Magnetic resonance elastography of liver

Magnetic Resonance Elastography and Other Magnetic Resonance Imaging Techniques in Chronic Liver Disease: Current Status and Future Directions

Recent advances in the noninvasive imaging of chronic liver disease have led to improvements in diagnosis, particularly with magnetic resonance imaging (MRI). A comprehensive evaluation of the liver may be performed with the quantification of the degree of hepatic steatosis, liver iron concentration, and liver fibrosis. In addition, MRI of the liver may be used to identify complications of cirrhosis, including portal hypertension, ascites, and the development of hepatocellular carcinoma. In this review article, we discuss the state of the art techniques in liver MRI, namely, magnetic resonance elastography, hepatobiliary phase MRI, and liver fat and iron quantification MRI. The use of these advanced techniques in the management of chronic liver diseases, including nonalcoholic fatty liver disease, will be elaborated.

Physiological ranges of matrix rigidity modulate primary mouse hepatocyte function in part through hepatocyte nuclear factor 4 alpha

Matrix rigidity has important effects on cell behavior and is increased during liver fibrosis; however, its effect on primary hepatocyte function is unknown. We hypothesized that increased matrix rigidity in fibrotic livers would activate mechanotransduction in hepatocytes and lead to inhibition of liver-specific functions. To determine the physiologically relevant ranges of matrix stiffness at the cellular level, we performed detailed atomic force microscopy analysis across liver lobules from normal and fibrotic livers. We determined that normal liver matrix stiffness was around 150 Pa and increased to 1-6 kPa in areas near fibrillar collagen deposition in fibrotic livers. In vitro culture of primary hepatocytes on collagen matrix of tunable rigidity demonstrated that fibrotic levels of matrix stiffness had profound effects on cytoskeletal tension and significantly inhibited hepatocyte-specific functions. Normal liver stiffness maintained functional gene regulation by hepatocyte nuclear factor 4 alpha (HNF4α), whereas fibrotic matrix stiffness inhibited the HNF4α transcriptional network. Fibrotic levels of matrix stiffness activated mechanotransduction in primary hepatocytes through focal adhesion kinase. In addition, blockade of the Rho/Rho-associated protein kinase pathway rescued HNF4α expression from hepatocytes cultured on stiff matrix.

CONCLUSION

Fibrotic levels of matrix stiffness significantly inhibit hepatocyte-specific functions in part by inhibiting the HNF4α transcriptional network mediated through the Rho/Rho-associated protein kinase pathway. Increased appreciation of the role of matrix rigidity in modulating hepatocyte function will advance our understanding of the mechanisms of hepatocyte dysfunction in liver cirrhosis and spur development of novel treatments for chronic liver disease. (Hepatology 2016;64:261-275).

Liver Stiffness Measurements with MR Elastography: Agreement and Repeatability across Imaging Systems, Field Strengths, and Pulse Sequences

Purpose To prospectively assess agreement and repeatability of magnetic resonance (MR) elastography liver stiffness measurements across imager manufacturers, field strengths, and pulse sequences. Materials and Methods This prospective cross-sectional study was approved by the institutional review board; informed consent was obtained from all subjects. On the basis of an a priori power calculation, 24 volunteer adult subjects underwent MR elastography with four MR imaging systems (two vendors) and multiple pulse sequences (two-dimensional [2D] gradient-echo [GRE] imaging, 2D spin-echo [SE] echo-planar imaging, and three-dimensional [3D] SE echo-planar imaging). Each sequence was performed twice in each patient with each imaging system. Intraclass correlation coefficients (ICCs) were used to assess agreement and repeatability. P < .05 was considered indicative of a statistically significant difference. Results Pairwise ICCs were 0.67-0.82 and 0.62-0.83 for agreement between pulse sequences across manufacturers (n = 4) and field strengths (n = 5), respectively. ICCs were 0.45-0.90 for pairwise agreement between sequences while fixing manufacturer and field strength (n = 8). Test-retest repeatability across the various manufacturer, field strength, and pulse sequence combinations (n = 10) was excellent (ICCs, 0.77-0.94). The overall ICC for all manufacturer, field strength, and sequence combinations (n = 10) was 0.68 (95% confidence interval [CI]: 0.55, 0.82). ICC according to field strength was 0.78 (95% CI: 0.67, 0.88) at 1.5 T (n = 5) and 0.64 (95% CI: 0.49, 0.78) at 3.0 T (n = 5). ICCs according to vendor were 0.83 (95% CI: 0.73, 0.91) (n = 4) and 0.65 (95% CI: 0.51, 0.79) (n = 6). Average patient level variance was 0.042 kPa, with a coefficient of variation of 10.7%. Conclusion MR elastography is a reliable method for assessing liver stiffness, with small amounts of variability between imager manufacturers, field strengths, and pulse sequences. ^© RSNA, 2016.

