Dynamic susceptibility contrast-enhanced first-pass perfusion MR imaging in patients with subclinical hepatic encephalopathy

Efficacy and safety of albumin for the treatment of hepatic encephalopathy: an updated systematic review and meta-analysis of randomized controlled trials

Background

Albumin acts as a scavenger of reactive oxygen species and an inhibitor of inflammatory processes that underlie hepatic encephalopathy (HE). However, the role of albumin in hepatic encephalopathy is not well-established. The authors performed this meta-analysis to evaluate the efficacy and safety of albumin in the management of hepatic encephalopathy.

Methods

The authors carried out an extensive search across multiple databases, including MEDLINE (via PubMed), Embase, CENTRAL, and various trial registries, to identify randomized controlled trials (RCTs) evaluating the impact of albumin administration in HE. The authors used a random-effects model for analyses and presented dichotomous outcomes and continuous outcomes as relative risk and mean difference, along with corresponding 95% CIs, respectively. Heterogeneity was assessed using both the I2 index and χ2 test.

Results

Our meta-analysis included 4 RCTs involving 306 patients. Our primary outcomes, mortality, and persistence of HE were reported by all four studies. Albumin was found to significantly decrease mortality in patients with HE [risk ratio (RR) 0.52, 95% CI 0.32-0.83; I2 =0%]. Persistence of HE was found to be comparable between the two groups (RR 0.83, 95% CI 0.68-1.00; I2 =24%). There was no significant difference between the albumin and control groups regarding length of hospital stay (MD -1.55, 95% CI -3.5 to 0.14; I2 =41%), adverse events (RR 1.00, 95% CI 0.87-1.16; I2 =0%), and severe adverse events (RR 0.89, 95% CI 0.59-1.35).

Conclusion

Albumin administration in patients with hepatic encephalopathy decreases mortality but does not significantly impact the persistence of HE. Further high-quality, large-scale randomized controlled trials are needed to provide conclusive evidence.

Identifying Minimal Hepatic Encephalopathy: A New Perspective from Magnetic Resonance Imaging

Type C hepatic encephalopathy (HE) is a condition characterized by brain dysfunction caused by liver insufficiency and/or portal-systemic blood shunting, which manifests as a broad spectrum of neurological or psychiatric abnormalities, ranging from minimal HE (MHE), detectable only by neuropsychological or neurophysiological assessment, to coma. Though MHE is the subclinical phase of HE, it is highly prevalent in cirrhotic patients and strongly associated with poor quality of life, high risk of overt HE, and mortality. It is, therefore, critical to identify MHE at the earliest and timely intervene, thereby minimizing the subsequent complications and costs. However, proper and sensitive diagnosis of MHE is hampered by its unnoticeable symptoms and the absence of standard diagnostic criteria. A variety of neuropsychological or neurophysiological tests have been performed to diagnose MHE. However, these tests are nonspecific and susceptible to multiple factors (eg, aging, education), thereby limiting their application in clinical practice. Thus, developing an objective, effective, and noninvasive method is imperative to help detect MHE. Magnetic resonance imaging (MRI), a noninvasive technique which can produce many objective biomarkers by different imaging sequences (eg, Magnetic resonance spectroscopy, DWI, rs-MRI, and arterial spin labeling), has recently shown the ability to screen MHE from NHE (non-HE) patients accurately. As advanced MRI techniques continue to emerge, more minor changes in the brain could be captured, providing new means for early diagnosis and quantitative assessment of MHE. In addition, the advancement of artificial intelligence in medical imaging also presents the potential to mine more effective diagnostic biomarkers and further improves the predictive efficiency of MHE. Taken together, advanced MRI techniques may provide a new perspective for us to identify MHE in the future. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Whole brain atlas-based diffusion kurtosis imaging parameters for evaluation of minimal hepatic encephalopathy

BACKGROUND AND PURPOSES

Minimal hepatic encephalopathy (MHE) has no recognizable clinical symptoms, but patients have cognitive and psychomotor deficits. Hyperammonemia along with neuroinflammation lead to microstructural changes in cerebral parenchyma. Changes at conventional imaging are detected usually at the overt clinical stage, but microstructural alterations by advanced magnetic resonance imaging techniques can be detected at an early stage.

