Utility of shear wave elastography and high-definition color for diagnosing carpal tunnel syndrome

OBJECTIVE

The diagnostic values of measuring median nerve (MN) stiffness and vascularity with shear wave elastography (SWE) and high-definition (HD) color were investigated in carpal tunnel syndrome (CTS).

METHODS

Seventy patients (123 wrists) with CTS and thirty-five healthy volunteers (70 wrists) were enrolled. Based on nerve conduction studies (NCS), the patients were subdivided into NCS-negative, mild-to-moderate, and severe CTS groups. MN and abductor pollicis brevis (APB) SWE and MN HD color were performed on a longitudinal plane.

RESULTS

The mild-to-moderate and severe CTS groups showed increased MN stiffness at the wrist and MN stiffness ratio (wrist-to forearm) compared with the control (p < 0.001). The NCS-negative CTS group showed increased MN stiffness at the wrist (p = 0.022) and MN stiffness ratio (p = 0.032) compared with the control. The severe CTS group showed increased MN stiffness at the wrist compared with the mild-to-moderate CTS group (p = 0.034). The cutoff-values in diagnosing NCS-confirmed CTS were 50.12 kPa for MN stiffness at the wrist, 1.91 for MN stiffness ratio, and grade 1 for HD color.

CONCLUSIONS

SWE and HD color are good supportive tools in diagnosing and assessing severity in CTS.

SIGNIFICANCE

SWE and HD color demonstrated that MN in CTS was associated with increased stiffness and hypervascularity.

Diagnostic accuracy of elastography and magnetic resonance imaging in patients with NAFLD: A systematic review and meta-analysis

BACKGROUND AND AIMS

Vibration-controlled transient elastography (VCTE), point shear wave elastography (pSWE), 2-dimensional shear wave elastography (2DSWE), magnetic resonance elastography (MRE), and magnetic resonance imaging (MRI) have been proposed as non-invasive tests for patients with non-alcoholic fatty liver disease (NAFLD). This study evaluated their diagnostic accuracy for liver fibrosis and non-alcoholic steatohepatitis (NASH).

METHODS

PubMED/MEDLINE, EMBASE and the Cochrane Library were searched for studies examining the diagnostic accuracy of these index tests, against histology as the reference standard, in adult patients with NAFLD. Two authors independently screened and assessed methodological quality of studies and extracted data. Summary estimates of sensitivity, specificity and area under the curve (sAUC) were calculated for fibrosis stages and NASH, using a random effects bivariate logit-normal model.

RESULTS

We included 82 studies (14,609 patients). Meta-analysis for diagnosing fibrosis stages was possible in 53 VCTE, 11 MRE, 12 pSWE and 4 2DSWE studies, and for diagnosing NASH in 4 MRE studies. sAUC for diagnosis of significant fibrosis were: 0.83 for VCTE, 0.91 for MRE, 0.86 for pSWE and 0.75 for 2DSWE. sAUC for diagnosis of advanced fibrosis were: 0.85 for VCTE, 0.92 for MRE, 0.89 for pSWE and 0.72 for 2DSWE. sAUC for diagnosis of cirrhosis were: 0.89 for VCTE, 0.90 for MRE, 0.90 for pSWE and 0.88 for 2DSWE. MRE had sAUC of 0.83 for diagnosis of NASH. Three (4%) studies reported intention-to-diagnose analyses and 15 (18%) studies reported diagnostic accuracy against pre-specified cut-offs.

CONCLUSIONS

When elastography index tests are acquired successfully, they have acceptable diagnostic accuracy for advanced fibrosis and cirrhosis. The potential clinical impact of these index tests cannot be assessed fully as intention-to-diagnose analyses and validation of pre-specified thresholds are lacking.

LAY SUMMARY

Non-invasive tests that measure liver stiffness or use magnetic resonance imaging (MRI) have been suggested as alternatives to liver biopsy for assessing the severity of liver scarring (fibrosis) and fatty inflammation (steatohepatitis) in patients with non-alcoholic fatty liver disease (NAFLD). In this study, we summarise the results of previously published studies on how accurately these non-invasive tests can diagnose liver fibrosis and inflammation, using liver biopsy as the reference. We found that some techniques that measure liver stiffness had a good performance for the diagnosis of severe liver scarring.

Value of shear wave elastography combined with the Toronto clinical scoring system in diagnosis of diabetic peripheral neuropathy

To evaluate the diagnostic values of shear wave elastography (SWE) alone and in combination with the Toronto clinical scoring system (TCSS) on diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes mellitus (T2DM).The study included 41 DPN patients, 42 non-DPN patients, and 21 healthy volunteers. Conventional ultrasonography and SWE were performed on the 2 sides of the tibial nerves, and cross-sectional area (CSA) and nerve stiffness were measured. TCSS was applied to all patients. A receiver operating characteristic curve analysis was performed.The stiffness of the tibial nerve, as measured as mean, minimum or maximum elasticity, was significantly higher in patients in the DPN group than the other groups (P < .05). The tibial nerve of subjects in the non-DPN group was significantly stiffer compared to the control group (P < .05). There was no significant difference of the tibial nerve CSA among the 3 groups (P > .05). Mean elasticity of the tibial nerve with a cutoff of 71.3 kPa was the most sensitive (68.3%) and had a higher area under the curve (0.712; 0.602-0.806) among the 3 shear elasticity indices for diagnosing DPN when used alone. When combining SWE with TCSS in diagnosing DPN, the most effective parameter was the EMax, which yielded a sensitivity of 100.00% and a specificity of 95.24%.SWE is a better diagnostic tool for DPN than the conventional ultrasonic parameter CSA, and a higher diagnostic value is attained when combining SWE with TCSS.

Using vibration controlled transient elastography and FIB-4 to assess liver cirrhosis in a hepatitis C virus infected population

We assessed the performance characteristics of the Fibrosis-4 (FIB-4) score in a veteran population with chronic hepatitis C virus (HCV) infection and used vibration controlled transient elastography (VCTE) as the gold standard.All VCTE studies were performed by a single operator on United States veterans with HCV infection presenting for care at the Atlanta VA Medical Center (AVAMC) over a 2 year period. VCTE liver stiffness measurements (LSM) were categorized as cirrhotic if LSM was >12.5 kPa and non-cirrhotic if LSM was ≤12.5 kPa. FIB-4 scores ≤3.25 were considered non-cirrhotic and scores >3.25 were considered cirrhotic. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the FIB-4 score. A second analysis was done which identified and excluded indeterminate FIB-4 scores, defined as any value between 1.45 and 3.25.When FIB-4 was used to screen for liver cirrhosis using VCTE as the gold standard, sensitivity was 42%, specificity was 88%, PPV was 62%, and NPV was 76%. When indeterminate FIB-4 scores were excluded from the analysis, sensitivity was 95%, specificity was 61%, PPV was 62%, and NPV was 94.4%. In a veteran population with chronic HCV infection, we found the sensitivity of the FIB-4 score to be unacceptably low for ruling out liver cirrhosis when using a binary cutoff at 3.25. Using a second staging method like VCTE may be an effective way to screen for liver cirrhosis in persons with chronic HCV, especially when the FIB-4 score is in the indeterminate range.

Liver stiffness measured by magnetic resonance elastography in early recurrence of hepatocellular carcinoma after treatment: A protocol for systematic review and meta analysis

BACKGROUND

With high diagnostic accuracy, magnetic resonance elastography (MRE) is a noninvasive tool and can be adopted to measure liver stiffness (LS). In this study, meta-analysis was carried out to further evaluate whether LS measured by MRE can predict early recurrence in patients with hepatocellular carcinoma (HCC).

METHODS

PUBMED, EMBASE, Web of Science, China National Knowledge Infrastructure, and Cochrane Library database were searched for studies related to LS measured by MRE in the prediction of recurrence in patients with HCC. Survival outcome was estimated by hazard ratios and 95% confidence intervals. Meta-analysis was conducted with the Stata 16.0.

RESULTS

The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.

CONCLUSION

This study will provide evidence support for LS measured by MRE in predicting the recurrence of HCC.

