In vivo FID-based 3D Multivoxel Longitudinal Hadamard Spectroscopic Imaging In the Human Brain at 3 T

摘要

We propose and demonstrate a full 3D longitudinal Hadamard Spectroscopic Imaging (L-HSI) scheme for obtaining chemical shift maps, by employing adiabatic inversion pulses to encode the spins’ positions. The approach offers several advantages over conventional Fourier-based encoding methods, including a localized point spread function; no aliasing, allowing for VOIs smaller than the object being imaged; an option for acquiring non-contiguous voxels; and inherent outer volume rejection. The latter allows for doing away with conventional outer volume suppression schemes, such as PRESS or STEAM, and acquiring non spin-echo spectra with short acquisition delay times, limited only by the excitation pulse’s duration. This, in turn, minimizes T2 decay, maximizes the signal to noise ratio, and reduces J-coupling induced signal decay. Results are presented for both a phantom and an in-vivo healthy volunteer at 3T.