Acoustic radiation force impulse elastography as compared to transient elastography and liver biopsy in patients with chronic hepatopathies

How to Identify Advanced Fibrosis in Adult Patients with Non-Alcoholic Fatty Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH) Using Ultrasound Elastography-A Review of the Literature and Proposed Multistep Approach

Non-alcoholic fatty liver disease (NAFLD), and its progressive form, non-alcoholic steatohepatitis (NASH), represent, nowadays, real challenges for the healthcare system. Liver fibrosis is the most important prognostic factor for NAFLD, and advanced fibrosis is associated with higher liver-related mortality rates. Therefore, the key issues in NAFLD are the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis. We critically reviewed the ultrasound (US) elastography techniques for the quantitative characterization of fibrosis, steatosis, and inflammation in NAFLD and NASH, with a specific focus on how to differentiate advanced fibrosis in adult patients. Vibration-controlled transient elastography (VCTE) is still the most utilized and validated elastography method for liver fibrosis assessment. The recently developed point shear wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) techniques that use multiparametric approaches could bring essential improvements to diagnosis and risk stratification.

Diagnostic accuracy of magnetic resonance elastography and point-shear wave elastography for significant hepatic fibrosis screening: Systematic review and meta-analysis

The hepatic diseases are extremely common in clinical practice. The correct classification of liver fibrosis is extremely important, as it influences therapy and predicts disease outcomes. The purpose of this study is to compare the diagnostic performance of point-shear wave elastography (pSWE) and magnetic resonance elastography (MRE) in the hepatic fibrosis diagnostic. A meta-analysis was carried out based on articles published until October 2020. The articles are available at following databases: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Scientific Electronic Library Online, LILACS, Scopus, and CINAHL. Diagnostic performances were analyzed per METAVIR F2, using 3.5kPa as target fibrosis. Assessment of the methodological quality of the incorporated papers by the QUADAS-2 tool for pSWE and MRE. A total 2,153 studies articles were evaluated and 44 studies, comprising 6,081 patients with individual data, were included in the meta-analysis: 28 studies for pSWE and 16 studies for MRE. The pooled sensitivity and specificity were 0.86 (95%CI 0.80-0.90) and 0.88 (95%CI 0.85-0.91), respectively, for pSWE, compared with 0.94 (95%CI 0.89-0.97) and 0.95 (95%CI 0.89-0.98) respectively, for MRE. The pooled SROC curve for pSWE shows in the area under the curve (AUC) of 0.93 (95%CI 0.90-0.95), whereas the AUC for MRE was 0.98 (95%CI 0.96-0.99). The diagnostic odds ratio for pSWE and MRE were 41 (95%CI 24-72) and 293 (95%CI 86-1000), respectively. There was statistically significant heterogeneity for pSWE sensitivity (I² = 85.26, P<0.001) and specificity (I² = 89.46, P<0.001). The heterogeneity for MRE also was significant for sensitivity (I² = 73.28, P<0.001) and specificity (I² = 87.24, P<0.001). Therefore, both pSWE and MRE are suitable modalities for assessing liver fibrosis. In addition, MRE is a more accurate imaging technique than pSWE and can be used as alternative to invasive biopsy.

The role of elastography in viral hepatitis and autoimmune hepatitis

The prognosis of chronic liver diseases, which represent a major public health problem, is mainly linked to the extent and progression of liver fibrosis and the subsequent risk of developing cirrhosis and related complications, mainly hepatocellular carcinoma. During the past decade many noninvasive methods and in particular electrographic techniques, have been developed to reduce the need for liver biopsy in staging fibrosis and to overcome whenever possible its limitations, mainly: invasiveness, costs, low reproducibility and poor acceptance by patients. The aim of this review was to provide a comprehensive review of the role of elastography techniques in viral chronic liver diseases and autoimmune hepatitis, with the focus on the possible advantages and limitations of these techniques and on their diagnostic accuracy in predicting the stage of liver fibrosis.

Shear wave-based sound touch elastography in liver fibrosis assessment for patients with autoimmune liver diseases

Background

Shear wave-based ultrasonic elastography (USE) has been widely used for the assessment of liver fibrosis in patients with chronic liver diseases (CLD). However, diagnostic criteria and accuracy vary between different etiologies and specific elastography techniques. We aimed to evaluate the tissue stiffness measured by shear wave-based sound touch elastography (STE) in staging liver fibrosis in patients with autoimmune liver diseases (AILD).

Methods

One hundred and two AILD patients who had undergone STE liver stiffness measurements (LSMs) by using a Resona 7 ultrasound system were retrospectively studied. With the Scheuer liver fibrosis staging system as the reference, we investigated the diagnostic performance and cutoff values of STE measured liver stiffness in staging liver fibrosis through receiver operating characteristic (ROC) curve analysis. Moreover, comparisons of areas under the curve (AUCs) were made between LSMs and calculated biomarker scores, including the aspartate aminotransferase (AST)-to-platelet ratio index (APRI), and fibrosis-4 (FIB-4) index.

Results

Median LSMs increased with the advancing fibrosis stages with values of 6.89 kPa (1.51 m/s), 8.00 kPa (1.63 m/s), 9.60 kPa (1.79 m/s), 11.37 kPa (1.95 m/s) and 14.50 kPa (2.20 m/s), from stage 0 to stage 4 respectively. The cutoff values of STE for identifying significant fibrosis (≥ stage 2), severe fibrosis (≥ stage 3) and cirrhosis (stage 4) were 9.07 kPa (1.74 m/s), 9.97 kPa (1.82 m/s) and 10.48 kPa (1.87 m/s), respectively, with corresponding sensitivity of 79.1%, 93.3%, and 100%; specificity of 80.0%, 70.8% and 71.8%. The AUCs of LSMs in identifying fibrosis ≥ stage 2, ≥ stage 3 and stage 4 (0.82, 0.87, and 0.91, respectively) were significantly higher than that of APRI (0.67, 0.64, and 0.72, respectively) and FIB-4 (0.70, 0.68, and 0.75, respectively) (all P<0.05).

Conclusions

LSM obtained by STE exhibited its good capability to evaluate liver fibrosis stages in patients with AILD. As a noninvasive modality for liver fibrosis staging, STE is superior to APRI and FIB-4 biomarker scores.

A review of physical and engineering factors potentially affecting shear wave elastography

It has been recognized that tissue stiffness provides useful diagnostic information, as with palpation as a screening for diseases such as cancer. In recent years, shear wave elastography (SWE), a technique for evaluating and imaging tissue elasticity quantitatively and objectively in diagnostic imaging, has been put into practical use, and the amount of clinical knowledge about SWE has increased. In addition, some guidelines and review papers regarding technology and clinical applications have been published, and the status as a diagnostic technology is in the process of being established. However, there are still unclear points about the interpretation of shear wave speed (SWS) and converted elastic modulus in SWE. To clarify these, it is important to investigate the factors that affect the SWS and elastic modulus. Therefore, physical and engineering factors that potentially affect the SWS and elastic modulus are discussed in this review paper, based on the principles of SWE and a literature review. The physical factors include the propagation properties of shear waves, mechanical properties (viscoelasticity, nonlinearity, and anisotropy), and size and shape of target tissues. The engineering factors include the region of interest depth and signal processing. The aim of this review paper is not to provide an answer to the interpretation of SWS. It is to provide information for readers to formulate and verify the hypothesis for the interpretation. Therefore, methods to verify the hypothesis for the interpretation are also reviewed. Finally, studies on the safety of SWE are discussed.

