| Objective:Cognitive impairment(CI), according to the severity, can be divided into mild cognitive impairment(MCI) and dementia. Alzheimer’s disease(AD) is a common pathologic type of patients with dementia. Hydrogenproton magnetic resonance spectroscopy(1HMRS) plays an important role in the diagnosis and differential diagnosis of CI. Through the application of 3.0T magnetic resonance machine, the topic analyzed and compared the changing characteristics of metabolites in bilateral hippocampus among MCI, AD patients and the aging, discussed the difference of metabolite ratios in the hippocampus among the three kinds of people and the correlation with Mini-Mental State Examination(MMSE) scores and event related potential(ERPs) P300, aiming to assess application value of 1HMRS in the early diagnosis and differential diagnosis.Method:From December 2012 to January 2015, the patients were chosen from neurology inpatient department and outpatient clinic in the fourth hospital of Hebei Medical University to carry out the collection of medical records, MMSE score and P300 test. According to the clinical features, people were divided into three groups: group MCI(n=30), group AD(n=28) and group normal cognitive state(n=30). All the patients of group MCI were according to the standards of MCI diagnostic standards which was recommended by the commentary of dementia and cognitive impairment in 2010. Of the patients, there were 16 males and 14 females. The oldest was 81 years old while the youngest was 65 years old. The average age was 72.10±4.82 years old. All the patients of group AD met the standards of NINCDS-ADRDA probable AD, of whom, 12 males and 16 females. The oldest was 81 years old and the youngest was 66 years old. The average age was 72.36±4.38 years old. There were 15 males and 15 femates in group NC. The oldest was 78 years old and the youngest was 64 years old. The average age was 70.20±4.16 years old.We adopted 3.0T superconducting magnetic resonance machine produced by Siemens company to carry on conventional MRI scans on all the research objects in order to rule out other diseases which caused damage to the memory, then gathered 1HMRS of bilateral hippocampal brain region of interests, automatically measuring the concentration of the metabolites, included N-acetylaspartate(NAA), creatine(Cr), Inositol(Ins), choline(Cho) and calculated their corresponding ratios, including NAA/Cr, Ins/Cr, NAA/Ins and Cho/Cr. We compared the differences between the ratios of NAA/Cr, Ins/Cr, NAA/Ins, Cho/Cr in the left and right sides of each group of NC, MCI and AD and analyzed the correlation among parametric variation, MMSE score and P300. Statistical analysis: We adopted SPSS 19.0 software for analysis and processing. The main statistical methods included chi-square test, Homogeneity of variance test, analysis of variance, LSD test and Spearman correlation analysis, et al. With P<0.05 represented a statistically significant difference.Results:1 General information and MMSE scoreThe object of study, a total of 88 cases, of which the group MCI of 30 cases, group AD of 28 cases, group NC of 30 cases. Three groups of age, sex, years of education compared to the statistical analysis showed no significant difference(P>0.05).MMSE score MMSE score in group MCI(28.07±1.08) points; group AD(19.96±2.46) points; group NC(29.20±0.81) points. Compared with each other of the three groups, the statistical analysis showed there were significant differences(P<0.05).2 The changes of the left hippocampus metabolites parameters in 1HMRSNAA/Cr: Group MCI and group AD, the average ratio respectively(1.37±0.22) and(1.27±0.27). Comparing the two groups, the statistical analysis showed no significant differences(P>0.05); Respectively compared with group NC(1.55±0.39), the statistical analysis showed there were significant differences(P<0.05).Ins/Cr: Group MCI and group AD, the average ratio respectively(0.69±0.18) and(0.96±0.18). Comparing the two groups, the statistical analysis showed significant differences(P<0.05); Respectively compared with NC group(0.54±0.15), the statistical analysis showed there were significant differences(P<0.05).NAA/Ins: Group MCI and group AD, the average ratio respectively(2.09±0.50) and(1.36±0.39). Comparing the two groups, the