Hepatic cirrhosis: magnetisation transfer contrast in the globus pallidus

Development of a New Index to Distinguish Hepatic Encephalopathy through Automated Quantification of Globus Pallidal Signal Intensity Using MRI

Hyperintensities within the bilateral globus pallidus on T1-weighted magnetic resonance images were present in some liver cirrhosis patients with hepatic encephalopathy. The symptoms of covert hepatic encephalopathy are similar to those of mild dementia. We aimed to develop a new diagnostic index in which to distinguish hepatic encephalopathy from dementia. The globus pallidus signal hyperintensity was quantified using three-dimensional images. In addition, the new index value distribution was evaluated in a cohort of dementia patients. Signal intensity of globus pallidus significantly increased in liver cirrhosis patients with hepatic encephalopathy compared to those without hepatic encephalopathy (p < 0.05), healthy subjects (p < 0.05) or dementia patients (p < 0.001). Only 12.5% of liver cirrhosis patients without hepatic encephalopathy and 2% of dementia patients exceeded the new index cut-off value of 0.994, which predicts hepatic encephalopathy. One dementia patient in our evaluation had a history of liver cancer treatment and was assumed to have concomitant hepatic encephalopathy. The automatic assessment of signal intensity in globus pallidus is useful for distinguishing liver cirrhosis patients with hepatic encephalopathy from healthy subjects and liver cirrhosis patients without hepatic encephalopathy. Our image analyses exclude possible cases of hepatic encephalopathy from patients with neurocognitive impairment, including dementia.

Quantitative magnetic resonance imaging in patients with cirrhosis: a cross-sectional study

Cerebral magnetic resonance imaging was undertaken, at 3 Tesla field strength, employing magnetization transfer (MT) and diffusion-weighted imaging (DWI) sequences, in 26 patients with well-compensated cirrhosis, free of overt hepatic encephalopathy. Results were compared to those from 18 aged-matched healthy volunteers. Cerebral magnetization transfer ratios (MTR) were reduced in the frontal white matter, caudate, putamen and globus pallidus in patients with cirrhosis, compared to healthy controls, while the apparent diffusion coefficients (ADC) on DWI were significantly increased in the genu and body of the corpus callosum. An association between previous excessive alcohol consumption and both MTR and ADCs was noted, but this association was lost when controls were exercised for the severity of liver disease and psychometric impairment on multivariate analysis. Eight (31 %) of the 26 patients had impaired psychometric performance consistent with a diagnosis of minimal hepatic encephalopathy. No statistically significant difference in regional cerebral MTRs or ADCs was found in relation to neuropsychiatric status, although there was a trend towards lower MTRs in patients with impaired psychometric performance. The alterations in MTR and ADC in the patients with functionally compensated cirrhosis are compatible with theories governing the genesis of hepatic encephalopathy, including changes in astrocyte membrane permeability, with subsequent redistribution of macromolecules.

Early primary biliary cholangitis is characterised by brain abnormalities on cerebral magnetic resonance imaging

BACKGROUND

Brain change can occur in primary biliary cholangitis (PBC), potentially as a result of cholestatic and/or inflammatory processes. This change is linked to systemic symptoms of fatigue and cognitive impairment.

AIM

To identify whether brain change occurs early in PBC. If the change develops early and is progressive, it may explain the difficulty in treating these symptoms.

METHODS

Early disease brain change was explored in 13 patients with newly diagnosed biopsy-proven precirrhotic PBC using magnetisation transfer, diffusion-weighted imaging and ¹ H magnetic resonance spectroscopy. Results were compared to 17 healthy volunteers.

RESULTS

Cerebral magnetisation transfer ratios were reduced in early PBC, compared to healthy volunteers, in the thalamus, putamen and head of caudate with no greater reduction in patients with greater symptom severity. Mean apparent diffusion coefficients were increased in the thalamus only. No ¹ H magnetic resonance spectroscopy abnormalities were seen. Serum manganese levels were elevated in all PBC patients, but no relationship was seen with imaging or symptom parameters. There were no correlations between neuroimaging data, laboratory data, symptom severity scores or age.

CONCLUSIONS

This is the first study to be performed in this precirrhotic patient population, and we have highlighted that neuroimaging changes are present at a much earlier stage than previously demonstrated. The neuroimaging abnormalities suggest that the brain changes seen in PBC occur early in the pathological process, even before significant liver damage has occurred. If such changes are linked to symptom pathogenesis, this could have important implications for the timing of second-line-therapy use.