MATERIALS AND METHODS

Whole brain diffusion kurtosis imaging (DKI) data acquired at 3T was analyzed to investigate microstructural parenchymal changes in 15 patients with MHE and compared with 15 age- and sex-matched controls. DKI parametric maps, namely kurtosis fractional anisotropy (kFA), mean kurtosis (MK), axial kurtosis (AK) and radial kurtosis (RK), were evaluated at 64 white matter (WM) and gray matter (GM) regions of interest (ROIs) in the whole brain and correlated with the psychometric hepatic encephalopathy score (PHES).

RESULTS

The MHE group showed a decrease in kFA and AK across the whole brain, whereas MK and RK decreased in WM ROIs but increased in several cortical and deep GM ROIs. These alterations were consistent with brain regions involved in cognitive function. Significant moderate to strong correlations (-0.52 to -0.66; 0.56) between RK, MK and kFA kurtosis metrics and PHES were observed.

CONCLUSION

DKI parameters show extensive microstructural brain abnormalities in MHE with minor correlation between the severity of tissue damage and psychometric scores.

Hepatic Encephalopathy in Patients in Lviv (Ukraine)

Background and Objectives

Hepatic encephalopathy (HE) research has long been impeded by the vague definition of this disabling complication of liver failure. This article provides an overview of the etiology and impact of HE on neuromuscular functions as well as its role in the development of infections and anemia.

Materials and Methods

This was a descriptive study conducted in 36 patients with HE. Close monitoring of these patients was done by checking on several parameters.

Results

The etiological distribution: alcohol (67%), hepatitis C virus (HCV; 17%), HCV and alcohol (8%), hepatitis B virus (HBV; 3%), HBV and alcohol (3%), HBV and HCV (6%), and cryptogenic (3%). The laboratory results indicated an elevation of De Ritis level in 69% of cases and in 92% of total bilirubin values. The Halstead-Reitan (H-R) test score with regards to gender indicated that more than half of the patients had a score of 2, while only few cases received the scores 3 and 4. The frequency of H-R score with regards to Child-Pugh score showed the significant preponderance of Child-Pugh score of 7–9 (B): 58.3% compared to others groups of results, and these results indicated patients’ poor prognosis.

Conclusion

Findings showed the preponderance of female patients towards developing HE and the poor survival rate of patients older than 65 years. Alcohol and hepatitis C were the main causes associated with the development of HE. The neurological assessment marked the preponderance of Child-Pugh grades B and C and also the prevalence in female patients with neuropsychological disabilities through the assessment of H-R test.

Combining arterial-spin labeling with functional magnetic resonance imaging measurement for characterizing patients with minimal hepatic encephalopathy

AIM

Our objective is to explore key changes in brain functions in relation to minimal hepatic encephalopathy (MHE). We incorporated both resting-state functional magnetic resonance imaging (fMRI) and arterial spin labeling (ASL) to enhance the detection of MHE.

METHODS

We undertook fMRI scanning for 56 MHE patients and 66 healthy controls. Region functional connectivity was carried out to assess the connectivity status between pairs of regions among 90 brain regions. Additionally, blood flow (BF) status was measured by ASL for all subjects. Spearman's correlation test was implemented to identify any correlation among z-values, results from number connection test type A, and digit symbol tests. Finally, the receiver operating characteristic curve was generated for assessing the accuracy of BF in MHE diagnosis.

RESULTS

The corresponding functional connectivity was significantly different between MHE and control groups in 15 regions. For MHE patients, BF showed an increasing pattern in regions of interest. Blood flood in the putamen was positively correlated with number connection test type A neuropsychological performance, whereas it was negatively correlated with the digit symbol test. Blood flood in the right putamen showed the highest value of area under the curve with a sensitivity of 85.7% and specificity of 89.4%.

CONCLUSION

Connectivity impairment resulting from ganglia-thalamo-cortical circuits may play important roles in mediating the development of MHE patients. An increase in the BF, particularly in the right putamen, may be considered as evidence for the presence of MHE.

