetes appeared to have the greatest need for dietary interventions. Structured mobile technology lifestyle interventions using Fitbit and personalized coaching showed promise but require further validation with a focus on sustainability of intervention and improvement in outcomes.

Velacur ACE outperforms FibroScan CAP for diagnosis of MASLD.

BACKGROUND: As the prevalence of metabolic dysfunction-associated steatotic liver disease increases, it is imperative to have noninvasive alternatives to liver biopsy. Velacur offers a non-invasive, point-of-care ultrasound-based method for the assessment of liver stiffness and attenuation. The aim of this study was to perform a head-to-head comparison of liver stiffness and liver fat determined by Velacur and FibroScan using MRI-based measurements as the reference standard. METHODS: This prospective cross-sectional study included 164 adult participants with well-characterized metabolic dysfunction-associated steatotic liver disease. Patients underwent a research exam including Velacur, FibroScan and contemporaneous magnetic resonance elastography, and magnetic resonance imaging proton density fat fraction (MRI-PDFF) scans. The primary outcome was the presence of advanced fibrosis (>F2) as measured by magnetic resonance elastography and the presence of liver fat (>5%) as measured by MRI-PDFF. RESULTS: The mean age and body mass index were 57±12 years and 30.6±4.8 kg/m2, respectively. The mean liver stiffness on magnetic resonance elastography was 3.22±1.39 kPa and the mean liver fat on MRI-PDFF was 14.2±8%. The liver stiffness assessments by Velacur and FibroScan were similar for the detection of advanced fibrosis (AUC 0.95 vs. 0.97) and were not statistically different (p=0.43). Velacur was significantly better than FibroScan (AUC 0.94 vs. 0.79, p=0.01), for the detection of MRI-PDFF >5% (diagnosis of metabolic dysfunction-associated liver disease). CONCLUSIONS: Velacur was superior to FibroScan for liver fat detection with MRI-PDFF as the reference. Velacur and FibroScan were not statistically different for liver stiffness assessment as defined by magnetic resonance elastography.

Noninvasive assessment of liver fibrosis and portal hypertension.

PURPOSE OF REVIEW: The result of ongoing liver injury - and disease, regardless of cause - is fibrosis, and fibrosis appears to be a critically important result of ongoing injury. Further, in a number of different liver diseases, the presence of fibrosis has prognostic value. Therefore, the assessment of fibrosis is of critical clinical importance. Given the importance of fibrosis, there has been a rapid evolution in the use of noninvasive liver tests. This review highlights a number of the core principles surrounding. RECENT FINDINGS: The use of noninvasive test has progressed rapidly over the last decade and data are rapidly accumulating. New terminology has been adapted by the American Association for the Study of Liver Disease (AASLD) for noninvasive assessment of liver disease and termed 'NILDA' (Non-Invasive Liver Disease Assessment). Blood based such as APRI and or FIB-4 and imaging tests such as liver stiffness measurement (LSM) have moderate to high degrees of accuracy for detection of advanced liver fibrosis (≥ F2) and even higher accuracy for detection of severe fibrosis (F4 or cirrhosis). NILDA are particularly effective at the ends of the liver disease spectrum. For example, a very low LSM (less than 7 kPa) essentially excludes significant fibrosis or portal hypertension, and a very high LSM (> 25 kPa) makes significant fibrosis with portal hypertension (cirrhosis) highly likely. SUMMARY: NILDA are currently front and center in terms of assessment of the severity of liver disease. In all patients with known or suspected liver disease, noninvasive blood tests, including APRI and or FIB-4, should be the initial choice to assess the severity of liver fibrosis and/or portal hypertension. In most patients, these tests should be followed with imaging evaluation. The most commonly available imaging is LSM, which appears to be more accurate in predicting fibrosis severity, and is superior to blood tests in the assessment of portal hypertension. In situations in which there is diagnostic uncertainly, liver biopsy with or without HVPG remains an important consideration.

Shear shock wave injury in vivo: High frame-rate ultrasound observation and histological assessment.