What does liver elastography measure? Technical aspects and methodology

Elastography can be thought as an extension of the ancient technique of palpation. After giving a short introduction to the history of elastography, the different technologies that are nowadays available and the physics behind them, the article focuses on the assessment of liver stiffness in patients with diffuse liver disease using shear wave elastography (SWE). Practical advices on how to perform the SWE techniques and on the factors that should be considered for a correct interpretation of the results are given. This paper aimed to provide a practical guide for beginners and advanced clinical users to better understand technical aspects, methodologies and terminology.

Non-invasive splenic parameters of portal hypertension: Assessment and utility

BACKGROUND

Portal hypertension is a major complication of cirrhosis that is associated with significant morbidity and mortality. The present gold-standard method to risk stratify and observe cirrhosis patients with portal hypertension is hepatic venous pressure gradient measurement or esophagogastroduodenoscopy. However, these methods are invasive, carry a risk of complications and are associated with significant patient discomfort. Therefore, non-invasive splenic parameters are of clinical interest as potential useful markers in determining the presence of portal hypertension. However, diagnostic accuracy and reproducibility remains unvalidated.

AIM

To assess the diagnostic accuracy of spleen stiffness, area and diameter in predicting the presence of portal hypertension.

METHODS

Of 50 patients with varying liver disease pathologies were prospectively recruited from the St. Mary’s Hospital Liver Unit in London; 25 with evidence of portal hypertension and 25 with no evidence of portal hypertension. Liver stiffness, spleen stiffness, spleen diameter and spleen area were measured using the Philips Affiniti 70 elastography point quantification point shear wave elastography system. The aspartate aminotransferase-to-platelet-ratio-index (APRI) score was also calculated. Performance measures, univariate and multivariate logistic regression were used to evaluate demographic, clinical and elastography variables. Interclass correlation coefficient was used to determine the reproducibility of splenic area and diameter.

RESULTS

On univariate and individual performance, platelet count [area under the receiver operating characteristic (AUROC) 0.846, P value < 0.001], spleen area (AUROC 0.828, P value = 0.002) and APRI score (AUROC 0.827, P value < 0.001) were the most accurate variables in identifying the presence of portal hypertension. On multivariate logistic regression models constructed, the combination of spleen area greater than 57.90 cm² and platelet count less than 126 × 10⁹ had 63.2% sensitivity and 100% specificity, 100% positive predictive value and 100% negative predictive value. An alternative combination of spleen stiffness greater than 29.99 kPa and platelet count less than 126 × 10⁹ had 88% sensitivity, 75% specificity, 78.6% positive predictive value and 85.7% negative predictive value. An interclass correlation coefficient value of 0.98 (95%CI: 0.94-0.99, P value < 0.001) and 0.96 (95%CI: 0.91-0.99, P value < 0.001) were determined for inter-operator variability for spleen area and diameter respectively.

CONCLUSION

Spleen area, spleen stiffness and platelet count may be useful markers to assess the presence of portal hypertension in patients of various etiologies.

Organ Stiffness in the Work-Up of Myelofibrosis and Philadelphia-Negative Chronic Myeloproliferative Neoplasms

To define the role of spleen stiffness (SS) and liver stiffness (LS) in myelofibrosis and other Philadelphia (Ph)-negative myeloproliferative neoplasms (MPNs), we studied, by ultrasonography (US) and elastography (ES), 70 consecutive patients with myelofibrosis (MF) (no.43), essential thrombocythemia (ET) (no.10), and polycythemia vera (PV) (no.17). Overall, the median SS was not different between patients with MF and PV (p = 0.9); however, both MF and PV groups had significantly higher SS than the ET group (p = 0.011 and p = 0.035, respectively) and healthy controls (p < 0.0001 and p = 0.002, respectively). In patients with MF, SS values above 40 kPa were significantly associated with worse progression-free survival (PFS) (p = 0.012; HR = 3.2). SS also correlated with the extension of bone marrow fibrosis (BMF) (p < 0.0001). SS was higher in advanced fibrotic stages MF-2, MF-3 (W.H.O. criteria) than in pre-fibrotic/early fibrotic stages (MF-0, MF-1) (p < 0.0001) and PFS was significantly different in the two cohorts, with values of 63% and 85%, respectively (p = 0.038; HR = 2.61). LS significantly differed between the patient cohort with MF and healthy controls (p = 0.001), but not between the patient cohorts with ET and PV and healthy controls (p = 0.999 and p = 0.101, respectively). We can conclude that organ stiffness adds valuable information to the clinical work-up of MPNs and could be employed to define patients at a higher risk of progression.

Global hepatitis C elimination: history, evolution, revolutionary changes and barriers to overcome

The fundamental discovery of the hepatitis C virus (HCV) in 1989 has led to winning this year's Nobel Prize in Medicine. This achievement guided all the steps in identifying the elements of the virus, in order to develop the treatment and to increase the screening solutions, which have slowed the exposure to the virus. The management of infection started with interferon-alpha (IFN-α), which has later enhanced by adding Ribavirin. Nowadays, HCV treatment is based on direct-acting antiviral agents (DAAs). Currently, HCV infection benefits of curative treatment, with which most patients can be cured. When speaking about hepatitis C future, we can say it is looking bright, considering all the progress that has been made in recent years and all the options that we have for curing all genotypes of HCV infection. The aim of this review is to sum up the historical characteristics of HCV discovery, the evolution of treatment and screening actions, gaps, and stages for achieving the international elimination target of the World Health Organization.

Normal values of shear wave velocity in liver tissue of healthy children measured using the latest acoustic radiation force impulse technology

BACKGROUND

Several studies have demonstrated the feasibility and effectiveness of using ultrasound elastography to assess liver tissue stiffness. Virtual touch imaging quantification (VTIQ) based on acoustic radiation force impulse imaging has been developed as a latest and noninvasive method for assessing liver stiffness in children.

AIM

To determine the standard value in healthy children, and to identify possible factors that might influence the VTIQ measurement.

METHODS

With the ethical approval, 202 children between 1 month and 15 years old were included in this study. None of them had any liver or systematic diseases. All children had a normal ultrasound scan and normal body mass index (BMI) range. The subjects were divided into four age and BMI groups. The effects of gender, age, liver lobe, measurement depth, and BMI on liver elasticity were investigated.

RESULTS

A significant correlation was found between age and shear wave velocity (SWV) value. At measurement depths of 1.5 cm and 2.0 cm in the left lobe, there were significant differences among the age groups. SWV values were significantly negatively correlated with the measurement depth. Gender, liver lobe, and BMI showed no significant effect on the SWV values. Age and BMI may influence the quality of the elastogram.

CONCLUSION

VTIQ is a noninvasive technique that is feasible to measure liver stiffness in children. The afore-mentioned velocity value obtained utilizing VTIQ method could be used as reference value for normal liver stiffness in children.

Ultrasound Elastography as a Non-Invasive Method to Monitor Liver Disease in Children with Short Bowel Syndrome: Updated Results

PURPOSE

The purpose of the study was to determine the accuracy of acoustic radiation force impulse (ARFI) ultrasound elastography in assessing the degree of liver disease in children with short bowel syndrome (SBS).

METHODS

A prospective observational cohort study of patients with SBS who underwent a liver biopsy and ARFI elastography was performed. Mean shear wave speed (SWS) and stage of fibrosis was evaluated using t-tests. Receiver operating characteristic curves (ROC) were generated and the area under the curves (AUC) estimated in order to assess the accuracy of SWS measurements to discriminate between stages of fibrosis.

RESULTS

Thirty-seven paired elastography and biopsy samples from 31 patients were included. The median age was 0.6 years, and 61% were male. There was a significant positive correlation between stage of fibrosis and mean SWS (β=0.16 m/s increase per stage, p=<0.001). ROC analysis revealed that mean SWS had good accuracy for discriminating between mild liver fibrosis (F0-F1) and moderate to severe fibrosis (F2-F4) (AUC=0.80, 95% CI 0.65-0.95). In addition, ROC analysis demonstrated that mean SWS can also accurately discriminate between mild to moderate fibrosis (F0-F2) and more severe fibrosis (F3-F4) (AUC=0.84, 95% CI 0.71-0.96).

