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

Abstract

2Cerebral 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 ( A D C ) o n D W I 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 patient had impaired psychometric performance consistent with a diagnosis of minimal hepatic encephalopathy. No statistically significant difference in regional cerebral MTRs or ADCs were 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.Key words: apparent diffusion coefficients; diffusion-weighted imaging; hepatic encephalopathy; magnetic resonance imaging; magnetization transfer ratios 3 Hepatic encephalopathy (HE) is the term used to describe the spectrum of neuropsychiatric changes that can be observed in patients with cirrhosis. In the recent guideline published jointly by the European and AmericanAssociations for the Study of the Liver hepatic encephalopathy was defined as 'a brain dysfunction caused by liver insufficiency or portal systemic shunting' (AASLD/EASL, 2014;Vilstrup et al., 2014).Clinically apparent or overt HE manifests as a neuropsychiatric syndrome encompassing a wide spectrum of mental and motor disorders (Weissenborn, 1998;Ferenci et al., 2002). Individuals with overt HE also show a wide spectrum of other abnormalities, including impaired psychomotor performance (Schomerus & Hamster, 1998) and disturbed neurophysiological function (Parsons-Smith et al., 1957;Chu et al., 1997). The term minimal HE is used to describe patients with cirrhosis who are 'clinically normal', but who show abnormalities in neuropsychometric and/or neurophysiological performance (Ferenci et al., 2000).The presence of HE, whether minimal or overt, is associated with significant impairment in the performance of complex tasks, such as driving (Bajaj et al., 2007;Schomerus et al., 1981;Wein et al., 2004); healthrelated quality of life (Groeneweg et al., 1998); earning potential (Schomerus & Hamster 2001); safety (Roman et al., 2011); neurocognitive function post-transplantati...

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

“…It has been previously hypothesised that disrupted activity in these areas of the brain leads to decreased motivation in these conditions, perceived by the individual as fatigue . Furthermore, the basal ganglia and the globus pallidus in particular have been shown to be susceptible to manganese accumulation associated with cholestasis of any cirrhotic state, while patients with chronic liver disease exhibit pallidal hyperintensity on T 1 ‐weighted magnetic resonance imaging (MRI), similar to that seen in hypermanganesaemic states, such as chronic parenteral nutrition administration and manganese toxicity from industrial exposure …”

The Neurobiology of Hepatic Encephalopathy

“…Studies in patients with cirrhosis have shown that these changes correlate with the incidence of attention deficit, executive dysfunction, and increase in the number of falls [30]. The largest reductions appear to occur in the frontal white matter and in the globus pallidus [27]. In addition, cortical thickness decreases in several regions, such as the lateral superior temporal gyrus and the precuneus, which may also present correlations, respectively, with attention and visuospatial deficits [30].…”

“…Studies with cultures of astrocytes and neurons show that only the former increase the production of free radicals when exposed to glutamine [12] and that's why astrocytes can be considered the basic morphofunctional unit of hepatic encephalopathy: the histopathological milestone of the disease is the swelling of astrocytes, both in the cytoplasm and in the nucleus, with chromatin marginalization, prominent nucleoli and glycogen accumulation, accompanied by little neuronal alteration [4,27].…”

“…The diffusion-weighted imaging, in turn, shows interstitial edema resulting from the exportation of osmolytes from the astrocytes into the extracellular space, both in the white and gray matters. Because of that, multiple sites in the brain have an increase in mean diffusivity, including the frontal, temporal, inferior parietal, and insular lobes, as well as the corpus callosum, putamen, thalamus, and pons [22,27]. The diffusion of water molecules, however, is not free; it reflects interactions with macromolecules, fibers, and membranes.…”

Early Primary Biliary Cholangitis is Characterised by Brain Abnormalities on Cerebral Magnetic Resonance Imaging

“…18 Furthermore, the basal ganglia and the globus pallidus in particular have been shown to be susceptible to manganese accumulation associated with cholestasis of any cirrhotic state, while patients with chronic liver disease exhibit pallidal hyperintensity on T 1 -weighted magnetic resonance imaging (MRI), similar to that seen in hypermanganesaemic states, such as chronic parenteral nutrition administration and manganese toxicity from industrial exposure. 19,20 The main investigative modality for CNS abnormalities in PBC is, therefore, cerebral magnetic resonance imaging (MRI) as manganese is a relaxation agent affecting both T 1 and T 2 parameters. 18 Imaging studies performed to date have identified the presence of white matter lesions in the brains of PBC patients and there is objective evidence of a cerebral auto-regulation abnormality.…”