Advances in Imaging of the Pediatric Pituitary Gland

High-resolution MRI of the pediatric sella can help identity or confirm clinical abnormalities, assess pituitary gland size and structure, and reveal acquired lesions. This article reviews contemporary techniques for imaging of the sella and associated structures in this population. Strengths and weaknesses of conventional imaging are discussed, as are techniques that can enhance yield. Some new and emerging technologies are discussed, including MR elastography, perfusion imaging, spectroscopy, and diffusion-weighted and diffusion-tensor imaging. It is expected that this overview will provide insight as to where pediatric sella imaging is currently and where it may head in the future.

Vascular assessment of liver disease-towards a new frontier in MRI

Complex haemodynamic phenomena underpin the pathophysiology of chronic liver disease. Non-invasive MRI-based assessment of hepatic vascular parameters therefore has the potential to yield meaningful biomarkers for chronic liver disease. In this review, we provide an overview of vascular sequelae of chronic liver disease amenable to imaging evaluation and describe the current supportive evidence, strengths and the limitations of MRI methodologies, including dynamic contrast-enhanced, dynamic hepatocyte-specific contrast-enhanced, phase-contrast, arterial spin labelling and MR elastography in the assessment of hepatic vascular parameters. We review the broader challenges of quantitative hepatic vascular MRI, including the difficulties of motion artefact, complex post-processing, long acquisition times, validation and limitations of pharmacokinetic models, alongside the potential solutions that will shape the future of MRI and deliver this new frontier to the patient bedside.

Performance of 2-Dimensional Ultrasound Shear Wave Elastography in Liver Fibrosis Detection Using Magnetic Resonance Elastography as the Reference Standard: A Pilot Study

OBJECTIVES

To investigate the correlation between 2-dimensional (2D) ultrasound shear wave elastography (SWE) and magnetic resonance elastography (MRE) in liver stiffness measurement and the diagnostic performance of 2D SWE for liver fibrosis when imaging from different intercostal spaces and using MRE as the reference standard.

METHODS

Two-dimensional SWE was performed on 47 patients. One patient was excluded from the study. Each of the remaining 46 patients underwent same-day MRE for clinical purposes. The study was compliant with the Health Insurance Portability and Accountability Act and approved by the Institutional Review Board. Informed consent was obtained from each patient. Two-dimensional SWE measurements were acquired from the ninth, eighth, and seventh intercostal spaces. The correlation with MRE was calculated at each intercostal space and multiple intercostal spaces combined. The performance of 2D SWE in diagnosing liver fibrosis was evaluated by receiver operating characteristic curve analysis using MRE as the standard.

RESULTS

The 47 patients who initially underwent 2D SWE included 22 female and 25 male patients (age range, 19-77 years). The highest correlation between 2D SWE and MRE was from the eighth and seventh intercostal spaces (r = 0.68-0.76). The ranges of the areas under the receiver operating characteristic curves for separating normal or inflamed livers from fibrotic livers using MRE as the clinical reference were 0.84 to 0.92 when using the eighth and seventh intercostal spaces individually and 0.89 to 0.90 when combined.

