Brain Regional Metabolite In Mild Cognitive Impairment: A ~1H-MRS Study

Objective To study the brain regional metabolite in the mild cognitive impairment(MCI) patient with the proton magnetic resonance spectroscopy (1H-MRS) in the posterior cingulate gyri, the middle frontal gyrus cortex and the left occipital cortex,and compared with the 1H-MRS findings in the same regions of interest of the Alzheimer's Disease(AD) patient and the normal control, then to explore the characteristic changes of 1H-MRS in the MCI and to assess 1H-MRS in the diagnosis and differential diagnosis of MCI.Methods A single voxel 1H-MRS studies were performed to twenty patients with MCI, twenty patients with AD, and twenty normal control volunteers at Philips Intera Achieva 3.0T clinical scanner. The mode of spectral acquisition was STEAM technique. The region of interest(ROI) were in the posterior cingulate gyri, the middle frontal gyrus cortex and the left occipital cortex, localizing 2cm×2cm×2cm voxels. After scanning, we got spectrum and the metabolites in the spectra collected for quantilation included N-acetyl aspartate(NAA),choline(Cho),creatine(Cr) and myo-inositol(mI). The ratios of NAA/Cr, mI/Cr and Cho/Cr were calculated and compared among the groups.Results The NAA/Cr ratios of the posterior cingulate gyri and the middle frontal gyrus cortex region between AD group and MCI group, AD group and NC group were significantly different(P<0.05). The mI/Cr ratios of the posterior cingulate gyri and the middle frontal gyrus cortex region among the three groups were significantly different(P<0.05).The Cho/Cr ratios of the posterior cingulate gyri and the middle frontal gyrus cortex region among the three groups showed no significant difference(P <0.05). The NAA/Cr ratios, the mI/Cr ratios and the Cho/Cr ratios of the left occipital cortex among the three groups showed no significant difference(P<0.05). Conclusion We found the reduction of NAA/Cr ratios and the increase of mI/Cr ratios in the posterior cingulate gyri and the middle frontal gyrus cortex in patients with AD, but only the increase of mI/Cr ratios in patients with MCI. 1H-MRS could provide biochemical and metabolic information on the patients with MCI and AD by noninvasively, which is helpful for the early diagnosis of MCI and can be a tool for differentiating MCI from AD.