Quantitative Measurement Of Brain Iron Deposition In Patients With Minimal Hepatic Encephalopathy Using Susceptibility Mapping

Objective To evaluate the relationship between the distribution of brain iron and minimal hepatic encephalopathy,QSM was used to measure the magnetic susceptibility of bilateral frontal white matter and deep gray structures in patients with minimal hepatic encephalopathy,and investigate the association between iron deposition and cognitive impairment in MHE patients,to explore the use of QSM in assessing of MHE.Materials and Methods The study subjects selected from the inpatients with post-hepatitis B cirrhosis diagnosed in the Department of Infectious Diseases of our hospital.Digit symbol test(DST)and connection test-A(NCT-A)were used to divide the patients into MHE group and simple cirrhosis group,and there are 30 cases in each group.In addition,30age-and sex-matched normal volunteers were included as healthy controls.Routine MRI and unfiltered SWI scan were performed on all participants to obtain the original magnitude and phase image,that was post-processes by the Susceptibility Mapping and Phase Artifacts Removal Toolbox(SMART)software to obtain SM.The regions of interest,the bilateral caudate nucleus,globus pallidus,putamen,thalamus,red nucleus substantia nigra,and bilateral frontal white matter,manually outlined on SM and the was measured by the SPIN software.Correlation analysis was performed between the mean susceptibility value of ROI in healthy control group and the reference value of iron content in corresponding brain areas of normal adults measured by autopsy.Wilcoxon test and One-way ANOVA were used to compare the susceptibility value of ROI of the left and right sides of the healthy control group and the susceptibility values of the ROI between the three groups.Correlation analysis was performed between the susceptibility values of the MHE group and the NCT-A and DST scores.Results1.The mean susceptibility value of ROI in healthy volunteers was positively correlated with the brain iron content reported by Hallgren and Sourander at autopsy study(r=0.836,p=0.01).2.In the healthy controls,There was significant difference between susceptibility values of the bilateral globus pallidus,thalamus,and substantia nigra(P <0.05),and there was no significant difference in the rest of bilateral ROI(P>0.05).3.In MHE group,the bilateral putamen,bilateral globus pallidus,left caudate nucleus,right thalamus,right red nucleus,left substantia nigra,left dentate nucleus,right frontal white matter was higher than that in healthy control group(P <0.05);And the susceptibility of the right thalamus,left caudate nucleus,right red nucleus,left substantia nigra,and left dentate nucleus of MHE was higher than that in simple cirrhosis group(P <0.05).In the simple cirrhosis group,the susceptibility of bilateral globus pallidus was higher than that in healthy controls(P <0.05).4.The susceptibility of the left putamen is negatively correlated with the completion time of NCT-A(r=-0.415,P=0.047),while the susceptibility of the right caudate nucleus is positively correlated with the DST score(r = 0.362,P = 0.040).Conclusion1.The susceptibility value measured by QSM is positively correlated with the brain iron concentration reported in the post-mortem brain studies,suggesting that the susceptibility can indirectly reflect the actual iron content.QSM is feasible for accurately quantitative measurement of the brain iron deposition.2.In healthy people,there is an asymmetry in the iron distribution in the bilateral cerebral hemispheres.The iron content in the right putamen is higher than the left,while in the right thalamus and substantia nigra is slightly lower than the left.3.In the MHE group,the brain iron contents of left caudate nucleus,right thalamus,right red nucleus,left substantia nigra,left dentate nucleus and right frontal white matter was higher than that in normal controls and simple liver cirrhosis group.In the simple liver cirrhosis group,the brain iron contents of bilateral globus pallidus was higher than that in the normal controls.4.The decreased cognitive function in MHE patients may be related to the abnormal iron deposition in the left putamen and the right caudate nucleus.5.Quantitative measurement of iron deposition in the brain of MHE patients by QSM may provide a more objective and accurate new method for the diagnosis of MHE.