ETHICS AND DISSEMINATION

The private information from individuals will not be published. This systematic review also should not damage participants' rights. Ethical approval is not available. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/ OSF.IO / SURH3.

A Novel Score to Predict Esophageal Varices in Patients with Compensated Advanced Chronic Liver Disease

BACKGROUND AND AIMS

Several criteria have been described to noninvasively predict the presence of high-risk esophageal varices in patients with compensated advanced chronic liver disease (cACLD). However, a recent study showed that treatment with β blockers could increase decompensation-free survival in patients with clinically significant portal hypertension, thereby making it important to predict the presence of any esophageal varices. We aimed to develop a simple scoring system to predict any esophageal varices.

METHODS

We retrospectively reviewed patients who had vibration-controlled transient elastography (VCTE) at Cook County Hospital, Chicago, USA. Patients with cACLD and liver stiffness measurement (LSM) ≥ 10 kPa with esophagogastroduodenoscopy performed within one year of VCTE were analyzed. We generated a novel score to predict esophageal varices, using the beta coefficient of predictive variables. The score was validated in an external cohort at the University of Iowa Hospital, USA.

RESULTS

There were 372 patients in the development cohort and 200 patients in the validation cohort. LSM, platelet count, and albumin were identified as predictors of esophageal varices and were included for generating the Cook County score as "platelet count * - 0.0155872 + VCTE score * 0.0387052 + albumin * - 0.8549209." The area under receiver operating curve for our score was 0.86 for any varices and 0.85 for high risk varices and avoided more endoscopies than the expanded Baveno VI criteria while maintaining a very low miss rate (negative predictive value > 99%).

CONCLUSION

We propose a new, highly accurate, and easy-to-use scoring system to predict the presence of not only high-risk but any esophageal varices in patients with cACLD.

Comparison of 2 shear wave elastography systems in reproducibility and accuracy using an elasticity phantom

This study aimed to compare the accuracy and inter- and intra-observer reproducibility of the measured elasticity between 2 shear wave elastography systems. Three breast radiologists examined 8 targets of 4 different levels of stiffness (size: 11 mm, 4 mm) in an elasticity phantom (Customized 049A Elasticity QA Phantom, CIRS, Norfolk, VA, USA) using 2 different shear wave ultrasound elastography systems: SuperSonic Imagine (SSI) (SSI, Aix en Provence, France) and ShearScan (RS-80A, Samsung Medison, Seoul, Korea). Three radiologists performed ultrasound (US) elastography examinations for the phantom lesions using 2 equipment over a 1-week interval. Intra- and inter-observer reproducibility and the accuracy of the measured elasticity were analyzed and compared between the 2 systems. The accuracy of shape was also analyzed by shape-matching between B-mode and elastography color image. Intra-class correlation coefficients (ICC) were used in statistical analysis. For measured elasticity, the intra-observer and inter-observer reproducibility were excellent in both SSI and ShearScan (0.994 and 0.998). The overall accuracy was excellent in both systems, but the accuracy in small lesions (4 mm target) was lower in SSI than ShearScan (0.780 vs 0.967). The accuracy of shape-matching on the elastography image was 59.0% and 81.4% in the SSI and ShearScan, respectively. In conclusion, the SSI and ShearScan showed excellent intra- and inter-observer reproducibility. The accuracy of the Young's modulus was high in both the SSI and ShearScan, but the SSI showed decreased accuracy in measurement of elasticity in small targets and poor shape-matching between the B-mode image and color-coded elastography image.

Role of shear-wave and strain elastography to differentiate malignant vs benign subpleural lung lesions

Elastosonography is a non-invasive diagnostic method to evaluate tissue stiffness. The aim of our study was to demonstrate the applicability and efficacy of elastosonography to differentiate benign vs malignant subpleural lung lesions compared to clinical, radiological and histological findings.We performed both strain and shear wave velocity (SWV) elastosonography on subpleural lung lesions. Moreover, we elaborated a composite score called "elasto index".Fourteen patients, 10 males and 4 females were recruited. On strain elastography, 9 lesions showed a hard pattern (type 3), 3 lesions showed an intermediate pattern (type 2), and 2 lesions a soft pattern (type 1). All lesions showed a mean SWV value of 4.46 ± 2.37 m/second. The mean SWV for malignant lesions (n = 6) was 5.92 ± 2.8 m/second. The mean SWV for benign lesions (n = 8) was 3.36 ± 1.20 m/second. SWV shows an area under the curve (AUC) of 0.792, and the Youden index shows a value of 3.6 m/second. The ROC curve elaborated for the diagnosis of malignancy by strain elastography showed an AUC of 0.688. ROC curve for the diagnosis of malignancy by elasto index demonstrated an AUC of 0.802.SWV values obtained by ARFI elastosonographic method are higher in malignant lung lesions (mean SWV: 5.92 m/second) than in benign ones (mean SWV: 3.36); a composite score (elasto index) is characterized by better statistical significance for the differentiation of the lesions.

Non-invasive fibrosis algorithms are clinically useful for excluding cirrhosis in prisoners living with hepatitis C

Background and aims

Prison-based HCV treatment rates remain low due to multiple barriers, including accessing transient elastography for cirrhosis determination. The AST-to-platelet ratio index (APRI) and FIB-4 scores have excellent negative predictive value (NPV) in hospital cohorts to exclude cirrhosis. We investigated their performance in a large cohort of prisoners with HCV infection.

Methods

This was a retrospective cohort study of participants assessed by a prison-based hepatitis program. The sensitivity, specificity, NPV and positive predictive value (PPV) of APRI and FIB-4 for cirrhosis were then analysed, with transient elastography as the reference standard. The utility of age thresholds as a trigger for transient elastography was also explored.

Results

Data from 1007 prisoners were included. The median age was 41, 89% were male, and 12% had cirrhosis. An APRI cut-off of 1.0 and FIB-4 cut-off of 1.45 had NPVs for cirrhosis of 96.1% and 96.6%, respectively, and if used to triage prisoners for transient elastography, could reduce the need for this investigation by 71%. The PPVs of APRI and FIB-4 for cirrhosis at these cut-offs were low. Age ≤35 years alone had a NPV for cirrhosis of 96.5%. In those >35 years, the APRI cut-off of 1.0 alone had a high NPV >95%.

Conclusion

APRI and FIB-4 scores can reliably exclude cirrhosis in prisoners and reduce requirement for transient elastography. This finding will simplify the cascade of care for prisoners living with hepatitis C.

Accuracy of FibroScan in analysis of liver fibrosis in patients with concomitant chronic Hepatitis B and nonalcoholic fatty liver disease

Liver steatosis could affect the accuracy of FibroScan in patients with chronic hepatitis B (CHB) and nonalcoholic fatty liver disease (NAFLD). This study aimed to assess the accuracy and cut-off values of FibroScan for diagnosing liver fibrosis and cirrhosis in patients with concomitant CHB and NAFLD.A total of 116 patients with concomitant CHB and NAFLD who underwent FibroScan test and liver biopsy were retrospectively enrolled. Liver fibrosis was staged according to the METAVIR scoring system. Calculations of the areas under receiver-operating characteristic curves (AUROC) were performed and compared for the staging of liver fibrosis.The AUROCs for FibroScan, gamma-glutamyl transpeptidase to platelet ratio (GPR), aspartate aminotransferase to platelet ratio index (APRI), fibrosis index based on 4 factors (FIB-4), and NAFLD Fibrosis Score (NFS) were 0.87, 0.73, 0.69, 0.57, and 0.57 for the diagnosis of significant liver fibrosis (METAVIR ≥ F2); 0.89, 0.77, 0.75, 0.68, and 0.60 for severe liver fibrosis (METAVIR ≥ F3); and 0.94, 0.86, 0.80, 0.74, and 0.63 for cirrhosis (F4), respectively. The cutoff values of FibroScan for staging liver fibrosis with sensitivity at least 90% were: 8.0 kPa for significant liver fibrosis, and 10.5 kPa for cirrhosis. The cutoff values of FibroScan for staging liver fibrosis with specificity at least 90% were: 10.8 kPa for significant liver fibrosis, and 17.8 kPa for cirrhosis.FibroScan provides high value for the diagnosis of liver fibrosis and cirrhosis in patients with concomitant CHB and NAFLD.