CONCLUSIONS

The results suggest that 2D SWE and MRE are well correlated when SWE is performed at the eighth and seventh intercostal spaces. The ninth intercostal space is less reliable for diagnosing fibrosis with 2D SWE. Combining measurements from multiple intercostal spaces does not significantly improve the performance of 2D SWE for detection of fibrosis.

Fontan-associated liver disease: Implications for heart transplantation

Chronic liver diseases are associated with multiple complications, including cirrhosis, portal hypertension, ascites, synthetic dysfunction and hepatocellular carcinoma, and these processes are increasingly recognized in post-Fontan patients. Fontan-associated liver disease (FALD) can be defined as abnormalities in liver structure and function that result from the Fontan circulation and are not related to another disease process. FALD arises due to chronic congestion of the liver created by the elevated venous pressure and low cardiac output of the Fontan circulation, which may be superimposed on previous liver injury. Pathology studies have generally shown that FALD worsens as time post-Fontan increases, but the prevalence of FALD is not well defined because the majority of Fontan patients, even those with significant hepatic fibrosis, appear to be asymptomatic and biochemical or functional hepatic abnormalities are usually subtle or absent. Alternate non-invasive investigations, derived from the study of other chronic liver diseases, have been tested in small series of pediatric and adult Fontan patients, but they have been confounded by congestion and do not correlate well with liver biopsy findings. Liver disease can complicate Fontan circulatory failure and may even be significant enough to be considered a contraindication to heart transplantation or require combined heart-liver transplantation. The search for the optimal management strategy continues in the setting of increasing numbers of Fontan patients surviving to adulthood and being referred for heart transplantation. Thus, in this review we attempt to define the scope and significance of FALD and address transplant-related assessment and management of this challenging disorder.

Interplatform reproducibility of liver and spleen stiffness measured with MR elastography

PURPOSE

To assess interplatform reproducibility of liver stiffness (LS) and spleen stiffness (SS) measured with magnetic resonance elastography (MRE) based on a 2D gradient echo (GRE) sequence.

MATERIALS AND METHODS

This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved study involved 12 subjects (five healthy volunteers and seven patients with liver disease). A multislice 2D-GRE-based MRE sequence was performed using two systems from different vendors (3.0T GE and 1.5T Siemens) on the same day. Two independent observers measured LS and SS on confidence maps. Bland-Altman analysis (with coefficient of reproducibility, CR), coefficient of variability (CV), and intraclass correlation (ICC) were used to analyze interplatform, intra- and interobserver variability. Human data were validated using a gelatin-based phantom.

RESULTS

There was excellent reproducibility of phantom stiffness measurement (CV 4.4%). Mean LS values were 3.44-3.48 kPa and 3.62-3.63 kPa, and mean SS values were 7.54-7.91 kPa and 8.40-8.85 kPa at 3.0T and 1.5T for observers 1 and 2, respectively. The mean CVs between platforms were 9.2%-11.5% and 13.1%-14.4% for LS and SS, respectively, for observers 1 and 2. There was excellent interplatform reproducibility (ICC >0.88 and CR <36.2%) for both LS and SS, and excellent intra- and interobserver reproducibility (intraobserver: ICC >0.99, CV <2.1%, CR <6.6%; interobserver: ICC >0.97, CV and CR <16%).

CONCLUSION

This study demonstrates that 2D-GRE MRE provides platform- and observer-independent LS and SS measurements.

Short-Term Repeatability of Magnetic Resonance Elastography at 3.0T: Effects of Motion-Encoding Gradient Direction, Slice Position, and Meal Ingestion

PURPOSE

Magnetic resonance elastography (MRE) can estimate liver stiffness (LS) noninvasively. We prospectively assessed whether motion-encoding gradient (MEG) direction, slice position, or high-caloric food intake affects the repeatability of MRE measurements of LS.

