Phase Encoding Without Gradients at High Field: TRASE RF MRI at 3T

Scott B. King¹, Peter Latta¹, Vyacheslav Volotovskyy¹, Jonathan C. Sharp², Boguslaw Tomanek²

Recently, a new RF B1-field method of spatial encoding was introduced whereby k-space is traversed in the phase encoding direction without using B0 field gradients, but by applying different B1-phase gradient fields produced by a Tx-array, TRansmit Array Spatial Encoding (TRASE). We demonstrate 1D gradient-free TRASE MRI of large phantom and fixed brain within inhomogeneous B1 fields at 3T using both a switched 1- and 8-channel transmitter, and a 2-channel spiral birdcage array. Once perfected, this new silent k-space traversal method will allow the exploration of new data acquisition schemes that may reduce gradient related artifacts/deficiencies and improve imaging speed.