Gadi Goelman

Transverse Hadamard spectroscopic imaging technique

Abstract A new Hadamard spectroscopic imaging (HSI) technique based on transverse magnetization encoding is presented and tested experimentally. Using average Hamiltonian theory, we have defined the conditions under which a proper combination of gradients and RF functions can produce, as a good approximation, a plane rotation whose flip angle is the Fourier transform of the RF function even in the presence of chemical-shift and B0 inhomogeneity. Hence, the generation of RF pulses to perform any order HSI is simplified.

Spectral localization of arbitrarily shaped regions of interest (SLASH) using single voxel signals

A method for obtaining localized spectra from arbitrarily shaped regions of interest is described. When a sample consists of homogeneous compartments or domains, spectra localized in each compartment can be obtained from signals of single voxels with regular shapes by solving a set of simultaneous linear equations. Experimental demonstrations on a phantom and on human brain in vivo for a two compartment, two voxel case are presented. The issue of signal-to-noise ratio is also discussed.