In-vivo spatially encoded magnetic resonance spectroscopy with solvent

Abstract

A binomial pulse generator (32) selectively generates binomial radio frequency excitation pulses (60) which induce magnetic resonance only in selected hydrogen dipoles and suppresses resonance in others. An inversion pulse generator (34) generates a first inversion pulse (70) in the presence of a first magnetic field gradient (72) generated by a gradient control (22). The inversion pulse only inverts the magnetization of resonating nuclei in a first plane defined by the first magnetic field gradient. A second inversion pulse (74) applied in the presence of a second magnetic field gradient (76) inverts the magnetization of resonating nuclei in a second planar region defined by the second magnetic field gradient. A third inversion pulse (78) applied concurrently with a third magnetic field gradient (80) inverts the magnetization of resonating nuclei in a third planar region defined by the third magnetic field gradient. Only resonating nuclei in a volumetric element defined at the intersection of the first, second, and third planes are inverted all three times. The magnetization of other dipoles will have dephased differently from the dipoles in the volumetric element. In this manner, only the dipoles in the volumetric element contribute to a spin echo (82) which follows the third inversion pulse. Data acquired during the third spin echo may be spectrographically analyzed to determine the chemical composition within the volumetric element. Alternately, a phase encoding gradient (90) and a read gradient (92) may be applied as part of the sequence to provide the appropriate phase encoding to the acquired data such that the acquired data can be reconstructed into an image representation.