Using high frame-rate ultrasound and ¡1µm sensitive motion tracking we previously showed that shear waves at the surface of ex vivo and in situ brains develop into shear shock waves deep inside the brain, with destructive local accelerations. However post-mortem tissue cannot develop injuries and has different viscoelastodynamic behavior from in vivo tissue. Here we present the ultrasonic measurement of the high-rate shear shock biomechanics in the in vivo porcine brain, and histological assessment of the resulting axonal pathology. A new biomechanical model of brain injury was developed consisting of a perforated mylar surface attached to the brain and vibrated using an electromechanical shaker. Using a custom sequence with 8 interleaved wide beam emissions, brain imaging and motion tracking were performed at 2900 images/s. Shear shock waves were observed for the first time in vivo wherein the shock acceleration was measured to be 2.6 times larger than the surface acceleration ( 95g vs. 36g). Histopathology showed axonal damage in the impacted side of the brain from the brain surface, accompanied by a local shock-front acceleration of >70g. This shows that axonal injury occurs deep in the brain even though the shear excitation was at the brain surface, and the acceleration measurements support the hypothesis that shear shock waves are responsible for deep traumatic brain injuries.

Feasibility of assessing non-invasive intracranial compliance using FSI simulation-based and MR elastography-based brain stiffness.

Intracranial compliance (ICC) refers to the change in intracranial volume per unit change in intracranial pressure (ICP). Magnetic resonance elastography (MRE) quantifies brain stiffness by measuring the shear modulus. Our objective is to investigate the relationship between ICC and brain stiffness through fluid-structure interaction (FSI) simulation, and to explore the feasibility of using MRE to assess ICC based on brain stiffness. This is invaluable due to the clinical importance of ICC, as well as the fast and non-invasive nature of the MRE procedure. We employed FSI simulation in hydrocephalus patients with aqueductal stenosis to non-invasively calculate ICP which is the basis of the calculation of ICC and FSI-based brain stiffness. The FSI simulated parameters used have been validated with experimental data. Our results showed that there is no relationship between FSI simulated-based brain stiffness and ICC in hydrocephalus patients. However, MRE-based brain stiffness may be sensitive to changes in intracranial fluid dynamic parameters such as cerebral perfusion pressure (CPP), cerebral blood flow (CBF), and ICP, as well as to mechano-vascular changes in the brain, which are determining parameters in ICC assessment. Although optimism has been found regarding the assessment of ICC using MRE-based brain stiffness, especially for acute-onset brain disorders, further studies are necessary to clarify their direct relationship.

The usefulness of shear wave elastography in evaluating erectile dysfunction severity before and after prostaglandin E1 test.

Prostaglandin E1 intracavernous injection test is an established method for diagnosing erectile dysfunction. However, the evaluation is non-objective and often influenced by the evaluator's subjectivity. Herein, we measured and objectively evaluated shear wave elastography results of the corpus cavernosum before and after injection in 16 patients who underwent prostaglandin E1 testing. The response score of prostaglandin E1 tests were "1" in 2 cases, "2" in 2 cases, and "3" in 12 cases. The average transmission velocity before the injection and at the time of maximum erection after the injection were 2.21 m/s and 1.57 m/s, respectively. Transmission velocity decreased during erection in 14 of 16 cases (87.5%). The overall rate of change in transmission velocity due to injection was -26.7% and was significantly different between the poor (responses 1 and 2: -16.1%) and good erection (response 3: -30.2%) groups. To the best of our knowledge, this is the first attempt to evaluate erectile phenomenon using percutaneous ultrasonic elastography in Japan. Rate of change in shear wave transmission velocity due to prostaglandin E1 injection in the corpus cavernosum penis was associated with the degree of erection. Therefore, the rate of change in shear wave transmission velocity in the corpus cavernosum penis could be used as an objective index of erectile phenomenon. Percutaneous ultrasonic elastography is a non-invasive and useful test method for diagnosing erectile dysfunction, determining the therapeutic effect, and predicting prognosis.

Reliability of muscle stiffness measures in popliteus, medial and lateral gastrocnemius muscles by ultrasound shear wave elastography in participants with knee osteoarthritis accompanied by myofascial trigger points.

