Localized high‐resolution proton NMR spectroscopy using stimulated echoes: Initial applications to human brain <i>in vivo</i>

TLDR

The STEAM sequence localizes a 64‑ml occipital VOI by exciting three intersecting slices, uses CHESS pulses for water suppression, and acquires spectra in 1 s to 10 min on a 1.5‑T MRI. The technique produced 0.05‑ppm proton spectra of healthy volunteers on a 1.5‑T MRI, detecting metabolites such as N‑acetyl aspartate, glutamate, creatine, choline compounds, taurine, inositols, and lactate up to 0.5 mM. © 1989 Academic Press, Inc.

Abstract

Abstract Water‐suppressed localized proton NMR spectroscopy using stimulated echoes has been successfully applied to detect metabolites in the human brain in vivo . The STEAM spectroscopy sequence allows single‐step localization by exciting three intersecting slices. Water suppression is achieved by preceding chemical‐shift‐selective (CHESS) rf pulses. High‐resolution (0.05 ppm) proton NMR spectra of healthy volunteers have been obtained on a conventional 1.5‐T whole‐body MRI system (Siemens Magnetom). Volumes‐of‐interest (VOI) of 64 ml(4 × 4 × 4 cm 3 ) were localized in the occipital area of the brain and spectra were recorded within measuring times ranging from I s (single scan) to about 10 min. The experimental procedure is described in detail. Resonance assignments include acetate, N ‐acetyl aspartate, γ‐amino butyrate, glutamine, glutamate, aspartate, creatine and phosphocreatine, choline‐containing compounds, taurine, and inositols. Cerebral lactate was found to be at a maximum concentration of 0.5 m M when assuming N ‐acetyl aspartate in white matter to be 6 m M . © 1989 Academic Press, Inc.