CONCLUSION

ARFI elastography is an accurate, non-invasive method to monitor liver disease in children with SBS.

TYPE OF STUDY

Retrospective Cohort Study LEVEL OF EVIDENCE: II.

Rational arrangement of measuring shear wave speed in the liver

BACKGROUND

Shear wave speed has been widely applied to quantify a degree of liver fibrosis. However, there is no standardized procedure, which makes it difficult to utilize the speed universally.

AIM

To provide procedural standardization of shear wave speed measurement.

METHODS

Point shear wave elastography (pSWE) was measured in 781 patients, and two-dimensional shear wave elastography (2dSWE) was measured on the same day in 18 cases. Regions-of-interest were placed at 12 sites, and the median and robust coefficient-of-variation (CVR) were calculated. A residual sum-of-square (Σdi²) was computed for bootstrap values of 1000 iterations in 18 cases with each assumption of 1 to 12 measurements. The proportion of the Σdi² (%Σdi²) was calculated as the ratio of Σdi² to pSWE after converting it based on the correlation between pSWE and 2dSWE.

RESULTS

The CVR showed a significantly broader distribution in the left lobe (P < 0.0001), and the smallest CVR in the right anterior segment that covered 95% cases was 40.4%. pSWE was significantly higher in the left lobe than in the right lobe (1.63 ± 0.78 m/s vs 1.61 ± 0.78 m/s, P = 0.0004), and the difference between the lobes became further discrete when the subjects were limited to the cases with a CVR less than 40.4% in any segment (1.76 ± 0.80 m/s vs 1.70 ± 0.82 m/s, P < 0.0001). The highest values of the CVR in every 0.1 m/s interval were plotted in convex upward along pSWE and peaked at 1.93 m/s. pSWE and 2dSWE were significantly correlated (P < 0.0001, r = 0.95). In 216000 resamples from 18 cases, the %Σdi² of 12 sites was 8.0% and gradually increased as the acquisition sites decreased to reach a significant difference with a %Σdi² of 7 sites (P = 0.027).

CONCLUSION

These data suggest that shear wave speed should be measured at 8 or more sites of spreading in both lobes.

The role of acoustic radiation force impulse elastography in the differentiation of benign and malignant focal liver masses

BACKGROUND/AIMS

The aim of this study was to evaluate elasticity of benign and malign focal liver lesions and surrounding parenchyma as measured by acoustic radiation force impulse (ARFI).

MATERIALS AND METHODS

34 hemangiomas, 4 focal nodular hyperplasia (FNH), 10 hepatocellular carcinoma (HCC) and 22 metastatic lesions from a total of 62 patients were examined with ARFI elastography. ARFI measurements for each tumor type were expressed as mean ± standard deviation for liver mass and surrounding parenchyma. ARFI values were compared between tumor types and surrounding parencyhma.

RESULTS

The mean stiffness values were 2.15±0.73 m/s for hemangiomas (n=34), 3.22±0.18 m/s for FNH (n=4), 2.75±0.53 m/s for HCC (n=10) and 3.59±0.51 m/s for metastasis (n=22). Although there was not a significant difference between hemangiomas and HCC lesions in ARFI values (p>0.05), hemangiomas showed significantly different ARFI values from FNH and metastases (p<0.05). Also, there were significant differences in ARFI values between malignant and benign masses. The area under the receiver-operating characteristics curves for discriminating the malignant from benign liver masses was 0.826 (p<0.001). An ARFI value of 2.32 m/s was selected as cut-off value to differentiate malignant liver masses from benign ones (sensitivity: 0.93, specificity: 0.60).

CONCLUSION

Although currently ARFI is not a definitive method for the primary diagnosis of focal solid liver lesions, it provides additional important information non-invasively for differential diagnosis.

Evaluation of acoustic radiation force impulse (ARFI) elastography as non-invasive diagnostic tool in living donor liver transplantation

BACKGROUND AND AIMS

Role of acoustic radiation force impulse (ARFI) elastography, in transplant setting, is not well established. We aimed to define the normal mean values of the liver stiffness by ARFI Elastography in healthy liver donors and to evaluate ARFI elastography as predictor of graft fibrosis post living donor liver transplant (LDLT) in comparison to other non-invasive methods (transient elastography [TE], APRI and FIB4).

PATIENTS AND METHODS

A total of 100 subjects (70 recipients and 30 donors) were recruited. APRI and FIB4 scores were calculated for all recipients. TE and ARFI elastography (Siemens Acuson S2000 Ultrasound System, Germany) were performed to all subjects. All donors and only 30 recipients had liver biopsy. Significant fibrosis was defined as ≥ F2.

RESULTS

The mean ARFI velocity among the donors was 1.05 ± 0.09 m/s. Regarding the recipients: mean age was 49.5 ± 8.49 years, 85.7% males, fibrosis stages < F2 were the most frequent stages by liver biopsy (86.7%) and TE (67.1%). ARFI median was significantly correlated with TE median, APRI and FIB-4 (r = 0.888, p = 0.000; r = 0.62, p = 0.000, and r = 0.585, p = 0.000, respectively). ARFI performed well in discriminating patients with ≥ F2 (AUROC = 0.93, 95% CI 0.86-0.99, p < 0.01) with best cutoff median value of 1.34 m/s (sensitivity 90%, specificity 82%).

CONCLUSION

ARFI can be used as a reliable method in assessment of significant fibrosis post-LDLT.

Assessment of Liver Fibrosis With Elastography Point Quantification vs Other Noninvasive Methods

BACKGROUND & AIMS

Elastography point quantification (ElastPQ) is a non-invasive method for assessing liver fibrosis based on liver stiffness. We evaluated the accuracy of ElastPQ for the staging of liver fibrosis in patients with chronic liver disease (CLD) compared with aspartate transaminase to platelet ratio index, fibrosis-4 index, and transient elastography (TE), using liver biopsy as reference standard.

METHODS

We performed a retrospective study of 406 patients with CLD of any etiology who underwent liver biopsy analysis from September 2012 through June 2017 at a clinic in Bologna, Italy. We obtained liver stiffness measurements, made by ElastPQ and TE, for 361 patients. Liver fibrosis stage was assessed by the METAVIR scoring system. Areas under the receiver operating characteristic curve (AUROC) were used to assess the diagnostic performance of ElastPQ.

RESULTS

ElastPQ values correlated with histologic detection of fibrosis (r = 0.718; P < .001). The AUROC values were 0.856 for detection of significant fibrosis (F≥2), 0.951 for advanced fibrosis (F≥3), and 0.965 for cirrhosis. The best cut-off values identified for classifying patients with F≥2, F≥3, or cirrhosis were 6.0 kPa, 6.2 kPa, and 9.5 kPa, respectively: these were lower than those for TE. Comparison of ElastPQ with TE data resulted in superimposable diagnostic accuracy of both methods for each stage of liver fibrosis. Both elastography techniques performed better than aspartate transaminase to platelet ratio index or fibrosis-4 index scores (P < .05 for all AUROC comparisons).

CONCLUSIONS

ElastPQ has good to excellent performance for the non-invasive staging of liver fibrosis in patients with CLD. ElastPQ identified patients with fibrosis or cirrhosis with levels of accuracy that were not inferior to those of TE, and outperformed serum fibrosis indexes in identifying each stage of liver fibrosis.

