Multi-voxel Magnetic Resonance Spectroscopy of Cerebral Metabolites in Healthy Adults at 3 Tesla

Rationale and Objectives

The objective of this study was to determine how metabolite values (total N-acetyl aspartate [tNAA], glutamate plus glutamine [Glx], total choline [tCho], myoinositol [mI], and total creatine [tCr]) vary across brain regions in healthy subjects. This study was implemented to create an internal reference database for patients with psychiatric disorders and epilepsy.

Materials and Methods

Using the multivoxel technique with a voxelwise phantom calibration on a 3-T magnetic resonance imaging scanner, metabolite levels of 29 healthy controls (13 men, 16 women; average age, 29 years) were obtained from the hippocampi, basal ganglia, insula cortex, cingulum, and precuneus. Additionally, gray and white matter metabolite values were obtained from the frontal and parietal lobes.

Results

No significant effect of gender was noticed. The total magnitude of variation was greatest for Glx, followed by tNAA, mI, tCho, and tCr. Glx/tCr, Glx, and tCr were increased in gray matter, while tNAA/tCr, tCho/tCr, respectively tNAA and tCho, were elevated in white matter. These findings indicate (1) anterior-to-posterior increases of tNAA/tCr and Glx/tCr, respectively tNAA and Glx, along the midline in gray matter (cingulum); (2) increased tNAA/tCr, respectively tNAA, in white matter in the fiber tracts of the precentral region; (3) an accentuated anterior-to-posterior increase of tCr in the insula cortex; and (4) an anterior-to-posterior decrease of tCho/tCr and tCho in white matter.

Conclusions

There are significant metabolic differences within tissue types and within tissue types at different locations; therefore, the spectra and metabolite values presented should provide a useful internal reference for both clinical and research studies.

Key Words: Spectroscopy, MRS, healthy adults, 3 telsa MRI