Diffusion tensor imaging of the extracorticospinal network in the brains of patients with Wilson disease

Altered microstructural pattern of the cortex and basal forebrain cholinergic system in wilson's disease: an automated fiber quantification tractography study

Basal forebrain (BF) cholinergic projection neurons form a highly extensive input to the cortex. Failure of BF cholinergic circuits is responsible for the cognitive impairment associated with Wilson's disease (WD), but whether and how the microstructural changes in fiber projections between the BF and cerebral cortex influence prospective memory (PM) remain poorly understood. We collected diffusion tensor imaging (DTI) data from 21 neurological WD individuals and 26 healthy controls (HCs). The experiment reconstructed the probabilistic streamlined tractography of 18 white matter tracts using an automated fiber quantification (AFQ) toolkit. Tract properties (FA, MD, RD, and AD) were computed for 100 points along each tract for each participant, and the differences between the groups were examined. Subsequently, correlation analysis was performed to evaluate whether abnormal microstructural white matter integrity measures correlate with PM performance. Additional investigations used a tract-based spatial statistics (TBSS) approach to identify regions with altered white matter structure between groups and verify the reliability of the AFQ results. The highest nonoverlapping DTI-related differences were detected in the anterior thalamic radiation (ATR), corticospinal tract (CST), corpus callosum, association fibers, and limbic system fibers. Additionally, PM parameters of the patient group were highly correlated with white matter microstructure changes in the inferior longitudinal fasciculus. Our study highlights that the performance of projections between cholinergic input and output areas-the cerebral cortex and BF-may serve as neural biomarkers of PM and disease prognosis.

Neuroimaging correlates of brain injury in Wilson's disease: a multimodal, whole-brain MRI study

Wilson's disease is an autosomal-recessive disorder of copper metabolism with neurological and hepatic presentations. Chelation therapy is used to 'de-copper' patients but neurological outcomes remain unpredictable. A range of neuroimaging abnormalities have been described and may provide insights into disease mechanisms, in addition to prognostic and monitoring biomarkers. Previous quantitative MRI analyses have focused on specific sequences or regions of interest, often stratifying chronically treated patients according to persisting symptoms as opposed to initial presentation. In this cross-sectional study, we performed a combination of unbiased, whole-brain analyses on T1-weighted, fluid-attenuated inversion recovery, diffusion-weighted and susceptibility-weighted imaging data from 40 prospectively recruited patients with Wilson's disease (age range 16-68). We compared patients with neurological (n = 23) and hepatic (n = 17) presentations to determine the neuroradiological sequelae of the initial brain injury. We also subcategorized patients according to recent neurological status, classifying those with neurological presentations or deterioration in the preceding 6 months as having 'active' disease. This allowed us to compare patients with active (n = 5) and stable (n = 35) disease and identify imaging correlates for persistent neurological deficits and copper indices in chronically treated, stable patients. Using a combination of voxel-based morphometry and region-of-interest volumetric analyses, we demonstrate that grey matter volumes are lower in the basal ganglia, thalamus, brainstem, cerebellum, anterior insula and orbitofrontal cortex when comparing patients with neurological and hepatic presentations. In chronically treated, stable patients, the severity of neurological deficits correlated with grey matter volumes in similar, predominantly subcortical regions. In contrast, the severity of neurological deficits did not correlate with the volume of white matter hyperintensities, calculated using an automated lesion segmentation algorithm. Using tract-based spatial statistics, increasing neurological severity in chronically treated patients was associated with decreasing axial diffusivity in white matter tracts whereas increasing serum non-caeruloplasmin-bound ('free') copper and active disease were associated with distinct patterns of increasing mean, axial and radial diffusivity. Whole-brain quantitative susceptibility mapping identified increased iron deposition in the putamen, cingulate and medial frontal cortices of patients with neurological presentations relative to those with hepatic presentations and neurological severity was associated with iron deposition in widespread cortical regions in chronically treated patients. Our data indicate that composite measures of subcortical atrophy provide useful prognostic biomarkers, whereas abnormal mean, axial and radial diffusivity are promising monitoring biomarkers. Finally, deposition of brain iron in response to copper accumulation may directly contribute to neurodegeneration in Wilson's disease.

Study on different pathogenic factors in different disease stages of patients with Wilson disease

OBJECTIVE

To investigate in different stages of patients with Wilson disease (WD), there are different pathogenic factors such as metal deposition, oxidative stress, and inflammatory response in the brain.