Significance of progressive liver fibrosis in pediatric liver transplants: A review of current evidence

This article reviews the current evidence and knowledge of progressive liver fibrosis after pediatric liver transplantation. This often-silent histologic finding is common in long-term survivors and may lead to allograft dysfunction in advanced stages. Surveillance through protocolized liver allograft biopsy remains the gold standard for diagnosis, and recent evidence suggests that chronic inflammation precedes fibrosis.

Validation and Refinement of Noninvasive Methods to Assess Hepatic Fibrosis: Magnetic Resonance Elastography Versus Enhanced Liver Fibrosis Index

BACKGROUND

Noninvasive fibrosis markers are routinely used in patients with liver disease. Magnetic resonance elastography (MRE) is recognized as a highly accurate methodology, but a reliable blood test for fibrosis would be useful. We examined performance characteristics of the Enhanced Liver Fibrosis (ELF) Index compared to MRE in a cohort including those with HCV, HIV, and HCV/HIV.

METHODS

Subjects enrolled in the Miami Adult Studies on HIV (MASH) cohort underwent MRE and blood sampling. The ELF Index was scored and receiver-operator curves constructed to determine optimal cutoff levels relative to performance characteristics. Cytokine testing was performed to identify new markers to enhance noninvasive marker development.

RESULTS

The ELF Index was determined in 459 subjects; more than half were male, non-white, and HIV-infected. MRE was obtained on a subset of 283 subjects and the group that had both studies served as the basis of the receiver-operator curve analysis. At an ELF Index of > 10.633, the area under the curve for cirrhosis (Metavir F4, MRE > 4.62 kPa) was 0.986 (95% CI 0.994-0.996; p < 0.001) with a specificity of 100%. For advanced fibrosis (Metavir F3/4), an ELF cutoff of 10 was associated with poor sensitivity but high specificity (98.9%, 95% CI 96.7-99.8%) with an AUC of 0.80 (95% CI 0.749-0.845). ELF Index performance characteristics exceeded FIB-4 performance. HCV and age were associated with increased fibrosis (p < 0.05) in a multivariable model. IP-10 was found to be a promising biomarker for improvement in noninvasive prediction algorithms.

CONCLUSIONS

The ELF Index was a highly sensitive and specific marker of cirrhosis, even among HIV-infected individuals, when compared with MRE. IP-10 may be a biomarker that can enhance performance characteristics further, but additional validation is required.

Comparison of acoustic radiation force impulse imaging with the convex probe 6C1 and linear probe 9L4

BACKGROUND

Acoustic radiation force impulse imaging (ARFI) is a noninvasive method to detect liver fibrosis. The aims of the study were to evaluate the difference between 2 different probes, 6 C1 and 9 L4, and to study inter- and intraobserver reproducibility for the probes.

METHODS

We enrolled 100 patients in this cross-sectional comparative study. All patients underwent liver stiffness measurement with both probes. Intraobserver, interobserver, intralobe, and interlobe agreement was analyzed using the intraclass correlation coefficient.

RESULTS

A significant difference in success rates was observed for both probes between the right and left liver lobes. A success rate of 91% was observed in the right liver lobe compared with 77% in the left liver for the convex probe (P = .007), and 91% vs 68% for the linear probe (P < .001). There was a significant correlation in ARFI-shear wave velocity (ARFI-SWV) between both probes in the right liver lobe (P = .01; r = .508) and in the left liver lobe (P = .05; r = .278); however, there was no significant correlation in ARFI-SWV between the liver lobes for both probes (convex probe r = .19 P = .112; linear probe r = .144 P = .23). Good or excellent inter- and intraobserver was detected for both probes. Poor agreement was found only for the interobserver agreement in the left lobe with the convex probe (ICC = .320).

CONCLUSION

ARFI can be performed successfully with both probes in both liver lobes. There was no significant correlation in ARFI between the liver lobes for both probes; however, the right liver lobe should be favored. Standardization of the procedure is needed for the comparability of different studies.

Prospective evaluation of non-alcoholic fatty liver disease by elastographic methods of liver steatosis and fibrosis; controlled attenuation parameter and liver stiffness measurements

AIMS

To examine the temporal changes of both controlled attenuation parameter (CAP) and liver stiffness measurements (LSM), assessed by Fibroscan, in a large sample of patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

In this prospective, observational study, we consecutively enrolled 507 adult individuals with Fibroscan-defined NAFLD who were followed for a mean period of 21.2 ± 11.7 months.

RESULTS

During the follow-up period, 84 patients (16.5%) had a progression of CAP of at least 20% with a median time of 39.93 months, while 201 (39.6%) patients had a progression of LSM of at least 20% with median time of 30.46 months. There were significant differences in the proportion of LSM progression across body mass index (BMI) categories, with obese patients having the highest risk of progression over the follow-up (hazard ratio 1.66; 95%CI 1.23-2.25). Multivariable regression analysis showed that BMI and serum creatinine levels were the strongest predictors for CAP progression in the whole population, while HOMA-estimated insulin resistance was an independent predictor of LSM progression over time in the subgroup of obese patients.

CONCLUSION

This prospective study shows for the first time that the progression risk of both liver steatosis and fibrosis, detected non-invasively by Fibroscan, is relevant and shares essentially the same metabolic risk factors that are associated with NAFLD progression detected by other invasive methods.

Interobserver agreement and diagnostic accuracy of shearwave elastography for the staging of hepatitis C virus-associated liver fibrosis

PURPOSE

Our study aimed to evaluate the technical success rate, interobserver reproducibility, and accuracy of shearwave elastography (SWE) in the staging of hepatitis C virus (HCV)-associated liver fibrosis.

METHODS

A total of 10 healthy controls and 49 patients with chronic liver disease were enrolled prospectively. Two examiners performed point shearwave elastography (pSWE) and two-dimensional shearwave elastography (2D-SWE) measurements with an RS85A ultrasound scanner using the S-Shearwave application (Samsung Medison, Hongcheon, Korea). The performance of S-Shearwave in the staging (METAVIR F0-F4) of liver fibrosis was compared with prior transient elastography (TE) with receiver operating characteristic (ROC) curve analysis.

RESULTS

The interobserver reproducibility was excellent with pSWE (ICC = 0.92, 95% CI: 0.86-0.95, P < .001). A very good agreement was found between pSWE and TE measurements (ICC =0.85, 95% CI: 0.78-0.89, P < .001). The ROC analysis determined the optimal cut-off values of pSWE for the staging of chronic hepatitis C-associated fibrosis (F2, 1.46 m/s; F3, 1.63 m/s; F4, 1.95 m/s). Both observers achieved excellent diagnostic accuracy (AUROC: 94% vs 97%) in the detection of significant (≥F2) liver fibrosis.

CONCLUSION

The interobserver agreement is excellent with S-Shearwave pSWE, and observers can diagnose significant liver fibrosis with a comparable accuracy to TE.

Reliability Indicators for 2-Dimensional Shear Wave Elastography

Ultrasound (US) shear wave technology providers have either point shear wave elastography (SWE) or 2-dimensional SWE available on their US systems. With 2-dimensional SWE, larger regions of interest can be interrogated, with both the main acoustic radiation pulses and the resultant shear waves potentially being affected by US artifacts. Some providers assist the operator with elastographic maps indicating the reliability or precision of the shear wave propagation. This Technical Innovation explores the importance of the consideration of the precision maps and standard deviation output available on some devices and the implications for conversion of shear wave speed to pressure.

Comparison of Liver Shear Wave Elastography Measurements using Siemens Acuson S3000, GE LOGIQ E9, Philips EPIQ7 and Toshiba Aplio 500 (Software Versions 5.0 and 6.0) in Healthy Volunteers

AIM

 To compare ARFI-based elastography procedures of the GE LOGIQ E9, Philips EPIQ7, and Toshiba Aplio 500 (versions 5.0 and 6.0) ultrasound scanners with the Siemens Acuson S3000 reference scanner in subjects with healthy livers, taking various impact factors into account.

