Hybrid Three Dimensional (1D‐Hadamard, 2D‐Chemical Shift Imaging) Phosphorus Localized Spectroscopy of Phantom and Human Brain

Abstract

A hybrid of two localized spectroscopy techniques, chemical shift imaging (CSI) and Hadamard spectroscopic imaging (HSI), is used to obtain an array of 16 x 16 x 4 (3 x 3 x 3 cm3 voxels) proton-decoupled phosphorus (31P) spectra of human brain. For equal spatial resolution, this organ's oblate shape requires fewer axial than coronal or sagittal slices. These different spatial requirements are well suited to 1D, 4th order, transverse HSI in the axial direction, combined with 2D 16 x 16 CSI in the other two orientations. The reduced localization matrix (16 x 16 x 4 over just the brain versus a cubic-16 x 16 x 16 matrix of equal resolution, over the entire head) may proportionally shorten data acquisition if the voxel size is not signal-to-noise limited. In addition, the use of Hadamard encoding can improve the intervoxel spectral isolation.

3D localized in vivo1H spectroscopy of human brain by using a hybrid of 1D‐hadamard with 2D‐chemical shift imaging

“…Fig. 3e (12). This -10% contamination in the 1.5-cm partitions in the HSI direction is analogous to CSIs "voxelbleed" with the following distinctions: it affects only adjoining slices not the entire FOV; does not depend on the FIG.…”

Multiple-voxel double-quantum lactate-edited spectroscopy using two-dimensional longitudinal Hadamard encoding

“…The advantages of using Hadamard encoding as a localization strategy have been fully discussed elsewhere (23,24,(31)(32)(33) Hadamard encoding is insensitive to B 1 imperfections and the repetition time; d) the method gives spectra with high signal-to-noise ratio per unit time; and e) data can be recovered if acquisition is interrupted. However, there are also limitations to the use of longitudinal Hadamard encoding.…”

A localized double-quantum filter for in vivo detection of taurine

“…Second, only four ISIS steps are required instead of eight to achieve 3D localization, thus reducing sensitivity to motion. Moreover, by switching the single band inversion pulses to multiple band inversion pulses and using Hadamard encoding, taurine editing with multiple-voxel inplane localization can be obtained (40).…”