A Serial Study Of High Field MRI In Parkinson's Disease

PartⅠMeasurement of brain iron in patients with Parkinson's disease usingsusceptibility weighted imagingObjective To comprehensively measure iron content in nucleus of midbrain andbasal ganglia in patients with Parkinson's disease (PD) on phase images ofsusceptibility weighted imaging (SWI) sequence.Materials and Methods 42 PD patients and 37 healthy subjects were examinedby using SWI sequence.Corrected phase images were obtained after postprocessed.Nucleus of midbrain and basal ganglia were drawn by hand and the phase values weremeasured on corrected phase images.The regions evaluated included substantia nigracompacta (SNc),substantia nigra reticulate (SNr),red nucleus (RN),subthalamicnucleus(STN),fasicula nigrale (FN),putamen (PUT),globus pallidus (GP),caudatenucleus (CN) and thalamus(THA).According to the anatomical and pathologicalfeatures,corresponding brain regions were subdivided into several subregionsfurthermore.The correlation between phase values of 37 healthy subjects in our studyand values of regional brain iron concentration in published in literatures wereanalyzed.Phase values were compared between PD patients and 23 age,sex-matchednormal controls (NC).Phase values were also compared between two groups withdifferent severity and duration of disease..Results①Phase values of healthy subjects were negatively correlated withpublished values of regional brain iron concentration (r~2=-0.839,p=0.037).②Phasevalues of SNc-internal and SNc-external in PD were significantly lower than that inthe NC,but other brain regions no.Phase values of the more affected SNc were lowerthan that of the less affected side.③A significantly difference in phase values wasobserved in the more affected SNc-internal and SNc-external between early stage andadvanced PD groups,but not in other brain regions.Phase values of the more affectedSNc-internal and SNc-external in early stage group were significantly lower than that in advanced group.④No difference in phase values was observed in any brainregions between two groups with different duration of disease.Conclusion①Specific increasement of iron content of PD was observed onlyin SNc,but not in other brain regions.This suggests excessive iron accumulation isclosely related to the apoptosis of dopaminergic neurons in SNc and the specificdistribution pattern can afford useful information to differeate from other diseases.②Iron content was significantly difference on bilateral SNcs and the more affectedSNc were higher than that of the less affected side.Iron content of the more affectedSNc increased with evolution of PD patient's pathogenetic condition,but not withdisease duration.These suggest excessive iron accumulation is likely to be a primarypathogenesis and iron measurement can be an important biomarker to evaluate theseverity of disease.③SWI can be used to improve the visibility of the STN forprecise surgical targeting because of higher iron content in normal STN.④Thephase images acquired by SWI sequence have superb anatomic resolution.It is theoptimal modality to measure brain iron content in vivo and has important significancein the study of PD and other neural degeneration diseases.PartⅡA whole-brain analysis in patients with Parkinson's disease usingVoxel-based MRI morphometryObjective To analyze the structural changes of whole brain gray matter in PDusing voxel-based morphometry (VBM).Furthermore,to disclosure bain structuralchanges closely related to mild cognitive impairment.Materials and Methods 35 PD patients and 20 NC were examined by usingTlWI three-dimensional Brain Volume (BRAVO)sequence.We further classified PDpatients into 2 groups according to the extent of cognitive impairment:14 cases ofnone mild cognitive impairment (nMCI) and 21 cases of mild cognitive impairment(MCI).The data were analyzed by using VBM based on SPM5 to generate gray matter density map.Results①Compared to NC,PD patients showed extensived_decreased graymatter density in widespread brain region involving bilateral temporal,frontal,parietal,occipital lobes,right hippocampus,right parahippocampus gyrus,rightcerebellar hemisphere and left CN.②Compared to NC,decreased gray matter densityin PD-nMCI was observed in right temporal lobe,including middle temporal gyrus,inferior temporal gyrus,and right hippocampus and ACC.