Simultaneous multivolume spectroscopy (simuvosp) using local techniques

Abstract

MR spectra simultaneously acquired from different locations in the human body may be obtained with the SIMUVOSP technique (Simultaneous Multivolume Spectroscopy). SIMUVOSP is based on multifrequency selective RF pulses which encode positional information of the spins into the phase of the MR signal. This paper describes SIMUVOSP strategies for 1H, 31P and 13C spectroscopy. For 1H SIMUVOSP the STEAM experiment may be modified by replacing the selective RF pulses with SIMUFREX pulses (Simultaneous Multifrequency Excitation pulses). This modification allows the simultaneous spectroscopic examination of different regions in the human brain. For 31P SIMUVOSP the ISIS method is combined with SIMUFRIN (Simultaneous Multifrequency Inversion) pulses, which generate the inversion of multiple regions during the RF pulse. An application of 31P SIMUVOSP is the study of the metabolic heterogeneity of the high energy phosphates within the human body. For 13C spectroscopy a localized polarization transfer experiment is combined with multivolume excitation. In this way SIMUVOSP on protons is extended to 13C multivolume spectroscopy.