BACKGROUND: The objective of this investigation is to evaluate the consistency of intra-rater and inter-rater assessments utilizing ultrasound elastography to examine the muscle stiffness of the popliteus and gastrocnemius (medial and lateral heads) in patients with knee osteoarthritis accompanied by myofascial trigger points. METHODS: Thirty individuals with knee osteoarthritis accompanied by myofascial trigger points were assessed. Two examiners independently measured the muscle stiffness levels of the popliteus and gastrocnemius (medial and lateral heads) three times using ultrasound elastography in the first session. The second session was conducted one week later. RESULTS: In the initial test session, the mean shear modulus values for the popliteus and gastrocnemius (medial and lateral heads) muscles were measured as follows for tester 1 (12.75, 13.72, 14.13 kPa) and tester 2 (11.66, 12.81, 13.17 kPa). During the retest session, the previously measured variables by tester 1 and tester 2 yielded the following values: (12.61, 13.43, 14.26 kPa) and (11.62, 12.87, 13.30 kPa) respectively." Good to excellent intra-rater reliability (ICC = 0.912-0.986) and inter-rater reliability (ICC = 0.766-0.956) were reported for the shear moduli of the popliteus, medial and lateral gastrocnemius muscles. CONCLUSIONS: The assessment of muscle stiffness in the popliteus and gastrocnemius (medial and lateral heads) using ultrasound elastography is a reliable method in patients with knee osteoarthritis accompanied by myofascial trigger points.

Investigating the impact of elevated urinary trace elements on non-alcoholic fatty liver disease using vibration-controlled transient elastography.

Introduction: Non-alcoholic fatty liver disease (NAFLD) is a global public health concern. However, limited data are available on urinary trace elements and NAFLD caused by various exposure factors. This study aimed to investigate the relationship between the presence of 16 trace elements in urine and NAFLD using data from the National Health and Nutrition Examination Survey (NHANES). Methods: By utilizing the NHANES data from 2017 to 2018, 1613 participants who fulfilled the research criteria were identified from the initial pool of 2979 participants with available urine trace element detection data. Among them, 706 individuals had been diagnosed with NAFLD based on a coefficient of attenuation parameter (CAP) value of at least 274 db/m, determined using vibration-controlled transient elastography (VCTE); whereas the remaining 907 participants were classified as non-NAFLD. The data obtained were used to construct univariate and multivariate logistic regression models and restricted cubic spline models (RCS) analyses. Results: The presence of arsenic, iodine, barium, cesium, molybdenum, lead, tin, and tungsten in the urine of individuals with NAFLD showed a positive correlation with the likelihood of developing NAFLD. The risk of NAFLD had a non-linear dose-dependent relationship with urinary iodine, molybdenum, barium, and cesium. NAFLD was also associated with elevated levels of barium and cesium in urine, which were identified as significant risk factors. Conclusion: These findings suggest a positive association between exposure to trace elements in the urine and the risk of NAFLD. Specifically, urinary barium and cesium appeared to have the greatest impact on the risk of NAFLD. These results provide novel insights into the diagnosis and treatment of NAFLD.

Correlation of shear-wave elastography stiffness and apparent diffusion coefficient values with tumor characteristics in breast cancer.

We aimed to investigate the correlation between shear-wave elastography (SWE) and apparent diffusion coefficient (ADC) values in breast cancer and to identify the associated characteristics. We included 91 breast cancer patients who underwent SWE and breast MRI prior to surgery between January 2016 and November 2017. We measured the lesion's mean (Emean) and maximum (Emax) elasticities of SWE and ADC values. We evaluated the correlation between SWE, ADC values and tumor size. The mean SWE and ADC values were compared for categorical variable of the pathological/imaging characteristics. ADC values showed negative correlation with Emean (r = - 0.315, p = 0.002) and Emax (r = - 0.326, p = 0.002). SWE was positively correlated with tumor size (r = 0.343-0.366, p < 0.001). A higher SWE value indicated a tendency towards a higher T stage (p < 0.001). Triple-negative breast cancer showed the highest SWE values (p = 0.02). SWE were significantly higher in breast cancers with posterior enhancement, vascularity, and washout kinetics (p < 0.02). SWE stiffness and ADC values were negatively correlated in breast cancer. SWE values correlated significantly with tumor size, and were higher in triple-negative subtype and aggressive imaging characteristics.

Multimodal ultrasonography evaluation in thyroid nodule characterization: what is the ideal algorithm?