MATERIALS AND METHODS

 The study consisted of two subsequent study parts. Study 1 (n = 205) evaluated the 2D-SWE techniques of GE and Toshiba 5.0 and the pSWE technique of the Philips scanner against the reference scanner Siemens. Study 2 (n = 113) evaluated Toshiba 6.0 against Siemens in a different cohort. Out of 433 study participants in both studies, 318 (M:F = 122:196) met the inclusion criteria. Elastography measurements were performed in the right lobe of the liver at depths of 3, 5 and 7 cm. At each depth, five measurements were acquired with the Siemens and Philips scanners and one measurement each with the GE and Toshiba machines.

RESULTS

 The Philips (r = 0.58, p < 0.0001) and the GE (r = 0.63, p < 0.0001) scanners showed the strongest correlation of shear wave velocities between Siemens and comparator scanners, at a depth of 5 cm. We found the strongest relationship with Toshiba (software version 6.0) at a depth of 3 cm (r = 0.57, p < 0.0001). Toshiba software version 5.0 did not give satisfactory results. The factors of sex and BMI showed scanner-specific differences in the values measured (p < 0.05). The age of the subjects did not seem to have any effect.

CONCLUSION

 With the exception of Toshiba software version 5.0, all of the scanners we tested can be recommended without reservation for comparative ultrasound elastography of the healthy liver at measurement depths of 3 cm up to 5 cm.

Changes in liver stiffness after ART initiation in HIV-infected Nigerian adults with and without chronic HBV

BACKGROUND

There are limited data from sub-Saharan Africa on long-term liver fibrosis changes in HIV- and HIV/HBV-infected individuals.

OBJECTIVES

To assess the effects of ART on liver stiffness measurement (LSM) using transient elastography (TE) in HIV- and HIV/HBV-infected Nigerian adults and examine factors associated with fibrosis regression.

METHODS

We included ART-naive HIV- and HIV/HBV-infected adults (≥18 years) enrolled in a prospective, longitudinal study of liver disease between July 2011 and February 2015 at Jos University Teaching Hospital HIV Care and Treatment Centre in Nigeria. Patients initiated ART and had TE at baseline and follow-up (year 3). LSM cut-offs for Metavir scores were 5.9, 7.6 and 9.4 kPa for moderate fibrosis, advanced fibrosis and cirrhosis, respectively. We used multivariable regression to identify factors associated with TE (≥1 Metavir) stage decline.

RESULTS

A total of 106 HIV- and 71 HIV/HBV-infected patients [70.5% female and median age = 34 years (IQR = 29-42 years)] were studied. Baseline LSM and median LSM decline were significantly higher in HIV/HBV- versus HIV-infected patients; 41% of HIV/HBV-infected patients regressed ≥1 Metavir stage versus 17% of HIV-infected patients (P < 0.01); LSM scores at year 3 were not significantly different between HIV- and HIV/HBV-infected patients. In multivariable analyses, patients with baseline CD4+ T cells ≥200 (versus <200) cells/mm3 and lower BMIs were more likely to experience LSM stage decline.

CONCLUSIONS

HBV coinfection does not attenuate LSM declines in HIV-infected patients after ART initiation despite being a risk factor for more advanced liver disease prior to therapy. The inverse association between BMI and TE stage decline needs further investigation.

Interoperator Reproducibility of Carotid Elastography for Identification of Vulnerable Atherosclerotic Plaques

Ultrasound-based carotid elastography has been developed to evaluate the vulnerability of carotid atherosclerotic plaques. The aim of this study was to investigate the in vivo interoperator reproducibility of carotid elastography for the identification of vulnerable plaques, with high-resolution magnetic resonance imaging (MRI) as reference. Ultrasound radio-frequency data of 45 carotid arteries (including 53 plaques) from 32 volunteers were acquired separately by two experienced operators in the longitudinal view and then were used to estimate the interframe axial strain rate (ASR) with a two-step optical flow method. The maximum 99th percentile of absolute ASR of all plaques in a carotid artery was used as the elastographic index. MRI scanning was also performed on each volunteer to identify the vulnerable plaque. The results showed no systematic bias in the Bland-Altman plot and an intraclass correlation coefficient of 0.66 between the two operators. In addition, no statistical significance was found between the receiver operating characteristic (ROC) curves from the two operators ( ), and their areas under the ROC curves were 0.83 and 0.77, respectively. Using the mean measurements of the two operators as the classification criterion, a sensitivity of 71.4%, a specificity of 87.1%, and an accuracy of 82.2% were obtained with a cutoff value of 1.37 [Formula: see text]. This study validates the interoperator reproducibility of ultrasound-based carotid elastography for identifying vulnerable carotid plaques.

Natural Shear Wave Imaging in the Human Heart: Normal Values, Feasibility, and Reproducibility

Left ventricular myocardial stiffness could offer superior quantification of cardiac systolic and diastolic function when compared to the current diagnostic tools. Shear wave elastography in combination with acoustic radiation force has been widely proposed to noninvasively assess tissue stiffness. Interestingly, shear waves can also result from intrinsic cardiac mechanical events (e.g., closure of valves) without the need for external excitation. However, it remains unknown whether these natural shear waves always occur, how reproducible they can be detected and what the normal range of shear wave propagation speed is. The present study, therefore, aimed at establishing the feasibility of detecting shear waves created after mitral valve closure (MVC) and aortic valve closure (AVC), the variability of the measurements, and at reporting the normal values of propagation velocity. Hereto, a group of 30 healthy volunteers was scanned with high-frame rate imaging (>1000 Hz) using an experimental ultrasound system transmitting a diverging wave sequence. Tissue Doppler velocity and acceleration were used to create septal color M-modes, on which the shear waves were tracked and their velocities measured. Overall, the methodology was capable of detecting the transient vibrations that spread throughout the intraventricular septum in response to the closure of the cardiac valves in 92% of the recordings. Reference velocities of 3.2±0.6 m/s at MVC and 3.5±0.6 m/s at AVC were obtained. Moreover, in order to show the diagnostic potential of this approach, two patients (one with cardiac amyloidosis and one undergoing a dobutamine stress echocardiography) were scanned with the same protocol and showed markedly higher propagation speeds: the former presented velocities of 6.6 and 5.6 m/s; the latter revealed normal propagation velocities at baseline, and largely increased during the dobutamine infusion (>15 m/s). Both cases showed values consistent with the expected changes in stiffness and cardiac loading conditions.

Elastography-based screening for esophageal varices in patients with advanced chronic liver disease

Elastography-based liver stiffness measurement (LSM) is a non-invasive tool for estimating liver fibrosis but also provides an estimate for the severity of portal hypertension in patients with advanced chronic liver disease (ACLD). The presence of varices and especially of varices needing treatment (VNT) indicates distinct prognostic stages in patients with compensated ACLD (cACLD). The Baveno VI guidelines suggested a simple algorithm based on LSM < 20 kPa (by transient elastography, TE) and platelet count > 150 G/L for ruling-out VNT in patients with cACLD. These (and other) TE-based LSM cut-offs have been evaluated for VNT screening in different liver disease etiologies. Novel point shear-wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) methodologies for LSM have also been evaluated for their ability to screen for “any” varices and for VNT. Finally, the measurement of spleen stiffness (SSM) by elastography (mainly by pSWE and 2D-SWE) may represent another valuable screening tool for varices. Here, we summarize the current literature on elastography-based prediction of “any” varices and VNT. Finally, we have summarized the published LSM and SSM cut-offs in clinically useful scale cards.

Adherence to quality criteria improves concordance between transient elastography and ElastPQ for liver stiffness assessment-A multicenter retrospective study

BACKGROUND

Assessment of liver stiffness provides important diagnostic and prognostic information in patients with chronic liver disease.