METHODS

A total of 32 untreated WD patients and 10 normal controls were enrolled in the study. The neurological symptoms were evaluated using the modified Young scale. Liver function, metal metabolism, susceptibility-weighted imaging (SWI), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS) examination were done. The clinical disease stages were divided into metal deposition period, fiber damage period, and neuronal necrosis period according to the imaging results. The content of 24-h urine copper, serum copper, and serum iron; and the levels of catalase (CAT), glutathione peroxidase (GSH-PX), malondialdehyde (MDA), nitric oxide (NO), nitric oxide synthase (NOS), superoxide dismutase (SOD), interleukin (IL-1), and tumor necrosis factor alpha (TNF-α) were detected.

RESULTS

The contents of urinary copper in WD patients at neuronal necrosis stage were lower than those in patients at the metal deposition stage (P = 0.011) and fiber injury stage (P = 0.023). The contents of NOS (P = 0.039) and NO (P = 0.047) in WD patients at the stage of fiber injury were higher than those of the normal control, while GSH-PX (P = 0.025) and CAT (P = 0.041) were lower in the neuronal necrosis stage. In the stage of neuronal necrosis, the levels of IL-1 (P = 0.030) and TNF-α were higher than those of the normal control (P = 0.042). The neurological symptom scores in patients with fiber injury (P = 0.013) and neuron injury were higher than those with metal deposition (P = 0.026).

CONCLUSION

There are different pathogenic factors in different stages of WD. At the neuronal necrosis stage, copper deposition was decreased in WD patients. In the stage of fiber injury and neuronal necrosis, there is oxidative stress injury in WD patients. In the neuronal necrosis phase, WD patients have an inflammatory response.

Structural and functional brain changes in hepatic and neurological Wilson disease

Wilson disease (WD) can manifest with hepatic or neuropsychiatric symptoms. Our understanding of the in vivo brain changes in WD, particularly in the hepatic phenotype, is limited. Thirty subjects with WD and 30 age- and gender-matched controls participated. WD group underwent neuropsychiatric assessment. Unified WD Rating Scale neurological exam scores were used to determine neurological (WDN, score > 0) and hepatic-only (WDH, score 0) subgroups. All subjects underwent 3 Tesla anatomical and resting-state functional MRI. Diffusion tensor imaging (DTI) and susceptibility-weighted imaging (SWI) were performed only in the WD group. Volumetric, DTI, and functional connectivity analyses were performed to determine between-group differences. WDN and WDH groups were matched in demographic and psychiatric profiles. The entire WD group compared to controls showed significant thinning in the bilateral superior frontal cortex. The WDN group compared to control and WDH groups showed prominent structural brain changes including significant striatal and thalamic atrophy, more subcortical hypointense lesions on SWI, and diminished white matter integrity in the bilateral anterior corona radiata and corpus callosum. However, the WDH group also showed significant white matter volume loss compared to controls. The functional connectivity between the frontostriatal nodes was significantly reduced in the WDN group, whereas that of the hippocampus was significantly increased in the WDH group compared to controls. In summary, structural and functional brain changes were present even in neurologically non-manifesting WD patients in this cross-sectional study. Longitudinal brain MRI scans may be useful as biomarkers for prognostication and optimization of treatment strategies in WD.

Microstructure changes in whiter matter relate to cognitive impairment in Wilson's disease

Purpose: Wilson’s disease (WD) is a genetic disorder of copper metabolism with pathological copper accumulation in the brain. The purpose of the present study was to evaluate the relationship between the damaged white matter and the impaired cognitive function in WD patients. Materials and methods: Thirty WD adolescents and thirty age- and sex-matched healthy controls (HC) were enrolled. All subjects had received brain MRI, including conventional and diffusion-tensor imaging (DTI) scans. The DTI parameter of fractional anisotropy (FA) was calculated by diffusion kurtosis estimator software. The t test was used to compare the differences between two groups. The correlation between cognitive function and whiter matter disorders were analyzed by linear regression. The results of FA parameter and MD parameter intergroup analysis were both corrected with False Discovery Rate (FDR) simulations by SPSS. Results: WD adolescents showed significantly lower scores of time-based prospective memory (TBPM) and verbal fluency test (VFT) compared with HC. We found significantly higher FA in the right thalamus, right lentiform nucleus, left thalamus, left lentiform nucleus, and brain stem in WD adolescents. Besides, WD adolescents exhibited significantly lower FA in right cerebellum and cingulum and left middle frontal lobe compared with controls (P<0.05). There were significantly negative correlations between FA in bilateral lentiform and thalamus and cognitive impairment in WD adolescents (P<0.05). Conclusion: The whiter matter of WD adolescents was impaired and mainly distributed in subcortical brain regions. The impaired cognitive function was affected by the damaged whiter matter. The present study may be helpful for recognition and understanding of WD.

