Clinical Study On The Early Diagnosis Of Elderly Patients With Cognitive Deficiency Using Functional MRI

PartⅠ:Brain microstructural alterations in elderly patients with cognitive deficiency: a diffusional kurtosis imaging studyObject: Diffusional kurtosis imaging(DKI), a new technology of magnetic resonance imaging based on diffusion tensor imaging(DTI), can examine the non-Gaussian diffusion effects of water known to occur in the brain. We investigated the capability of DKI parameters for detecting microstructural changes in the hippocampus and the temporal, parietal and frontal white matter(WM) in elderly patients with mild cognitive impairment(MCI) and Alzheimer’s disease(AD). We also sought to analyse the correlation between these DKI parameters and MMSE score.Materials and Methods: 54 subjects: 20 MCI patients, 16 AD patients and 18 normal controls(NC groups) were involved in this study. All the subjects were required to be evaluated their cognitive function with mini- mental state examination(MMSE). Then magnetic resonance imaging and DKI were performed. The bilateral mean kurtosis(MK), mean diffusivity(MD) and fractional anisotrophy(FA) in the temporal, parietal and frontal white matter as the MK/MD/FA values, and volumes of the hippocampus, were compared for the three groups using analysis of variance. The correlations between regional DKI parameters or hippocampus volume and MMSE score were tested using Pearson correlation.Results: ①In MCIs, significantly decreased kurtosis parameters were observed in both right and left hippocampus as compared to NCs. No significant difference in HCV was found between the MCI and NC groups. ②In ADs, significantly increased diffusivity and decreased kurtosis parameters were observed in bilateral hippocampus, parietal and frontal WM and the left temporal WM as compared to NCs. Only in the parietal WM, significantly decreased FA values were observed. There were significant differences between the AD and NC groups and between the AD and MCI groups in terms of normalized bilateral hippocampus volume(HCV). ③Both left and right hippocampus volume, the MK values in bilateral hippocampus, parietal WM and the right frontal WM exhibited the positive correlation with MMSE score. Furthermore, the negative correlation was present between the MD values and MMSE score in bilateral hippocampus, temporal, frontal WM and the left parietal WM.Conclusion: The bilateral hippocampal MK values may be more sensitive than HCV in the diagnosis of elderly MCI patients. DKI parameters, which can characterize microstructural changes in the brain tissue, may provide sensitive imaging imformation for assessing the severity of cognitive deficiency.PartⅡ:Susceptibility weighted MRI measures brain iron deposition in mild cognitive impairmentObject: It’s known that brain iron occur excessively in a variety of neurodegenerative disorders. We investigated features of brain iron deposition in patients with MCI and AD using susceptibility- weighted imaging(SWI) and analysed its correlation with MMSE score. The other purpose of this study is to test whether the increase of iron concentration may help predict cognitive decline.Materials and Methods: 18 normal control subjects, 22 patients with MCI and 20 patients with AD were included in this study. All the subjects were required to be evaluated their cognitive function with MMSE table, and then underwent conventional magnetic resonance imaging(MRI) and SWI using axial/oblique coronal sequences. Phase images were used to calculate bilateral iron deposition in the hippocampus and caudete nucleus. The radian angle value was calculated and compared between the three participant groups. Patients with MCI underwent neuropsychologic follow-up after one year. SWI was performed on MCIs again in order to compare iron deposition in the hippocampus and caudete nucleus between pa tients with stable MCI and those with progressive MCI.Results: ①The difference in radian angle value was significant between the MCI and control groups in the left(L)- hippocampus, L-head of the caudate nucleus. The difference in radian angle value was significant between the AD and control groups in bilateral hippocampus and L-head of the caudate nucleus. ② Radian angle value in bilateral hippocampus exhibited the correlation with MMSE score. ③During follow-up, 5 of these 22 MCI patients converted to AD(22.7%). The 5 converters had significantly greater increases in radian angle values in the L- hippocampus than non-AD converters.Conclusion: Regionally excessive iron deposition in brain may have association with cognitive deficiency. For patients with MCI, greater increase of iron concentration in the L-hippocampus may provide predictive information about the conversion from MCI to AD.