MATERIALS AND METHODS

Twenty healthy volunteers (8 women, 12 men; age, 48 ± 12 years) were imaged in a 3.0T scanner at four timepoints: twice after overnight fasting (B1 , B2 ) and twice after consuming a 1050-calorie standardized meal (A1 , A2 ; after 30 and 60 min, respectively). Each session comprised sequential MRE acquisitions in which MEG was applied in three orthogonal directions with three slices positioned over the liver for each. Between sessions, the participants were repositioned to assess test-retest reproducibility.

RESULTS

The LS measurements before/after food intake were 3.36 ± 1.31 kPa/3.22 ± 1.03 kPa, 2.04 ± 0.33 kPa/2.27 ± 0.38 kPa, and 2.47 ± 0.50 kPa/2.64 ± 0.76 kPa for MEG superimposed along the anterior-posterior (AP), foot-head (FH), and right-left (RL) directions, respectively. Before and after food intake, LS estimates were lower and more reproducible (<10% coefficient of variation) when the MEG was in the FH direction, not the AP or RL direction. Liver stiffness estimates were significantly elevated after meal consumption when the MEG was in the FH direction (P < 0.05 for B1 vs. A1 , B1 vs. A2 , B2 vs. A1 , and B2 vs. A2 ).

CONCLUSION

MRE estimates of LS were highly reproducible, particularly when MEG was applied in the FH direction, suggesting that this method could be used for long-term monitoring of antifibrotic therapy without repeated biopsies. High-caloric food intake resulted in slightly elevated LS on MRE.

Evaluation of Liver Fibrosis Using Texture Analysis on Combined-Contrast-Enhanced Magnetic Resonance Images at 3.0T

Purpose. To noninvasively assess liver fibrosis using combined-contrast-enhanced (CCE) magnetic resonance imaging (MRI) and texture analysis. Materials and Methods. In this IRB-approved, HIPAA-compliant prospective study, 46 adults with newly diagnosed HCV infection and recent liver biopsy underwent CCE liver MRI following intravenous administration of superparamagnetic iron oxides (ferumoxides) and gadolinium DTPA (gadopentetate dimeglumine). The image texture of the liver was quantified in regions-of-interest by calculating 165 texture features. Liver biopsy specimens were stained with Masson trichrome and assessed qualitatively (METAVIR fibrosis score) and quantitatively (% collagen stained area). Using L₁ regularization path algorithm, two texture-based multivariate linear models were constructed, one for quantitative and the other for quantitative histology prediction. The prediction performance of each model was assessed using receiver operating characteristics (ROC) and correlation analyses. Results. The texture-based predicted fibrosis score significantly correlated with qualitative (r = 0.698, P < 0.001) and quantitative (r = 0.757, P < 0.001) histology. The prediction model for qualitative histology had 0.814–0.976 areas under the curve (AUC), 0.659–1.000 sensitivity, 0.778–0.930 specificity, and 0.674–0.935 accuracy, depending on the binary classification threshold. The prediction model for quantitative histology had 0.742–0.950 AUC, 0.688–1.000 sensitivity, 0.679–0.857 specificity, and 0.696–0.848 accuracy, depending on the binary classification threshold. Conclusion. CCE MRI and texture analysis may permit noninvasive assessment of liver fibrosis.

Elastography Assessment of Liver Fibrosis: Society of Radiologists in Ultrasound Consensus Conference Statement

The Society of Radiologists in Ultrasound convened a panel of specialists from radiology, hepatology, pathology, and basic science and physics to arrive at a consensus regarding the use of elastography in the assessment of liver fibrosis in chronic liver disease. The panel met in Denver, Colo, on October 21-22, 2014, and drafted this consensus statement. The recommendations in this statement are based on analysis of current literature and common practice strategies and are thought to represent a reasonable approach to the noninvasive assessment of diffuse liver fibrosis.