AIMS: The aim of this study is to investigate the diagnostic performances of Ultrasonography (US), Shear-wave Elastography (SWE), and Superb Microvascular Imaging (SMI) findings in the diagnosis of malignant thyroid nodules (MTNs) and to determine the US algorithm with the best diagnostic performance. MATERIAL AND METHODS: Eighty-one nodules in 77 patients who had underwent multimodal US with biopsy results, were evaluated. Echogenicity, nodule components, contours, presence and type of calcification, and size were analyzed with US. Nodule stiffness and vascular index (VI) measurements were performed via SWE and SMI. The power of the US algorithm in predicting malignancy was evaluated. RESULTS: Hypoechogenicity, irregular contour, aspect ratio (anteroposterior (AP)/transvers diameter) >1, and >43.9 kPa were the characteristicshad significant efficacy in the diagnosis of MTNs. Sensitivity, specificity, and AUC values were respectively 100%, 48.5%, and 0.742 for hypoechogenicity; 80%, 90.1%, and 0.855 for irregular contour; 60%, 71.2%, and 0.656 for aspect ratio >1; 60%, 72.7%, and 0.671 for >43.9 kPa; and 93.3%, 90.9%, and 0.921 for the US algorithm. VI did not show significant efficacy in diagnosis. CONCLUSION: Some B-mode and SWE findings showed sufficient efficacy in differentiating benign and malign nodules on their own. However, diagnostic accuracy increased significantly when the US algorithm was applied.

Vibration-Controlled Transient Elastography Scores to Predict Liver-Related Events in Steatotic Liver Disease.

Importance: Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most common chronic liver disease worldwide. It is important to develop noninvasive tests to assess the disease severity and prognosis. Objective: To study the prognostic implications of baseline levels and dynamic changes of the vibration-controlled transient elastography (VCTE)-based scores developed for the diagnosis of advanced fibrosis (Agile 3+) and cirrhosis (Agile 4) in patients with MASLD. Design, Setting, and Participants: This cohort study included data from a natural history cohort of patients with MASLD who underwent VCTE examination at 16 tertiary referral centers in the US, Europe, and Asia from February 2004 to January 2023, of which the data were collected prospectively at 14 centers. Eligible patients were adults aged at least 18 years with hepatic steatosis diagnosed by histologic methods (steatosis in ≥5% of hepatocytes) or imaging studies (ultrasonography, computed tomography or magnetic resonance imaging, or controlled attenuation parameter ≥248 dB/m by VCTE). Main Outcomes and Measures: The primary outcome was liver-related events (LREs), defined as hepatocellular carcinoma or hepatic decompensation (ascites, variceal hemorrhage, hepatic encephalopathy, or hepatorenal syndrome), liver transplant, and liver-related deaths. The Agile scores were compared with histologic and 8 other noninvasive tests. Results: A total of 16 603 patients underwent VCTE examination at baseline (mean [SD] age, 52.5 [13.7] years; 9600 [57.8%] were male). At a median follow-up of 51.7 (IQR, 25.2-85.2) months, 316 patients (1.9%) developed LREs. Both Agile 3+ and Agile 4 scores classified fewer patients between the low and high cutoffs than most fibrosis scores and achieved the highest discriminatory power in predicting LREs (integrated area under the time-dependent receiver-operating characteristic curve, 0.89). A total of 10 920 patients (65.8%) had repeated VCTE examination at a median interval of 15 (IQR, 11.3-27.7) months and were included in the serial analysis. A total of 81.9% of patients (7208 of 8810) had stable Agile 3+ scores and 92.6% of patients (8163 of 8810) had stable Agile 4 scores (same risk categories at both assessments). The incidence of LREs was 0.6 per 1000 person-years in patients with persistently low Agile 3+ scores and 30.1 per 1000 person-years in patients with persistently high Agile 3+ scores. In patients with high Agile 3+ score at baseline, a decrease in the score by more than 20% was associated with substantial reduction in the risk of LREs. A similar trend was observed for the Agile 4 score, although it missed more LREs in the low-risk group. Conclusions and Relevance: Findings of this study suggest that single or serial Agile scores are highly accurate in predicting LREs in patients with MASLD, making them suitable alternatives to liver biopsy in routine clinical practice and in phase 2b and 3 clinical trials for steatohepatitis.

Viscoelastic polyacrylamide MR elastography phantoms with tunable damping ratio independent of shear stiffness.