Brain magnetic resonance in hepatic encephalopathy

The term hepatic encephalopathy (HE) covers a wide spectrum of neuropsychiatric abnormalities caused by portal-systemic shunting. The diagnosis requires demonstration of liver dysfunction or portal-systemic shunts and exclusion of other neurologic disorders. Most patients with this condition have liver dysfunction caused by cirrhosis, but it also occurs in patients with acute liver failure and less commonly, in patients with portal-systemic shunts that are not associated with hepatocellular disease. Various magnetic resonance (MR) techniques have improved our knowledge about the pathophysiology of HE. Proton MR spectroscopy and T1-weighted imaging can detect and quantify accumulations of brain products that are normally metabolized or eliminated such as glutamine and manganese. Other MR techniques such as T2-weighted and diffusion-weighted imaging can identify white matter abnormalities resulting from disturbances in cell volume homeostasis secondary to brain hyperammonemia. Partial or complete recovery of these abnormalities has been observed with normalization of liver function or after successful liver transplantation. MR studies have undoubtedly improved our understanding of the mechanisms involved in the pathogenesis of HE, and some findings can be considered biomarkers for monitoring the effects of therapeutic measures focused on correcting this condition.

Pharmacotherapy for hyperammonemia

INTRODUCTION

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that is seen in patients with liver failure. The pathogenesis of HE is not entirely understood, but several hypotheses have emerged and persisted during the years. Despite the many prevalent hypotheses, most of the existing evidence point to ammonia as the main culprit behind primary and secondary symptoms making it the center of potential therapeutic options for the treatment of HE. Most treatments of hyperammonemia target the organs and metabolic processes involved in ammonia detoxification.

AREAS COVERED

This article provides a review of the current targets of therapy as well as the drugs used for hyperammonemia treatment.

EXPERT OPINION

Lactulose and rifaximin have a proven role as measures to use for secondary prophylaxis and are the mainstay of current therapy. The use of molecular adsorbent recirculating system in patients with severe HE has been proven to be efficacious, but through mechanisms that appear to be independent of ammonia. The main challenge that faces the further development of treatments for HE is finding appropriate end points, and the next step would be to provide evidence of the effectiveness of established treatments and define the role of emerging new treatments.

Progress in diagnosis of minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) is defined as HE without symptoms on clinical/neurological examination, but with deficits in some cognitive areas that can only be measured by neuropsychometric testing. MHE is associated with reduced quality of working, driving, memory, and cognitive function, and is a risk factor for the development of overt HE. Compared with non-MHE patients, MHE patients have a high mortality rate, so positive screening and intervention in patients with MHE are needed to improve the quality of life in patients with cirrhosis and reduce traffic accidents and the social burden of medical care. The current approach to the diagnosis of MHE includes mental scales (paper pencil test, computer test, or the combination of the two), electrophysiological examination, and imaging examination. Diagnosis of MHE is still a challenge now, and it is needed to establish a better clinical diagnosis standard to improve the diagnostic level.

Multimodality magnetic resonance imaging in hepatic encephalopathy: An update

Hepatic encephalopathy (HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging (MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight of the increasingly important role of blood oxygen level dependent functional MRI.

Transjugular intrahepatic portosystemic shunt induced short- and long-term cerebral blood flow variations in cirrhotic patients: an arterial spin labeling MRI study

Short- and long-term effects of transjugular intrahepatic portosystemic shunt (TIPS) on cerebral blood flow (CBF) in patients with cirrhosis are still unclear. The purpose of this longitudinal study was to explore CBF alteration patterns in cirrhotic patients after TIPS. Thirteen cirrhotic patients (7 male, 6 female, mean age 50.0 ± 9.3 years) underwent arterial-spin labeling (ASL) MRI 1-9 days (median 1 days) before TIPS. Follow-up MR examinations were performed about 1 week (median 6 days), 3 months (n = 6), 6-9 months (n = 5) and 12-18 months (n = 5) after TIPS. CBF, ammonia level, Child-Pugh score, number connection test type A (NCT-A) and digit symbol test (DST) scores were converted into relative values by dividing by his/her pre-TIPS values, and then, compared via one-way analysis of variance (ANOVA). Correlations between the pre- and post-TIPS changes of relative CBF (rCBF) and the changes of relative ammonia (rAmmonia), Child-Pugh (rChild-Pugh), and NCT-A/DST (rNCT-A/rDST) scores were calculated by crossing subjects. Compared with the pre-TIPS level, the global rCBF slightly increased by 10.9 % about 1 week later, then rapidly decreased by 14.2 % 3 months later, and flatly decreased by 17.2 % in 6-9 months and 18.0 % in 12-18 months following TIPS. The changes of 3-month rDST score were slightly correlated with 3-month rCBF rather than 1-week rCBF, (P < 0.1, FDR-corrected) No difference was found between the pre- and post-TIPS rAmmonia levels, rChild-Pugh and rNCT-A/rDST scores (Post-hoc P > 0.05). CBF measured at different time points after TIPS insertion showed different patterns, indicating varying longitudinal effects of TIPS on CBF. A sharp decline of rCBF was found in the 1 week to 3 months period after insertion, indicating that high event rate of hepatic encephalopathy might relate with the unadaptable CBF in patients undergoing TIPS insertion.