AIMS

To investigate whether the use of quality criteria (i) improves the concordance between transient elastography (TE) and a novel point shear wave elastography technique (ElastPQ^®) and (ii) impacts on the performance of ElastPQ^® for liver fibrosis staging using TE as the reference standard.

METHODS

In this multicenter retrospective study, data of patients undergoing liver stiffness measurements (LSM) in five European centers were collected. TE was performed with FibroScan^® (Echosens, France) and ElastPQ^® with EPIQ^® or Affiniti^® systems (Philips, The Netherlands). The agreement between TE and ElastPQ^® LSMs was assessed with Lin's concordance correlation coefficient (CCC). Diagnostic performance of ElastPQ^® was assessed by the area under receiver operating characteristic (AUROC) curves.

RESULTS

Overall, 664 patients were included: mean age: 54.8(13.5) years, main etiologies: viral hepatitis (83.1%) and NAFLD (7.5%). CCC increased significantly when LSMs with ElastPQ^® were obtained with IQR/M ≤ 30% (p < 0.001). The diagnostic performance of ElastPQ^® for fibrosis staging also increased if LSM values were obtained with IQR/M ≤ 30%.

CONCLUSION

Quality criteria should be followed when using ElastPQ^® for LSM, since the concordance with TE fibrosis staging was better at an ElastPQ^® IQR/M ≤ 30.

Is the reproducibility of shear wave elastography of thyroid nodules high enough for clinical use? A methodological study

OBJECTIVE

To systematically assess the reproducibility of thyroid ultrasonographic shear wave elastography (SWE).

CONTEXT

SWE has been suggested as a potential tool for thyroid nodule evaluation, but assessment of its reproducibility has been insufficiently addressed.

DESIGN

SWE examinations were performed prospectively by two investigators.

PATIENTS

Seventy-two patients (male/female: 19/53; mean age: 53 ± 14 years; malignant/benign 17/55) undergoing thyroid surgery were enrolled in the study.

MEASUREMENTS

Repeated and blinded measurements of elasticity index (EI) in predefined regions of interest (ROI) were collected. The inter- and intrarater agreement, along with the day-to-day agreement, was evaluated in terms of the 95% limits of agreement (LOA). Results are presented as a ratio, by which 1·0 indicates perfect agreement.

RESULTS

The interrater, intrarater and day-to-day LOA showed ratios between repeated measurements of 1·7-3·6, 1·8-3·7 and 2·2-2·9, respectively. These values reflect a low to moderate degree of agreement for all EI outcomes. The interrater LOA was higher for malignant nodules compared with benign nodules for six of seven EI outcomes (P < 0·001-0·03). The proportion of agreement calculated from the optimum cutoff point for differentiating malignant from benign nodules was 63-88% for the investigated EI outcomes.

CONCLUSIONS

In this methodological study, EI measured by thyroid SWE seems suboptimal for clinical use, due to a low inter- and intrarater agreement. That EI varies from day to day furthermore jeopardizes the validity of the method. Although the proportion of agreement was acceptable for some EI parameters, it is questionable whether EI assessments can reliably differentiate malignant from benign nodules in the individual patient.

Comparative study of shear wave-based elastography techniques in optical coherence tomography

We compare five optical coherence elastography techniques able to estimate the shear speed of waves generated by one and two sources of excitation. The first two techniques make use of one piezoelectric actuator in order to produce a continuous shear wave propagation or a tone-burst propagation (TBP) of 400 Hz over a gelatin tissue-mimicking phantom. The remaining techniques utilize a second actuator located on the opposite side of the region of interest in order to create three types of interference patterns: crawling waves, swept crawling waves, and standing waves, depending on the selection of the frequency difference between the two actuators. We evaluated accuracy, contrast to noise ratio, resolution, and acquisition time for each technique during experiments. Numerical simulations were also performed in order to support the experimental findings. Results suggest that in the presence of strong internal reflections, single source methods are more accurate and less variable when compared to the two-actuator methods. In particular, TBP reports the best performance with an accuracy error < 4.1 % . Finally, the TBP was tested in a fresh chicken tibialis anterior muscle with a localized thermally ablated lesion in order to evaluate its performance in biological tissue.

A Meta-analysis for the Diagnostic Performance of Transient Elastography for Clinically Significant Portal Hypertension

We aimed to evaluate the correlation between liver stiffness measurement using transient elastography (TE-LSM) and hepatic venous pressure gradient and the diagnostic performance of TE-LSM in assessing clinically significant portal hypertension through meta-analysis. Eleven studies were included from thorough literature research and selection processes. The summary correlation coefficient was 0.783 (95% confidence interval [CI], 0.737-0.823). Summary sensitivity, specificity and area under the hierarchical summary receiver operating characteristic curve (AUC) were 87.5% (95% CI, 75.8-93.9%), 85.3 % (95% CI, 76.9-90.9%) and 0.9, respectively. The subgroup with low cut-off values of 13.6-18 kPa had better summary estimates (sensitivity 91.2%, specificity 81.3% and partial AUC 0.921) than the subgroup with high cut-off values of 21-25 kPa (sensitivity 71.2%, specificity 90.9% and partial AUC 0.769). In summary, TE-LSM correlated well with hepatic venous pressure gradient and represented good diagnostic performance in diagnosing clinically significant portal hypertension. For use as a sensitive screening tool, we propose using low cut-off values of 13.6-18 kPa in TE-LSM.

WFUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography: Part 4. Thyroid

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced guidelines for the use of elastography techniques including basic science, breast and liver. Here we present elastography in thyroid diseases. For each available technique, procedure, reproducibility, results and limitations are analyzed and recommendations are given. Finally, recommendations are given based on the level of evidence of the published literature and on the WFUMB expert group's consensus. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of thyroid diseases.

WFUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography: Part 5. Prostate

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced guidelines for the use of elastography techniques, including basic science, breast, liver and thyroid elastography. Here we present elastography in prostate diseases. For each available technique, procedure, reproducibility, results and limitations are analyzed and recommendations are given. Finally, recommendations are given based on the level of evidence of the published literature and on the WFUMB expert group's consensus. This document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of prostate diseases.

The pursuit of normal reference values of pancreas stiffness by using Acoustic Radiation Force Impulse (ARFI) elastography

AIM

The purpose of this study is to evaluate pancreatic stiffness by ARFI abdominal elastography. In the current literature, there are relatively few studies that have assessed the clinical utility of this technique.

MATERIAL AND METHOD

A number of 37 healthy subjects were included. The data were collected in a prospective manner and afterwards included in an observational, analytical and longitudinal study. Subsequently viewing the pancreatic parenchyma in bidimensional mode (2D-US) mode, 10 shear wave velocity (SWV) measurements for each segment: head, body and tail were performed. Statistical analysis by regression models targeted also the possible influence of other factors in assessing SWV. A comparative analysis was performed regarding the statistical significance of 5 versus 10 SWV measurements for each segment.

RESULTS

The pancreas was entirely evaluated in all subjects. The mean SWV from the entire parenchyma was 1.216 m/s±0.36 and between the three segments SWV were similar (head: 1.224 m/s, body: 1.227 m/s and tail: 1.191 m/s). A ratio of the IQR/Median >0.4 was interpreted as statistically invalid, relevant data being highlighted in the percentage of 83.78% for the head of the pancreas, 78.37% for the body, and 67.56% at the caudal level. Significant correlations were observed between the data (mean and median SWV) provided by the group with 5 measurements of the SWV versus the standard group: 93.9% for the head, 96.6% for the body, and 98.7% accordingly to the tail.

CONCLUSIONS

SWV determination by percutaneous approach represents a useful imaging method for evaluating pancreatic stiffness, of course within these limitations. Because we did not observe statistically significant differences between the results obtained by 5 or 10 measurements, we suggest that it would be sufficient to perform only five measurements of the SWV per pancreatic segment. The data obtained in the normal pancreas could be used in future comparative assessments regarding the inflammatory or tumoral pathology of the pancreas.