HIGHER VALUES IN LIVER ELASTOGRAPHY AND MELD SCORE ARE MORTALITY PREDICTORS ON LIVER TRANSPLANT WAITING LIST

BACKGROUND

Liver elastography have been reported in hepatocellular carcinoma (HCC) with higher values; however, it is unclear to identify morbimortality risk on liver transplantation waiting list.

AIM

To assess liver stiffness, ultrasound and clinical findings in cirrhotic patients with and without HCC on screening for liver transplant and compare the morbimortality risk with elastography and MELD score.

METHOD

Patients with cirrhosis and HCC on screening for liver transplant were enrolled with clinical, radiological and laboratory assessments, and transient elastography.

RESULTS

103 patients were included (without HCC n=58 (66%); HCC n=45 (44%). The mean MELD score was 14.7±6.4, the portal hypertension present on 83.9% and the mean transient elastography value was 32.73±22.5 kPa. The median acoustic radiation force impulse value of liver parenchyma was 1.98 (0.65-3.2) m/s and 2.16 (0.59-2.8) m/s in HCC group. The HCC group was significantly associated with HCV infection (OR 26.84; p<0.0001), higher levels of serum alpha-fetoprotein (OR 5.51; p=0.015), clinical portal hypertension (OR 0.25; p=0.032) and similar MELD score (p=0.693). The area under the receiver operating characteristics (AUROC) showed sensitivity and specificity for serum alpha-fetoprotein (cutoff 9.1 ng/ml), transient elastography value (cutoff value 9 kPa), and acoustic radiation force impulse value (cutoff value 2.56 m/s) of 50% and 86%, 92% and 17% and 21% and 92%, respectively. The survival group had a mean transient elastography value of 31.65±22.2 kPa vs. 50.87±20.9 kPa (p=0.098) and higher MELD scores (p=0.035).

CONCLUSION

Elastography, ultrasound and clinical findings are important non-invasive tools for cirrhosis and HCC on screening for liver transplant. Higher values in liver elastography and MELD scores predict mortality.

Shear wave elastography predicts hepatocellular carcinoma risk in hepatitis C patients after sustained virological response

AIM

To evaluate the relationship between fibrosis and HCC after sustained virological response (SVR) to treatment for chronic hepatitis C (HCV).

METHODS

This single-center study retrospectively evaluated 196 patients who achieved SVR after HCV infection. The associations of risk factors with HCC development after HCV eradication were evaluated using univariate and multivariate Cox proportional hazards regression models.

RESULTS

Among the 196 patients, 8 patients (4.1%) developed HCC after SVR during a median follow-up of 26 months. Multivariate analyses revealed that HCC development was independently associated with age of ≥75 years (risk ratio [RR] = 35.16), α- fetoprotein levels of ≥6 ng/mL (RR = 40.30), and SWE results of ≥11 kPa (RR = 28.71).

CONCLUSIONS

Our findings indicate that SWE may facilitate HCC surveillance after SVR and the identification of patients who have an increased risk of HCC after HCV clearance.

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.

What we need to know when performing and interpreting US elastography

According to the increasing need for accurate staging of hepatic fibrosis, the ultrasound (US) elastography techniques have evolved significantly over the past two decades. Currently, US elastography is increasingly used in clinical practice. Previously published studies have demonstrated the excellent diagnostic performance of US elastography for the detection and staging of liver fibrosis. Although US elastography may seem easy to perform and interpret, there are many technical and clinical factors which can affect the results of US elastography. Therefore, clinicians who are involved with US elastography should be aware of these factors. The purpose of this article is to present a brief overview of US techniques with the relevant technology, the clinical indications, diagnostic performance, and technical and biological factors which should be considered in order to avoid misinterpretation of US elastography results.

Factors Influencing the Diagnostic Accuracy of Acoustic Radiation Force Impulse Elastography in Patients with Chronic Hepatitis B

Background/Aims

To determine factors predictive of discordance in staging liver fibrosis using liver biopsy (LB) and acoustic radiation force impulse (ARFI) elastography in patients with chronic hepatitis B (CHB).

Methods

Consecutive patients with CHB who underwent LB and ARFI elastography on the same day from November 2010 to March 2013 were prospectively recruited from three tertiary hospitals.

Results

We analyzed 105 patients (median age of 47 years). The F0–1, F2, F3, and F4 fibrosis stages were identified in 27 (25.7%), 27 (25.7%), 21 (20.0%), and 30 (28.6%) patients, respectively. The areas under the receiver operating characteristics curves for ARFI elastography in assessing ≥F2, ≥F3, and F4 was 0.814, 0.848, and 0.752, respectively. The discordance of at least one stage between LB and ARFI was observed in 68 patients (64.8%) and of at least two stages in 16 patients (15.2%). In a multivariate analysis, advanced fibrosis stage (F3–4) was the only factor that was negatively correlated with one-stage discordance (p=0.042). Moreover, advanced fibrosis stage was negatively (p=0.016) correlated and body mass index (BMI) was positively (p=0.006) correlated with two-stage discordance.

Conclusions

Advanced fibrosis stage (F3–4) was a predictor of nondiscordance between LB and ARFI elastography; BMI also influenced the accuracy of ARFI elastography.

Diagnostic Accuracy of Acoustic Radiation Force Impulse (ARFI) in Diagnosis of Liver Fibrosis among Egyptian Patients with Chronic HCV Infection

BACKGROUND:

Acoustic radiation force impulse (ARFI) evaluates liver stiffness non-invasively and was invented recently. This technique can easily and accurately assess the degree of liver fibrosis in clinical practice.

AIM:

The aim of this study was to detect the diagnostic performance of ARFI elastography in the staging of fibrosis in some Egyptian patients with chronic HCV infection.

PATIENTS AND METHODS:

One hundred ninety patients with chronic HCV infection; 142 men and 48 women were enrolled in the study. They underwent liver biopsy examination for liver fibrosis detection. All demographic; clinical and biochemical data were recoded. ARFI examination was done for all subjects to detect liver stiffness measurement in relation to liver fibrosis detected by pathological examination of liver biopsies.

RESULTS:

Medians of liver stiffness measurement by shear wave velocity showed a significant increase as a grade of liver fibrosis increases (p ≤ 0.0001, highly significant). Liver stiffness was directly correlated to age, AST; ALT; INR and liver steatosis (p values were: 0.009; 0.0001; 0.013; 0.006 and 0.04 respectively, significant). On the other hand, liver stiffness was inversely correlated to albumin; prothrombin concentration and platelets (p values were: 0.0001; 0.001, and 0.0001, respectively, significant). We found that shear wave velocity can predict F1; F2; F3 and F4 at cut-off values: 1.22; 1.32; 1.44 and 1.8 respectively.

CONCLUSION:

ARFI is a diagnostic noninvasive promising technique for liver fibrosis diagnosis among Egyptian patients with chronic HCV infection.

ARFI: from basic principles to clinical applications in diffuse chronic disease-a review

Abstract

The many factors influencing the shear wave velocity (SWV) measured with Acoustic Radiation Force Impulse (ARFI) are examined in order to define the most correct examination technique. In particular, attention is given to the information achieved by experimental models, such as phantoms and animal studies. This review targets the clinical applications of ARFI in the evaluation of chronic diffuse disease, especially of liver and kidneys. The contribution of ARFI to the clinical workout of these patients and some possible perspectives are described.

Teaching Points

• Stiffness significantly varies among normal and abnormal biological tissues.

• In clinical applications physical, geometrical, anatomical and physiological factors influence the SWV.

• Elastographic techniques can quantify fibrosis, which is directly related to stiffness.

• ARFI can be useful in chronic diffuse disease of liver and kidney.

