SPEN with Non-linear Gradient Implementation using Pulseq

Motivation: SPatiotemporal-ENcoding (SPEN) provides an alternative encoding method in MRI by applying a quadratic phase-profile to counteract distortions due to magnetic field inhomogeneities. However, SAR-constraints arising from the use of chirp-RF pulses hinders clinical application. Goal(s): Overcoming current SAR-constraints of SPEN by inducing a quadratic phase, using non-linear gradients to demonstrate the feasibility for a clinical application. Approach: Use of a custom-built matrix gradient coil for generating a quadratic phase-profile instead of SAR-intensive chirp-RF pulses. Results: SPEN with non-linear gradients is possible and delivers comparable results to the chirp-RF pulse method while overcoming its current limitations, demonstrating the potential for clinical application. Impact: Non-linear gradient-based spatiotemporal-encoding overcomes SAR-limitations resulting from the use of chirp-RF pulses for quadratic phase profile generation, while providing comparable results, making clinical application feasible.