Localized proton NMR spectroscopy in different regions of the human brain <i>in vivo.</i> Relaxation times and concentrations of cerebral metabolites

TLDR

High‑resolution proton NMR spectra were obtained from 27–64 ml volumes of interest in the insular, occipital, thalamic, and cerebellar regions using STEAM sequences on a 1.5‑T Siemens Magnetom system. The spectra revealed metabolites with T1 ≈ 1100–1700 ms and T2 ranging 100–500 ms, with NAA methyl protons showing the longest T2 (~500 ms) in occipital white matter, NAA concentrations 35 % higher in gray/white matter and 13–18 mM (2–3× higher than prior reports), lactate peaking at ~1.0 mM, while choline and creatine T2 values were regionally uniform. © 1989 Academic Press, Inc.

Abstract

Abstract High‐resolution proton NMR spectra of normal human brain in vivo have been obtained from selected 27‐ and 64‐ml volumes‐of‐interest (VOI) localized in the insular area, the occipital area, the thalamus, and the cerebellum of normal volunteers. Localization was achieved by stimulated echo (STEAM) sequences using a conventional 1.5‐T whole‐body MRI system (Siemens Magnetom). The proton NMR spectra show resonances from lipids, lactate, acetate, Nacetylaspartate (NAA), γ‐aminobutyrate, glutamine, glutamate, aspartate, creatine and phosphocreatine, choline‐containing compounds, taurine, and inositols. While T 1 relaxation times of most of these metabolites were about 1100–1700 ms without significant regional differences, their T 2 relaxation times varied between 100 and 500 ms. The longest T 2 values of about (500 ± 50) ms were observed for the methyl protons of NAA in the white matter of the occipital lobe compared to (320 ± 30) ms in the other parts of the brain. No significant regional T 2 differences were found for choline and creatine methyl resonances. The relative concentrations of NAA in gray and white matter were found to be 35% higher than those in the thalamus and cerebellum. Assuming a concentration of 10 m M for total creatine the resulting NAA concentrations of 13–18 m M are by a factor of 2–3 higher than previously reported using analytical techniques. Cerebral lactate reached a maximum concentration of about 1.0 m M . © 1989 Academic Press, Inc.