The asymmetry of neural symptoms in Wilson's disease patients detecting by diffusion tensor imaging, resting-state functional MRI, and susceptibility-weighted imaging

OBJECTIVE

To investigate the cause of the motor asymmetry in Wilson's disease (WD) patients using functional MRI.

METHODS

Fifty patients with WD and 20 age-matched healthy controls were enrolled. Neurological symptoms were scored using the modified Young Scale. All study subjects underwent diffusion tensor imaging (DTI), susceptibility-weighted imaging (SWI), and resting-state functional MRI (rs-fMRI) of the brain. Six regions of interest (ROI) were chosen. Fiber volumes between ROIs on DTI, corrected phase (CP) values on SWI, amplitude of low-frequency fluctuation (ALFF), and regional homogeneity (REHO) values on rs-fMRI were determined. Asymmetry index (right or left value/left or right value) was evaluated.

RESULTS

Asymmetry of rigidity, tremor, choreic movement, and gait abnormality (asymmetry index = 1.33, 1.39, 1.36, 1.40), fiber tracts between the GP and substantia nigra (SN), GP and PU, SN and thalamus (TH), SN and cerebellum, head of the caudate nucleus (CA) and SN, PU and CA, CA and TH, TH and cerebellum (asymmetry index = 1.233, 1.260, 1.269, 1.437, 1.503, 1.138, 1.145, 1.279), CP values in the TH, SN (asymmetry index = 1.327, 1.166), ALFF values, and REHO values of the TH (asymmetry index = 1.192, 1.233) were found. Positive correlation between asymmetry index of rigidity and fiber volumes between the GP and SN, SN and TH (r = .221, .133, p = .043, .036), and tremor and fiber volumes between the CA and TH (r = .045, p = .040) was found.

CONCLUSIONS

The neurological symptoms of patients with WD were asymmetry. The asymmetry of fiber projections may be the main cause of motor asymmetry in patients with WD.

Age-dependent changes of cerebral copper metabolism in Atp7b -/- knockout mouse model of Wilson's disease by [64Cu]CuCl2-PET/CT

Copper is a nutritional metal required for brain development and function. Wilson's disease (WD), or hepatolenticular degeneration, is an inherited human copper metabolism disorder caused by a mutation of the ATP7B gene. Many WD patients present with variable neurological and psychiatric symptoms, which may be related to neurodegeneration secondary to copper metabolism imbalance. The objective of this study was to explore the feasibility and use of copper-64 chloride ([⁶⁴C]CuCl₂) as a tracer for noninvasive assessment of age-dependent changes of cerebral copper metabolism in WD using an Atp7b ^-/- knockout mouse model of WD and positron emission tomography/computed tomography (PET/CT) imaging. Continuing from our recent study of biodistribution and radiation dosimetry of [⁶⁴C]CuCl₂ in Atp7b ^-/- knockout mice, PET quantitative analysis revealed low ⁶⁴Cu radioactivity in the brains of Atp7b ^-/- knockout mice at 7th weeks of age, compared with ⁶⁴Cu radioactivity in the brains of age- and gender-matched wild type C57BL/6 mice, at 24 h (h) post intravenous injection of [⁶⁴C]CuCl₂ as a tracer. Furthermore, age-dependent increase of ⁶⁴Cu radioactivity was detected in the brains of Atp7b ^-/- knockout mice from the 13th to 21th weeks of age, based on the data derived from a longitudinal [⁶⁴C]CuCl₂-PET/CT study of Atp7b ^-/- knockout mice with orally administered [⁶⁴Cu]CuCl₂ as a tracer. The findings of this study support clinical use of [⁶⁴Cu]CuCl₂-PET/CT imaging as a tool for noninvasive assessment of age-dependent changes of cerebral copper metabolism in WD patients presenting with variable neurological and psychiatric symptoms.