High-Accuracy Ultra-short Inner-Volume Saturation Pulse for 3D Steady-State Imaging

Motivation: Spatially-tailored excitation is often favorable in MR applications where the region-of-interest only occupies a small portion of the whole FOV. Goal(s): In this study, we sought to design an inner-volume saturation pulse for steady-state imaging. Approach: We propose an extension to the AutoDiff tool by Luo et al. Here we use steady-state magnetization error as the design objective instead of one-time excitation error in the original design. Results: Our proposed pulse design can excite spatially-selective patterns with ultra-short duration(~1.2ms) and high accuracy (error reduced by 50% compared to the original design). Impact: Our pulse design tool enables highly accurate multi-dimensional spatially-tailored excitations with ultra-short pulses. Such pulses can be plugged into functional MRI sequences, and be played in clinical scenarios where ROI-specific excitations can mitigate motion artifacts and reduce image encoding time.