Point-Spread-Functions for RF Imaging with TRASE: Implications for Phase Gradient Coil Design and Flip Angle Calibration

Introduction – TRASE – Imaging without B0-Gradients TRASE is a k-space imaging method which uses RF phase gradients instead of B0-gradients (1). A 1D TRASE sequence consists of excitation followed by an echo train in which the RF refocusing pulses are alternately applied with fields ‘A’ and ‘B’. These 2 fields are ideally of uniform magnitude but with positive and negative B1 phase gradients respectively. This results in k-space evolution occurring from one echo to the next, and sampling of an echo train yields a line of k-space. TRASE is a general k-space method and 2D imaging and slice selection have been demonstrated (1).