[Fast 1H-NR spectroscopic imaging of the human brain]

Techniques allowing the reduction of the measurement time of MR spectroscopic imaging of protons (1H SI) were studied in a 1.5-T whole-body MR tomograph. The purpose was to facilitate the inclusion of the modality into an MRT routine protocol for examination of the human brain. The techniques were evaluated in a study with 6 healthy volunteers. Shortening of the measurement times can be achieved by reducing the number of phase-encoding steps with spherical k-space sampling, or by using delay times during TR periods for excitation and detection of several slices or echos. Since the tomograph enables echo-planar imaging, multi-gradiennt-echo techniques were implemented, thus sparing one phase-encoding gradient and shortening the measurement time by a factor of N. Due to signal loss, however, this technique is applicable only when the concentration of the metabolites of interest is sufficiently high to obtain a signal-to-noise ratio of at least 2 with a single acquisition.