Ultrasound Elastography and MR Elastography for Assessing Liver Fibrosis: Part 1, Principles and Techniques

OBJECTIVE

The purpose of this article is to provide an overview of ultrasound and MR elastography, including a glossary of relevant terminology, a classification of elastography techniques, and a discussion of their respective strengths and limitations.

CONCLUSION

Elastography is an emerging technique for the noninvasive assessment of mechanical tissue properties. These techniques report metrics related to tissue stiffness, such as shear-wave speed, magnitude of the complex shear modulus, and the Young modulus.

Validity and Reliability of Magnetic Resonance Elastography for Staging Hepatic Fibrosis in Patients with Chronic Hepatitis B

PURPOSE

We evaluated the validity and reliability of magnetic resonance elastography (MRE) for staging hepatic fibrosis in patients with chronic hepatitis B.

METHODS

The study included 73 patients with chronic hepatitis B and confirmed stages of pathological fibrosis. Two radiologists measured liver stiffness using MRE in all cases. We compared the area under the receiver operating characteristic (ROC) curve (Az) for distinguishing stages of fibrosis compared with MRE liver stiffness measurements and serum fibrosis markers. We used intraclass correlation coefficients to analyze interobserver agreement for measurements of liver stiffness and 2 one-sided t-tests to test the equivalence of the measurements by the 2 observers.

RESULTS

ROC analyses revealed the significantly superior discrimination abilities of MRE for liver fibrosis staging (Az = 0.945 to 0.978 [Observer 1] and 0.936 to 0.967 [Observer 2]) to those of serum fibrosis markers (0.491 to 0.742) for both observers (P < 0.0004). The intraclass correlation coefficient between the 2 observers was excellent (ρ = 0.971), and the measurements of liver stiffness by the 2 observers were statistically equivalent within a 0.1-kPa difference (P = 0.0157)CONCLUSION: MRE is a valid and reliable technique for discriminating the stage of hepatic fibrosis in patients with chronic hepatitis B.

Hepatic ADC map as an adjunct to conventional abdominal MRI to evaluate hepatic fibrotic and clinical cirrhotic severity in biliary atresia patients

OBJECTIVES

Hepatic apparent diffusion coefficient (ADC) values and ADC-related indices were correlated with the Mayo risk score for primary biliary cirrhosis (MRSPBC) and METAVIR scores of liver specimens to determine the clinical and pathological significance of diffusion-weighted magnetic resonance imaging (DWMRI).

METHODS

Thirty-two patients with biliary atresia (BA; mean age 461 days, range 11-4616 days) received magnetic resonance examinations from March 2009 to August 2013. A free-breathing DWMRI sequence was performed with the single-shot echo-planar imaging technique with b = 0 and 500 s/mm(2) in all 32 BA patients and 24 controls. We used the ordinal logistic regression test and Spearman rank correlation test to analyse the relationships between the MRSPBC and METAVIR fibrosis scores and right liver-to-psoas ADC ratios (LTPARs).

RESULTS

BA patients had significantly lower LTPARs in both hepatic lobes than controls (p < 0.01). Right LTPARs, showing moderate intraobserver agreement (intraclass correlation coefficient = 0.736) and interobserver reliability (intraclass correlation coefficient = 0.659), were negatively correlated with MRSPBC and METAVIR fibrosis scores (R(2) = 0.398, p = 0.024 and R(2) = 0.628, p < 0.001, respectively).

CONCLUSION

Right LTPARs may be used for long-term follow-up of cirrhosis severity in BA patients.

KEY POINTS

• Hepatic ADC values by DWI correlates well with clinical/pathologic fibrosis scores • Periodic, non-invasive, quantitative imaging follow-up of patients with biliary cirrhosis is feasible • Information on cirrhosis severity could help decide on management options in children with BA • ADC values may be useful in this regard.

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.

Non-invasive Testing for NASH and NASH with Advanced Fibrosis: Are We There Yet?

