High SNR rapid T1-weighted MP-RAGE and MP-FISP using a 3D stack-of-spirals trajectory at 0.55 T

Motivation: Acquiring High SNR T1-weighted MP-RAGE at low field strengths, such as 0.55T, often requires multiple averages due to reduced equilibrium polarization (~30 min for 3 averages). Goal(s): Provide high SNR MP-RAGE (and MP-FISP) within a reasonable scan time (~15 min) using an SNR-efficient readout while mitigating spatial blurring caused by static off-resonance and concomitant fields. Approach: MP-RAGE and MP-FISP sequences with a stack-of-spirals trajectory were implemented with the Pulseq framework. Spatial blurring was mitigated using the MaxGIRF framework implemented in BART. Results: Spiral MP-RAGE achieves comparable image quality and higher SNR relative to Cartesian MP-RAGE given only half of the scan time. Impact: This work demonstrates the feasibility of acquiring high SNR T1-weighted structural brain imaging at 0.55T within a reasonable scan time (~15 min). This opens opportunities for structural neuroimaging and harmonized multi-site studies via code sharing with open-source frameworks.