The Study Of Hippocampal 3-dimensional MRI Features In Amnestic Mild Cognitive Impairment

Background Alzheimer's disease is the most common neurodegenerative disorder in the elderly.As our population ages,the incidence of Alzheimer's disease will increase.Mlid cognitive impairment is an intermediate cognitive state between normal ageing and dementia.10%-15%patients having mild cognitive impairment convert dementia annually.Most patients having aMCI,amnestic mild cognitive impairment(aMCI),a subtype of mild cognitive impairment develop Alzheimer's disease.The hippocampus is one of the first regions affected by Alzheimer's pathology.Surface-based hippocampal analytic technique can detect microstructural change in the early stage of cognitive impairment through 3-dimensional mesh reconstruction of hippocampal magnetic resonance imaging.Using this innovative surface-based hippocampal analytic technique we analysed the structural magnetic resonance hippocampal data of 15 aMCI and 16 healthy subjects.Patients diagnosed aMCI whose hippocampal morphologic features can provibe MRI evidence for diagnosing Alzheimer's disease in early stage.Objective To identify the pattern of hippocampal characteristics of 3-dimensional magnetic imaging in patients diagnosed as having subtypes of amnesic mild cognitive impairment(aMCI) using surface-based hippocampal analytic technique.Methods All subjects were recruited by a screening in the retired military personnel. In the screening,those with cognitive impairment was reinvestigated with Mini-Mental State Examination(MMSE),Montreal Cognitive Assessment(MOCA), Activity of Daily Living Scale(ADL),memory for figure,word-list memory, trial-making A examination and insight test.15 subjects with aMCI and 16 healthy controls who were equivalent in age and education(NC) were selected.3-dimensional magnetic imaging was carried out on a GE-Hc-3.0T MR scanner(GeneralElectric, United States) using a standard circularly polarized head coil.After the imaging was acquired,the borders of the hippocampus were manually traced in coronal view using the software of InsightSNAP1.4.1,hippocampal volume was computed automatically then statistical analyses Hippocampal 3-dimension MRI transformed into 3D parametric surface mesh models.Hippocampal radial distance measures were statistically compared between two groups.The radial atrophy significance maps were adjusted for multiple comparisons.Hippocampal morphological difference maps of aMCI in contrast with NC were acquired.Results:1.Balance analysis between aMCI and NCThere were no statistical difference in age and education between aMCI and NC, which were comparable.2.Comparison of neuropsychological test between aMCI and NCThere were investigated significant difference between aMCI and NC in MMSE, MOCA,memory for figure and word-list memory,and none in trial-making A,clock drawing and figure naming examination.3.Comparison of hippocampal volume between aMCI and NCAt a global level,the volume of the left and right hippocampus did not differ significantly between aMCI and NC subjects(t-test,P＞0.05).4.Surface-based hippocampal morphologic analysesWe found regional atrophy of the lateral and inferior hippocampus area bilaterally corresponding to the CA1 and subiculum hippocampal subfield and reginal expand in the heads and tails bilaterally in aMCI compared with NC.Conclusion:Through surface-based hippocampal morphologic analyses,we found partial regional atrophy of hippocampus at some degree,mainly localized in the lateral and inferior hippocampus area bilaterally in aMCI compared with NC.This selective regional atrophy of hippocampal 3-dimensional MRI morphologic features in aMCI is associated with aMCI patients' memory dysfunction.