Critical comparison of elastography methods to assess chronic liver disease

Staging of liver fibrosis and diagnosis, or exclusion, of early compensated liver cirrhosis are important in the treatment decisions and surveillance of patients with chronic liver disease. Good diagnostic accuracy, increased availability and the possibility to perform follow-up examinations led to the implementation of noninvasive methods into clinical practice. Noninvasive tests are increasingly included in national and international guidelines, leaving liver biopsy reserved for patients with unexplained discordance or suspected additional aetiologies of liver disease. In addition to staging of liver fibrosis, data on the prognostic value of these methods have increased in the past few years and are of great importance for patient care. This Review focuses on elastography methods for noninvasive assessment of liver fibrosis, disease severity and prognosis. Although liver elastography started with transient elastography, at present all large ultrasonography companies offer an elastography technique integrated in their machines. The goal of this Review is to summarize the methodological problems of noninvasive tests in general, in addition to providing an overview on currently available techniques and latest developments in liver elastography.

ACOUSTIC RADIATION FORCE IMPULSE IS EQUIVALENT TO LIVER BIOPSY TO EVALUATE LIVER FIBROSIS IN PATIENTS WITH CHRONIC HEPATITIS C AND NONALCOHOLIC FATTY LIVER DISEASE

BACKGROUND

Liver biopsy is recommended as the gold standard method for assessing the stage of liver fibrosis in patients with chronic liver disease. However, it is invasive, with potential risks and complications. Elastography is an ultrasound technique that provides information of changes in the liver tissue, evaluating tissue elasticity and acoustic radiation force impulse is one of the available techniques.

OBJECTIVE

The main objective of this study was to evaluate the sensitivity and specificity of acoustic radiation force impulse comparing to liver biopsy to evaluate fibrosis in patients with chronic hepatitis C virus and nonalcoholic fatty liver disease.

METHODS

Twenty four patients were included, everyone underwent liver biopsy and acoustic radiation force impulse, and the results were compared with values described in the literature by several authors.

RESULTS

In the population of patients with chronic hepatitis C, our data were better correlated with data published by Carmen Fierbinteanu-Braticevici et al., with an accuracy of 82.4%, sensitivity of 71.4% and specificity of 90%. For nonalcoholic fatty liver disease, our data were better correlated with data published by Masato Yoneda et al., with an accuracy of 85.7%, sensitivity 80% and specificity of 100%.

CONCLUSION

Acoustic radiation force impulse is a method with good accuracy to distinguish initial fibrosis from advanced fibrosis in hepatitis C virus and nonalcoholic fatty liver disease and can replace biopsy in most cases.

Application of liver shear wave velocity and serum total bile acids in Child-Pugh grading in chronic hepatitis C cirrhosis

AIM: To explore the characteristics of the shear wave velocity (SWV) of acoustic radiation force impulse (ARFI) and serum total bile acids (TBAs) in patients with chronic hepatitis C cirrhosis, and to analyze their relations with Child-Pugh grade.

METHODS: Eighty-six patients diagnosed with chronic hepatitis C cirrhosis were enrolled in this study. According to the biochemical indexes and clinical manifestations, Child-Pugh scoring was performed. Liver SWV and serum TBAs were measured and analyzed. Thirty healthy volunteers were chosen as a control group, and their SWV and serum TBAs were studied and compared with those in the study group.

RESULTS: The mean age of the patients was 56 ± 11.2, and there were 40 males and 46 females. Mean SWV was 2.44 m/s ± 0.39 m/s, and mean TBAs were 27.2 μmol/L ± 29.7 μmol/L. There were no statistical significances in gender or age among patients with Child-Pugh A, B or C liver function. The SWV and TBAs values were significantly higher in the study group than in the control group (P < 0.05). The mean value of SWV and TBAs in patients with Child-Pugh A, B and C liver function were 2.34 m/s ± 0.33 m/s and 14.6 μmol/L ± 13.8 μmol/L; 2.39 m/s ± 0.39 m/s and 35.6 μmol/L ± 36.5 μmol/L; 2.76 m/s ± 0.34 m/s and 38.9 μmol/L ± 31.8 μmol/L, respectively. The differences in SWV and TBAs were statistically significant in patients with Child-Pugh A, B and C liver function (P < 0.05). SWV and TBAs had good correlations with Child-Pugh grade, and increased with the increase in Child-Pugh grade. SWV and TBAs have a high sensitivity in the diagnosis of liver cirrhosis, and the area under the ROC curve of SWV was larger than that of TBAs.

CONCLUSION: SWV of the liver and TBAs in serum have good correlation with hepatic Child-Pugh grade. SWV and TBA can serve as an effective supplement for Child-Pugh grading, to better evaluate the liver functional reserve.

Non-invasive diagnosis of liver fibrosis and cirrhosis

The evaluation and follow up of liver fibrosis and cirrhosis have been traditionally performed by liver biopsy. However, during the last 20 years, it has become evident that this “gold-standard” is imperfect; even according to its proponents, it is only “the best” among available methods. Attempts at uncovering non-invasive diagnostic tools have yielded multiple scores, formulae, and imaging modalities. All are better tolerated, safer, more acceptable to the patient, and can be repeated essentially as often as required. Most are much less expensive than liver biopsy. Consequently, their use is growing, and in some countries the number of biopsies performed, at least for routine evaluation of hepatitis B and C, has declined sharply. However, the accuracy and diagnostic value of most, if not all, of these methods remains controversial. In this review for the practicing physician, we analyze established and novel biomarkers and physical techniques. We may be witnessing in recent years the beginning of the end of the first phase for the development of non-invasive markers. Early evidence suggests that they might be at least as good as liver biopsy. Novel experimental markers and imaging techniques could produce a dramatic change in diagnosis in the near future.

Ultrasound-based elastography for the diagnosis of portal hypertension in cirrhotics

Progressive fibrosis is encountered in almost all chronic liver diseases. Its clinical signs are diagnostic in advanced cirrhosis, but compensated liver cirrhosis is harder to diagnose. Liver biopsy is still considered the reference method for staging the severity of fibrosis, but due to its drawbacks (inter and intra-observer variability, sampling errors, unequal distribution of fibrosis in the liver, and risk of complications and even death), non-invasive methods were developed to assess fibrosis (serologic and elastographic). Elastographic methods can be ultrasound-based or magnetic resonance imaging-based. All ultrasound-based elastographic methods are valuable for the early diagnosis of cirrhosis, especially transient elastography (TE) and acoustic radiation force impulse (ARFI) elastography, which have similar sensitivities and specificities, although ARFI has better feasibility. TE is a promising method for predicting portal hypertension in cirrhotic patients, but it cannot replace upper digestive endoscopy. The diagnostic accuracy of using ARFI in the liver to predict portal hypertension in cirrhotic patients is debatable, with controversial results in published studies. The accuracy of ARFI elastography may be significantly increased if spleen stiffness is assessed, either alone or in combination with liver stiffness and other parameters. Two-dimensional shear-wave elastography, the ElastPQ technique and strain elastography all need to be evaluated as predictors of portal hypertension.

Feasibility study for assessing liver fibrosis in paediatric and adolescent patients using real-time shear wave elastography

INTRODUCTION

The objective of this study was to evaluate the feasibility of shear wave elastography (SWE), as a non-invasive means of assessing liver fibrosis stage in paediatric and adolescent patients.

MATERIALS AND METHODS

Consecutive paediatric and adolescent subjects scheduled for liver biopsy (LB) evaluation of known or suspected diffuse liver disease were included after informed guardian consent and subject assent in this IRB-approved single institution study. Elastograms were acquired prior to liver biopsy, from the liver under a breath-hold after normal inspiration when possible. Biopsy specimens underwent blinded pathologist review using the METAVIR scoring system.