Acquired hepatocerebral degeneration: clinical characteristics and MRI findings

OBJECTIVE

To determine the prevalence of acquired hepatocerebral degeneration (AHD), its clinical and neuroimaging characteristics and response to treatments.

BACKGROUND

Acquired hepatocerebral degeneration is a chronic encephalopathy with predominant motor signs in the context of severe liver disease. Its clinical picture is not well defined, and its prevalence and risk factors are not well known.

METHODS

Review of a database of 1000 patients with cirrhosis to identify cases of AHD. Clinical and neuroimaging data, follow-up and response to treatments, including liver transplantation, were recorded.

RESULTS

Eight patients with AHD were identified. Its prevalence was 0.8% of patients with cirrhosis. The main risk factor for AHD was the presence of portosystemic shunts. Movement disorders, especially a combination of parkinsonism and cerebellar signs were observed in all patients. All AHD cases showed on MRI T1-weighted images hyperintensities in the globus pallidus, and 75% had extrapallidal involvement as well. Antiparkisonian drugs and treatments to prevent acute encephalopathies were ineffective. Three patients who underwent liver transplantation did not experience neurological improvement. Persistence of portosystemic shunts was demonstrated in two cases.

CONCLUSIONS

Acquired hepatocerebral degeneration is a chronic encephalopathy which occurs in ∼1% of patients with liver cirrhosis and seems related to portosystemic shunts. Its is characterized by a combination of parkinsonism and cerebellar signs. MRI pallidal and extrapallidal lesions are seen in most patients, probably reflecting intracerebral deposits of manganese. Liver transplant did not improve the neurological signs in our patients, perhaps because of the persistence of portosystemic shunts.

Voxel-based analyses of magnetization transfer imaging of the brain in hepatic encephalopathy

AIM: To evaluate the spatial distribution of cerebral abnormalities in cirrhotic subjects with and without hepatic encephalopathy (HE) found with magnetization transfer imaging (MTI).

METHODS: Nineteen cirrhotic patients graded from neurologically normal to HE grade 2 and 18 healthy control subjects underwent magnetic resonance imaging. They gave institutional-review-board-approved written consent. Magnetization transfer ratio (MTR) maps were generated from MTI. We tested for significant differences compared to the control group using statistical non-parametric mapping (SnPM) for a voxel-based evaluation.

RESULTS: The MTR of grey and white matter was lower in subjects with more severe HE. Changes were found in patients with cirrhosis without neurological deficits in the basal ganglia and bilateral white matter. The loss in magnetization transfer increased in severity and spatial extent in patients with overt HE. Patients with HE grade 2 showed an MTR decrease in white and grey matter: the maximum loss of magnetization transfer effect was located in the basal ganglia [SnPM (pseudo-)t = 17.98, P = 0.0001].

CONCLUSION: The distribution of MTR changes in HE points to an early involvement of basal ganglia and white matter in HE.

Quantification of cerebral edema on diffusion tensor imaging in acute-on-chronic liver failure

Cerebral edema is a major complication of acute liver failure but may also be seen in other forms of liver failure such as acute-on-chronic liver failure (ACLF) and chronic liver failure (CLF). ACLF develops in patients with previously well-compensated chronic liver disease following acute hepatitis A or E superimposed on underlying liver cirrhosis. The aim of this study was to detect the occurrence, and determine the nature, of cerebral edema in patients with the defined subset of ACLF using diffusion tensor imaging (DTI) metrics. Twenty-three patients with ACLF were studied and compared with 15 healthy controls and 15 patients with CLF. DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), linear anisotropy (CL), planar anisotropy (CP), and spherical isotropy (CS) were calculated by selecting regions of interest in the white matter and deep grey matter of the brain. Significantly decreased FA and increased CS were observed in the anterior limb (ALIC) and posterior limb (PLIC) of the internal capsule and frontal white matter (P<0.05) in patients with different grades (1-4) of ACLF when compared with healthy controls. No significant changes in MD and CP were seen in any brain region. However, significantly decreased CL was observed in the PLIC, caudate nuclei and putamen. In patients with CLF, significantly decreased FA with increased CS in the ALIC and PLIC along with significantly increased MD in the ALIC and caudate nuclei were observed. The presence of significantly decreased FA and CL and increased CS along with no significant change in MD and CP suggests the presence of both intracellular and extracellular components of cerebral edema in patients with ACLF.