③Compared to PD-nMCI,decreased gray matter density in PD-MCI was observed in right cuneus,precuneus,bilateral precentral gyrus,right orbit frontal cortex (OFC),bilateral midtemporalgyrus and left fusiform gyrus.Conclusion①Gray matter atrophy in widespread brain region can exist in PDpatients,involving bilateral temporal,frontal,parietal,occipital lobes,righthippocampus,parahippocamus gyrus etc.②Decreased gray density in PD-nMCI wasmainly located in right temporal lobe and right hippocampus and ACC.Withoccurrence of mild cognitive impairment,abnormal brain regions were graduallyextended.③Gray matter atrophy in bilateral parietal,occipital lobe association cortex,right OFC,and bilateral middle temporal gyrus are related to the mild cognitiveimpairment.④VBM can evaluate the early structural changes of full-brain in vivoand is the first choice to the study of brain morphology.PARTⅢResting-state functional connectivity of striaturn in PDObjective To demonstrate brain functional changes of PD in resting state usingfunctional connectivity MRI (Fc-MRI).Materials and Methods 35 PD patients and 17 NC accepted fMRI scan duringresting state.The fMRI data were processed with statistical parametric mapping 5(SPM5).Bilateral striatum (STR) areas were defined as the seed voxels.Wholebrain map of functional connectivity for every subject was acquired.The difference offunctional connectivity between PD patients and NC was compared. Results①Compared to NC,PD patients showed decreased positive functionalconnectivity in right dorsolateral prefrontal cortex (DLPFC) and bilateral posteriorcingulate cortex (PCC) related to bilateral STR.In addition,left parietal posteriorcortex (including precuneus,inferior parietal lobule,supramarginal gyrus) showeddecreased positive functional connectivity with L-STR.②Regions of limbic systemincluding hippocamp,parahippocamp,insular lobes showed increased positivefunctional connectivity with the bilateral STR.Conclusion Extensive changes happened in the neural network in PD patientsduring resting state.Frontal and parietal cortex may be the main substrate of cognitiveimpairment,but limbic system including hippocamp,parahippocamp,insular lobesplay an important compensative role in PD.PARTⅣThe analysis of regional homogeneity in resting-state in PDObjective To demonstrate brain functional changes of PD in resting state usingregional homogeneity (ReHo).Materials and Methods 35 PD patients and 17 NC accepted fMRI scan duringresting state.According to the severity,PD subjects were further classified into twogroups:early stage group,15 cases (Hohen&Yahr score≤1.5) and advanced stagegroup,20 cases (Hohen&Yahr score＞1.5).The fMRI data were processed withstatistical parametric mapping5 (SPMS).ReHo map for each subject was acquired bycalculating each voxel's Kendall's coefficient concordance (KCC) in whole brain.The difference of ReHo between PD patients and NC was compared.The differenceof ReHo in both groups was compared and analyzed.Results①Compared to NC,the PD patients showed decreased ReHo in motorcortex,including primary motor areas (M1),premotor cortex(PMC),supplementarymotor area (SMA),anterior cingulate cortex (ACC),and left DLPFC,right posteriorlobe of cerebellum and right superior temporal gyrus.②In early stage of PD,decreased ReHo was located in bilateral posterior insula,DLPFC,parietal lobe and right superior temporal gyrus,right posterior lobe of cerebellum,besides motor cortex.③With disease evolution,regions of decreased ReHo gradually increased andinvolved right posterior lobe of cerebellum,bilateral OFC,rectus gyri and leftmiddle-inferior temporal gyrus.At the same time,increased ReHo was located inbilateral mid-occipital gyri,anterior insula,cingulated gyri,superior temporal gyri,and right middle temporal gyrus,right thalamus.No changes were observed inbilateral motor cortex.Conclusion①Regions of decreased ReHo was located mainly in motor cortexand left DLPFC.②In early stage of PD,bilateral posterior insula,DLPFC,parietallobe and right superior temporal gyms,fight posterior lobe of cerebellum besidesmotor cortex was impaired.OFC impaired occurred in advanced stage.③In restingstate,motor cortex showed regional neuron activity decreased and no markedvariation with disease progression.Decreased cognitive impairment may be the maincause of motor control deterioration.