Regional N-acetylaspartate reduction in the hippocampus detected with fast proton magnetic resonance spectroscopic imaging in patients with Alzheimer disease

Objective: To detect regional metabolic changes that resemble the expected spatial pattern of neuronal loss in patients with Alzheimer disease (AD). Methods: Thirty-four patients with AD and 22 healthy control subjects were included in the study. Single-slice fast proton spectroscopic imaging was performed in parallel angulation to the temporal lobes. Proton spectra were selected from the hippocampus, the lateral temporal lobe, and the occipital lobe of both hemispheres to determine metabolite concentration of N-acetylaspartate (NAA), total creatine (tCr), including phosphocreatine and creatine, and choline-containing compounds (Cho). The metabolic ratios of NAA/tCr and Cho/tCr were calculated and compared between patients with AD and healthy volunteers. Results: The NAA/tCr ratios were significantly reduced in the left (F-1,F-1 = 4.34, P = .04) and right hippocampus (F-1,F-1 = 9.96, P = .003) in patients with AD. The Cho/tCr ratios remained unchanged in both hippocampi. There was no significant change of either NAA/tCr or Cho/tCr in the lateral temporal and occipital lobes of patients with AD. Conclusion: This study provides evidence that fast proton spectroscopic imaging may detect the regional pattern of disturbed neuronal integrity in patients with AD with high spatial resolution in a short acquisition time.