Physiologically modeled test samples with known properties and characteristics, or phantoms, are essential for developing sensitive, repeatable, and accurate quantitative MRI techniques. Magnetic resonance elastography (MRE) is one such technique used to estimate tissue mechanical properties, and it is advantageous to use phantoms with independently tunable mechanical properties to benchmark the accuracy of MRE methods. Phantoms with tunable shear stiffness are commonly used for MRE, but tuning the viscosity or damping ratio has proven to be difficult. A promising candidate for MRE phantoms with tunable damping ratio is polyacrylamide (PAA). While pure PAA has very low attenuation, viscoelastic hydrogels have been made by entrapping linear polyacrylamide strands (LPAA) within the PAA network. In this study, we evaluate the use of LPAA/PAA gels as physiologically accurate phantoms with tunable damping ratio, independent of shear stiffness, via MRE. Phantoms were made with 15.3 wt% PAA while the LPAA concentration ranged from 4.5 wt% to 8.0 wt%. MRE was performed at 9.4 T with 400 Hz vibration on all phantoms revealing a strong, positive correlation between damping ratio and LPAA content (p < 0.001). There was no significant correlation between shear stiffness and LPAA content, confirming a constant PAA concentration yielded constant shear stiffness. Rheometry at 10 Hz was performed to verify the damping ratio of the phantoms. Nearly identical slopes for damping ratio versus LPAA content were found from both MRE and rheometry (0.0073 and 0.0075 respectively). Ultimately, this study validates the adaptation of polyacrylamide gels into physiologically-relevant MRE phantoms to enable testing of MRE estimates of damping ratio.

Novel high-resolution contrast agent ultrasound techniques HiFR CEUS and SR CEUS in combination with shear wave elastography, fat assessment and viscosity of liver parenchymal changes and tumors.

BACKGROUND: The continuous development of ultrasound techniques increasingly enables better description and visualization of unclear lesions. New ultrasound systems must be evaluated with regard to all these diagnostic possibilities. METHODS: A multifrequency C1-7 convex probe (SC7-1M) with the new high-end system Resona A20 Series was used. Modern technologies, including HiFR CEUS, SR CEUS and multimodal tissue imaging with shear wave elastography (SWE), fat evaluation and viscosity measurements (M-Ref) were applied. RESULTS: Of n = 70 (mean value 48,3 years±20,3 years, range 18-84 years) cases examined, a definitive diagnosis could be made in n = 67 cases, confirmed by reference imaging and/or follow-up. Of these, n = 22 cases were malignant changes (HCC (hepatocellular carcinoma) n = 9, CCC (cholangiocellular carcinoma) n = 3, metastases of colorectal carcinomas or recurrences of HCC n = 10). In all 12 cases of HCC or CCC, the elastography measurements using the shear wave technique (with values >2 m/s to 3.7 m/s) showed mean values of 2.3±0.31 m/s and a degree of fibrosis of F2 to F4. In n = 14 cases, changes in the fat measurement (range 0.51 to 0.72 dB/cm/MHz, mean values 0.58±0.12 dB/cm/MHz) in the sense of proportional fatty changes in the liver were detected. In the 4 cases of localized fat distribution disorders, the values were >0.7 dB/cm/MHz in the sense of significant fatty deposits in the remaining liver tissue. Relevant changes in the viscosity measurements with values >1.8 kPa were found in n = 31 cases, in n = 5 cases of cystic lesions with partially sclerosing cholangitis, in n = 13 cases of malignant lesions and in n = 9 cases post-interventionally, but also in n = 4 cases of benign foci with additional systemic inflammation. CONCLUSIONS: The results are promising and show a new quality of ultrasound-based liver diagnostics. However, there is a need for further investigations with regard to the individual aspects, preferably on a multi-center basis.

Comparative evaluation of shear wave elastography elasticity values in thyroid nodules with cytology results and TI-RADS scoring in differentiation of benign-malignant nodules.

