Acoustic radiation force impulse and supersonic shear imaging versus transient elastography for liver fibrosis assessment

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.

Preliminary Results on the Feasibility of Using ARFI/SWEI to Assess Cutaneous Sclerotic Diseases

In this study, acoustic radiation force impulse (ARFI) and shear wave elasticity imaging (SWEI) were applied to the skin to investigate the feasibility of their use in assessing sclerotic skin diseases. Our motivation was to develop a non-invasive imaging technology with real-time feedback of sclerotic skin disease diagnosis. This paper shows representative results from an ongoing study, recruiting patients with and without sclerosis. The stiffness of the imaged site was evaluated using two metrics: mean ARFI displacement magnitude and bulk shear wave speed inside the region of interest (ROI). In a subject with localized graft versus host disease (GVHD), the mean ARFI displacement inside sclerotic skin was 61% lower (p < 0.01) and shear wave speed 128% higher (p < 0.005) compared to those in normal skin-indicating stiffer mechanical properties in the sclerotic skin. This trend persisted through disease types. We conclude ARFI and SWEI can successfully differentiate sclerotic lesions from normal dermis.

Contemporary use of elastography in liver fibrosis and portal hypertension

The risk and speed of progression from fibrosis to compensated and decompensated cirrhosis define the prognosis in liver diseases. Therefore, early detection and preventive strategies affect outcomes. Patients with liver disease have traditionally been diagnosed at an advanced stage of disease, in part due to lack of non-invasive markers. Ultrasound elastography to measure liver stiffness can potentially change this paradigm. The purpose of this review was therefore to summarize advances in the field of ultrasound elastography with focus on diagnosis of liver fibrosis, cirrhosis and clinically significant portal hypertension, techniques and limitations. Four types of ultrasound elastography exist, but there is scarce evidence comparing the different techniques. The majority of experience concern transient elastography for diagnosing fibrosis and cirrhosis in patients with chronic viral hepatitis C. That said, the role of elastography in other aetiologies such as alcoholic- and non-alcoholic liver fibrosis still needs clarification. Although elastography can be used to diagnose liver fibrosis and cirrhosis, its true potential lies in the possibility of multiple, repeated measurements that allow for treatment surveillance, continuous risk stratification and monitoring of complications. As such, elastography may be a powerful tool for personalized medicine. While elastography is an exciting technique, the nature of ultrasound imaging limits its applicability, due to the risk of failures and unreliable results. Key factors that limit the applicability of liver stiffness measurements are as follows: liver vein congestion, cholestasis, a recent meal, inflammation, obesity, observer experience and ascites. The coming years will show whether elastography will be widely adapted in general care.

Performance of 2-D shear wave elastography in liver fibrosis assessment compared with serologic tests and transient elastography in clinical routine

Liver stiffness values assessed with 2-D shear wave elastography (SWE), transient elastography (TE) and simple serologic tests were compared with respect to non-invasive assessment in a cohort of 127 consecutive patients with chronic liver diseases. The rate of reliable liver stiffness measurements was significantly higher with 2-D SWE than with TE: 99.2% versus 74.8%, p < 0.0001 (different reliability criteria used, according to current recommendations). In univariate analysis, liver stiffness measured with 2-D SWE correlated best with fibrosis stage estimated with TE (r = 0.699, p < 0.0001), followed by Forns score (r = 0.534, p < 0.0001) and King's score (r = 0.512, p < 0.0001). However, in multivariate analysis, only 2-D SWE-measured values remained correlated with fibrosis stage (p < 0.0001). The optimal 2-D SWE cutoff values for predicting significant fibrosis were 8.03 kPa for fibrosis stage ≥2 (area under the receiver operating characteristic curve = 0.832) and 13.1 kPa for fibrosis stage 4 (area under the receiver operating characteristic curve = 0.915), respectively. In conclusion, 2-D SWE can be used to obtain reliable liver stiffness measurements in almost all patients and performs very well in predicting the presence of liver cirrhosis.