RESULTS

Twenty-four patients (M : F = 13:11) with a mean age of 17 years (range: 1-21 years) underwent liver biopsy. The distribution of fibrosis on pathological examination was: F0 = 10, F1 = 9, F2 = 1, F3 = 3, and F4 = 1. Subjects with stages F0 and F1 fibrosis had a mean SWE value of 6.93 kPa (95% CI: 6.33-7.44 kPa) and 8.33 kPa (95% CI: 6.83-10.80 kPa) respectively. The SWE value for the one subject with stage F2 fibrosis was 6.36 kPa, whereas for F3 and F4 were 8.86 (95% CI: 5.70-11.40) and 17.85 kPa respectively. The correlation between SWE values and fibrosis grade was strong (r = 0.58, P = 0.003), and the area under the ROC curve differentiatiang ≥F2 fibrosis was 0.62 (95% CI: 0.26-0.98).

CONCLUSION

Estimation of liver stiffness using real-time SWE is feasible using the SC6-1 ultrasound probe in paediatric and adolescent patients and strongly correlates with the stage of fibrosis.

Shear-wave elasticity imaging of a liver fibrosis mouse model using high-frequency ultrasound

The objective of this study was to develop a high-frequency imaging platform for evaluating liver fibrosis in mice based on shear-wave elasticity imaging (SWEI). Although SWEI has been used to diagnose hepatic fibrosis clinically, it is performed at relatively low frequencies (<20 MHz). For preclinical ultrasound imaging in small animals, a high-frequency (>30 MHz) single-element transducer with mechanical scanning is often used. In this study we developed a new SWEI system based on a 40-MHz single-element transducer for imaging and a separate 20-MHz excitation transducer for producing the radiation force and the associated shear waves. Liver fibrosis was induced in ten C57BL/6 (B6) mice using carbon tetrachloride; the other ten mice served as the control group. Synchronizing the excitation beam (i.e., the beam from the excitation transducer) and the detection beam sequence (i.e., the beam from the imaging transducer) allows this mechanical-scanning setup to analyze the shear-wave dispersion relation. The liver viscoelastic properties were determined in vivo by measuring the shear-wave dispersion curve followed by fitting to the Voigt model. The mice were then killed and the fibrosis stage was evaluated (from F0 to F4) based on the METAVIR score. The measured mean values of liver elasticity and viscosity, respectively, ranged from 1.06 to 1.89 kPa and from 1.29 to 1.75 Pa∙s for normal F0 and fibrosis stages of F3 and F4. The Spearman coefficients for the correlations between the measured elasticity and viscosity at various fibrosis stages as assessed by the METAVIR score were 0.73 (p < 0.001) and 0.634 (p = 0.0013), respectively. We also found that the collagen content in the liver was linearly correlated with the measured elasticity (r(2) = 0.54, p < 0.001) and less strongly with the viscosity (r2 = 0.26, p = 0.022). Finally, the diagnosis performance of high-frequency SWEI was evaluated using multivariate receiver operating characteristic curve (ROC) analysis. The areas under the multivariate ROC curve for diagnosing fibrosis stages of F ≥ 3, F = 4, F0 vs. F3, F0 vs. F4, and F3 vs. F4 were 0.9, 0.98, 0.83, 1.0, and 0.96, respectively. Compared with traditional ROC analysis, an improved diagnosis performance was found for diagnosing fibrosis stages of F ≥ 3 and F0 vs. F3. These results demonstrate that the developed high-frequency SWEI platform can yield quantitative viscoelastic properties for diagnosing various fibrosis stages in mice. It is a promising tool for studying the progression of liver fibrosis in preclinical animal models both noninvasively and quantitatively.

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.

Ultrasound Elastography and MR Elastography for Assessing Liver Fibrosis: Part 2, Diagnostic Performance, Confounders, and Future Directions

OBJECTIVE

The purpose of the article is to review the diagnostic performance of ultra-sound and MR elastography techniques for detection and staging of liver fibrosis, the main current clinical applications of elastography in the abdomen.

CONCLUSION

Technical and instrument-related factors and biologic and patient-related factors may constitute potential confounders of stiffness measurements for assessment of liver fibrosis. Future developments may expand the scope of elastography for monitoring liver fibrosis and predict complications of chronic liver disease.

Reliability analysis of acoustic radiation force impulse ultrasound imaging with virtual touch tissue quantification: ex vivo ox liver

The effect of scanning angle and region of interest (ROI) depth on shear-wave velocity (SWV) was investigated in this study. Shear-wave velocity of ox liver ex vivo was measured with different approaches. Region of interest was set underneath the liver capsule at depths of 1, 2, 3, 4, and 5 cm. Three groups of measurements were performed at different scanning angles. One group of measurement was conducted with a scanning angle of 0 to 15 degrees from the midline, and the other 2 groups were performed with scanning angles of 15 to 30 degrees and 30 to 45 degrees. The data on SWV from different scan angles and ROI depths were analyzed statistically. Scanning angle and ROI depth were found to be the 2 factors that affect SWV. Interaction was observed between the scan angle and ROI depth. The data at different depths within 0- to 15-degree scanning angles exhibited no significant difference. However, the reliability of SWV decreased with the increase in ROI depth. In the groups of 15 to 30 degrees and 30 to 45 degrees, a significant difference was found between the 2 different measured depths. Scanning angle and ROI depth affected the reliability of SWV measurement. The scanning angle should be confined within 15 degrees from the midline. Therefore, SWV from shallow ROI is more reliable than that at deep ROI.

A health technology assessment of transient elastography in adult liver disease

BACKGROUND

An estimated one in 10 Canadians have some form of liver disease. The reference standard for staging and monitoring liver fibrosis is percutaneous liver biopsy--an invasive procedure associated with risks and complications. Transient elastography (TE) represents a noninvasive, ultrasound-based alternative.

OBJECTIVE

To assess the efficacy of TE compared with liver biopsy for fibrosis staging in adults with five common types of liver disease: hepatitis B, hepatitis C, nonalcoholic fatty liver disease, cholestatic liver disease and complications post-liver transplantation.

METHODS

A systematic review of published and grey literature from 2001 to June 2011 was conducted. Included were observational studies evaluating the accuracy of TE using liver biopsy as the comparator. An economic model was developed to estimate the cost per correct diagnosis gained with liver biopsy compared with TE. Identification of moderate fibrosis (stages 2 to 4) and cirrhosis (stage 4) were considered.

RESULTS

Fifty-seven studies were included in the review. The diagnostic accuracy of TE for the five clinical subgroups had sensitivities ranging from 0.67 to 0.92 and specificities ranging from 0.72 to 0.95. Liver biopsy was associated with an additional $1,427 to $7,030 per correct diagnosis gained compared with TE. The model was sensitive to the sensitivity and specificity of TE and the prevalence of fibrosis.

CONCLUSIONS

TE is an accurate diagnostic method in patients with moderate fibrosis or cirrhosis. TE is less effective but less expensive than liver biopsy. Systemic implementation of TE should be considered for the noninvasive assessment of liver fibrosis.

Non invasive tools for the diagnosis of liver cirrhosis

Liver cirrhosis (LC), the end stage of many forms of chronic hepatitis of different etiologies is a diffuse process characterized by fibrosis and the conversion of normal liver architecture into structurally abnormal nodules surrounded by annular fibrosis. This chronic progressive clinical condition, leads to liver cell failure and portal hypertension, which can favour the onset of hepatocellular carcinoma. Defining the phase of the natural history is crucial for therapeutic choice and prognosis. Liver biopsy is currently considered the best available standard of reference but it has some limits, so alternative tools have been developed to substitute liver biopsy when assessing liver fibrosis. Serum markers offer a cost-effective alternative to liver biopsy being less invasive and theoretically without complications. They can be classified into direct and indirect markers which may be used alone or in combination to produce composite scores. Diagnostic imaging includes a number of instruments and techniques to estimate liver fibrosis and cirrhosis like ultrasound (US), US Doppler, contrast enhanced US and Elastography. US could be used for the diagnosis of advanced LC while is not able to evaluate progression of fibrosis, in this case Elastography is more reliable. This review aims to revise the most recent data from the literature about non invasive methods useful in defining liver fibrosis.