MR imaging findings in hepatic encephalopathy

The term hepatic encephalopathy (HE) includes a spectrum of neuropsychiatric abnormalities occurring in patients with liver dysfunction. Most cases are associated with cirrhosis and portal hypertension or portal-systemic shunts, but the condition can also be seen in patients with acute liver failure and, rarely, with portal-systemic bypass and no associated intrinsic hepatocellular disease. Although HE is a clinical condition, several neuroimaging techniques, particularly MR imaging, may eventually be useful for the diagnosis because they can identify and measure the consequences of central nervous system (CNS) increase in substances that under normal circumstances, are efficiently metabolized by the liver. Classic MR imaging abnormalities include high signal intensity in the globus pallidum on T1-weighted images, likely a reflection of increased tissue concentrations of manganese, and an elevated glutamine/glutamate peak coupled with decreased myo-inositol and choline signals on proton MR spectroscopy, representing disturbances in cell-volume homeostasis secondary to brain hyperammonemia. Recent data have shown that white matter abnormalities, also related to increased CNS ammonia concentration, can also be detected with several MR imaging techniques such as magnetization transfer ratio measurements, fast fluid-attenuated inversion recovery sequences, and diffusion-weighted images. All these MR imaging abnormalities, which return to normal with restoration of liver function, probably reflect the presence of mild diffuse brain edema, which seems to play an essential role in the pathogenesis of HE. It is likely that MR imaging will be increasingly used to evaluate the mechanisms involved in the pathogenesis of HE and to assess the effects of therapeutic measures focused on correcting brain edema in these patients.

Value of the apparent diffusion coefficient for quantification of low-grade hepatic encephalopathy

BACKGROUND AND AIMS

Minimal hepatic encephalopathy (HE) is associated with poorer quality of life and increased work disability. Recently, low-grade cerebral edema has been implicated in chronic liver disease.

METHODS

We measured the apparent diffusion coefficient (ADC) of water in various regions of the brains of patients with cirrhosis, and elucidated the significance of the evaluation of ADC in quantifying low-grade HE and predicting overt HE and survival. Forty patients with cirrhosis and 24 controls underwent diffusion-weighted imaging, and patients were followed up every month.

RESULTS

The mean ADC values were increased in cirrhotic patients with minimal HE versus no HE or controls. Minimal HE patients separated from no HE patients with a sensitivity of 70 approximately 90% and a specificity of 85 approximately 90%. ADC values correlated with individual neuropsychological tests. ADC values of white matter, such as the frontal (log-rank test 4.35, P < 0.05) and parietal (log-rank test 5.98, P < 0.05) white matter, was predictive of further bouts of overt HE.

CONCLUSIONS

ADC is a reliable tool for quantification of low-grade HE, and could predict the development of overt HE.

Demonstration of interstitial cerebral edema with diffusion tensor MR imaging in type C hepatic encephalopathy

Brain water may increase in hepatic encephalopathy (HE). Diffusion tensor imaging was performed in patients with cirrhosis with or without HE to quantify the changes in brain water diffusivity and to correlate it with neuropsychological (NP) tests. Thirty-nine patients with cirrhosis, with minimal (MHE) or overt HE, were studied and compared to 18 controls. Mean diffusivity (MD) and fractional anisotropy (FA) were calculated in corpus callosum, internal capsule, deep gray matter nuclei, periventricular frontal, and occipital white matter regions in both cerebral hemispheres. The MD and FA values from different regions in different groups were compared using analysis of variance and Spearman's rank correlation test. In 10 patients with MHE, repeat studies were performed after 3 weeks of lactulose therapy to look for any change in MD, FA, and NP scores. Significantly increased MD was found with insignificant changes in FA in various regions of brain in patients with MHE or HE compared with controls, indicating an increase in interstitial water in the brain parenchyma without any microstructural changes. A significant correlation was found between MD values from corpus callosum, internal capsule, and NP test scores. After therapy, MD values decreased significantly and there was a corresponding improvement in NP test scores. Further analysis showed that MD values were different for different grades of minimal or overt HE. In conclusion, the increase in MD with no concomitant changes in FA in cirrhosis with minimal or early HE indicates the presence of reversible interstitial brain edema.

