Application Of Magnetic Resonance Imaging To Explore The Brain Gray Matter Volume Change In The Process Of Brain Aging

Objective: Application of magnetic resonance imaging (MRI) and VBMtechnology to explore the Age-related changes of grey matter volume inhealthy aging.Methods: Study124subject who conform to the eligibility did the braincranial MRI（magnetic resonance imaging） in The Second Affiliated Hospitalof Hebei Medical University from June2012to November2012, with63cases of male and61female cases, ages from22to78years old(mean age45.67years old，median age47years old). All of the cases were performed bymagnetic resonance imaging (MRI) in a regular examination and T1-FFEsequence. Applying of VBM (Voxel-based morphometry) image processinggot gray matter volume. The t test was used to compare data obtained frommale and female cases. The ANOVA was used to compare data obtained fromdifferent age groups. Statistical significance was designated at P<0.05. Finally,VBM-style analyses were run to assess associations of gray matter volumewith age.Results:1VBM analysis of sex differences in gray matter volume: women thanmen have more gray matter volume (t=4.81, P=0.0000, FDR correction).Regional sex dimorphism was present, with men having more GM volume inmid-brain, right inferior temporal cortex (BA20), lingual gyrus, posteriorcingutate, bilateral calcarine area, bilateral limbic lobe, right fusiform gyrus,right middle temporal gyrus, bilateral cuneus and cerebellarhemispheres.Women showed more gray matter in superior frontal gyrus,middle frontal gyrus, inferior frontal gyrus, precentral gyrus, lentiform nucleus,amygdale, insular lobe, anterior piriform cortex of parietal lobe, thalamus,cerebellar vermis and left rolandic operculum. 2VBM analysis of differences age groups in gray matter volume: Weused two-factor variance analysis between young, middle-aged and old group.there were significant main effect of age (P<0.05, FDR correction) betweenevery two groups. Among middle-aged group compared with young group,obvious atrophy of brain regions located in the frontal gyrus, bilateral triangleinferior frontal gyrus, right inferior frontal gyrus, bilateral thalamus in return,middle temporal gyrus, right superior frontal gyrus, middle temporal gyruspole, right insula, the right caudate nucleus and right parietal lobe. Among oldgroup compared with middle-aged group, obvious atrophy of brain regionslocated in right middle temporal gyrus pole, amygdale, posterior cingutate,lingual gyrus, hippocampus/parahippocampus and inferior temporal pole.Compared with young group, old group gray matter widespread decline inwhole brain in addition to the occipital lobe. We found no significantinteraction effect age by gender (P<0.05, FDR correction) each in the twogroups. When without multiple contrast correction, interaction effect could beobserved between the young and middle-aged group in the right middletemporal gyrus, right superior temporal gyrus, left angular gyrus, rightoccipital lobe, central left cingulate gyrus, right inferior frontal gyrus incentral triangle (P<0.001, unadjusted). Women had a protective effect in theabove brain regions.3VBM analysis of gray matter volume on age: The result showed linearnegative correlation of gray matter volume with age(r=-0.529, P<0.001). InVBM analysis result of ROI, Most cortical regions, with the exception ofoccipital pole, showed an extensive and different modes linear negativecorrelation of gray matter volume with age, particularly in the frontal, parietal,and deep cortex. One of the most relevant area was located in the right frontallobe (male), r=-0.83, P <0.001.Conclusion:1There are sex differences in gray matter volume after adjusting totalcerebral volume. In most brain regions, women show greater gray mattervolume than men in the process of aging, such as in the right middle temporal gyrus, right superior temporal gyrus, left angular gyrus, right occipital lobe,central left cingulate gyrus, right inferior frontal gyrus in central triangle.Women had a protective effect in the above brain regions.2In normal aging process, whole brain gray matter volume presents alinear negative correlation on age. However, different exist different shrinkmodel. Generally regions follow the longstanding “last in, first out”hypothesis. The frontal lobe is the most easily affected by age.3Limbic system shows complex age-related shrinkage mode. Fourimportant pattern of age-related changes were highlighted for the limbic subregions:(1) early maturation of gray matter with late loss in the hippocampusand amygdale;(2) an extreme pattern of gray matter preservation in theentorhinal cortex;(3) a flat pattern of reduced gray matter loss in the anteriorcingulat and the parahippocampus;(4) accelerated gray matter loss in theposterior cingulate.