Non-invasive diagnosis of advanced fibrosis and cirrhosis

Liver cirrhosis is a common and growing public health problem globally. The diagnosis of cirrhosis portends an increased risk of morbidity and mortality. Liver biopsy is considered the gold standard for diagnosis of cirrhosis and staging of fibrosis. However, despite its universal use, liver biopsy is an invasive and inaccurate gold standard with numerous drawbacks. In order to overcome the limitations of liver biopsy, a number of non-invasive techniques have been investigated for the assessment of cirrhosis. This review will focus on currently available non-invasive markers of cirrhosis. The evidence behind the use of these markers will be highlighted, along with an assessment of diagnostic accuracy and performance characteristics of each test. Non-invasive markers of cirrhosis can be radiologic or serum-based. Radiologic techniques based on ultrasound, magnetic resonance imaging and elastography have been used to assess liver fibrosis. Serum-based biomarkers of cirrhosis have also been developed. These are broadly classified into indirect and direct markers. Indirect biomarkers reflect liver function, which may decline with the onset of cirrhosis. Direct biomarkers, reflect extracellular matrix turnover, and include molecules involved in hepatic fibrogenesis. On the whole, radiologic and serum markers of fibrosis correlate well with biopsy scores, especially when excluding cirrhosis or excluding fibrosis. This feature is certainly clinically useful, and avoids liver biopsy in many cases.

Kidney shear wave speed values in subjects with and without renal pathology and inter-operator reproducibility of acoustic radiation force impulse elastography (ARFI)--preliminary results

AIM

to assess the inter-operator reproducibility of kidney shear wave speed, evaluated by means of Acoustic Radiation Force Impulse (ARFI) elastography, and the factors which influence it.

METHODS

Our prospective pilot study included 107 subjects with or without kidney pathology in which kidney shear wave speed was evaluated by means of ARFI elastography. Intraclass correlation coefficient (ICC) was used to assess ARFI elastography reproducibility.

RESULTS

A strong agreement was obtained between kidney shear wave speed measurements obtained by the two operators: ICC = 0.71 (right kidney) and 0.69 (left kidney). Smaller ICCs were obtained in "healthy subjects", as compared to patients with kidney diseases (0.68 vs. 0.75), in women as compared with men (0.59 vs. 0.78), in subjects younger than 50 years as compared with those aged at least 50 years (0.63 vs. 0.71), in obese as compared with normal weight and overweight subjects (0.36 vs. 0.66 and 0.78) and in case of measurements depth <4 cm or >6 cm as compared with those performed at a depth of 4-6 cm from the skin (0.32 and 0.60 vs. 0.81).

CONCLUSION

ARFI elastography is a reproducible method for kidney shear wave speed assessment.

Kidney transplant: usefulness of real-time elastography (RTE) in the diagnosis of graft interstitial fibrosis

The aim of this study is to evaluate the usefulness of real-time elastography (RTE) in the diagnosis of graft interstitial fibrosis. We prospectively enrolled 50 patients clinically suspected of graft fibrosis. RTE was performed with a broadband linear transducer using a dedicated ultrasound machine. Tissue mean elasticity (TME) was calculated by two blinded operators. All patients underwent biopsy after RTE. To determine cortical fibrosis Banff score was used. The receiver operating characteristic curves analysis was performed to evaluate the accuracy of TME to discriminate between patients with mild fibrosis (F1) versus patients with moderate to severe fibrosis (F2-F3). Inverse correlation between TME values and the degree of fibrosis has been shown (p < 0.05). Patients with F1 had mean TME values significantly higher compared with TME in patients with F2 (p = 0.005) and F3 (p = 0.004). The diagnostic accuracy of TME measurement for F2-F3 evaluated by area under the curve-receiver operating characteristic analysis was 0.95. RTE was able to evaluate kidney fibrosis in a non-invasive way and could be used as complementary imaging during follow-up of renal transplant patients.

Latest developments in the imaging of fibrotic liver disease

According to the World Health Organization, liver cirrhosis accounted for 1.8% of all deaths in Europe, causing about 170,000 deaths per year. Approximately 29 million persons in the EU suffer from chronic liver disease and this trend is on the rise. Liver disease is the EU's fifth most common cause of death accounting for at least one in six deaths. Early detection and monitoring of fibrosis has the potential to direct management of these chronic liver diseases and avert morbidity and mortality. Although the available techniques are in their infancy and the very early stages of fibrosis are difficult to detect, there have been significant advances in imaging over the last decade that has resulted in the use of these new imaging techniques being introduced into the patient pathway. This review explores the accuracies of these imaging techniques, their role in the management of patients, and the potential for the future.

Acoustic Radiation Force Impulse (ARFI) and Transient Elastography (TE) for evaluation of liver fibrosis in HIV-HCV co-infected patients

BACKGROUND

Transient elastography (TE) is widely used for non-invasive assessment of liver fibrosis in HIV-HCV co-infected patients. TE, however, cannot determine liver morphology. Acoustic radiation force impulse (ARFI) imaging is a novel procedure enabling assessment of liver fibrosis during a conventional ultrasonographic examination. This study evaluated the correlation between liver fibrosis measurements by TE and ARFI.

METHODS

Each of 46 HIV-HCV patients underwent both ARFI and TE within 6 months. Patients were evaluated by the "equivalent METAVIR" scoring system, using previously established cut-off values. Agreements between the ARFI and TE scores were estimated by Kappa coefficients, with Kappa values ≥0.40, ≥0.60, and ≥0.80 defined as moderate, good and very good agreement, respectively.

RESULTS

ARFI and TE yielded "Equivalent Metavir" fibrosis scores of F1 in 26 and 31 patients, respectively; F2 in nine and seven, respectively; F3 in three and two, respectively; and F4 in eight and six, respectively. The two methods showed very good agreement in predicting overall stages [Kappa = 0.82] and for F ≥3 [Kappa = 0.80] and moderate agreement in predicting significant fibrosis F ≥2 [Kappa = 0.50]. Morphologic ultrasound analysis concomitant to ARFI detected two hepatocarcinomas.

CONCLUSIONS

ARFI showed promising results in the non-invasive assessment of liver fibrosis in HIV-HCV patients, with liver fibrosis staging similar to that of TE. Moreover, ARFI can assess morphology and fibrosis during the same session.

Noninvasive diagnosis of cirrhosis: A review of different imaging modalities

Progressive hepatic fibrosis can lead to cirrhosis, so its early detection is fundamental. Staging fibrosis is also critical for prognosis and management. The gold standard for these aims is liver biopsy, but it has several drawbacks, as it is invasive, expensive, has poor acceptance, is prone to inter observer variability and sampling errors, has poor repeatability, and has a risk of complications and mortality. Therefore, non-invasive imaging tests have been developed. This review mainly focuses on the role of transient elastography, acoustic radiation force impulse imaging, and magnetic resonance-based methods for the noninvasive diagnosis of cirrhosis.

Ultrasound in chronic liver disease

Background

With the high prevalence of diffuse liver disease there is a strong clinical need for noninvasive detection and grading of fibrosis and steatosis as well as detection of complications.

Methods

B-mode ultrasound supplemented by portal system Doppler and contrast-enhanced ultrasound are the principal techniques in the assessment of liver parenchyma and portal venous hypertension and in hepatocellular carcinoma surveillance.

