A Novel Approach to Investigate 1D TRASE MRI Pulse Sequence Performance in Imperfect B1 Fields

The Transmit Array Spatial Encoding (TRASE) MRI technique uses transmit radio-frequency (RF) magnetic field (B₁) phase gradients for spatial encoding. Imaging performance is reliant on |B₁| homogeneity. This study investigates the performance of a set of variants of 1-dimensional TRASE under conditions of |B₁| inhomogeneity. Both Bloch equation simulations and experimental confirmations are presented. Results show that one variant of the sequence allows imaging over ~90% of the FOV for Δ|B₁| = ± 15% allowing the use of practical B₁ transmit coil designs. This improves upon the previous sequence which generated ~75% usable field-of-view (FOV).