1H magnetic resonance in the study of hepatic encephalopathy in humans

1H magnetic resonance (1H MR) studies of the brain in patients with liver diseases have shown several abnormalities that may be relevant for the pathogenesis of hepatic encephalopathy. 1H magnetic resonance imaging shows a typical pallidal hyperintensity on T1-weighted images. This abnormality appears to be secondary to the accumulation of manganese in basal ganglia because of portal-systemic shunting. No direct correlation between the magnitude of pallidal hyperintensity and the grade of hepatic encephalopathy has been found, but some studies have related pallidal hyperintensity to parkinsonism. 1H magnetic resonance spectroscopy shows relative to creatine an increase in glutamine/glutamate (Glx) signal and a decrease of choline containing compounds (Cho) and myo-inositol. Abnormalities in the Glx signal have been interpreted as an increase in brain glutamine secondary to the metabolism of ammonia in astrocytes. Disturbances of Cho and myo-inositol have been interpreted as a compensatory response to the increase in intracellular osmolality caused by the accumulation of glutamine in astrocytes. In addition, magnetization transfer imaging shows signs compatible with low-grade cerebral edema. Altogether, 1H MR studies suggest the accumulation of manganese and the development of osmotic abnormalities in the brain of patients with cirrhosis. These abnormalities appear to participate in some of the neurological manifestations of hepatic encephalopathy.

The development of low-grade cerebral edema in cirrhosis is supported by the evolution of (1)H-magnetic resonance abnormalities after liver transplantation

BACKGROUND/AIMS

Liver failure may cause brain edema through an increase in brain glutamine. However, usually standard neuroimaging techniques do not detect brain edema in cirrhosis. We assessed magnetization transfer ratio and (1)H-magnetic resonance (MR) spectroscopy before and after liver transplantation to investigate changes in brain water content in cirrhosis.

METHODS

Non-alcoholic cirrhotics without overt hepatic encephalopathy (n=24) underwent (1)H-MR of the brain and neuropsychological tests. (1)H-MR results were compared with those of healthy controls (n=10). In a subgroup of patients (n=11), the study was repeated after liver transplantation.

RESULTS

Cirrhotic patients showed a decrease in magnetization transfer ratio (31.5+/-3.1 vs. 37.1+/-1.1, P<0.01) and an increase in glutamine/glutamate signal (2.22+/-0.47 vs. 1.46+/-0.26, P<0.01). The increase in glutamine/glutamate signal was correlated to the decrease in magnetization transfer ratio and to neuropsychological function. Following liver transplantation, there was a progressive normalization of magnetization transfer ratio, glutamine/glutamate signal and neuropsychological function. Accordingly, correlations between these variables were lost after liver transplantation.

CONCLUSIONS

Cirrhotic patients show reversible changes in magnetization transfer ratio that are compatible with the development of low-grade cerebral edema. Minimal hepatic encephalopathy and low-grade cerebral edema appear to be the consequences of the metabolism of ammonia in the brain.

Manganese deposition in the globus pallidus in patients with biliary atresia

BACKGROUND

Chronic liver diseases may alter trace element contents in the brain. Among these trace elements, manganese is a ubiquitous transition metal excreted by the liver into the bile. Blood concentrations of manganese are elevated in patients with biliary atresia who have undergone hepatic portoenterostomy. The present study investigated the effects of liver transplantation on manganese deposition in the brain in such patients.

METHODS

The signal intensity of the globus pallidus was calculated as an index defined as the percentile ratio of signal intensity in the globus pallidus to the subcortical frontal white-matter in sagittal T1-weighted magnetic resonance imaging planes.

RESULTS

Brain magnetic resonance imaging revealed hyperintense signals in the globus pallidus due to manganese deposition in biliary atresia patients. Few neurologic symptoms related to manganese intoxication were observed. However, one 23-year-old female with biliary atresia had depressive symptoms and dyskinesia; she improved after oral administration of the dopamine precursor, L-DOPA. Manganese deposition disappeared in two patients after living-related reduced-size hepatic transplantation.

CONCLUSIONS

Manganese accumulates in the brain during cholestasis associated with biliary atresia and disappears after hepatic transplantation. Manganese deposition is likely to be subclinical and reversible but may be associated with some age-related neurologic symptoms.