Evaluating the Improvement in Shear Wave Speed Image Quality Using Multidimensional Directional Filters in the Presence of Reflection Artifacts

Shear waves propagating through interfaces where there is a change in stiffness cause reflected waves that can lead to artifacts in shear wave speed (SWS) reconstructions. Two-dimensional (2-D) directional filters are commonly used to reduce in-plane reflected waves; however, SWS artifacts arise from both in- and out-of-imaging-plane reflected waves. Herein, we introduce 3-D shear wave reconstruction methods as an extension of the previous 2-D estimation methods and quantify the reduction in image artifacts through the use of volumetric SWS monitoring and 4-D-directional filters. A Gaussian acoustic radiation force impulse excitation was simulated in phantoms with Young's modulus (E) of 3 kPa and a 5-mm spherical lesion with E = 6, 12, or 18.75 kPa. The 2-D-, 3-D-, and 4-D-directional filters were applied to the displacement profiles to reduce in-and out-of-plane reflected wave artifacts. Contrast-to-noise ratio and SWS bias within the lesion were calculated for each reconstructed SWS image to evaluate the image quality. For 2-D SWS image reconstructions, the 3-D-directional filters showed greater improvements in image quality than the 2-D filters, and the 4-D-directional filters showed marginal improvement over the 3-D filters. Although 4-D-directional filters can further reduce the impact of large magnitude out-of-plane reflection artifacts in SWS images, computational overhead and transducer costs to acquire 3-D data may outweigh the modest improvements in image quality. The 4-D-directional filters have the largest impact in reducing reflection artifacts in 3-D SWS volumes.

Evaluating the Improvement in Shear Wave Speed Image Quality Using Multidimensional Directional Filters in the Presence of Reflection Artifacts

Shear waves propagating through interfaces where there is a change in stiffness cause reflected waves that can lead to artifacts in shear wave speed (SWS) reconstructions. Two-dimensional (2-D) directional filters are commonly used to reduce in-plane reflected waves; however, SWS artifacts arise from both in- and out-of-imaging-plane reflected waves. Herein, we introduce 3-D shear wave reconstruction methods as an extension of the previous 2-D estimation methods and quantify the reduction in image artifacts through the use of volumetric SWS monitoring and 4-D-directional filters. A Gaussian acoustic radiation force impulse excitation was simulated in phantoms with Young's modulus (E) of 3 kPa and a 5-mm spherical lesion with E = 6, 12, or 18.75 kPa. The 2-D-, 3-D-, and 4-D-directional filters were applied to the displacement profiles to reduce in-and out-of-plane reflected wave artifacts. Contrast-to-noise ratio and SWS bias within the lesion were calculated for each reconstructed SWS image to evaluate the image quality. For 2-D SWS image reconstructions, the 3-D-directional filters showed greater improvements in image quality than the 2-D filters, and the 4-D-directional filters showed marginal improvement over the 3-D filters. Although 4-D-directional filters can further reduce the impact of large magnitude out-of-plane reflection artifacts in SWS images, computational overhead and transducer costs to acquire 3-D data may outweigh the modest improvements in image quality. The 4-D-directional filters have the largest impact in reducing reflection artifacts in 3-D SWS volumes.

Age-related changes in pancreatic elasticity: When should we be concerned about their effect on strain elastography?

BACKGROUND

Ultrasound strain elastography is one of the useful methods for evaluating pancreatic lesions. During aging, several pancreatic parenchymal changes occur that may interfere with the interpretation of the ultrasound images. We studied age-related changes in pancreatic elasticity using transabdominal ultrasound strain elastography in subjects without known pancreatic disease.

METHODS

This study was conducted at Nagoya University Hospital, which is an academic medical center, and included 102 subjects (66 women and 39 men) aged 20-85years (mean 58.6±17.5) who underwent transabdominal ultrasonography for screening and follow-up for non-pancreatic diseases. Strain elastography of the pancreas was performed, and the results were subjected to quantitative strain histogram analysis. The correlations of age with four elastographic parameters (Mean, Standard deviation, Skewness, and Kurtosis) and other findings, including hyperechoic pancreas, hyperechoic liver, and diabetes, were evaluated.

RESULTS

There was a significant correlation between increasing age and elastographic parameters such as the Mean (P=0.004), Skewness (P=0.007), and Kurtosis (P=0.03), and these differences became significant after the age of 40. The prevalence of hyperechoic pancreas increased with age (P<0.001), and the Means were lower in those with hyperechoic pancreas (P=0.004) and a higher body mass index (BMI, P=0.008). No significant correlations with diabetes, hyperechoic liver, or elastographic parameters were demonstrated.

CONCLUSION

Strain elastography demonstrated elastographic changes in the pancreas with aging that included a decreasing Mean and increasing Skewness and Kurtosis after the age of 40. The prevalence of pancreatic hyperechogenicity increased, and the pancreatic hyperechogenicity was significantly negatively correlated with the Mean.

Magnetic resonance elastography for staging liver fibrosis in non-alcoholic fatty liver disease: a diagnostic accuracy systematic review and individual participant data pooled analysis

OBJECTIVES

We conducted an individual participant data (IPD) pooled analysis on diagnostic accuracy of MRE to detect fibrosis stage in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

Through a systematic literature search, we identified studies of MRE (at 60-62.5 Hz) for staging fibrosis in patients with NAFLD, using liver biopsy as gold standard, and contacted study authors for IPD. Through pooled analysis, we calculated the cluster-adjusted AUROC, sensitivity and specificity of MRE for any (≥stage 1), significant (≥stage 2) and advanced (≥stage 3) fibrosis and cirrhosis (stage 4).

RESULTS

We included nine studies with 232 patients with NAFLD (mean age, 51 ± 13 years; 37.5% males; mean BMI, 33.5 ± 6.7 kg/m(2); interval between MRE and biopsy <1 year, 98.3%). Fibrosis stage distribution (stage 0/1/2/3/4) was 33.6, 32.3, 10.8, 12.9 and 10.4%, respectively. Mean AUROC (and 95% CIs) for diagnosis of any, significant or advanced fibrosis and cirrhosis was 0.86 (0.82-0.90), 0.87 (0.82-0.93), 0.90 (0.84-0.94) and 0.91 (0.76-0.95), respectively. Similar diagnostic performance was observed in stratified analysis based on sex, obesity and degree of inflammation.

CONCLUSIONS

MRE has high diagnostic accuracy for detection of fibrosis in NAFLD, independent of BMI and degree of inflammation.

KEY POINTS

• MRE has high diagnostic accuracy for detection of fibrosis in NAFLD. • BMI does not significantly affect accuracy of MRE in NAFLD. • Inflammation had no significant influence on MRE performance in NAFLD for fibrosis.

Comparison of color-Doppler and qualitative and quantitative strain-elastography for differentiation of thyroid nodules in daily practice

OBJECTIVE

Strain-elastography provides a new ultrasound-based method that can offer information about the stiffness of thyroid nodules as an indicator of malignancy. The aim of our study was to compare the utility of color-Doppler and strain-elastography in differentiating between benign and malignant nodules.

DESIGN AND METHODS

77 thyroid nodules (70 benign and 7 malignant) from 70 unselected patients (48 female/22 male, mean age 49.7±14.3 years) were evaluated with color-Doppler and elastography based on a five-scale elastogram score for qualitative elastography and strain ratio for quantitative elastography. As reference tissue we chose normal thyroid tissue [strain ratio a (SR a)] and cervical muscles [strain ratio b (SR b)]. The cytological or histological results were used as a reference standard. Diagnostic performances of qualitative and quantitative elastography were compared using ROC curves.

RESULTS

Vascularization score 3 or 4 was associated with malignancy (p=0.024) as well as elastogram score 4 or 5 (p=0.070, n.s.s.). SR a was indicatively higher and SR b lower in the group of malignant nodules (p=0.065 and p=0.246, n.s.s.). The best cut-off points predicting malignancy were 3.32 for SR a (66.7% sensitivity, 83.3% specificity) and 0.10 for SR b (71.4% sensitivity, 67.1% specificity).

