Multivoxel 3D proton spectroscopy in the brain at 1.5 versus 3.0 T: signal-to-noise ratio and resolution comparison

BACKGROUND AND PURPOSE: The new 3.0-T imagers theoretically yield double th e signal-to-noise ratio (SNR) and spectral resolution of 1.5-T instruments. To assess the possible improvements for multivoxel 3D proton MR spectrosco py (H-1-MRS) in the human brain, we compared the SNR and spectral resolutio n performance with both field strengths. METHODS: Three-dimensional 1H-MRS was performed in four 21-29-year-old subj ects at 1.5 and 3.0 T. In each, a volume of interest of 9 X 9 X 3 cm was ob tained within a field of view of 16 X 16 X 3 cm that was partitioned into f our (0.75-cm-thick) 16 X 16-voxel sections, yielding 324 (0.75-cm(3)) signa l voxels per examination. RESULTS: In an acquisition protocol of approximately 27 min, average voxel SNRs increased 23-46% at 3.0 versus 1.5 T in the same brain regions of the same subjects. SNRS for N-acetylaspartate, creatine, and choline, respectiv ely, were as follows: 15.3 +/- 4, 8.2 +/- 2.2, and 8.0 +/- 2.0 at 1.5 T and 22.4 +/- 7.0, 10.1 +/- 3.5, and 10.1 +/- 3.6 at 3.0 T. Spectral resolution (metabolite linewidths) were 3.5 +/- 0.5 Hz; at 1.5 T versus 6.1 +/- 1.5 H z at 3.0 T in approximately 900 voxels. Spectral baselines were noticeably flatter at 3.0 T. CONCLUSION: Expected gains in SNR and spectral resolution were not fully re alized in a realistic experiment because of intrinsic and controllable fact ors. However, the 23-46% improvements obtained enable more reliable peak-ar ea estimation and an H-1-MRS acquisition approximately 50% shorter at 3.0 v ersus 1.5 T.