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent etiology of chronic liver disease in America. NAFLD can be broadly classified in two subtypes: nonalcoholic fatty liver (NAFL), which is generally considered a benign condition with negligible risk of progression to cirrhosis, and nonalcoholic steatohepatitis (NASH), which is generally considered to be progressive with substantial risk of progression to cirrhosis. Additionally, recent studies suggest the odds of liver mortality increases amongst NASH patients with advanced fibrosis (bridging fibrosis ± cirrhosis). Liver biopsy examination is the current gold standard to accurately discriminate between NAFL vs. NASH as well as diagnose advanced fibrosis. However, due to its invasive nature, risk of bleeding (and even rarely death), prohibitive cost, and sampling error, liver biopsies are imperfect for diagnosis and monitoring of NAFLD. As a result, noninvasive biomarkers that can accurately detect NASH and advanced fibrosis without biopsy are needed. This article will discuss the most novel noninvasive biomarkers in diagnosing NASH and advanced fibrosis.

Noninvasive imaging assessment of non-alcoholic fatty liver disease: focus on liver scintigraphy

Noninvasive diagnoses of nonalcoholic fatty-liver disease (NAFLD) involve the use of serologic markers and imaging methods, such as conventional ultrasonography (US), computed tomography, and magnetic resonance imaging. Although these methods are reliable for the noninvasive detection of moderate to severe fatty changes in the liver, they are not reliable for detecting nonalcoholic steatohepatitis (NASH) and fibrosis. New imaging technologies, such as US-based transient elastography, acoustic radiation force impulse and magnetic resonance-based elastography, can reportedly be used to determine the severity of liver fibrosis associated with NASH. In this context, the field of nuclear medicine through liver scintigraphy has recently been proposed, and is being explored for use in the diagnosis of NASH. More importantly, nuclear medicine may contribute to the distinction between simple steatosis and NASH. For example, the enhanced release of cytokines and the decrease in the phagocytic activity of Kupffer cells play important roles in the pathogenesis of NASH. Removal of technetium-99m colloid from circulation by Kupffer cell phagocytosis therefore provides a valuable imaging technique. Thus, nuclear medicine is poised to provide useful tools for the evaluation of patients with NAFLD. However, the evidence is still scarce, and more studies with larger samples are needed to identify their role before they are used in clinical practice.

Non-invasive detection of liver fibrosis: MR imaging features vs. MR elastography

PURPOSE

To compare accuracy of morphological features of liver on MRI and liver stiffness with MR elastography (MRE) for detection of significant liver fibrosis and cirrhosis.

MATERIALS AND METHODS

In this retrospective study, we evaluated 62 patients who underwent liver MRI with MRE and histological confirmation of liver fibrosis within 6 months. Two radiologists, blinded to histology results, independently evaluated liver parenchyma texture, surface nodularity, signs of volumetric changes, and portal hypertension for presence of significant fibrosis and cirrhosis. Two more readers independently calculated mean liver stiffness values with MRE. Interobserver agreement was evaluated with kappa and intra-class correlation coefficient (ICC) analysis. Diagnostic accuracy was assessed with area under receiver operating characteristic (AUROC) analysis. Comparison of AUROCs of MRI and MRE was performed.

RESULTS

Liver fibrosis was present in 37 patients. The interobserver agreement was poor to good (κ = 0.12-0.74) for MRI features and excellent for MRE (ICC 0.97, 95% CI 0.95-0.98). MRI features had 48.5%-87.9% sensitivity, 55.2%-100% specificity, and 71.5%-81.6% accuracy/for detection of significant fibrosis. MRE performed better with 100% sensitivity, 96.5% specificity, and 98.9% accuracy. For the detection of cirrhosis, MRE performed better than MRI features with 88.2% sensitivity (vs. 41.2%-82.3%), 91.1% specificity (vs. 64.4%-95.6%), and 93.5% accuracy (vs. 60.6%-80.5%). Among the MRI features, surface nodularity and overall impression had the best accuracies of 80.3% and 81.6% for detection of significant fibrosis, respectively. For cirrhosis, parenchyma texture and overall impression had the best accuracies of 80.5% and 79.7%, respectively. Overall, MRE had significantly greater AUROC than MRI features for detection of both significant fibrosis (0.98.9 vs 0.71-0.82, P < 0.001) and cirrhosis (0.93.5 vs. 0.61-0.80.5, P < 0.01).

