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 voxelbased 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 defi cits 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.

Shared and distinct abnormalities of brain magnetization transfer ratio in schizophrenia and major depressive disorder:a comparative voxel-based meta-analysis

Background:Patients with schizophrenia(SCZ)and major depressive disorder(MDD)share significant clinical overlap,although it remains unknown to what extent this overlap reflects shared neural profiles.To identify the shared and specific abnormalities in SCZ and MDD,we performed a whole-brain voxel-based meta-analysis using magnetization transfer imaging,a technique that characterizes the macromolecular structural integrity of brain tissue in terms of the magnetization transfer ratio(MTR).Methods:A systematic search based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted in PubMed,EMBASE,International Scientific Index(ISI)Web of Science,and MEDLINE for relevant studies up to March 2022.Two researchers independently screened the articles.Rigorous scrutiny and data extraction were performed for the studies that met the inclusion criteria.Voxel-wise meta-analyses were conducted using anisotropic effect size-signed differential mapping with a unified template.Meta-regression was used to explore the potential effects of demographic and clinical characteristics.Results:A total of 15 studies with 17 datasets describing 365 SCZ patients,224 MDD patients,and 550 healthy controls(HCs)were identified.The conjunction analysis showed that both disorders shared higher MTR than HC in the left cerebellum(P=0.0006)and left fusiform gyrus(P=0.0004).Additionally,SCZ patients showed disorder-specific lower MTR in the anterior cingulate/paracingulate gyrus,right superior temporal gyrus,and right superior frontal gyrus,and higher MTR in the left thalamus,precuneus/cuneus,posterior cingulate gyrus,and paracentral lobule;and MDD patients showed higher MTR in the left middle occipital region.Meta-regression showed no statistical significance in either group.Conclusions:The results revealed a structural neural basis shared between SCZ and MDD patients,emphasizing the importance of shared neural substrates across psychopathology.Meanwhile,distinct disease-specific characteristics could have implications for future differential diagnosis and targeted treatment.