CONCLUSION

In our study, the accuracy of elastography did not surpass other sonographic parameters in differentiating thyroid nodules. The technique can play a role as a supplementary parameter in assessment of malignancy to improve diagnostic efficacy. The best parameter is SR a, but SR b can serve as an alternative if SR a is not assessable.

Diagnostic accuracy of shear wave elastography for prediction of breast malignancy in patients with pathological nipple discharge

OBJECTIVES

Pathological nipple discharge (PND) may indicate malignant breast lesions. As the role of shear wave elastography (SWE) in predicting these malignant lesions has not yet been evaluated, we aim to evaluate the diagnostic value of SWE for this condition.

DESIGN

Prospective diagnostic accuracy study comparing a combination of qualitative and quantitative measurements of SWE (index test) to a ductoscopy and microdochectomy for histological diagnosis (reference test).

SETTING

Fuzhou General Hospital of Nanjing military command.

PARTICIPANTS

A total of 379 patients with PND were finally included from January, 2011 to March 2014, after we screened 1084 possible candidates. All participants were evaluated through SWE, with qualitative parameters generated by Virtual Touch tissue imaging (VTI) and quantitative parameters generated by Virtual Touch tissue quantification (VTQ). All the patients were consented to receive a ductoscopy and microdochectomy for histological diagnosis, and the results were set as a reference test.

OUTCOME MEASURES

Sensitivity and specificity of the combined VTI and VTQ of the SWE for detection of malignancy in patients with PND.

RESULTS

The 379 participants presented with 404 lesions. The results of pathological examination showed that 326 (80.7%) of the 404 lesions were benign and the other 78 (19.3%) were malignant. An area under the curve of elasticity score, VTQm and VTQc, were 0.872, 0.825 and 0.857, respectively, with the corresponding cut-off point as 2.50, 2.860 m/s and 3.015 m/s, respectively. After a combination of these measurements, the sensitivity, specificity, and positive and negative predictive value (PPV and NPV), were 89.7%, 72.1%, 43.5% and 96.7%, respectively. The sensitivity analysis showed 82% of the sensitivity and 96.8% of the specificity, in which patients with no pathological findings in ductoscopy were excluded.

CONCLUSIONS

Ultrasonographic elastography is sensitive for patients with PND and could be used as a triage test before ductoscopy examination. Studies for further improvement of diagnostic sensitivity are warranted.

Reliability of real-time elastography to diagnose thyroid nodules previously read at FNAC as indeterminate: a meta-analysis

The main limit of thyroid fine-needle aspiration cytology (FNAC) is represented by indeterminate report. Recently, real-time elastography (RTE) has been described in the management of these cases. Here, we performed a meta-analysis of published studies specifically focused on the use of RTE in indeterminate thyroid nodules. A comprehensive literature search of PubMed/MEDLINE and Google Scholar databases was conducted by using the combination of the terms "thyroid" and "indeterminate" and "elastography." Pooled sensitivity, specificity, accuracy, PPV and NPV of RTE as predictor of malignancy in thyroid nodules with indeterminate FNAC were calculated, including 95% confidence intervals (95% CI). The area under the summary ROC curve (AUC) was also assessed. Databases found 572 papers, and eight were included in the meta-analysis. Of these, six studies had prospective design and two were retrospective. Pooled malignancy rate was 31%. As common denominator, all studies set the prevalence of hardness within the nodule as risk factor for malignancy of the lesion. Sensitivity of RTE ranged from 11 to 89% (pooled estimate of 69%; 95% CI 55-82%), specificity varied from 6 to 100% (pooled estimate of 75%; 95% CI 42-96%), and accuracy was comprised between 35 and 94% (pooled estimate of 73%; 95% CI 54-89%). The AUC was 0.77. RTE has suboptimal diagnostic accuracy to diagnose thyroid nodules previously classified as indeterminate. Then, RTE alone should not be used for selecting these patients for surgery or not. We advice for further studies using other elastographic approaches and combined RTE and B-mode ultrasonography.

Transient Elastography for Assessment of Liver Fibrosis and Steatosis: An Evidence-Based Analysis

BACKGROUND

Liver fibrosis is a sign of advanced liver disease and is often an indication for treatment. The current standard for diagnosing liver fibrosis and steatosis is biopsy, but noninvasive alternatives are available; one of the most common is transient elastography (FibroScan).

OBJECTIVES

The objective of this analysis was to assess the diagnostic accuracy and clinical utility of transient elastography alone for liver fibrosis and with controlled attenuation parameter (CAP) for steatosis in patients with hepatitis C virus, hepatitis B virus, nonalcoholic fatty liver disease, alcoholic liver disease, or cholestatic diseases. The analysis also aimed to compare the diagnostic accuracy of transient elastography with two alternative noninvasive technologies: FibroTest and acoustic force radiation impulse (ARFI).

DATA SOURCES

Ovid MEDLINE, Ovid MEDLINE In-Process, Ovid Embase, and all EBM databases were searched for all studies published prior to October 2, 2014.

REVIEW METHODS

An overview of reviews was conducted using a systematic search and assessment approach. The results of the included systematic reviews were summarized, analyzed, and reported for outcomes related to diagnostic accuracy and clinical utility as a measure of impact on diagnoses, therapeutic decisions, and patient outcomes.

RESULTS

Fourteen systematic reviews were included, summarizing more than 150 studies. The reviews demonstrated that transient elastography (with or without CAP) has good diagnostic accuracy compared to biopsy for the assessment of liver fibrosis and steatosis. Acoustic force radiation impulse and FibroTest were not superior to transient elastography.

LIMITATIONS

None of the included systematic reviews reported on the clinical utility of transient elastography.

CONCLUSIONS

Transient elastography (with or without CAP) offers a noninvasive alternative to biopsy for the assessment of liver fibrosis and steatosis, given its comparable diagnostic accuracy.

Can continuous scans in orthogonal planes improve diagnostic performance of shear wave elastography for breast lesions?

BACKGROUND

Static shear wave elastography (SWE) is used to detect breast lesions, but slice and plane selections result in discrepancies.

OBJECTIVE

To evaluate the intraobserver reproducibility of continuous SWE, and whether quantitative elasticities in orthogonal planes perform better in the differential diagnosis of breast lesions.

METHOD

One hundred and twenty-two breast lesions scheduled for ultrasound-guided biopsy were recruited. Continuous SWE scans were conducted in orthogonal planes separately. Quantitative elasticities and histopathology results were collected. Reproducibility in the same plane and diagnostic performance in different planes were evaluated.

RESULTS

The maximum and mean elasticities of the hardest portion, and standard deviation of whole lesion, had high inter-class correlation coefficients (0.87 to 0.95) and large areas under receiver operation characteristic curve (0.887 to 0.899). Without loss of accuracy, sensitivities had increased in orthogonal planes compared with single plane (from 73.17% up to 82.93% at most). Mean elasticity of whole lesion and lesion-to-parenchyma ratio were significantly less reproducible and less accurate.

CONCLUSION

Continuous SWE is highly reproducible for the same observer. The maximum and mean elasticities of the hardest portion and standard deviation of whole lesion are most reliable. Furthermore, the sensitivities of the three parameters are improved in orthogonal planes without loss of accuracies.

Applicability of shear wave elastography of the major salivary glands: values in healthy patients and effects of gender, smoking and pre-compression

Our aim in this study was to determine normal shear wave elastography (SWE) values for the parenchyma of the major salivary glands and to evaluate the influences of gender, smoking, side and type of gland and varying amounts of ultrasound probe pressure on SWE values. Twenty-five consecutive healthy patients were examined with ultrasound. SWE velocities were measured with acoustic radiation force imaging in the hilum and central region of both glands with "normal" and very low pressure. Mean SWE velocities were 1.854 m/s for the parotid gland and 1.932 m/s for the submandibular gland. No statistically significant differences were detected between males and females, smokers and non-smokers, parotid and submandibular gland and left and right sides. Greater pre-compression with the ultrasound probe resulted in a statistically significant increase in the SWE values of both salivary glands (p < 0.000). The degree of pre-compression by the ultrasound transducer should be standardized, so that the reliability and reproducibility of this innovative method can be improved.