CONCLUSION

MRE is superior to MRI for the non-invasive diagnosis of significant liver fibrosis and cirrhosis.

Magnetic resonance elastography of abdomen

Many diseases cause substantial changes in the mechanical properties of tissue, and this provides motivation for developing methods to noninvasively assess the stiffness of tissue using imaging technology. Magnetic resonance elastography (MRE) has emerged as a versatile MRI-based technique, based on direct visualization of propagating shear waves in the tissues. The most established clinical application of MRE in the abdomen is in chronic liver disease. MRE is currently regarded as the most accurate noninvasive technique for detection and staging of liver fibrosis. Increasing experience and ongoing research is leading to exploration of applications in other abdominal organs. In this review article, the current use of MRE in liver disease and the potential future applications of this technology in other parts of the abdomen are surveyed.

Contemporary assessment of hepatic fibrosis

Newer noninvasive tests have begun to replace liver biopsy for staging purposes. The clinician must evaluate these tools and apply them to individual patients. None of these modalities give the exact same staging of fibrosis as a liver biopsy, but they are excellent tools for risk stratification. Still, it should be recognized that there are disease-specific issues with different utilizations and cutoffs for different clinical diseases. This article provides a framework for incorporating the use of serum biomarkers and elastography-based approaches to stage fibrosis into clinical practice. This review also covers recent developments in this rapidly advancing area.

State-of-the-art cross-sectional liver imaging: beyond lesion detection and characterization

Cross-sectional imaging with computed tomography or magnetic resonance imaging is routinely used to detect and diagnose liver lesions; however, these examinations can provide additional important information. The improvement of equipment and techniques has allowed outstanding evaluation of the vascular and biliary anatomy, which is practicable in most routine examinations. Anatomical variants may exclude patients from certain therapeutic options and may be the cause of morbidity or mortality after surgery or interventional procedures. Diffuse liver disease, such as steatosis, hemochromatosis, or fibrosis, must be diagnosed and quantified. Usually these conditions are silent until the late stages, and imaging plays an important role in detecting them early. Additionally, a background of diffuse disease may interfere in a focal lesion systematic reasoning. The diagnostic probability of a particular nodule varies according to the background liver disease. Nowadays, most diffuse liver diseases can be easily and accurately quantified by imaging, which has allowed better understanding of these diseases and improved patient management. Finally, cross-sectional imaging can calculate total and partial liver volumes and estimate the future liver remnant after hepatectomy. This information helps to select patients for portal vein embolization and reduces postoperative complications. Use of a specific hepatic contrast agent on magnetic resonance imaging, in addition to improving detection and characterization of focal lesions, provides functional global and segmental information about the liver parenchyma.

An update on the management of chronic hepatitis C: 2015 Consensus guidelines from the Canadian Association for the Study of the Liver

Chronic hepatitis C remains a significant medical and economic burden in Canada, affecting nearly 1% of the population. Since the last Canadian consensus conference on the management of chronic hepatitis C, major advances have occurred that warrant a review of recommended management approaches for these patients. Specifically, direct-acting antiviral agents with dramatically improved rates of virological clearance compared with standard therapy have been developed and interferon-free, all-oral antiviral regimens have been approved. In light of this new evidence, an update to the 2012 Canadian Association for the Study of the Liver consensus guidelines on the management of hepatitis C was produced. The present document reviews the epidemiology of hepatitis C in Canada, preferred diagnostic testing approaches and recommendations for the treatment of chronically infected patients with the newly approved antiviral agents, including those who have previously failed peginterferon and ribavirin-based therapy. In addition, recommendations are made regarding approaches to reducing the burden of hepatitis C in Canada.