Assessment of liver fibrosis with 2-D shear wave elastography in comparison to transient elastography and acoustic radiation force impulse imaging in patients with chronic liver disease

Two-dimensional shear wave elastography (2-D SWE) is an ultrasound-based elastography method integrated into a conventional ultrasound machine. It can evaluate larger regions of interest and, therefore, might be better at determining the overall fibrosis distribution. The aim of this prospective study was to compare 2-D SWE with the two best evaluated liver elastography methods, transient elastography and acoustic radiation force impulse (point SWE using acoustic radiation force impulse) imaging, in the same population group. The study included 132 patients with chronic hepatopathies, in which liver stiffness was evaluated using transient elastography, acoustic radiation force impulse imaging and 2-D SWE. The reference methods were liver biopsy for the assessment of liver fibrosis (n = 101) and magnetic resonance imaging/computed tomography for the diagnosis of liver cirrhosis (n = 31). No significant difference in diagnostic accuracy, assessed as the area under the receiver operating characteristic curve (AUROC), was found between the three elastography methods (2-D SWE, transient elastography, acoustic radiation force impulse imaging) for the diagnosis of significant and advanced fibrosis and liver cirrhosis in the "per protocol" (AUROCs for fibrosis stages ≥2: 0.90, 0.95 and 0.91; for fibrosis stage [F] ≥3: 0.93, 0.95 and 0.94; for F = 4: 0.92, 0.96 and 0.92) and "intention to diagnose" cohort (AUROCs for F ≥2: 0.87, 0.92 and 0.91; for F ≥3: 0.91, 0.93 and 0.94; for F = 4: 0.88, 0.90 and 0.89). Therefore, 2-D SWE, ARFI imaging and transient elastography seem to be comparably good methods for non-invasive assessment of liver fibrosis.

Supersonic Shear Imaging and Transient Elastography With the XL Probe Accurately Detect Fibrosis in Overweight or Obese Patients With Chronic Liver Disease

BACKGROUND & AIMS

Assessment of the severity of liver fibrosis is an important step in evaluating patients with chronic liver disease and determining their prognosis. We compared liver stiffness measurements (LSMs) made by supersonic shear imaging (SSI) with those of transient elastography (TE)-XL for their ability to determine the degree of liver fibrosis in overweight or obese patients with chronic liver disease.

METHODS

We performed a prospective study of 258 patients with chronic hepatitis of different etiologies and a body mass index greater than 25, evaluated at the University of Miami from October 2013 to December 2014. Liver stiffness was measured using the TE-XL probe and SSI of the right and left lobes during the same clinic visit, and comparisons were made for fibrosis stage in 124 biopsy-proven patients. In addition, further analysis was performed on a subgroup of 102 chronic hepatitis C virus (HCV)-positive patients for whom biopsy data were available.

RESULTS

Reliable LSMs were obtained from 96.1%, 94.6%, and 72.1% of patients using the TE-XL probe, SSI of the right lobe, and SSI of the left lobe, respectively. TE-XL, SSI of the right lobe, and SSI of the left lobe detected severe fibrosis (fibrosis stages 3-4), with area under the receiver operating characteristic curve (AUROC) values of 0.955, 0.954, and 0.910, respectively, compared with results from histologic analysis for the 124 biopsy-proven patients included in the study; these values were 0.952, 0.949, and 0.917, respectively, for the 102 biopsy-proven patients with HCV infection. TE-XL, SSI of the right lobe, and SSI of the left lobe detected fibrosis stage 4 with AUROC values of 0.920, 0.930, and 0.910, respectively, compared with histologic analysis, in all 124-biopsy proven patients, and with AUROC values of 0.907, 0.914, and 0.887, respectively, in the 102 biopsy-proven patients with chronic HCV infection.

CONCLUSIONS

SSI and the TE-XL probe each accurately quantify liver fibrosis in overweight or obese patients with chronic liver disease, including those with HCV infection, when compared with data obtained from histologic analysis. SSI data obtained from the right lobe and the TE-XL probe can be used to evaluate fibrosis with similar accuracy.

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.

Liver and spleen stiffness and their ratio assessed by real-time two dimensional-shear wave elastography in patients with liver fibrosis and cirrhosis due to chronic viral hepatitis

OBJECTIVES

To investigate the performance of real-time 2D shear wave elastography (RT 2D-SWE) for non-invasive staging of liver disease in patients with chronic viral hepatitis (CVH).

MATERIALS AND METHODS

Naive CVH patients underwent liver (LS) and spleen stiffness (SS) measurements by an intercostal approach. Patients with ALT >3× upper limit of normal, cholestasis as revealed by dilated intrahepatic biliary tree, and liver congestion were excluded. Results were expressed in kPa and compared to histological stage (Ishak) of liver fibrosis (LF). Patients with decompensated liver cirrhosis (LC) were diagnosed using standard clinical, ultrasound, and endoscopic criteria.

