The importance of the voxel size in clinical 1H spectroscopy of the human brain

Abstract

It is demonstrated that it is possible to acquire two volume selective ¹H NMR spectra of human brain in vivo, consisting of voxels of 1.5 × 1.5 × 1.5 cm³, within 14 min with a good S/N ratio. This is mainly achieved by the application of a PRESS sequence generating a spin‐echo of the VOI at 135 ms in conjunction with the STABLE technique by which two spectra can be recorded in an interlaced mode. The B_o homogeneity over such small voxels is considerably higher than over larger voxels. With these methodological improvements it is possible to observe morphological heterogeneity of tumors. The results indicate that spectral changes seem to correlate with the metabolic state of the tumor rather than the tumor type. Additionally the spectrum of a patient with multiple sclerosis suggests that even differentiation between tumors and other lesions might not be possible.