Two-Dimensional MR Spectroscopy of Minimal Hepatic Encephalopathy and Neuropsychological Correlates In Vivo
Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1721, USA. Journal of Magnetic Resonance Imaging
(Impact Factor: 3.21).
07/2010; 32(1):35-43. DOI: 10.1002/jmri.22216
To evaluate regional cerebral metabolic and structural changes in patients with minimal hepatic encephalopathy (MHE) using two-dimensional (2D) MR spectroscopy (MRS) and T( (1) )-weighted MRI, to correlate the observed MR changes with neuropsychological (NP) test scores, and to compare the diagnostic accuracy of MRI, 2D MRS, and NP tests in discriminating between patients and healthy subjects.
Thirty-three MHE patients and 30 healthy controls were investigated. The 2D localized correlated spectroscopy (L-COSY) was performed in the frontal and occipital brain on a 1.5 Tesla (T) MR scanner. The NP test battery included 15 tests, grouped into 6 cognitive domains. Globus pallidus signal intensities were calculated from T(1)-weighted images.
The 2D MRS showed significant differences in ratios of the following metabolite(s) peaks with respect to creatine (Cr): decreased myo-inositol (mI), choline (Ch), mICh, and increased (glutamate plus glutamine) (Glx) in patients compared with healthy subjects in both occipital and frontal lobes. Frontal lobe taurine also showed a decline in patients. The NP test results revealed declines in cognitive speed, motor function, executive function, and global cognitive status. Significant correlations were found between the altered metabolites and NP tests. Alteration in the mICh/Cr ratio was noted as a powerful discriminant between healthy subjects and the patients.
The study demonstrates that relative metabolite levels determined by 2D MRS, in particular mICh/Cr, provide the best diagnostic prediction for MHE. The results suggest that depletions of myo-inositol, choline and taurine with respect to creatine correlate with measures of neuropsychological impairment.
Available from: Yu-Chen Chen
- "Several neuropathology mechanisms may promote the development of WM abnormalities in cirrhotic patients. First, the hyperammonemia caused by hepatic decompensation is known to induce metabolic disorders in brain tissues  . The primary result of these metabolic derangements is the development of dysfunctional astrocytes, which may lead to axonal degeneration as observed in multiple sclerosis . "
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ABSTRACT: White matter (WM) abnormalities are common in cirrhotic patients and possibly contribute to hepatic encephalopathy (HE), a frequent neuropsychiatric complication of cirrhosis. However, little is known about these WM abnormalities and their relationship to neurocognitive deficits in patients with HBV-related cirrhosis.
Three-dimensional T1-weighted magnetic resonance imaging and diffusion tensor imaging (DTI) scans were obtained from 67 patients with HBV-related cirrhosis and 40 controls. Voxel-based morphometry and voxel-based DTI were performed to detect macroscopic atrophy and damage to the microstructural integrity of the WM, respectively. Correlation analyses were performed to investigate the relationships between WM abnormalities and neurocognitive performances.
Patients with cirrhosis exhibited significantly decreased WM volume and fractional anisotropy (FA) values, especially in the corpus callosum, thalamus, extra-nuclear area, sensorimotor area, fusiform gyrus, lingual gyrus, and frontal lobes. These abnormalities were more severe with increasing Child-Pugh stage, minimal HE, and previous overt HE. Changes in the corpus callosum, frontal lobe, sensorimotor area, internal capsule, and temporal-occipital lobes were correlated with poor neurocognitive performance. Also, the significantly decreased global WM volume and mean FA value were correlated with poor neurocognitive performances.
Diffuse WM abnormalities are common in patients with HBV-related cirrhosis. Advanced liver disease and episodes of HE are two factors associated with WM abnormalities. The correlation between poor neurocognitive performance and WM abnormalities suggests that WM abnormalities may be one of mechanisms underlying neurocognitive deficits in patients with HBV-related cirrhosis.
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ABSTRACT: Minimal hepatic encephalopathy (MHE) is a neurocognitive disorder that affects up to 80% of cirrhotic patients. Similar to overt hepatic encephalopathy, ammonia and oxidative stress play key roles in the pathogenesis of MHE. However, MHE is characterized by subtle deficits and psychomotor abnormalities that can only be elicited by specialized psychometric tests. Although no gold standard exists for the diagnosis, MHE remains an important entity for clinicians to recognize because of its negative impact on a patient's health-related quality of life and association with driving impairment and vehicle accidents. MHE has also been associated with an increased rate in the development of overt hepatic encephalopathy and increased mortality; therefore, identification and treatment should not be delayed. Treatment to date has been focused on reducing serum ammonia levels with agents such as lactulose, probiotics, and synbiotics. MHE is a real and growing problem that is epidemic in cirrhosis, and increasing awareness of this condition is necessary for adequate management of these patients.
Available from: Rajakumar Nagarajan
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ABSTRACT: Hepatic encephalopathy (HE) is normally diagnosed by neuropsychological (NP) tests. The goals of this study were to quantify cerebral metabolites, separate glutamate (Glu) from glutamine (Gln) in patients with minimal hepatic encephalopathy (MHE) as well as healthy subjects using the prior-knowledge fitting (ProFit) algorithm on data acquired by two-dimensional (2D) localized correlated spectroscopy (L-COSY) on two different MR scanners, and to correlate the metabolite changes with neuropsychological (NP) tests. We studied 14 MHE patients and 18 healthy controls using a GE 1.5 T Signa MR scanner. Another group of 16 MHE patients and 18 healthy controls were studied using a Siemens 1.5 T Avanto MR scanner. The following parameters were used for L-COSY: TR/TE = 2 s/30 ms, 3 × 3 × 3 cm(3) voxel size, 96 Δt(1) increments with 8 averages per Δt(1). Using the ProFit algorithm, we were able to differentiate Gln from Glu on the GE 1.5 T data in the medial frontal white/gray matter. The ratios of myo-inositol (mI), Glu, total choline, scyllo-inositol (sI), phosphoethanolamine (PE), and total N-acetyl aspartate (NAA) showed statistically significant decline in HE patients compared to healthy controls, while the ratio of Gln was significantly increased. Similar trend was seen in the ProFit quantified Siemens 1.5 T data in the frontal and occipito-parietal white/gray regions. Among the NP domain scores, motor function, cognitive speed, executive function and the global scores showed significant differences. Excellent correlations between various NP domains and metabolite ratios were also observed. ProFit based cerebral metabolite quantitation enhances the understanding and basis of the current hypothesis of MHE.
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