Cerebral blood flow measured by arterial-spin labeling MRI: a useful biomarker for characterization of minimal hepatic encephalopathy in patients with cirrhosis

PURPOSE

To investigate the role of arterial-spin labeling (ASL) MRI to non-invasively characterize the patterns of cerebral blood flow (CBF) changes in cirrhotic patients and to assess the potential of ASL MRI to characterize minimal hepatic encephalopathy (MHE).

MATERIALS AND METHODS

This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Thirty six cirrhosis patients without overt hepatic encephalopathy (16 MHE patients and 20 non hepatic encephalopathy (non-HE) patients) and 25 controls underwent ASL MRI, and CBF was measured for each subject. One-way ANOCOVA test with age and gender as covariences was used to compare CBF difference among three groups, and post hoc analysis was performed between each two groups. Region-based correlation analysis was applied between Child-Pugh score, venous blood ammonia level, neuropsychological tests and CBF values in cirrhosis patients. Receiver operator characteristic (ROC) analysis was used for assessing CBF measurements in ASL MRI to differentiate MHE from non-HE patients.

RESULTS

The gray matter CBF of MHE patients (71.09 ± 11.88 mL min(-1)100g(-1)) was significantly higher than that of non-HE patients (55.28 ± 12.30 mL min(-1)100g(-1), P<0.01) and controls (52.09 ± 9.27 mL min(-1)100g(-1), P<0.001). Voxel-wise ANOCOVA results showed that CBFs were significantly different among three groups in multiple gray matter areas (P<0.05, Bonferroni corrected). Post hoc comparisons showed that CBF of these brain regions was increased in MHE patients compared with controls and non-HE patients (P<0.05, Bonferroni corrected). CBF of the right putamen was of the highest sensitivity (93.8%) and moderate specificity (75.0%) for characterization of MHE when using the cutoff value of 50.57 mL min(-1)100g(-1). CBFs in the bilateral median cingulate gyri, left supramarginal gyrus, right angular gyrus, right heschl gyrus and right superior temporal gyrus have both sensitivity and specificity of approximately 80% for the diagnosis of MHE.

CONCLUSION

Higher CBF was found in many brain regions in cirrhotic patients than controls and gradually increased with the progress of disease. CBF measured with ASL MRI can be a useful marker for differentiating MHE from non-HE patients.

Brain metabolism in patients with hepatic encephalopathy studied by PET and MR

We review PET- and MR studies on hepatic encephalopathy (HE) metabolism in human subjects from the point of views of methods, methodological assumptions and use in studies of cirrhotic patients with clinically overt HE, cirrhotic patients with minimal HE, cirrhotic patients with no history of HE and healthy subjects. Key results are: (1) Cerebral oxygen uptake and blood flow are reduced to 2/3 in cirrhotic patients with clinically overt HE but not in cirrhotic patients with minimal HE or no HE compared to healthy subjects. (2) Cerebral ammonia metabolism is enhanced due to increased blood ammonia in cirrhotic patients but the kinetics of cerebral ammonia uptake and metabolism is not affected by hyperammonemia. (3) Recent advantages in MR demonstrate low-grade cerebral oedema not only in astrocytes but also in the white matter in cirrhotic patients with HE.

Pathogenesis of hepatic encephalopathy

Hepatic encephalopathy can be a serious complication of acute liver failure and chronic liver diseases, predominantly liver cirrhosis. Hyperammonemia plays the most important role in the pathogenesis of hepatic encephalopathy. The brain-blood barrier disturbances, changes in neurotransmission, neuroinflammation, oxidative stress, GABA-ergic or benzodiazepine pathway abnormalities, manganese neurotoxicity, brain energetic disturbances, and brain blood flow abnormalities are considered to be involved in the development of hepatic encephalopathy. The influence of small intestine bacterial overgrowth (SIBO) on the induction of minimal hepatic encephalopathy is recently emphasized. The aim of this paper is to present the current views on the pathogenesis of hepatic encephalopathy.