RESULTS

Of 123 patients, LS was successfully measured in 79.7% and SS in 53.7%. LS accurately differentiated between liver disease stages, with cut-off values of 8.1 (AUC 0.991) for F ≥ 3, 10.8 kPa (AUC 0.954) for F ≥ 5, and 27 kPa (AUC 0.961) for decompensated LC. SS was significantly different between non-cirrhotic stages (F0-4) and LC (cut-off 24 kPa; AUC 0.821). While both LS and SS increased with liver disease progression, the difference between them decreased, as reflected by the stiffness ratio index.

CONCLUSIONS

RT 2D-SWE can accurately differentiate between the stages of LF, and can distinguish LF from LC and compensated from decompensated LC.

KEY POINTS

• RT 2D-SWE is an accurate method for assessment of liver fibrosis. • RT 2D-SWE is applicable in 80% of patients with chronic viral hepatitis. • RT 2D-SWE accurately differentiates compensated from decompensated liver cirrhosis. • Both liver and spleen stiffness increase with progression of liver fibrosis. • In cirrhosis, the difference between liver and spleen stiffness decreases.

Usefulness of real-time elastography strain ratio in the assessment of bile duct ligation-induced liver injury and the hepatoprotective effect of chitosan: an experimental animal study

The purpose of the study described here was to evaluate the usefulness of the elastographic strain ratio in the assessment of liver changes in an experimental animal setting and the hepatoprotective effects of chitosan. Ultrasonography and Strain Ratio calculation were performed before and after bile duct ligation (BDL) in three groups of Wistar albino rats (n = 10 animals per group): (i) rats subjected to bile duct ligation only; (ii) rats subjected to bile duct ligation and administered chitosan for 14 d; (iii) rats subjected to bile duct ligation and administered chitosan for 7 d. The results were compared with the laboratory data and pathologic findings. Strain ratios revealed an increase in liver stiffness after bile duct ligation (p < 0.05), except in the group with chitosan administered for 7 d, and agreed with laboratory and pathology data. In conclusion, strain ratio can be used as an experimental research instrument in the assessment of liver response to injury. To the best of our knowledge, this is the first study reporting on the usefulness of the sonoelastographic liver-to-kidney strain ratio in assessing the effects of experimentally induced liver lesions.

Acoustic structure quantification ultrasound software proves imprecise in assessing liver fibrosis or cirrhosis in parenchymal liver diseases

The present study was conducted to assess the diagnostic accuracy of Acoustic Structure Quantification (ASQ) ultrasound software in liver biopsy of patients with liver fibrosis and cirrhosis. Eighty patients (47 ± 14 y, 41 men) with chronic liver diseases underwent ultrasound examination of the liver and liver biopsy. In addition to the standard-care ultrasound examination, three valid gray-scale images were obtained for each patient. With the ASQ software, the average and peak values (Cm(2)) of each ultrasound gray-scale image were calculated and then compared with histologic fibrosis staging (F0-F4). No correlation was found between ASQ values and histologic fibrosis stage (p > 0.05). Areas under the curve for the diagnosis of no or mild fibrosis (F0 and F1), moderate/severe fibrosis (F2 and F3) and cirrhosis (F4) using average/peak Cm(2) values of small regions of interest were 0.46/0.43, 0.62/0.68 and 0.38/0.33. Determination of liver fibrosis with ASQ in its present form as an alternative approach to liver biopsy is too imprecise.

Noninvasive Biomarkers of Liver Fibrosis: Clinical Applications and Future Directions

Chronic liver disease is a significant cause of morbidity and mortality worldwide. Current strategies for assessing prognosis and treatment rely on accurate assessment of disease stage. Liver biopsy is the gold standard for assessing fibrosis stage but has many limitations. Noninvasive biomarkers of liver fibrosis have been extensively designed, studied, and validated in a variety of liver diseases. With the advent of direct acting antivirals and the rise in obesity-related liver disease, there is a growing need to establish these noninvasive methods in the clinic. In addition, it has become increasingly clear over the last few years that noninvasive biomarkers can also be used to monitor response to antifibrotic therapies and predict liver outcomes, including hepatocellular carcinoma development. This review highlights the most well-established noninvasive biomarkers to-date, with a particular emphasis on serum and imaging-based methodologies.