PURPOSE: The aim of this prospective study was to investigate the diagnostic performance of shear wave elastography (SWE) in differentiating benign and malignant thyroid nodules and their correlation with the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). METHODS: This prospective study included 370 thyroid nodules in 308 patients aged 18-70 years. All the patients underwent B-mode ultrasound (US), Doppler examination, and SWE and were given an ACR TI-RADS risk score before fine needle aspiration biopsy (FNAB) and/or surgery. The correlation between SWE parameters and ACR TI-RADS categories was investigated statistically and compared with histopathologic results. Additionally, the diagnostic performance of SWE was evaluated to distinguish malignant and benign thyroid nodules. RESULTS: One hundred and thirty-five of the 370 thyroid nodules were malignant, and 235 nodules were benign. The mean shear wave velocity (SWV) value of the malignant nodules (3.70 ± 0.98 m/s) was statistically higher than that of the benign nodules (2.70 ± 0.37 m/s). The best cutoff value of the mean SWV for differentiating benign and malignant nodules was found to be 2.94 m/s (sensitivity 90.4%, specificity 89.9%, positive predictive value 81.3%, negative predictive value 94.1%, p < 0.001). The average score of the nodules according to the ACR TI-RADS was 3.57 ± 1.83 in benign nodules and 7.38 ± 2.69 in malignant nodules (p ≤ 0.001). CONCLUSION: This study showed that combining SWE and TI-RADS improves the specificity of TI-RADS alone in differentiating benign and malignant nodules.

3D MR elastography-based stiffness as a marker for predicting tumor grade and subtype in cervical cancer.

BACKGROUND: Increasing evidence has indicated that high tissue stiffness (TS) may be a potential biomarker for evaluation of tumor aggressiveness. PURPOSE: To investigate the value of magnetic resonance elastography (MRE)-based quantitative parameters preoperatively predicting the tumor grade and subtype of cervical cancer (CC). STUDY TYPE: Retrospective. POPULATION: Twenty-five histopathology-proven CC patients and 7 healthy participants. FIELD STRENGTH/SEQUENCE: 3.0T, magnetic resonance imaging (MRI) (LAVA-flex) and MRE with a three-dimensional spin-echo echo-planar imaging. ASSESSMENT: The regions of interest (ROIs) were manually drawn by two observers in tumors to measure mean TS, storage modulus (G'), loss modulus (G″) and damping ratio (DR) values. Surgical specimens were evaluated for tumor grades and subtypes. STATISTICAL TESTS: Intraclass correlation coefficient (ICC) was expressed in terms of inter-observer agreements. t-test or Mann-Whitney nonparametric test was used to compare the complex modulus and apparent diffusion coefficient (ADC) values between different tumor groups. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate the diagnostic performance. RESULTS: The TS of endocervical adenocarcinoma (ECA) group was significantly higher than that in squamous cell carcinoma (SCC) group (5.27 kPa vs. 3.44 kPa, P = 0.042). The TS also showed significant difference between poorly and well/moderately differentiated CC (5.21 kPa vs. 3.47 kPa, P = 0.038), CC patients and healthy participants (4.18 kPa vs. 1.99 kPa, P < 0.001). The cutoff value of TS to discriminate ECA from SCC was 4.10 kPa (AUC: 0.80), while it was 4.42 kPa to discriminate poorly from well/moderately differentiated CC (AUC: 0.83), and 2.25 kPa to distinguish normal cervix from CC (AUC: 0.88), respectively. There were no significant difference in G″, DR and ADC values between any subgroups except for comparison of healthy participants and CC patients (P = 0.001, P = 0.004, P < 0.001, respectively). DATA CONCLUSION: 3D MRE-assessed TS shows promise as a potential biomarker to preoperatively assess tumor grade and subtype of CC.

Development of a suitable vibration pad for renal MR elastography.

The aim of this study was to develop a vibration pad suitable for renal MR elastography (MRE). Chronic kidney disease (CKD) is a progressive condition affecting >800 million people worldwide. Renal fibrosis is a common pathological feature of CKD that causes fibrotic regions to be much stiffer than those in normal renal tissues. Therefore, MRE can be used to diagnose CKD because it can image organ stiffness. In MRE, the shear modulus is obtained from the wavelength of the shear waves. Therefore, it is highly important to propagate shear waves with sufficient vibration strength in the tissue. By using a three-dimensional (3D) printer, we created a "Flexible Pad" suitable for renal MRE. The Flexible Pad was placed under the back of the participant in the supine position and deformed in response to the participant's weight, adhering closely to the body surface. Six healthy volunteers participated in this study. Our Flexible Pad allowed for coherent shear waves (clear waves with little scattering and interference) to be efficiently transmitted to the kidney deep-lying tissues in the abdomen. The shear moduli of the kidney (n = 6) were 8.95 ± 0.84 kPa in the right kidney and 9.70 ± 0.99 kPa in the left kidney. Our results indicate that using our Flexible Pad for renal MRE can provide a more reliable measurement of renal shear modulus.