Alternative winding patterns for twisted solenoid coils with improved characteristics for TRASE MRI

Transmit array spatial encoding (TRASE) is an MRI technique in which spatial encoding is achieved using phase gradients of the B₁ field. This approach offers potential advantages such as hardware simplicity and reduced acoustic noise. In this study, we present a numerical assessment of various winding patterns for twisted solenoid phase-gradient coils, including the twisted solenoid design from prior work (with and without return wire), a double-wound twisted solenoid, and a discrete-loop twisted solenoid. We analyze the magnetic field uniformity and phase linearity of these configurations using Biot-Savart simulations. Our results show that both the double-wound and discrete-loop designs offer similar improvements over existing designs. The discrete-loop pattern requires less wire than the double-wound version, making it the preferred option for practical coil construction and operation in a TRASE MRI system.