Results

Fibrosis can be detected and staged with reasonable accuracy using Transient Elastography and Acoustic Radiation Force Imaging. Newer elastography techniques are emerging that are undergoing validation and may further improve accuracy. Ultrasound grading of hepatic steatosis currently is predominantly qualitative.

Conclusion

A summary of methods including B-mode, Doppler, contrast-enhanced ultrasound and various elastography techniques, and their current performance in assessing the liver, is provided.

Teaching Points

• Diffuse liver disease is becoming more prevalent and there is a strong clinical need for noninvasive detection.

• Portal hypertension can be best diagnosed by demonstrating portosystemic collateral venous flow.

• B-mode US is the principal US technique supplemented by portal system Doppler.

• B-mode US is relied upon in HCC surveillance, and CEUS is useful in the evaluation of possible HCC.

• Fibrosis can be detected and staged with reasonable accuracy using TE and ARFI.

• US detection of steatosis is currently reasonably accurate but grading of severity is of limited accuracy.

Non-invasive diagnosis of liver fibrosis in chronic hepatitis C

Assessment of liver fibrosis in chronic hepatitis C virus (HCV) infection is considered a relevant part of patient care and key for decision making. Although liver biopsy has been considered the gold standard for staging liver fibrosis, it is an invasive technique and subject to sampling errors and significant intra- and inter-observer variability. Over the last decade, several noninvasive markers were proposed for liver fibrosis diagnosis in chronic HCV infection, with variable performance. Besides the clear advantage of being noninvasive, a more objective interpretation of test results may overcome the mentioned intra- and inter-observer variability of liver biopsy. In addition, these tests can theoretically offer a more accurate view of fibrogenic events occurring in the entire liver with the advantage of providing frequent fibrosis evaluation without additional risk. However, in general, these tests show low accuracy in discriminating between intermediate stages of fibrosis and may be influenced by several hepatic and extra-hepatic conditions. These methods are either serum markers (usually combined in a mathematical model) or imaging modalities that can be used separately or combined in algorithms to improve accuracy. In this review we will discuss the different noninvasive methods that are currently available for the evaluation of liver fibrosis in chronic hepatitis C, their advantages, limitations and application in clinical practice.

Influence of measurement depth on the stiffness assessment of healthy liver with real-time shear wave elastography

The purpose of this study was to determine the measurement depth range within which liver stiffness can be reliably assessed using real-time shear wave elastography (SWE) technology. Measurements were performed on phantoms and healthy volunteers. In the first group of patients, measurements were performed at depths of 2-8 cm from the probe surface. In the second group of patients, measurements were conducted 0-7 cm below the liver capsule. Success rate of measurements (SRoM), success rate of patients (SRoS) and coefficients of variation (CVs) of repeated measurements were compared. The SRoMs at 3-7 cm and the CVs at 2-5 cm from the probe surface were significantly higher and lower than those at other depths (p < 0.001), respectively. SRoS was zero 0-1 cm below the liver capsule. Furthermore, the features of 2-D stiffness mapping images were also found to change with depth. According to our results, the depth range for the most reliable liver stiffness assessment using SWE should be 3-5 cm from the probe surface and simultaneously 1-2 cm below the liver capsule.

Non-invasive diagnosis of hepatitis B virus-related cirrhosis

Chronic hepatitis B (CHB) infection is a major public health problem associated with significant morbidity and mortality worldwide. Twenty-three percent of patients with CHB progress naturally to liver cirrhosis, which was earlier thought to be irreversible. However, it is now known that cirrhosis can in fact be reversed by treatment with oral anti-nucleotide drugs. Thus, early and accurate diagnosis of cirrhosis is important to allow an appropriate treatment strategy to be chosen and to predict the prognosis of patients with CHB. Liver biopsy is the reference standard for assessment of liver fibrosis. However, the method is invasive, and is associated with pain and complications that can be fatal. In addition, intra- and inter-observer variability compromises the accuracy of liver biopsy data. Only small tissue samples are obtained and fibrosis is heterogeneous in such samples. This confounds the two types of observer variability mentioned above. Such limitations have encouraged development of non-invasive methods for assessment of fibrosis. These include measurements of serum biomarkers of fibrosis; and assessment of liver stiffness via transient elastography, acoustic radiation force impulse imaging, real-time elastography, or magnetic resonance elastography. Although significant advances have been made, most work to date has addressed the diagnostic utility of these techniques in the context of cirrhosis caused by chronic hepatitis C infection. In the present review, we examine the advantages afforded by use of non-invasive methods to diagnose cirrhosis in patients with CHB infections and the utility of such methods in clinical practice.

The influence of aminotransferase levels on liver stiffness assessed by Acoustic Radiation Force Impulse Elastography: a retrospective multicentre study

BACKGROUND

Acoustic Radiation Force Impulse Elastography is a new method for non-invasive evaluation of liver fibrosis.

AIM

To evaluate the impact of elevated alanine aminotransferase levels on liver stiffness assessment by Acoustic Radiation Force Impulse Elastography.

METHODS

A multicentre retrospective study including 1242 patients with chronic liver disease, who underwent liver biopsy and Acoustic Radiation Force Impulse. Transient Elastography was also performed in 512 patients.

RESULTS

The best Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis was 1.29 m/s in cases with normal alanine aminotransferase levels and 1.44 m/s in patients with alanine aminotransferase levels>5 × the upper limit of normal. The best cut-off for predicting liver cirrhosis were 1.59 and 1.75 m/s, respectively. Acoustic Radiation Force Impulse cut-off for predicting significant fibrosis and cirrhosis were relatively similar in patients with normal alanine aminotransferase and in those with alanine aminotransferase levels between 1.1 and 5 × the upper limit of normal: 1.29 m/s vs. 1.36 m/s and 1.59 m/s vs. 1.57 m/s, respectively. For predicting cirrhosis, the Transient Elastography cut-offs were significantly higher in patients with alanine aminotransferase levels between 1.1 and 5 × the upper limit of normal compared to those with normal alanine aminotransferase: 12.3 kPa vs. 9.1 kPa.

CONCLUSION

Liver stiffness values assessed by Acoustic Radiation Force Impulse and Transient Elastography are influenced by high aminotransferase levels. Transient Elastography was also influenced by moderately elevated aminotransferase levels.

Acoustic radiation force impulse of the liver

Acoustic radiation force impulse (ARFI) imaging is a new and promising ultrasound-based diagnostic technique that, evaluating the wave propagation speed, allows the assessment of the tissue stiffness. ARFI is implemented in the ultrasound scanner. By short-duration acoustic radiation forces (less than 1 ms), localized displacements are generated in a selected region of interest not requiring any external compression so reducing the operator dependency. The generated wave scan provides qualitative or quantitative (wave velocity values) responses. Several non-invasive methods for assessing the staging of fibrosis are used, in order to avoid liver biopsy. Liver function tests and transient elastography are non-invasive, sensitive and accurate tools for the assessment of liver fibrosis and for the discrimination between cirrhotic and non-cirrhotic liver. Many published studies analyse ARFI performance and feasibility in studying diffuse liver diseases and compare them to other diagnostic imaging modalities such as conventional ultrasonography and transient elastography. Solid focal liver lesions, both benign and malignant, are common findings during abdominal examinations. The accurate characterization and differential diagnosis are important aims of all the imaging modalities available today. Only few papers describe the application of ARFI technology in the study of solid focal liver lesions, with different results. In the present study, the existing literature, to the best of our knowledge, about ARFI application on diffuse and focal liver pathology has been evaluated and results and statistical analyses have been compared, bringing to the conclusion that ARFI can be used in the study of the liver with similar accuracy as transient elastography in diagnosing significant fibrosis or cirrhosis and has got some advantages in respect to transient elastography since it does not require separate equipment, better displays anatomical structures and measurements can be successfully carried out almost in every patient.