statistical analysis showed there were significant differences(P<0.05); Respectively compared with NC group(2.89±0.56), the statistical analysis showed there were significant differences(P<0.05).Cho/Cr: Group MCI, AD and NC, the average ratio respectively(0.93±0.12),(0.97±0.10) and(0.97±0.21). Compared with each other of the three groups, the statistical analysis showed there were no significant differences(P>0.05).Compared group AD with group MCI, there were no significant differences in NAA/Cr value, while the Ins/Cr value had the remarkable differences, which indicated that Ins/Cr value increased as early as NAA/Cr value decreased, suggesting that CI patients with the pathological changes of glial proliferation may be earlier than neuronal damage.3 The changes of the right hippocampus metabolites parameters in 1HMRSNAA/Cr: Group MCI and group AD, the average ratio respectively(1.33±0.23) and(1.32±0.27). Comparing the two groups, the statistical analysis showed no significant differences(P>0.05); Respectively compared with group NC(1.63±0.24), the statistical analysis showed there were significant differences(P<0.05).Ins/Cr: Group MCI and group AD, the average ratio respectively(0.88±0.27) and(0.89±0.21). Comparing the two groups, the statistical analysis showed no significant differences(P>0.05); Respectively compared with group NC(0.62±0.18), the statistical analysis showed there were significant differences(P<0.05).NAA/Ins: Group MCI and group AD, the average ratio respectively(1.67±0.57) and(1.55±0.38). Comparing the two groups, the statistical analysis showed no significant differences(P>0.05); Respectively compared with group NC(2.92±0.11), the statistical analysis showed there were significant differences(P<0.05).Cho/Cr: Group MCI, AD and NC, the average ratio respectively(0.96±0.08),(0.95±0.14) and(0.98±0.02). Compared with each other of the three groups, the statistical analysis showed there were no significant differences(P>0.05).Compared group AD with group MCI, the left hippocampal Ins/Cr, NAA/Ins ratios were significantly different, while the right hippocampal area ratio of Ins/Cr, NAA/Ins had no significant difference, indicated that CI patients on the left side of the metabolite ratio changed earlier than the right.4 P300 latency(PL) and amplitude(Amp)PL: The average value of group MCI, AD and NC respectively(397.97±45.35)ms,(419.25±38.54)ms and(351.70±25.70)ms. Compared with each other of the three groups, the statistical analysis showed there were significant differences(P<0.05).Amp: The average value of group MCI, AD and NC respectively(6.75±2.93)u V,(5.75±3.36)u V and(10.51±4.51)u V. Compared group MCI with group AD, there was no significant difference(P>0.05); Respectively, compared with group NC, there were significant differences(P<0.05).5 The Correlation between NAA/Ins ratio in the left hippocampus and MMSE scores, P300Left hippocampal NAA/Ins ratio average of(1.74±0.58), MMSE score average of(24.16±4.49) points, PL average of(408.24±44.27)ms in patients included group MCI and group AD. Statistical analysis showed that NAA/Ins ratio of the patients was positively correlated with MMSE scores(r=0.626, P<0.05); and negatively correlated with PL(r=-0.333, P<0.05). The results showed that patients with lower NAA/Ins ratio, the lower the MMSE score, while P300 PL extended.Conclusions:1 1HMRS, as a non-invasive diagnostic technique, has a higher sensitivity in the early diagnosis and differential diagnosis of MCI and AD.2 The increase of Ins/Cr ratio apeared earlier than the decline of NAA/Cr ratio, which hints glial proliferation of CI patients may be earlier than neuron damage. NAA/Ins ratio decreased to appear early, can be used as the objective reference for the early diagnosis of MCI and AD patients.3 The parameter variations of left hippocampus metabolites in right-handed CI patients was more significant than the right, which hints that in the process of disease progression, hippocampus apears asymmeric involvement and the left is more obvious.4 MMSE score, P300 examination and analysis of 1HMRS can synthetically assess the CI degree of patients and can provide objective foundations for instructing clinical medication and improving outcomes. |
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