Quantitative multivoxel proton MR spectroscopy study of brain metabolites in patients with amnestic mild cognitive impairment: a pilot study

The purpose of this study is to investigate brain metabolic changes in patients with amnestic mild cognitive impairment (aMCI) using multivoxel proton MR spectroscopy (1H-MVS). Fourteen aMCI patients and fifteen healthy control subjects participated in this experiment. All MR measurements were acquired using a 1.5-T GE scanner. 1H-MVS point resolved spectroscopy (2D PROBE-CSI PRESS) pulse sequence (TE = 35 ms; TR = 1,500 ms; phase × frequency, 18 × 18) was used for acquiring MRS data. All data were post-processed using Spectroscopy Analysis by General Electric software and linear combination of model (LCModel). The absolute concentrations of N-acetylaspartate (NAA), choline (Cho), myoinositol (MI), creatine (Cr), and the metabolite ratios of NAA/Cr, Cho/Cr, MI/Cr, and NAA/MI were measured bilaterally in the posterior cingulate gyrus (PCG), inferior precuneus (Pr), paratrigonal white matter (PWM), dorsal thalamus (DT), and lentiform nucleus (LN). Patients with aMCI displayed significantly lower NAA levels in the bilateral PCG (p < 0.01), PWM (p < 0.05), and left inferior Pr (p < 0.05). The metabolite ratio of NAA/MI was decreased in the bilateral PCG (p < 0.01) and PWM (p < 0.05) and in the left DT (p < 0.01). NAA/Cr was decreased in the left PCG (p < 0.01), DT (p < 0.05), right PWM (p < 0.05), and LN (p < 0.05). However, MI/Cr was elevated in the right PCG (p < 0.01) and left PWM (p < 0.05). Significantly increased Cho level was also evident in the left PWM (p < 0.05). Our observations of decreased NAA, NAA/Cr, and NAA/MI, in parallel with increased Cho and MI/Cr might be characteristic of aMCI patients.