Frequency adaptation for enhanced radiation force amplitude in dynamic elastography

In remote dynamic elastography, the amplitude of the generated displacement field is directly related to the amplitude of the radiation force. Therefore, displacement improvement for better tissue characterization requires the optimization of the radiation force amplitude by increasing the push duration and/or the excitation amplitude applied on the transducer. The main problem of these approaches is that the Food and Drug Administration (FDA) thresholds for medical applications and transducer limitations may be easily exceeded. In the present study, the effect of the frequency used for the generation of the radiation force on the amplitude of the displacement field was investigated. We found that amplitudes of displacements generated by adapted radiation force sequences were greater than those generated by standard nonadapted ones (i.e., single push acoustic radiation force impulse and supersonic shear imaging). Gains in magnitude were between 20 to 158% for in vitro measurements on agar-gelatin phantoms, and 170 to 336% for ex vivo measurements on a human breast sample, depending on focus depths and attenuations of tested samples. The signal-to-noise ratio was also improved more than 4-fold with adapted sequences. We conclude that frequency adaptation is a complementary technique that is efficient for the optimization of displacement amplitudes. This technique can be used safely to optimize the deposited local acoustic energy without increasing the risk of damaging tissues and transducer elements.

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 2: breast

The breast section of these Guidelines and Recommendations for Elastography produced under the auspices of the World Federation of Ultrasound in Medicine and Biology (WFUMB) assesses the clinically used applications of all forms of elastography used in breast imaging. The literature on various breast elastography techniques is reviewed, and recommendations are made on evidence-based results. Practical advice is given on how to perform and interpret breast elastography for optimal results, with emphasis placed on avoiding pitfalls. Artifacts are reviewed, and the clinical utility of some artifacts is discussed. Both strain and shear wave techniques have been shown to be highly accurate in characterizing breast lesions as benign or malignant. The relationship between the various techniques is discussed, and recommended interpretation based on a BI-RADS-like malignancy probability scale is provided. This document is intended to be used as a reference and to guide clinical users in a practical way.

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 1: basic principles and terminology

Conventional diagnostic ultrasound images of the anatomy (as opposed to blood flow) reveal differences in the acoustic properties of soft tissues (mainly echogenicity but also, to some extent, attenuation), whereas ultrasound-based elasticity images are able to reveal the differences in the elastic properties of soft tissues (e.g., elasticity and viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathologic lesions. Typically, all elasticity measurement and imaging methods introduce a mechanical excitation and monitor the resulting tissue response. Some of the most widely available commercial elasticity imaging methods are 'quasi-static' and use external tissue compression to generate images of the resulting tissue strain (or deformation). In addition, many manufacturers now provide shear wave imaging and measurement methods, which deliver stiffness images based upon the shear wave propagation speed. The goal of this review is to describe the fundamental physics and the associated terminology underlying these technologies. We have included a questions and answers section, an extensive appendix, and a glossary of terms in this manuscript. We have also endeavored to ensure that the terminology and descriptions, although not identical, are broadly compatible across the WFUMB and EFSUMB sets of guidelines on elastography (Bamber et al. 2013; Cosgrove et al. 2013).

Diagnostic performance of elastography in cytologically indeterminate thyroid nodules

Cytological examination of material from fine-needle aspiration biopsy is the mainstay of diagnosis of thyroid nodules, thanks to its remarkable accuracy and scarcity of complications. However, follicular lesions (also called indeterminate lesions or Thy3 in the current classification), a heterogeneous group of lesions in which cytology is unable to give a definitive diagnosis to, represent its main limit. Elastography has been proposed as a potential diagnostic tool to define the risk of malignancy in the aforementioned nodules, but at present there is no conclusive data due to the small number of specifically addressed studies and the lack of concordance among them. The objective of our study was to evaluate the role of real-time elastography (RTE) for refining diagnosis of Thy3 nodules, by integrating diagnostic information provided by traditional ultrasound (US). The study included 108 patients with Thy3 nodules awaiting for surgery, which were evaluated by US (considering hypoecogenicity, irregular margins, microcalcifications, halo sign, and intranodular vascularization) and RTE. Nodules were classified at RTE using a four-class color scale. At histologic examination, 75 nodules were benign and 33 malignant. As expected, none of the ultrasound parameters alone was adequate in predicting malignancy or benignity of the nodules; in the presence of at least two US risk factors, we obtained 61 % sensitivity, 83 % specificity, and 77 % accuracy with 6.8 OR (95 % CI 2.4-20.4). RTE scores 3 and 4 showed 76 % sensitivity, 88 % specificity, 74 % PPV, and 89 % NPV with diagnostic accuracy of 84 %; the data are statistically significant (p < 0.0001) with a OR of 21.9 (95 % CI 7.1-76). By combining RTE with US parameters, the presence of at least 2 characters of suspicion had 88 % sensitivity and 94 % NPV with 23.8 OR (95 % CI 7-106.3). The use of combined RTE and US leads to the identification of two patients subpopulations which have a significantly different malignancy risk (6 vs. 63 %); further studies are needed to verify if it is possible to send only the first group to thyroidectomy and the other to follow-up.

WFUMB guidelines and recommendations for clinical use of ultrasound elastography: Part 3: liver

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced these guidelines for the use of elastography techniques in liver disease. For each available technique, the reproducibility, results, and limitations are analyzed, and recommendations are given. Finally, recommendations based on the international literature and the findings of the WFUMB expert group are established as answers to common questions. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.

A versatile and experimentally validated finite element model to assess the accuracy of shear wave elastography in a bounded viscoelastic medium

The feasibility of shear wave elastography (SWE) in arteries for cardiovascular risk assessment remains to be investigated as the artery's thin wall and intricate material properties induce complex shear wave (SW) propagation phenomena. To better understand the SW physics in bounded media, we proposed an in vitro validated finite element model capable of simulating SW propagation, with full flexibility at the level of the tissue's geometry, material properties, and acoustic radiation force. This computer model was presented in a relatively basic set-up, a homogeneous slab of gelatin-agar material (4.35 mm thick), allowing validation of the numerical settings according to actual SWE measurements. The resulting tissue velocity waveforms and SW propagation speed matched well with the measurement: 4.46 m/s (simulation) versus 4.63 ± 0.07 m/s (experiment). Further, we identified the impact of geometrical and material parameters on the SW propagation characteristics. As expected, phantom thickness was a determining factor of dispersion. Adding viscoelasticity to the model augmented the estimated wave speed to 4.58 m/s, an even better match with the experimental determined value. This study demonstrated that finite element modeling can be a powerful tool to gain insight into SWE mechanics and will in future work be advanced to more clinically relevant settings.

Vascular elastography: a validation study

Vascular elastography techniques are promising tools for mechanical characterization of diseased arteries. These techniques are usually validated with simulations or phantoms or by comparing results with histology or other imaging modalities. In the study described here, vascular elastography was applied to porcine aortas in vitro during inflation testing (n = 10) and results were compared with those of standard bi-axial tensile testing, a technique that directly measures the force applied to the tissue. A neo-Hookean model was fit to the stress-strain data, valid for large deformations. Results indicated good correspondence between the two techniques, with GUS = 110 ± 11 kPa and GTT = 108 ± 10 kPa for ultrasound and tensile testing, respectively. Bland-Altman analysis revealed little bias (GUS-GTT = 2 ± 20 kPa). The next step will be the application of a non-linear material model that is also adaptable for in vivo measurements.

Romanian national guidelines and practical recommendations on liver elastography

The use of liver elastography has substantially developed in the past few years; the introduction of novel elastographic methods (Transient Elastography, point Shear Wave Elastography, Real Time Shear Wave Elastography, Strain Elastography) has changed the perspective in the evaluation of liver disease. The ongoing research in this area is mainly focused on diffuse liver diseases and for predicting liver cirrhosis complication. This guideline created under the auspice of Romanian Society of Ultrasound in Medicine and Biology is intended to accustomize the clinician with the current practical use of liver elastography and has been issued to help in maximizing the clinical benefit for the patients with chronic liver diseases.