Selective excitation in the rotating frame with hard pulses

Abstract

A new sequence of hard pulses for selective excitation in the rotating frame is proposed. A desired excitation spectrum M_xy(v₁) can be obtained if the lengths of the pulses are modulated. The relationship between the shape of the modulation and the excitation spectrum is derived using the rotation-operator formalism. This approach is also applied to the DANTE sequence and similarities and differences between these two sequences are discussed. An application of the proposed sequence to obtaining a depth discrimination with surface coils was investigated and experiments on phantoms were performed. Preliminary in vivo selective spectra were also obtained.