Magnetic resonance spectroscopy in evaluating hippocampus changes of patients with mild cognitive impairment

BACKGROUND: Mild cognitive impairment (MCI) represents early status of Alzheimer's disease. Magnetic resonance spectroscopy (MRS) has been used in early diagnosis and identification as well as monitoring of Alzheimer's disease. However, little data is available concerning relationship between cognitive impairment and changes of biochemical metabolites. OBJECTIVE: To investigate the relationship between cognitive impairment and changes of biochemical metabolites as well as volumes of hippocampal formation (HPF) in MCI patients, accordingly to evaluate the roles of MRS in the diagnosis and the state monitoring of MCI. DESIGN, TIME AND SETTING: Case-contrast observation. The study was performed at the Outpatient Department and ward of Department of Neurology, Lianyungang Hospital of Xuzhou Medical College between September 2006 and December 2008. PARTICIPANTS: A total of 20 MCI patients were selected and 20 elderly with normal cognition, matched in gender, age and education, were selected. METHODS: Before volumes of the left HPF were measured by MRS, mini-mentalstate examination (MMSE), the Montreal Cognitive Assessment (MoCA), activities of daily living (ADL), clinical dementia rating (CDR) and Wechsler memory scale (WMS) were used to examine each participant. In addition, the N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (ml)/Cr of HPF were obtained. Moreover, the correlations between the NAA/Cr, Cho/Cr, ml/Cr and the volume of HPF in MCI group were analyzed. MAIN OUTCOME MEASURES: Volume of HPF, NAA/Cr, Cho/Cr, and ml/Cr. RESULTS: Compared with control group, reduced NAA/Cr (P < 0.01), increased ml/Cr (P < 0.01) and reduced volume of HPF (P < 0.05) were found in the MCI subjects. No significant difference was observed in the Cho/Cr between two groups (P > 0.05). In the MCI group, the NAA/Cr remarkably correlated with MoCA, memory quotient, and volumes of left HPF (P < 0.01); Cho/Cr significantly correlated with memory quotient (P < 0.05); ml/Cr has remarkably negative correlation with MoCA and volumes of left HPF (P < 0.01), but positive correlation with memory quotient (P < 0.01). The volumes of left HPF also remarkably correlated with MoCA and memory quotient (P < 0.01). CONCLUSION: An increased ml/Cr ratio, a decreased left HPF volumes and NAA/Cr ratio were observed in the MCI patients. Significant correlations between biochemical metabolites of HPF, HPF volumes and MoCA as well as memory quotient were observed. MRS plays an important role in the diagnosis and state monitoring of MCI.