4D spectral-spatial pulse design for subject-specific fat saturation at 1.5 T

Motivation: Insufficient fat saturation compromises image quality in clinical examinations. Goal(s): To improve the quality of spectral fat saturation resulting in less residual fat signal in the acquired image. Approach: Individual 4D spectral-spatial pulses based on subject-specific field maps and a numerically found trajectory are designed within an online workflow. A universal RF solution is also calculated. Performance is compared to Gaussian and SLR pulses on ten cervical spine datasets and one in-vivo measurement. Results: Simulations show significantly improved fat saturation with individual and universal spectral-spatial pulses, while average water excitation remains low only for individual pulses. The in‑vivo measurement supports the simulation results. Impact: Customized and universal spectral-spatial fat saturation pulses outperform currently used spectral pre-saturation pulses enabling more definitive interpretation of fat‑suppressed MR images. Potential application to a variety of sequences is straightforward by replacing the pre-saturation pulse with our design.